WO2023062170A2

WO2023062170A2 - Adjuvants

Info

Publication number: WO2023062170A2
Application number: PCT/EP2022/078592
Authority: WO
Inventors: Francesco Doro; Donatello Laera; Malte Meppen; Arianna RAPONI
Original assignee: Glaxosmithkline Biologicals Sa
Priority date: 2021-10-15
Filing date: 2022-10-13
Publication date: 2023-04-20
Also published as: WO2023062170A3

Abstract

The present invention relates inter alia to particles comprising aluminium hydroxide and (a) a stabilising excipient selected from the list consisting of: octoxynol-9, polysorbate 20, polysorbate 80, sucrose, mannose, polyvinylpyrrolidone and glycine; and/or (b) histidine.

Description

Adjuvants

TECHNICAL FIELD

The present invention relates to methods of making compositions comprising aluminium hydroxide particles and related concepts.

BACKGROUND ART

Many vaccines require an adjuvant to induce a strong immune response. Aluminium- containing adjuvants include aluminium hydroxide and aluminium phosphate. Aluminium hydroxide is composed of small primary fibers with an average calculated dimension of 4.5 x 2.2 x 10 nm, whereas the primary particles of aluminium phosphate adjuvant are around 50 nm. In an aqueous solution, however, the size of the particles of both aluminium hydroxide and aluminium phosphate become 1 to 20 urn as a result of aggregation. Particles of a size less than 1um may be referred to as ‘nanoparticles’. Agitation of these solutions can reduce the size of the particles, but these particles quickly reaggregate over a matter of hours (Orr et al. 2019).

It is clear that the size of particulate vaccine carriers significantly affects their adjuvant activities, and there are data showing that particulate vaccine carriers of around 200 nm (or less) may be optimal. Fifis et al. 2004 reported that ovalbumin (OVA)-conjugated polystyrene particles of 230 nm induced stronger OVA-specific antibody and cellular immune responses than other larger OVA-conjugated polystyrene particles after being intradermally injected into mice. Li et al. 2011 reported that small solid lipid nanoparticles of 200 nm have a more potent adjuvant activity than larger solid lipid nanoparticles of 700 nm, when OVA as an antigen is surface-conjugated on them. Li et al. 2013 reported the synthesis of aluminium hydroxide ‘nanoparticles’ with a mean diameter of 112 nm and compared their adjuvant activity with that of the traditional aluminium hydroxide suspension with a mean diameter of 9.3 urn. It was found that protein antigens adsorbed on aluminium hydroxide nanoparticles induced a stronger antigen-specific antibody response than the same protein antigens adsorbed on the traditional aluminium hydroxide microparticles of around 9.3 urn. It was also found that local inflammation induced by aluminium hydroxide nanoparticles in the injection sites was milder than that induced by microparticles.

Orr et al. 2019 disclose formulations comprising aluminium oxyhydroxide nanoparticles and poly(acrylic acid) (PAA). Orr et al 2019 states that PAA may negatively impact antigen adsorption. Reducing the particle size of aluminium hydroxide particles and maintaining this reduced size during storage, using vaccine-compatible excipients, therefore represents a desirable objective. Additionally, from a regulatory perspective, clinical aluminium-based microparticles are not capable of being terminally sterilised by filtration through micron-sized filters (e.g. 0.8 urn, 0.45 urn or 0.22 urn), and are only sterilisable by radiation or autoclave; making their manufacture not amenable to a terminal sterilisation step when combined with antigens or other adjuvants.

There exists a need to provide aluminium-based nanoparticles that display reduced aggregation, using excipients which are suitable and convenient for inclusion in vaccine compositions.

SUMMARY OF THE INVENTION

In one aspect there are provided particles comprising aluminium hydroxide and

(a) a stabilising excipient selected from the list consisting of: octoxynol-9, polysorbate 20, polysorbate 80, sucrose, mannose, polyvinylpyrrolidone and glycine and/or

(b) histidine.

In a further aspect there is provided an aqueous composition comprising particles, wherein the particles comprise aluminium hydroxide and the aqueous composition also comprises

(b) histidine.

In a further aspect there is provided the use of

(a) a stabilising excipient selected from the list consisting of: octoxynol-9, polysorbate 20, polysorbate 80, sucrose, mannose, polyvinylpyrrolidone and glycine; and/or

(b) histidine for maintaining or reducing the size of aluminium hydroxide particles in an aqueous composition.

In a further aspect there is provided a method of maintaining or reducing the size of aluminium hydroxide particles in an aqueous composition comprising the step of adding to the aqueous composition

(a) a stabilising excipient selected from the list consisting of: octoxynol-9, polysorbate 20, polysorbate 80, sucrose, mannose, polyvinylpyrrolidone and glycine and/or (b) histidine.

Further aspects of the invention will be evident from the detailed description below.

BRIEF DESCRIPTION OF THE FIGURES

Fig. 1. Particle size distribution (PSD) of aluminium hydroxide particles after 10 minute sonication cycles using polysorbate 20 as stabilising excipient (Example 1).

Fig. 2. PSD of aluminium hydroxide particles after 6 sonication cycles over 147 days. Half the samples underwent mild centrifugation after the final sonication cycle. Polysorbate 20 was used as a stabilising excipient (Example 2).

Fig. 3. Polysorbate 20 or octoxynol-9 used as stabilising excipients. (A) Samples underwent 7 cycles of sonication with the final cycle completed with centrifugation. PSD was measured after each round. (B) The PSD was measured for 58 days postcentrifugation (Example 2).

Fig. 4. SDS-PAGE images depicting the proportion of antigen (A= ClfA, B= SpA, C= Hla) adsorbed to aluminium salt particles after preparation as described in Table 4 (Example 5). ‘Gr’ indicates group, ‘TCA’ is tri-chloro acetic acid (used for precipitation of antigen) and ‘PD’ is pellet desorbed.

Fig. 5. PSD of aluminium hydroxide particles after homogenisation using I KA T25 digital (Example 7).

Fig. 6. PSD of aluminium hydroxide particles after homogenisation using a larger homogeniser (Example 7).

Fig. 7. PSD of aluminium hydroxide particles after filtration over 56 days (Example 8).

Fig. 8. PSD of aluminium hydroxide particles after sonication, centrifugation and optional addition of PVP (Example 6).

Fig. 9 Short term impact of sonication volume on PSD (Example 9).

Fig. 10 Long term impact of sonication volume on PSD (Example 9).

Fig. 11 Impact of antigen concentration on PSD (Example 10).

Fig. 12 Impact on PSD of varying the order of addition of formulation components (Example 11).

Fig. 13 Effect of nanoalum or traditional aluminium hydroxide particles formulated with HlaCP5 antigen on total anti-Hla IgG induced following one or two immunisations (Example 13).

Fig. 14 Effect of nanoalum or traditional aluminium hydroxide particles formulated with HlaCP5 antigen on total anti-CP5 IgG induced following one or two immunisations (Example 13). Fig. 15 Effect of nanoalum or traditional aluminium hydroxide particles formulated with HlaCP5 antigen on Hla antigen-specific CD4+ T cells induced following two immunisations (Example 13).

Fig. 16 Effect of nanoalum or traditional aluminium hydroxide particles formulated with HlaCP5 antigen on Hla antigen-specific CD8+ T cells induced following two immunisations (Example 13).

BRIEF DESCRIPTION OF THE SEQUENCES

SEQ ID NO: 1 Polypeptide sequence of SpA antigen

SEQ ID NO: 2 Polypeptide sequence of Hla antigen

SEQ ID NO: 3 Polypeptide sequence of ClfA antigen

SEQ ID NO: 4 Polypeptide sequence of chicken ovalbumin protein

DETAILED DESCRIPTION OF THE INVENTION

Stabilising Excipients

The particles, compositions, methods and uses of the invention suitably incorporate a stabilising excipient selected from the list consisting of: octoxynol-9, polysorbate 20, polysorbate 80, sucrose, mannose, polyvinylpyrrolidone and glycine. More suitably, the stabilising excipient is selected from the list consisting of: octoxynol-9, polysorbate 20 and polysorbate 80, most suitably polysorbate 20.

Alternatively, the stabilising excipient is selected from the list consisting of: octoxynol-9, polysorbate 20, sucrose, mannose, polyvinylpyrrolidone and glycine. Alternatively, the stabilising excipient is selected from the list consisting of: mannose, polyvinylpyrrolidone and glycine. More suitably the stabilising excipient is selected from the list consisting of: octoxynol- 9, polysorbate 20 and glycine.

In one embodiment the stabilising excipient is octoxynol-9. In one embodiment the stabilising excipient is polysorbate 20. In one embodiment the stabilising excipient is polysorbate 80. In one embodiment the stabilising excipient is sucrose. In one embodiment the stabilising excipient is mannose. In one embodiment the stabilising excipient is polyvinylpyrrolidone. In one embodiment the stabilising excipient is glycine. The stabilising excipient serves to maintain the size of aluminium hydroxide particles when present in aqueous solution, i.e. prevent or reduce aggregation of aluminium hydroxide particles, thus forming larger particles.

The stabilising excipient also serves to reduce the size of aluminium hydroxide particles when present in aqueous solution, i.e. break down aggregated aluminium hydroxide particles into smaller particles. The stabilising excipient is particularly effective in this context when the stabilising excipient is mixed in the aqueous solution with the aluminium hydroxide particles, more particularly when mixed using a high energy source. The stabilising excipient can be added to the aqueous composition comprising aluminium hydroxide particles either before mixing, or after mixing. If the stabilising excipient has not been added to the aqueous composition at the time of mixing the composition, then ideally the stabilising excipient should be added shortly thereafter to minimise the time period of which the particles can re-aggregate.

Suitably the stabilising excipient is associated with the aluminium hydroxide particles.

Aluminium Hydroxide

‘Aluminium hydroxide’ as used herein includes both hydroxides and oxyhydroxides (e.g. see chapters 8 & 9 of Vaccine Design (1995) eds. Powell & Newman. ISBN: 030644867X.

Plenum). Mixtures of aluminium hydroxide and oxyhydroxides may be used, although it is preferred to use essentially AI(OH)₃. The aluminium hydroxide can take any suitable form (e.g. gel, crystalline, amorphous, etc.). Suitably the aluminium hydroxide is in powder form.

Suitably the aluminium hydroxide is selected from AI(OH)₃, AIO(OH), or a mixture thereof. More suitably the aluminium hydroxide consists essentially of, or more suitably consists of, AI(OH)₃.

Aluminium Hydroxide Particles

Aluminium hydroxide particles in aqueous solution are formed from aggregates of individual aluminium hydroxide particles (‘primary’ particles). During storage, particularly when such aqueous solutions are static, the aluminium hydroxide particles can increase in size (i.e. aggregates bind together and/or bind with further primary particles). The size of aluminium hydroxide particles can be reduced by agitating the solution, such as by mixing the solution. The stabilising excipient serves to reduce and/or maintain the size of the aluminium hydroxide particles in aqueous solution. In some embodiments the aggregation of the aluminium hydroxide particles is reduced by at least 5%, at least 10%, at least 20%, at least 25%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 75%, at least 80%, at least 90%, or even blocks the aggregation of the aluminium hydroxide by nearly 100% as compared to aluminium hydroxide particles formed and/or stored according to the prior art.

In certain embodiments of the compositions or uses of the invention, the concentration of the aluminium hydroxide is at least 1mg/ml. In some embodiments, the concentration of the aluminium hydroxide is at least 3mg/ml. In some embodiments, the concentration of the aluminium hydroxide is at least 4mg/ml. In some embodiments, the concentration of the aluminium hydroxide is at least 5mg/ml. In some embodiments, the concentration of the aluminium hydroxide is 0.5 to 10mg/ml, 1 to 9mg/ml, 2 to 7mg/ml; 3 to 6mg/ml; 4 to 5.5mg/ml; or 4.5 to 5.5mg/ml, such as about 5mg/ml.

In certain embodiments of the compositions or uses of the invention, the concentration of the aluminium hydroxide is no more than 5mg/ml, such as no more than 4mg/ml, such as no more than 3mg/ml, such as no more than 2mg/ml, such as no more than 1.5mg/ml, such as no more than 1mg/ml, such as no more than 0.9mg/ml, such as no more than 0.8mg/ml, such as no more than 0.7mg/ml, such as no more than 0.6mg/ml, such as no more than 0.5mg/ml, such as no more than 0.4mg/ml, such as no more than 0.3mg/ml, such as no more than 0.2mg/ml, such as no more than 0.1mg/ml.

In certain embodiments of the particles, compositions or uses of the invention, the size of the aluminium hydroxide particles is from about 50nm to 75nm. In some embodiments the size of the aluminium hydroxide particles is from about 50nm to 100nm. In some embodiments the size of the aluminium hydroxide particles is from about 50nm to 150nm. In some embodiments the size of the aluminium hydroxide particles is from about 50nm to 200nm. In some embodiments the size of the aluminium hydroxide particles is from about 50nm to 300nm. In some embodiments the size of the aluminium hydroxide particles is from about 50nm to 400nm. In some embodiments the size of the aluminium hydroxide particles is from about 50nm to 450nm. In some embodiments the size of the aluminium hydroxide particles is from about 20nm to 100nm. In some embodiments the size of the aluminium hydroxide particles is from about 20nm to 50nm. In some embodiments the size of the aluminium hydroxide particles is from about 10nm to 200nm. In some embodiments the size of the aluminium hydroxide particles is from about 10nm to 100nm. In some embodiments the size of the aluminium hydroxide particles is from about 10nm to 50nm. In certain embodiments of the particles, compositions or uses of the invention, the size of the aluminium hydroxide particles is about 1nm, is about 5nm, is about 10nm, is about 15nm, is about 20nm, is about 25nm, is about 30nm, is about 35nm, is about 40nm, is about 45nm, is about 50nm, is about 55nm, is about 60nm, is about 65nm, is about 70nm, is about 75nm, is about 80nm, is about 85nm, is about 90nm, is about 95nm, is about 100nm, is about 105nm, is about 110nm, is about 115nm, is about 120nm, is about 125nm, is about 130nm, is about 135nm, is about 140nm, is about 145nm, is about 150nm, is about 155nm, is about 160nm, is about 165nm, is about 170nm, is about 175nm, is about 180nm, is about 185nm, is about 190nm, is about 195nm, is about 200nm, is about 210nm, is about 220nm, is about 240 nm, is about 250nm, is about 260nm, is about 280nm, is about 200nm, is about 300nm, is about 320nm, is about 340nm, is about 350nm, is about 360nm, is about 380nm, is about 400nm, is about 420nm, is about 440nm, or is about 450nm.

Most suitably the sizes of the aluminium hydroxide particles are no greater than about 250nm, particularly no greater than 250nm.

An average particle size can be measured. Accordingly, in certain embodiments of the particles, compositions and uses of the invention, the average size of the aluminium hydroxide particles is about 1nm- 450nm. In some embodiments the average size of the aluminium hydroxide particles ranges from about 50nm to 75nm. In some embodiments the average size of the aluminium hydroxide particles ranges from about 50nm to 100nm. In some embodiments the average size of the aluminium hydroxide particles ranges from about 50nm to 150nm. In some embodiments the average size of the aluminium hydroxide particles ranges from about 50nm to 200nm. In some embodiments the average size of the aluminium hydroxide particles ranges from about 50nm to 300nm. In some embodiments the average size of the aluminium hydroxide particles ranges from about 50nm to 400nm. In some embodiments the average size of the aluminium hydroxide particles ranges from about 50nm to 450nm. In some embodiments the average size of the aluminium hydroxide particles ranges from about 20nm to 100nm. In some embodiments the average size of the aluminium hydroxide particles ranges from about 20nm to 50nm. In some embodiments the average size of the aluminium hydroxide particles ranges from about 10nm to 200nm. In some embodiments the average size of the aluminium hydroxide particles ranges from about 10nm to 100nm. In some embodiments the average size of the aluminium hydroxide particles ranges from about 10nm to 50nm. In some embodiments the average size of the aluminium hydroxide particles is about 1nm, is about 5nm, is about 10nm, is about 15nm, is about 20nm, is about 25nm, is about 30nm, is about 35nm, is about 40nm, is about 45nm, is about 50nm, is about 55nm, is about 60nm, is about 65nm, is about 70nm, is about 75nm, is about 80nm, is about 85nm, is about 90nm, is about 95nm, is about 100nm, is about 105nm, is about 110nm, is about 115nm, is about 120nm, is about 125nm, is about 130nm, is about 135nm, is about 140nm, is about 145nm, is about 150nm, is about 155nm, is about 160nm, is about 165nm, is about 170nm, is about 175nm, is about 180nm, is about 185nm, is about 190nm, is about 195nm, is about 200nm, is about 210nm, is about 220nm, is about 240nm,is about 250nm , is about 260nm, is about 280nm, is about 200nm,is about 300nm, is about 320nm, is about 340nm, is about 350nm, is about 360nm, is about 380nm,is about 400nm, is about 420nm, is about 440nm, or is about 450nm.

In certain embodiments of the particles, compositions and uses of the invention, the average size of the aluminium hydroxide particles is about 1nm, no greater than about 5nm, no greater than about 10nm, no greater than about 15nm, no greater than about 20nm, no greater than about 25nm, no greater than about 30nm, no greater than about 35nm, no greater than about 40nm, no greater than about 45nm, no greater than about 50nm, no greater than about 55nm, no greater than about 60nm, no greater than about 65nm, no greater than about 70nm, no greater than about 75nm, no greater than about 80nm, no greater than about 85nm, no greater than about 90nm, no greater than about 95nm, no greater than about 100nm, no greater than about 105nm, no greater than about 110nm, no greater than about 115nm, no greater than about 120nm, no greater than about 125nm, no greater than about 130nm, no greater than about 135nm, no greater than about 140nm, no greater than about 145nm, no greater than about 150nm, no greater than about 155nm, no greater than about 160nm, no greater than about 165nm, no greater than about 170nm, no greater than about 175nm, no greater than about 180nm, no greater than about 185nm, no greater than about 190nm, no greater than about 195nm, no greater than about 199nm, no greater than about 210nm, no greater than about 230nm, no greater than about 250nm, no greater than about 270nm, no greater than about 290nm, no greater than about 310nm, no greater than about 330nm, no greater than about 350nm, no greater than about 370nm, no greater than about 390nm, no greater than about 410nm, no greater than about 430nm, no greater than about 440nm, or no greater than about 449nm.

In some embodiments of the methods of the invention, the size of the aluminium hydroxide particles is reduced. In particular, the size of the aluminium hydroxide particles is reduced by at least 5%, such as at least 10%, such as at least 15%, such as at least 20%, such as at least 25%, such as at least 30%, such as at least 35%, such as at least 40%, such as at least 45%, such as at least 50%, such as at least 55%, such as at least 60%, such as at least 65%, such as at least 70%, such as at least 75%, such as at least 80%, such as at least 80%, such as at least 85%, such as at least 90%, such as at least 95%, such as at least 99%. In some embodiments, the aluminium hydroxide particles are capable of being filtered through at least a 0.45 micron filter. In some embodiments, the aluminium hydroxide particles are capable of being filtered through a 0.45 micron or smaller pore size filter. In some embodiments, the aluminium hydroxide particles are capable of being filtered through a 0.45 micron filter. In some embodiments, the aluminium hydroxide particles are capable of being filtered through at least a 0.22 micron filter. In some embodiments, the aluminium hydroxide particles are capable of being filtered through a 0.22 micron or smaller pore size filter. In some embodiments, the aluminium hydroxide particles are capable of being filtered through a 0.22 micron filter. In some embodiments, the aluminium hydroxide particles are capable of being filtered through at least a 0.08 micron filter. In some embodiments, the aluminium hydroxide particles are capable of being filtered through a 0.08 micron or smaller pore size filter. In some embodiments, the aluminium hydroxide particles are capable of being filtered through a 0.08 micron filter.

Suitably the aluminium hydroxide particles are capable of being filtered through a 0.45 micron filter, followed by a 0.22 micron filter, followed by a 0.08 micron filter.

The methods of the invention maintain or reduce the size of aluminium hydroxide particles in aqueous solution. As such, the aluminium hydroxide particles have a ‘starting’ size, wherein the starting size is before exposure to stabilising excipient and the final size is after exposure to stabilising excipient. Similarly, the methods of the invention may impact the concentration of aluminium hydroxide particles present in the aqueous solution (for example, if centrifugation and removal of the resultant aluminium hydroxide pellet is performed). Suitable final sizes and concentrations include those stated above in respect of the particles, compositions and uses of the invention. Suitable ‘starting’ sizes and concentrations in respect of the methods of the invention are as follows.

In certain embodiments of the methods of the invention, the size of the aluminium hydroxide particles before agitation and/or before addition of stabilising excipient is about 1 urn. In some embodiments, the size of the aluminium hydroxide is 0.5 to 5 urn; 0.5 to 4 urn; 0.5 to 3 urn; 0.5 to 2 urn; or 0.5 to 1 urn.

In certain embodiments of the methods of the invention, the starting concentration of the aluminium hydroxide is at least 10mg/ml. In some embodiments, the starting concentration of the aluminium hydroxide is at least 4mg/ml. In some embodiments, the starting concentration of the aluminium hydroxide is at least 2mg/ml. In some embodiments, the starting concentration of the aluminium hydroxide is 0.5 to 10mg/ml, 1 to 10mg/ml, 0.5 to 5mg/ml; 1 to 5mg/ml; 0.5 to 4mg/ml; 0.5 to 3mg/ml; or 0.5 to 2mg/ml.

In certain embodiments of the methods of the invention, the starting size of the aluminium hydroxide particles is 250 nm or greater, such as 300 nm or greater, such as 350 nm or greater, such as 500 nm or greater, such as 800 nm or greater.

In certain embodiments of the methods of the invention, the starting size of the aluminium hydroxide particles is about 1 urn. In some embodiments, the starting size of the aluminium hydroxide is 0.5 to 5 urn; 0.5 to 4 urn; 0.5 to 3 urn; 0.5 to 2 urn; or 0.5 to 1 urn.

In certain embodiments of the methods of the invention, the average starting size of the aluminium hydroxide particles is 0.5 to 5 urn; 0.5 to 4 urn; 0.5 to 3 urn; 0.5 to 2 urn; or 0.5 to 1 urn.

Uniformity of particle sizes is desirable. A polydispersity index (Pdl) of greater than 0.7 indicates that the sample has a very broad size distribution and a reported value of 0 means that size variation is absent, although values smaller than 0.05 are rarely seen. Suitably the aluminium hydroxide particles have a polydispersity of 0.5 or less, especially 0.3 or less, such as 0.2 or less.

The particle size, as used herein, means the average diameter of particles (optionally in an aqueous composition) and can be determined in various ways e.g. using the techniques of dynamic light scattering and/or single-particle optical sensing, using an apparatus such as the Accusizer™ and Nicomp™ series of instruments available from Particle Sizing Systems (Santa Barbara, USA), the Zetasizer™ instruments from Malvern Instruments (UK), or the Particle Size Distribution Analyzer instruments from Horiba (Kyoto, Japan). See Light Scattering from Polymer Solutions and Nanoparticle Dispersions Schartl, 2007. Dynamic light scattering (DLS) is the preferred method by which size is determined. The preferred method for defining the average particle diameter is a Z-average i.e. the intensity-weighted mean hydrodynamic size of the ensemble collection of particles measured by DLS. The Z-average is derived from cumulants analysis of the measured correlation curve, wherein a single particle size (diameter) is assumed and a single exponential fit is applied to the autocorrelation function. Thus, references herein to average particle size should be taken as an intensity-weighted average, and ideally the Z-average. Pdl values are easily provided by the same instrumentation which measures average diameter. Unless otherwise stated, the sizes described herein refer to the Z-average. Suitably the size of aluminium hydroxide particles is measured before antigen is adsorbed to the particles.

Suitably the particle comprises AI(OH)s and/or AIO(OH). More suitably the particle consists essentially of, or more suitably consists of, AI(OH)s.

The zeta potential (ZP) of the aluminium hydroxide particles may be measured. Suitably the aluminium hydroxide particles have a ZP of 20 to 100 mV, such as 30 to 90 mV, such as 40 to 80 mV, such as 50 to 70 mV, such as about 60 mV.

As used herein, ‘nanoalum’ refers to aluminium hydroxide particles having a Z-average diameter in the nm range, that is to say aluminium hydroxide particles having a Z-average diameter of less than 1 urn. As used herein ‘traditional’ refers to aluminium hydroxide particles having a Z-average diameter in the urn range, that is to say aluminium hydroxide particles having a Z-average diameter of more than 1 urn.

Aqueous Compositions Comprising Aluminium Hydroxide

A pharmaceutically acceptable osmolality will generally mean that solutions will have an osmolality which is approximately isotonic or mildly hypertonic. Suitably the compositions of the present invention when reconstituted will have an osmolality in the range of 150 to 750 mOsm/kg, for example, the osmolality may be in the range of 200 to 400 mOsm/kg, such as in the range of 240 to 360 mOsm/kg. Osmolality may be measured according to techniques known in the art, such as by the use of a commercially available osmometer, for example the AdvancedTM Model 2020 available from Advanced Instruments Inc. (USA).

Suitably the method of the invention comprises the additional step of adjusting the osmolarity of the composition to the ranges quoted above, such as 240 to 360 mOsm/kg.

In the composition of the invention, suitably the aluminium hydroxide particles will be present such that the concentration of Al³⁺ is at least 1 pg/ml (e.g. at least 10 pg/ml, at least 100 pg/ml, at least 200 pg/ml etc.). In the methods of the invention, suitably the aluminium hydroxide particles will be present such that the starting concentration of Al³⁺ is at least 0.1 mg/ml (e.g. at least 0.3mg/ml, at least 1 mg/ml, or at least 1.5 mg/ml). Suitably the compositions of the invention have a pH of 4 to 7, such as 5 to 6.5, more suitably 5.5 to 6. Similarly, the final pH of the composition according to the methods of the invention has a pH of 4 to 7, such as 5 to 6.5, more suitably 5.5 to 6. Suitably the methods of the invention comprise the additional step of adjusting the pH of the composition to the ranges quoted above, such as about 5 to 6.5.

Suitably the stabilising excipient is present at 0.01 to 5% w/v, more suitably 0.05 to 3% w/v, more suitably 0.08 to 1% w/v, most suitably about 0.1% w/v.

Suitably the stabilising excipient is present at 0.01 to 5% w/w, more suitably 0.05 to 3% w/w, more suitably 0.08 to 1% w/w, most suitably about 0.1% w/w.

Suitably the stabilising excipient is added to the aqueous composition while the composition is undergoing agitation, such as high shear mixing.

It has been found that optimal aluminium hydroxide particles sizes may be achieved by adding formulation components in particular orders. In one embodiment, if added to the formulation, the sucrose is added as the last component in the formulation. In a further embodiment, if added to the formulation, the sucrose and/or buffer are added after aluminium hydroxide particles and detergent. In one embodiment, if all of (1) aluminium salt particles, (2) polysorbate 20, (3) water for injection, (4) antigen, (5) buffer and (6) sucrose are included in a formulation, these components are added in this order.

Agitation of Solutions

Agitation of the aqueous composition may suitably be achieved by stirring or shaking, or more suitably by using a method which utilises a high energy source, such as high shear mixing. Suitable methods of high shear mixing include extrusion, sonication, microfluidisation, or homogenisation. Particularly suitable methods of high shear mixing are sonication and homogenisation, most suitably sonication. Suitably, stirring, such as by using a magnetic stirrer, is applied simultaneously.

In some embodiments, high shear mixing (in particular sonication) is performed at no less than 500, 1000, 2000, 5000, or 10,000 rpm.

In some embodiments, high shear mixing (in particular sonication) is performed at a power level of at least 50 watts, such as at least 100 watts, such as at least 130 watts. In some embodiments the high energy source (in particular a homogeniser) provides at least 5000 PSI, at least 10,000 PSI, at least 15,000 PSI at least 20,000 PSI, at least 25,000 PSI, at least 30,000 PSI, at least 35,000 PSI, at least 40,000 PSI, at least 45,000 PSI, or at least 50,000 PSI. In some embodiments the high energy source provides about 5000 to 50000; 5000 to 10000; 5000 to 15000; 5000 to 20000; 5000 to 25000; 5000 to 30000; 5000 to 35000; 5000 to 40000; 5000 to 45000; or 5000 to 50000 PSI. In some embodiments the high energy source (in particular a homogeniser) provides about 45000 to 50000; 40000 to 50000; 35000 to 50000; 30000 to 50000; 25000 to 50000; 20000 to 50000; 15000 to 50000; 10000 to 50000; or 5000 to 50000 PSI. In some embodiments the high energy source provides about 25000 to 35000; 25000 to 30000; or 30000 to 35000 PSI.

In some embodiments, the high shear mixing is performed for 1 minute or longer, such as 2 minutes or longer, such as 5 minutes or longer, such as 10 minutes or longer.

In some embodiments the composition is subjected to at least 1 , 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 50, or 100 passes of high shear mixing. In some embodiments the composition is subjected to 1-5, 6-10, 11-15, 16- 20, 21-30, 31-40, 41-50, 51-60, 61-70, 71-80, 81-90, or 91- 100 passes of high shear mixing. In some embodiments the composition is subjected to 3, 6, or 10 passes of high shear mixing. Most suitably the composition is subjected to at least 1 , such as at least 2, such as at least 3, such as at least 4, such as at least 5, such as at least 6, such as at least 7, such as at least 8 passes of high shear mixing.

Suitably the intervals between passes of high shear mixing are 10 seconds to 10 minutes, such as 30 seconds to 5 minutes, such as 45 seconds to 7 minutes, such as 1 to 3 minutes, such as 1 minute 30 seconds to 2 minutes 30 seconds, such as about 2 minutes.

Centrifugation can be used to remove larger particles from an aqueous composition, by removing the resultant pellet and retaining the supernatant. Accordingly, in some embodiments, the composition undergoes centrifugation. Suitably centrifugation is performed for 1 to 10 minutes, such as 3 to 7 minutes, such as about 5 minutes, at 10 to 100 g, such as 25 to 75 g, such as about 45g. Suitably centrifugation is performed multiple times. More suitably centrifugation is performed at least once after all passes of agitation have been completed. Most suitably, centrifugation is performed only once, after all passes of agitation have been completed. In some embodiments, the method is performed at 0 °C, at 4 °C, at 25 °C, at 30 °C, at 50 °C, or at 60 °C. In some embodiments, the method is performed at 0-4, 5-10, 11-15, 16-20, 21-25, 26-30, 31-35, 36-40, 41-45, 46-50, 51-55, or 56-60 °C.

In one embodiment there is provided a method of maintaining or reducing the size of aluminium hydroxide particles in an aqueous composition comprising the step of adding to the aqueous composition a stabilising excipient selected from the list consisting of: octoxynol-9, polysorbate 20, polysorbate 80, sucrose, mannose, polyvinylpyrrolidone and glycine. Alternatively, provided herein is a method of maintaining or reducing the size of aluminium hydroxide particles in an aqueous composition comprising the step of adding to the aqueous composition a stabilising excipient selected from the list consisting of: mannose, polyvinylpyrrolidone and glycine. Suitably, the aluminium hydroxide (most suitably aluminium hydroxide powder) is added to the aqueous composition after the stabilising excipient is added to the aqueous composition. Suitably the aluminium hydroxide (suitably aluminium hydroxide powder) is added to the aqueous composition while the composition is simultaneously agitated.

It has been found that optimal results may be achieved by continuously agitating the solution (such as by using sonication) throughout the process of adding excipient, aluminium hydroxide (such as aluminium hydroxide powder) and optionally buffer, to water.

Suitably the volume of aqueous composition which undergoes agitation has a volume of 1 to 100 ml, such as 10 to 75ml, such as about 50ml.

Suitably the volume of aqueous composition which undergoes agitation has a volume of 10ml or lower, such as 25ml or lower, such as 50ml or lower, such as 75ml or lower, such as 100ml or lower, such as 150ml or lower, such as 200ml or lower.

Aluminium Hydroxide Particle Stability

In some embodiments provided herein, the size of the aluminium hydroxide particles is stable, in that the aluminium hydroxide particles’ size is maintained, and in that the aluminium hydroxide particles exhibit reduced aggregation, or no aggregation, when compared to aluminium hydroxide particles in the absence of a stabilising excipient.

“Stable” refers to a composition comprising aluminium hydroxide particles which do not aggregate, displays little to no aggregation, or reduced aggregation and or demonstrate little to no overall increase in average particle size or polydispersity of the formulation over time compared to the starting particle size (i.e. the size of the particles before addition of stabilising excipient).

The stability of the aluminium hydroxide particles can be measured by techniques familiar to those of skill in the art. In some embodiments, the stability is observed visually. Visual inspection can include inspection for particulates, flocculence, cloudiness or aggregates. In some embodiments, the stability is determined by the size of the aluminium hydroxide particles, suitably measured according to the particle size measurement methods described above. For example, the size can be assessed by known techniques in the art, including but not limited to, x-ray and laser diffraction, dynamic light scattering (DLS) or CryoEM. In some embodiments, the size of the aluminium hydroxide particles refers to the Z-average diameter, suitably established using DLS such as using a Malvern Zetasizer.

In some embodiments, stability is assessed by the ability of the aluminium hydroxide particles to pass through a filter of a particular size, for example through a 0.8 urn, or 0.22 urn or 0.45 urn filter. In some embodiments, stability is determined by measurement of the polydispersity index (Pdl), for example with the use of the dynamic light scattering (DLS) technique.

In some embodiments, the Z-average diameter of the nanoparticle increases less than 50%, less than 40%, less than 30%, less than 25%, less than 20%, less than 15%, less than 12%, less than 10%, less than 7%, less than 5%, less than 3%, less than 1% over the time period assayed.

In some embodiments, the polydispersity index (Pdl) of the nanoparticle increases less than 50%, less than 40%, less than 30%, less than 25%, less than 20%, less than 15%, less than 12%, less than 10%, less than 7%, less than 5%, less than 3%, less than 1% over time period assayed. Suitable time periods assayed are, for example at least 5 minutes, for at least 10 minutes, for at least 15 minutes, for at least 20 minutes, for at least 25 minutes, for at least 30 minutes, for at least 35 minutes, for at least 40 minutes, for at least 45 minutes, for at least 50 minutes, for at least 55 minutes, for at least 1 hour, for at least 2 hours, for at least 6 hours, for at least 12 hours, for at least 18 hours, for at least 24 hours, for at least 48 hours, for at least 72 hours, for at least 1 week, for at least 2 weeks, for at least 3 weeks, for at least 1 month, for at least 2 months, for at least 3 months, for at least 4 months, for at least 5 months, for at least 6 months, for at least 7 months, for at least 8 months, for at least 9 months, for at least 10 months, for at least 11 months, for at least 1 year, for at least 2 years, or for at least 5 years. In some embodiments, the aluminium hydroxide particles are stable at below 20 °C, such as below 15 °C, such as below 10, such as below 8 °C, such as 2 to 8 °C.

In some embodiments, the aluminium hydroxide particles are stable at below 20 °C, such as below 15 °C, such as below 10, such as below 8 °C, such as 2 to 8 °C for at least 1 minute, for at least 5 minutes, for at least 10 minutes, for at least 15 minutes, for at least 20 minutes, for at least 25 minutes, for at least 30 minutes, for at least 35 minutes, for at least 40 minutes, for at least 45 minutes, for at least 50 minutes, for at least 55 minutes, for at least 1 hour, for at least

2 hours, for at least 6 hours, for at least 12 hours, for at least 18 hours, for at least 24 hours, for at least 48 hours, for at least 72 hours, for at least 1 week, for at least 2 weeks, for at least

3 weeks, for at least 1 month, for at least 2 months, for at least 3 months, for at least 4 months, for at least 5 months, for at least 6 months, for at least 7 months, for at least 8 months, for at least 9 months, for at least 10 months, for at least 11 months, for at least 1 year, for at least 2 years, or for at least 5 years.

Most suitably, the aluminium hydroxide particles are stable at 2 to 8 °C for at least 200 days, such as at least 100 days, such as at least 76 days, such as at least 48 days, such as at least 35 days, such as at least 28 days, such as at least 14 days, such as at least 7 days.

In some embodiments, a stable composition is a composition of the invention wherein the aluminium hydroxide particles do not exceed 250 nm after storage for at least 2 months, as measured by Z-average diameter using, for example, DLS. More suitably wherein the aluminium hydroxide particles do not exceed 250 nm after storage for at least 1 month, as measured by Z-average diameter using, for example, DLS. Alternatively wherein the aluminium hydroxide particles do not exceed 200 nm after storage for at least 2 months, as measured by Z-average diameter using, for example, DLS.

In some embodiments, the compositions are suitable for filtering prior to vialing. The filter is suitably of a pore size such that the compositions are sterilised by filtering. In some embodiments, the composition is capable of being filtered through a 0.8 micron filter. More suitably, the composition is capable of being filtered through a 0.45 micron filter. More suitably, the composition is capable of being filtered through a 0.22 micron filter.

It has been found that aqueous compositions comprising aluminium hydroxide particles may be subjected to sterilisation by heat, without substantial negative impact on particle size. Accordingly in one embodiment there is provided a method of sterilizing an aqueous composition comprising aluminium hydroxide particles wherein the composition is subjected to a temperature of at least 100°C, such as at least 110°C, such as at least 120°C for a period of time. Suitably the temperature is no more 200°C, such as no more 150°C, such as no more than 120°C. Suitably the period of time is at least 5 minutes, such as at least 10 minutes, such as at least 15 minutes, such as at least 20 minutes. Suitably the period of time is no more than 60 minutes, such as no more than 30 minutes, such as no more than 20 minutes. Suitably the temperature exposure is performed using heating apparatus such as an autoclave.

Histidine Buffer

The particles, compositions, methods and uses of the invention suitably incorporate histidine. As illustrated in the examples, it has been found that histidine can stabilise the particle size of aluminium hydroxide in aqueous solution.

Accordingly, in one embodiment the aqueous compositions described herein further comprise histidine. In another embodiment, there is provided a method of making an aqueous composition as described herein further comprising the step of adding histidine to the composition.

In an alternative embodiment, there is provided an aqueous composition comprising particles, wherein the particles comprise aluminium hydroxide and histidine. In another embodiment, there is provided a method of making an aqueous composition comprising histidine and particles, wherein the particles comprise aluminium hydroxide, comprising the step of adding histidine to an aqueous composition comprising particles wherein the particles comprise aluminium hydroxide. In another embodiment, there is provided a method of making an aqueous composition comprising histidine and particles, wherein the particles comprise aluminium hydroxide, comprising the step of adding particles to an aqueous composition comprising histidine, wherein the particles comprise aluminium hydroxide.

Suitably the histidine is present in the composition at a concentration of 1 to 20 mM, such as 5 to 15 mM, such as about 10 mM. In an alternative embodiment, suitably the histidine is present in the composition at a concentration of 10 to 100 mM, such as 30 to 70 mM, such as 40 to 60 mM, such as about 50 mM. Antigens

In some embodiments an antigen is adsorbed to the aluminium hydroxide particles. Suitably, the antigen is adsorbed to the aluminium hydroxide particles after performing the methods of the invention to reduce and/or maintain the size of aluminium hydroxide particles, including after any agitation, centrifugation and/or filtration steps.

Antigen may be comprised within the composition of the invention, and may be completely, or partially, adsorbed to the aluminium hydroxide particles. Suitably no less than 50% of the antigen is adsorbed to the particles, such as no less than 70%, such as no less than 90%, such as no less than 99%. Suitably the proportion of antigen adsorbed to the particles is determined by gel electrophoresis.

In certain embodiments of the compositions or uses of the invention, the concentration of the antigen is at least 0.05mg/ml, such as at least 0.10mg/ml, such as at least 0.15mg/ml, such as a least 0.20mg/ml, such as at least 0.25mg/ml, such as at least 0.30mg/ml, such as at least 0.35mg/ml, such as at least 0.40mg/ml, such as at least 0.45mg/ml, such as at least

0.50mg/ml, such as at least 0.55mg/ml, such as at least 0.60mg/ml, such as at least

0.65mg/ml, such as at least 0.70mg/ml, such as at least 0.75mg/ml, such as at least

0.80mg/ml, such as at least 0.85mg/ml, such as at least 0.90mg/ml, such as at least 0.95 mg/ml, such as at least 1.00mg/ml.

Suitably the administration of a composition of the invention comprising an antigen, when administered to a subject, stimulates an immune response in the subject, such as primarily a TH1 response, primarily a TH2 response, or both a TH1 and TH2 response. Accordingly, there is provided a method of stimulating an immune response in a subject comprising administering the composition of the invention comprising an antigen to the subject.

It is noted in Orr et al. 2019 that PAA negatively impacted adsorption of antigen to aluminium oxyhydroxide particles. Suitably the presence of the stabilising excipient of the invention does not substantially negatively impact the adsorption of an antigen to the aluminium hydroxide particles. Suitably, when compared to a control composition which does not comprise the stabilising excipient of the invention, adsorption of antigen to the aluminium hydroxide particles in the embodiments of the invention is reduced by no more than 50%, such as no more than 40%, such as no more than 30%, such as no more than 20%, such as no more than 10%, such as no more than 5%, such as no more than 2%, such as no more than 1%. In one embodiment the antigen has an isoelectric point which is similar to the isoelectric point of aluminium hydroxide, e.g. 9 to 11 , such as about 10.

In some embodiments the antigen is a polypeptide encoded by a polynucleotide. In some embodiments the antigen is a DNA polynucleotide. In some embodiments the antigen is an RNA polynucleotide. An antigen may be any target epitope, molecule (including a biomolecule), molecular complex (including molecular complexes that contain biomolecules), subcellular assembly, cell or tissue against which elicitation or enhancement of immunoreactivity in a subject is desired. Frequently, the term antigen will refer to a polypeptide antigen of interest. However, antigen, as used herein, may also refer to a recombinant construct which encodes a polypeptide antigen of interest (e.g., an expression construct). In certain embodiments the antigen may be, or may be derived from, or may be immunologically cross-reactive with, an infectious pathogen and/or an epitope, biomolecule, cell or tissue that is associated with infection, cancer, autoimmune disease, allergy, asthma, or any other condition where stimulation of an antigen-specific immune response would be desirable or beneficial.

Accordingly, certain embodiments contemplate an antigen that is derived from at least one infectious pathogen such as a bacterium, a virus or a fungus.

Suitably the antigens are derived from Staphylococcus spp., more suitably S. aureus and most suitably alpha-hemolysin (Hla), clumping factor A (ClfA) or staphylococcal protein A (SpA).

Suitably the antigens comprise antigen proteins derived from Staphylococcus spp., more suitably S. aureus and most suitably alpha-hemolysin (Hla), clumping factor A (ClfA) or staphylococcal protein A (SpA). Suitably the antigens are antigens comprising alphahemolysin (Hla, SEQ ID NO: 2), clumping factor A (ClfA, SEQ ID NO: 3) and/or staphylococcal protein A (SpA, SEQ ID NO: 1), such as the bioconjugates which additionally comprise the serotype 5 (CP5) or 8 (CP8) capsular polysaccharides, e.g. CP5-Hla and/or CP8-ClfA.

In certain embodiments, the antigen associates with the aluminium hydroxide particles. In some embodiments the antigen binds to the aluminium hydroxide particles. In some embodiments the antigen is adsorbed to the aluminium hydroxide particles. Such binding or adsorption refers to an interaction between molecules or portions thereof that exhibit mutual affinity or binding capacity, typically due to specific or non-specific binding or interaction, including, but not limited to, biochemical, physiological, and/or chemical interactions. In certain embodiments, binding to aluminium hydroxide particles can be determined by UV spectroscopy or gel electrophoresis. In some embodiments, the composition further comprises a pharmaceutically acceptable carrier, excipient or diluent. In some embodiments, the pharmaceutical composition is a vaccine composition.

Further Embodiments

In certain embodiments, the particles, composition, uses or methods of the invention consist essentially of, or more suitably consist of, aluminium hydroxide and

(b) histidine.

Clauses

Clauses setting out further embodiments of the invention are as follows:

1. Particles comprising aluminium hydroxide and

(b) histidine.

2. The particles according to clause 1 , wherein the particles comprise aluminium hydroxide and a stabilising excipient selected from the list consisting of: octoxynol-9, polysorbate 20, polysorbate 80, sucrose, mannose, polyvinylpyrrolidone and glycine.

3. The particles according to clause 1 , wherein the particles comprise aluminium hydroxide and histidine.

4. The particles of clause 1 , wherein the particles comprise

(a) a stabilising excipient selected from the list consisting of: octoxynol-9, polysorbate 20, polysorbate 80, sucrose, mannose, polyvinylpyrrolidone and glycine and

(b) histidine.

5. An aqueous composition comprising particles, wherein the particles comprise aluminium hydroxide and the aqueous composition also comprises

6. The aqueous composition of clause 5, wherein the particles comprise aluminium hydroxide and the aqueous composition comprises a stabilising excipient selected from the list consisting of: octoxynol-9, polysorbate 20, polysorbate 80, sucrose, mannose, polyvinylpyrrolidone and glycine.

7. The aqueous composition of clause 5, wherein the particles comprise aluminium hydroxide and the aqueous composition also comprises histidine.

8. The aqueous composition of clause 5, wherein the particles comprise aluminium hydroxide and the aqueous composition comprises

(b) histidine.

9. Use of

10. The use of a stabilising excipient selected from the list consisting of: octoxynol-9, polysorbate 20, polysorbate 80, sucrose, mannose, polyvinylpyrrolidone and glycine according to clause 9 for maintaining or reducing the size of aluminium hydroxide particles in an aqueous composition.

11. The use of histidine according to clause 10 for maintaining or reducing the size of aluminium hydroxide particles in an aqueous composition.

12. The use of a stabilising excipient or histidine according to any one of clauses 9 to 11 for maintaining the size of aluminium hydroxide particles in an aqueous composition.

13. The use of a stabilising excipient or histidine according to any one of clauses 9 to 11 for reducing the size of aluminium hydroxide particles in an aqueous composition. 14. The particles, composition or use of any one of clauses 1 to 13 wherein one or more antigens are adsorbed to the particles.

15. A method of eliciting an immune response in a subject comprising administering the particles or composition of clause 14 to a subject.

16. A method of enhancing an immune response to an antigen in a subject by administering the particles or composition of clause 14 to a subject.

17. A method of maintaining or reducing the size of aluminium hydroxide particles in an aqueous composition comprising the step of adding to the aqueous composition

(b) histidine.

18. The method of maintaining or reducing the size of aluminium hydroxide particles in an aqueous composition according to clause 17 comprising the step of adding to the aqueous composition a stabilising excipient selected from the list consisting of: octoxynol-9, polysorbate 20, polysorbate 80, sucrose, mannose, polyvinylpyrrolidone and glycine.

19. The method of maintaining or reducing the size of aluminium hydroxide particles in an aqueous composition according to clause 17 comprising the step of adding to the aqueous composition histidine.

20. The method of maintaining or reducing the size of aluminium hydroxide particles in an aqueous composition according to clause 17 comprising the step of adding to the aqueous composition

(b) histidine.

21. The method of maintaining the size of aluminium hydroxide particles in an aqueous composition according to any one of clauses 17 to 20.

22. The method of reducing the size of aluminium hydroxide particles in an aqueous composition according to any one of clauses 17 to 20. 23. The method of any one of clauses 17 to 22 further comprising the step of adsorbing one or more antigens to the particles.

24. An aqueous composition obtainable by any one of the methods of clauses 17 to 23.

25. The particles, composition, use or method according to any one of clauses 1 to 24 wherein the stabilising excipient is selected from octoxynol-9, polysorbate 20 and polysorbate 80.

26. The particles, composition, use or method according to any one of clauses 1 to 24 wherein the stabilising excipient is selected from octoxynol-9, polysorbate 20, sucrose, mannose, polyvinylpyrrolidone and glycine.

27. The particles, composition, use or method according to clause 26 wherein the stabilising excipient is selected from octoxynol-9, polysorbate 20 and glycine.

28. The particles, composition, use or method according to clause 26 wherein the stabilising excipient is selected from mannose, polyvinylpyrrolidone and glycine.

29. The particles, composition, use or method according to clause 27 wherein the stabilising excipient is polysorbate 20.

30. The composition, use or method according to any one of clauses 5 to 29 wherein the stabilising excipient is present at 0.01 to 5% w/v.

31 . The composition, use or method according to clause 30 wherein the stabilising excipient is present at 0.05 to 3% w/v.

32. The composition, use or method according to clause 31 wherein the stabilising excipient is present at 0.08 to 1 % w/v.

33. The composition, use or method according to clause 32 wherein the stabilising excipient is present at about 0.1 % w/v.

34. The composition, use or method according to any one of clauses 5 to 33 wherein the stabilising excipient is present at about 0.01 to 5% w/w. 35. The composition, use or method according to clause 34 wherein the stabilising excipient is present at about 0.05 to 3% w/w.

36. The composition, use or method according to clause 35 wherein the stabilising excipient is present at about 0.1% w/w.

37. The particles, composition, use or method according to any one of clauses 1 to 24 wherein the stabilising excipient is selected from sucrose or mannose.

38. The composition, use or method according to clause 37 wherein the stabilising excipient is present at 1 to 4% w/v.

39. The particles, composition, use or method according to clause 38 wherein the stabilising excipient is present at about 3% w/v.

40. The composition, use or method according to any one of clauses 5 to 39 wherein the histidine is present at a concentration of 1 to 20 mM.

41. The composition, use or method according to clause 40 wherein the histidine is present at a concentration of 5 to 15 mM.

42. The composition, use or method according to clause 41 wherein the histidine is present at a concentration of 7 to 13 mM.

43. The composition, use or method according to clause 42 wherein the histidine is present at a concentration of about 10 mM.

44. The composition, use or method according to any one of clauses 5 to 39 wherein the histidine is present at a concentration of 10 to 100 mM.

45. The composition, use or method according to clause 44 wherein the histidine is present at a concentration of 30 to 70 mM.

46. The composition, use or method according to clause 45 wherein the histidine is present at a concentration of 40 to 60 mM. 47. The composition, use or method according to clause 46 wherein the histidine is present at a concentration of about 50 mM.

48. The composition, use or method according to any one of clauses 5 to 47 wherein the composition comprises at least 50% water v/v.

49. The composition, use or method according to clause 48 wherein the composition comprises at least 90% water v/v.

50. The composition, use or method according to any one of clauses 5 to 49 wherein the pH of the composition comprising the stabilising excipient and/or histidine is 4 to 7.

51. The composition, use or method according to clause 50 wherein the pH of the composition comprising the stabilising excipient and/or histidine is 5 to 6.5.

52. The composition, use or method according to clause 51 wherein the pH of the composition comprising the stabilising excipient and/or histidine is 5.5 to 6.

53. The particles, composition, use or method according to any one of clauses 1 to 52, wherein the aluminium hydroxide is selected from AI(OH)s, AIO(OH), or a mixture thereof.

54. The particles, composition, use or method according to clause 53, wherein the aluminium hydroxide is AI(OH)s.

55. The particles or composition according to any one of clauses 1 to 54, wherein the particles have an average size of less than 500 nm.

56. The particles or composition according to clause 55, wherein the particles have an average size of less than 350 nm.

57. The particles or composition according to clause 56, wherein the particles have an average size of less than 250 nm.

58. The particles or composition according to any one of clauses 1 to 57, wherein the Pdl of the particles is 0.5 or less. 59. The particles or composition according to clause 58, wherein the Pdl of the particles is 0.3 or less.

60. The particles or composition according to clause 59, wherein the Pdl of the particles is 0.2 or less.

61. The method according to any one of clauses 17 to 60 wherein the average starting size of the particles is greater than 250 nm.

62. The method according to clause 61 wherein the average starting size of the particles is greater than 400 nm.

63. The method according to clause 62 wherein the average starting size of the particles is greater than 800 nm.

64. The method according to clause 63 wherein the average starting size of the particles is greater than about 1 urn.

65. The method according to any one of clauses 17 to 64 wherein the average final size of the particles is less than about 1 urn.

66. The method according to clause 65 wherein the average final size of the particles is less than 800 nm.

67. The method according to clause 66 wherein the average final size of the particles is less than 400 nm.

68. The method according to clause 67 wherein the average final size of the particles is less than 250 nm.

69. The method according to any one of clauses 17 to 68, wherein the starting Pdl of the particles is 0.2 or greater.

70. The method according to clause 69, wherein the starting Pdl of the particles is 0.3 or greater. 71. The method according to clause 70, wherein the starting Pdl of the particles is 0.4 or greater.

72. The method according to any one of clauses 17 to 67, wherein the final Pdl of the particles is 0.3 or less.

73. The method according to clause 72, wherein the final Pdl of the particles is 0.2 or less.

74. The method according to any one of clauses 17 to 73 wherein the size of the particles is maintained for a period of no less than 10 days.

75. The method according to clause 74 wherein the size of the particles is maintained for a period of no less than 76 days.

76. The method according to clause 75 wherein the size of the particles is maintained for a period of no less than 100 days.

77. The method according to any one of clauses 74 to 76 wherein the size of the particles is maintained for the duration of the period when stored at 2 to 8 °C.

78. The particles, composition, use or method according to any one of clauses 1 to 77 wherein the size and/or Pdl of the particles is determined by dynamic light scattering (DLS).

79. The method according to any one of clauses 17 to 78, further comprising the step of agitating the aqueous composition.

80. The method according to clause 79, wherein agitation is performed by high shear mixing.

81. The method according to clause 80, wherein the high shear mixing is selected from the list consisting of: extrusion, sonication, microfluidisation, or homogenisation.

82. The method according to clause 81 , wherein the high shear mixing is selected from the list consisting of: sonication or homogenisation.

83. The method according to clause 82, wherein the high shear mixing is sonication. 84. The method according to clause 83, wherein the sonication is performed at no less than 1000 rpm.

85. The method according to any one of clauses 17 to 84, wherein agitation is performed after addition of the stabilising excipient.

86. The method according to any one of clauses 17 to 85, wherein agitation is performed after addition of the histidine.

87. The method according to any one of clauses 79 to 86, wherein agitation is performed for 1 minute or longer.

88. The method according to any one of clauses 17 to 87, further comprising the step of centrifuging the composition.

89. The method according to clause 88, wherein the centrifuging is performed at 50 to 250 g-

90. The method according to clause 89, wherein the centrifuging is performed at 75 to 200 g-

91. The method according to any one of clauses 17 to 90, further comprising at least one step of filter sterilising the composition.

92. The method according to clause 91 , wherein a filter size is 0.8 urn.

93. The method according to either clause 91 or 92 wherein a filter size is 0.45 urn.

94. The method according to any one of clauses 91 to 93, wherein a filter size is 0.22 urn.

95. A method of making an aqueous composition comprising aluminium hydroxide particles and a stabilising excipient comprising the step of adding to water aluminium hydroxide particles and a stabilising excipient selected from the list consisting of: octoxynol-9, polysorbate 20, polysorbate 80, sucrose, mannose, polyvinylpyrrolidone and glycine.

96. The method of any one of clauses 1 to 95, wherein the stabilising excipient is sucrose and wherein the sucrose is added as the last component in the formulation.

97. The method of clause 96 wherein the aqueous composition comprises detergent, antigen and buffer. The method of clause 95 wherein the sucrose and/or buffer are added after the aluminium hydroxide particles and detergent. The method of clause 96 wherein the composition comprises detergent (such as polysorbate 20), antigen and buffer. The method of clause 99 wherein the components are added to the composition in the following order: (1) aluminium salt particles, (2) detergent (such as polysorbate 20), (3) water, (4) antigen, (5) buffer and (6) sucrose.

EXAMPLES

Example 1 - Reduction of aluminium salt particle size

Different stabilising excipients were tested to determine their impact on the particle size distribution (PSD) of aluminium hydroxide particles. 50 ml batches of 5 mg/mL (final concentration) resuspended aluminium hydroxide particles (AI(OH)s in powder form) were prepared by adding the aluminium hydroxide particles to the excipient whilst the excipient was undergoing sonication. The batches were then sonicated for 5 to 30 minute periods using an ultrasonic processor with intervals of around 2 minutes between the sonication cycles. This was continued until there was no major change in the PSD, which occurred at around the 6^th sonication cycle. PSD was measured as the Z average diameter of the aluminium salt particles using Dynamic Light Scattering Zetasizer Nano ZS (Malvern Panalytical). Mild centrifugation was then performed on each sample.

Exemplary results for the use of polysorbate 20 as a stabilising excipient are shown in Fig. 1, depicting the average and standard deviation of the PSD over each cycle. After 3 sonication cycles, an average PSD of less than 200 nm was achieved. After the 6^th sonication cycle the PSD had stabilised, with decreased standard deviation and a lower reduction in PSD after each cycle. After the 8^th sonication cycle the sample was centrifuged (Fig. 1 , far right bar), reducing the PSD and standard deviation further.

The resultant average PSD after a maximum of 8 cycles of sonication and a final centrifugation when different excipients were used are summarised in Table 1 below.

Table 1

The Zwittergent 3-14 listed above was n-Tetradecyl-N,N-dimethyl-3-ammonio-1- propanesulfonate (T7763, Sigma Aldrich). Polysorbate 20 is known commercially as Tween 20. Polysorbate 80 is known commercially as Tween 80. It was found that excipients such as octoxynol-9, polysorbate 20, polysorbate 80, sucrose, mannose, polyvinylpyrrolidone and glycine produced surprisingly small aluminium hydroxide particles.

A selection of the most effective excipients were tested further in the following examples. Example 2 - Measuring the stability of PSD overtime

The stability of aluminium hydroxide PSD in stabilising excipients over time was ascertained. Firstly, the protocol of Example 1 was followed using polysorbate 20 as the stabilising excipient to reduce the size of aluminium hydroxide particles, then changes in size of the particles over time were monitored. Two samples underwent 6 sonication cycles, with one of the samples undergoing mild centrifugation (43gx) after the final sonication cycle. After sonication and centrifugation steps, the size of the particles as a Z-average was measured at time points over 147 days, which is shown in Fig. 2. From 6 to 8 cycles there was found to be no major PSD reduction.

It was found that the PSD of the particles remained stable on days tested from days 7 to 76, with an increase in particle size when tested on day 147, for both the centrifuged and the noncentrifuged samples comprising 0.1% polysorbate 20.

An additional test was conducted using polysorbate 20 or octoxynol-9 as the stabilising excipient. The samples underwent 7 cycles of sonication with the final cycle completed with centrifugation, as detailed in Example 1. The PSD for each sample was measured after each cycle and at particular intervals for 58 days post-centrifugation to determine stability during storage. The results are shown in Fig. 3A-B.

Example 3 - Impact of antigen KPi buffer on aluminium hydroxide particle size

Samples produced in Example 1 using polysorbate 20 as the stabilising excipient were used to investigate the impact of antigen buffer (potassium phosphate, KPi) on the PSD of aluminium hydroxide particles. These samples underwent 8 sonication cycles and some of the samples were centrifuged after the final sonication cycle.

50 pl of formulation volume dose (10mM KPi at pH 6.5-7) was added to the aluminium salt particle formulations of different concentrations. The PSD, osmolarity and pH was then measured for each sample. The results are shown in Table 2.

Table 2

The addition of 10mM KPi to the aluminium hydroxide particle formulation induced an increase in PSD, with no correlation between the process the sample had undergone, nor the dosage of aluminium hydroxide. Example 4 - Impact of different formulation buffers on PSD

It was found that phosphate buffer induced aggregation of aluminium hydroxide particles with adsorbed antigen. Alternative formulation buffers which may be suitable for vaccine formulations were selected with pH 5-6. 50 pl of each buffer were added to each aluminium hydroxide particle sample along with 0.1% w/v polysorbate 20. PSD and pH were measured at 0 hours and 24 hours. The results are shown in Table 3.

Table 3

Centrifugation occurred after the final sonication cycle.

The use of NaOAc as the formulation buffer gave similar PSD irrespective of the preparation process of the aluminium hydroxide particle. Use of Histidine pH 5.5 as the formulation buffer increased the stability of the aluminium hydroxide particles after (a) sonication or (b) sonication and centrifugation, causing decreased PSD at both Oh and 24h when compared to the PSD of the unprocessed samples. It was noted that phosphate buffer caused aggregation of aluminium salt particles, whereas the histidine buffer did not.

Example 5 - PSD and adsorption of different antigens onto sonicated and centrifuged aluminium hydroxide particles

Aluminium salt particles were prepared as described in Example 1 using polysorbate 20 as the stabilising excipient. Each sample underwent six cycles of sonication. Some samples were centrifuged after the final cycle.

Antigen formulations comprising 0.2 mg/ml as 10 ug/50 ul, protein-based antigen in either 10 mM or 50 mM histidine buffer (pH 5.5) were prepared. The antigens used were

Staphylococcus aureus clumping factor A (ClfA), staphylococcal protein A (SpA, SEQ ID NO: 1) and alpha toxin (Hla). The antigen formulations were then added to aluminium salt particle formulation group 3 from table 3 above and the PSD was measured as Z-average and standard deviation at 0 hours and either 24 (“I exp”) or 72 hours (“II exp”). The results are shown in Table 4.

Table 4

ND = Not done

The proportion of each antigen adsorbed to the aluminium salt particles was measured using electrophoresis. After approximately 10 minutes of mixing (TO), the samples underwent centrifugation (80K RPM with Beckman Coulter Airfuge CLS Air-Driven Benchtop Ultracentrifuge 362781). Antigen adsorbed to the aluminium salt particles was detected by SDS-PAGE after desorbing the antigen from the alum particles. An SDS-PAGE was conducted using both the supernatant and the dissolved pellet. Antigen adsorbed to the aluminium salt particles does not appear on the SDS-PAGE, whilst antigen which had not been adsorbed is found in the supernatant.

The western blot results are depicted in Figures 4A-C, wherein all TCA lanes represent precipitated and concentrated supernatant, and all PD lanes represent the pellet (alum- adsorbed antigen).

Hla was found to be present in both the supernatant and the pellet, indicating that the Hla was not completely adsorbed to the aluminium salt. A greater amount of antigen was adsorbed when the aluminium salt particles were centrifuged after sonication. ClfA was well adsorbed to the aluminium salt particles after centrifugation, with some ClfA remaining free in the samples which were not centrifuged prior to antigen addition.

Example 6 - Sonication process and PVP stabilisation

The impact of polyvinylpyrrolidone (PVP) on stabilisation of aluminium salt particles was further investigated. The same protocol, stabilising excipients and histidine buffer was used as in Example 4. Sonication and centrifugation cycles were carried out on aluminium salt particle suspensions over various timepoints, followed by the addition of 1% PVP w/v. The results are shown in Fig. 8. PSD values are reported in the graph where on Y axis is reported the mean value of size with SD at different steps of the process or time point (X axis). The process to obtain the aluminium particle suspension includes both sonication steps (5 minutes each) followed by mild centrifugation cycles (5 minutes each at 43 g) in order to remove the larger particles (which are aggregate clusters). For example, the X axis label 30’ sonic & 5’ centrif refers to 30’ cumulative time of sonication (6 steps, each of 5’ minutes; after each step there is a centrifugation cycle of 5’), while 3 days & 5’ centrif is 3 days after preparation of the sample, pre-addition of PVP. ‘Suspension in milliQ’ refers to a suspension in purified water.

Example 7 - Reduction of PSD using homogenisation

Alternative methods of high shear mixing using high energy sources were tested. Samples of 5 g/l aluminium salt in 0.02% polysorbate 20 were homogenised using IKA T25 digital for increasing periods of time. The resultant PSD at each time point is depicted in Fig. 5.

The experiment was repeated using 20g/l aluminium salt with a larger homogeniser (OMNI Macro ES, OMNI International). The results are depicted in Fig. 6.

Example 8 - Impact of filtration on PSD

5 g/l aluminium salt particles in 0.02% polysorbate 20 underwent 70 minutes of sonication followed by 5 minutes of centrifugation. The PSD and Zeta Potential (ZP) were measured before filtration with a 0.8 pm filter, a 0.45 pm filter and a 0.22 pm filter, before the PSD was remeasured. The results are shown in Table 5.

Table 5

ND = not done

Filtration using a 0.8 pm filter removes larger aluminium salt particles. Use of a 0.45 pm filter did not have a further impact on the average PSD after filtration with a 0.8 pm filter. Further filtration with a 0.22 pm filter decreased the average PSD below that of the starting material, to 107 nm. The samples which had undergone 0.8 pm, 0.45 pm then 0.22 pm filtration or 0.8 pm then 0.22 pm filtration were then stored for 56 days at between 2°C and 8°C, during which the average PSD was measured. The results are shown in Fig. 7. The compositions which had undergone 0.8 pm, 0.45 pm then 0.22 pm filtration were more stable than the samples which had not undergone filtration.

of sonication volume on PSD

Experiments in the previous examples were carried out using a sonication volume of 50ml unless otherwise stated. In this experiment, the same concentration of aluminium salt particles (5mg/ml) was introduced into different volumes of polysorbate 20 (0.1% w/v) and water for injection (100ml, 50ml, 10ml) and sonication cycles were applied.

Fig. 9 provides the size of the particles after each sonication cycle was applied, wherein ‘Fv’ refers to volume of the vessel. Fig. 10 provides the size of the particles monitored over 28 days (wherein circle data points = 100ml, square data points = 50ml and cross data points = 10ml). Small, stable particles were produced with all sonication volumes tested.

Example 10 - Impact of antigen concentration on PSD

In a first experiment the impact of varying the concentration of antigen and the concentration of aluminium salt particles was investigated. Chicken ovalbumin protein (‘OVA’, accession number P01012, SEQ ID NO: 4) was used as a model antigen and adsorbed to aluminium salt particle samples which had undergone sonication in a 10ml volume as described above in Example 9. Formulations were prepared with equal concentrations of OVA and aluminium salt particles (e.g. a ‘formulation concentration’ of 0.1 mg/ml comprised 0.1 mg/ml of OVA and 0.1 mg/ml of aluminium salt particles). The results are provided in Fig. 11.

In a second experiment the impact of varying the concentration of antigen (OVA) while keeping the concentration of aluminium salt particles constant was investigated. This experiment was carried out in the same manner and under the same conditions as the first experiment except the concentration of aluminium salt particles was maintained at 0.5 mg/ml in all samples. The results are provided in Table 6. Table 6

Example 11 - Order of addition of components

A series of experiments were performed to ascertain the optimal order of addition of formulation components including OVA antigen, to prepare a final formulation simulating a vaccine. The formulation components were aluminium hydroxide particles 0.5mg/ml, polysorbate 20 0.1% w/v, OVA 0.2mg/ml, histidine 10mM pH6.5 and sucrose 7% w/v. Formulations were prepared in turn, one at a time, as illustrated in Fig. 12 in the order from bottom to top and Z-average particle sizes were measured. In Fig. 12, ‘nano’ refers to aluminium hydroxide particles, ‘det’ refers to polysorbate 20, ‘buffer’ refers to histidine, ‘OVA’ refers to ovalbumin protein and ‘WFI’ refers to water for injection (distilled water). Components were added in the order from left to right for each formulation.

Although small particles were achieved in all formulations, it was observed that (a) sucrose and/or buffer should ideally be added after aluminium hydroxide particles and detergent in order to obtain smaller particles and (b) sucrose should ideally be the last component added. The optimal overall order of addition for achieving the smallest particles in a completed immunogenic composition was (1) aluminium salt particles, (2) polysorbate 20, (3) water for injection, (4) OVA, (5) buffer and (6) sucrose (see Fig. 12, third bar down, achieving a particle size of 262 nm).

Example 12 - Sterilisation of immunogenic compositions

A vaccine formulation was prepared by adding components in the optimal order described above in Example 11 , but for replacing the ovalbumin protein with HlaCP5 antigen. HlaCP5 antigen was tested at both concentrations of 0.1ug/dose and 1.0ug/dose with 0.5mg/ml of aluminium hydroxide particles. It was found that the formulations prepared in Example 11 could not be efficiently passed through a 0.22 urn pore size filter to produce sterile formulations. Accordingly, sterilisation of the suspended aluminium hydroxide was attempted by autoclaving, before addition to further formulation components.

40mg of aluminium hydroxide particles was suspended in 0.1% w/v polysorbate 20 using 3 sonication cycles of 10 minutes each. Immediately after the final sonication cycle, the suspension was autoclaved at 121°C for 20 minutes. The size and polydispersity index of the particles at various timepoints is provided in Table 7, alongside a separate aliquot of the suspension which did not undergo autoclave sterilization.

Table 7

The sterilized suspension was used to prepare two vaccine formulations using the optimal order of addition of components set out in Example 11 above, except the Hla-CP5 antigen was adsorbed to the aluminium hydroxide particles in place of OVA (the Hla-CP5 antigen is a conjugate of the Hla (SEQ ID NO: 2) polypeptide and CP5 polysaccharide). The size and polydispersity index of the aluminium hydroxide particles in the vaccine formulation was measured after 84 days of storage. The results are provided in Table 8. Table 8

Example 13 - Immunogenicity of aluminium hydroxide particle-containing formulations

An in vivo study was performed to determine the relative immunogenicity of formulations containing aluminium hydroxide particles of differing sizes. Vaccine formulations comprising nano-size aluminium hydroxide particles (nanoalum) and Hla-CP5 were prepared as described in Example 12 above with autoclave sterilisation. Formulations containing Hla-CP5 antigen and traditional aluminium hydroxide particles with a particle size of -3000 nm were also prepared with autoclave sterilisation. The formulations were prepared with either 0.1 g or 1 pg HlaCP5 antigen per dose and with 0.5 mg/ml aluminium hydroxide particles. The formulations were prepared immediately prior to mouse immunisation.

Seven-week old CD-1 mice (16 per group) were each immunised intramuscularly with 50 pl total (25 pl per leg) of the vaccine formulations. Mice were immunised with a first dose of the formulations on day 1, followed by a second dose on day 29. Blood was collected on days 0, 28 (4 weeks post first immunisation) and 43 (two weeks post second immunisation). On day 43, mice were euthanised and spleens were collected.

Antigen-specific IgG

HlaCP5 antigen-specific IgG present in immunised mouse serum was measured using a LUMINEX assay. Briefly, sera were serially 3-fold diluted then each dilution was transferred to a 96-well plate. Beads coated with Hla or CP5 were added to the sample wells (10 pl/well) then incubated in the dark for 1 hour at room temperature. Beads were then washed three times with 100 pl PBS/well before addition of 25 pl/well 1:100 diluted R- Phycoerythrin AffiniPure F(ab’)2 Fragment Goat Anti-Mouse IgG, F(ab’)2 fragment specific (Jackson 115-116-072) for 15 minutes in the dark at room temperature. Beads were washed three times with PBS then plates were read using a LUMINEX plate reader. In Figs. 13-14 “AlumOH” refers to formulations comprising traditional aluminium hydroxide particles, RLU indicates the Relative Light Units, 4wpost 1° indicates testing of sera taken 4 weeks after the first immunisation, and 2wpost 2° indicates testing of sera taken 2 weeks after the second immunisation.

Fig. 13 shows the total Hla antigen-specific IgG detected in mice after the first or second immunisation with either 0.1 pg or 1 pg HlaCP5 antigen formulated with aluminium hydroxide particles. Anti-Hla IgG titres were equivalent between nanoalum and traditional aluminium hydroxide particles. A statistically significant but small difference in antigen-specific IgG titres in mice immunised with 1 pg HlaCP5 was observed between nanoalum and traditional aluminium hydroxide particles after the second immunisation. Fig. 14 shows the total CP5 antigen-specific IgG detected in mice after the first or second immunisation with either 0.1 pg or 1 pg HlaCP5 antigen formulated with aluminium hydroxide particles. Anti-CP5 IgG titres were equivalent between nanoalum and traditional aluminium hydroxide particles.

Antigen-specific T cells

Spleens harvested from euthanised mice were placed in 1.5 ml wash medium (RPMI 1640 (GIBCO Cat. 21875-034) + 10% foetal bovine serum + 1% penicillin/streptomycin), then crushed and filtered over a 70 pm cell strainer. Cells were washed a further two times before addition of 1X RBC lysis buffer (BIOLEGEND) on ice for 2 minutes. Splenocytes were washed then plated in 96-well plates at 2 x 10⁶cells/well with Hla peptide pool and 8 pg/ml anti-CD28. Splenocytes cultured with 1 pg/ml anti-CD3 and 8 pg/ml CD28 were used as a positive control. Splenocytes cultured with 8 pg/ml anti-CD28 and medium were used as a negative control. Plates were incubated at 37°C overnight then 5 pg/ml Brefeldin A was added for 4 hours. Cells were washed twice in PBS then stained with Live/Dead Near-IR for 20 minutes followed by surface staining with anti-CD44-APC-R700 (BD Pharmingen Cat. 565480) and CD62L-BB515 (BD Pharmingen Cat. 565261). Cells were washed and permeabilised in CytoFix/CytoPerm (Becton Dickinson Cat. 554722) at 4°C and 1X PermWash (Becton Dickinson 554723). Fc block (BD Pharmingen Cat. 553141) was added to cells for 20 minutes in the dark at room temperature then cells were stained with CD45-APC (BD Pharmingen Cat. 559864), CD3- BB700 (BD Pharmingen Cat. 566494), CD4-BUV395 (BD Pharmingen Cat. 740208), CD8- BUV805 (BD Pharmingen Cat. 612898), IFN-y-BV480 (BD Pharmingen Cat. 566097), TNF-a- BV711 (BD Pharmingen Cat. 563944), IL-2-BV421 (BD Pharmingen Cat. 562969), IL-13-PE (eBioscience Cat. 12-7133-82), IL-17-BV650 (BD Pharmingen Cat. 564170), IL-1 -PE-Cy7 (eBioscience Cat. 25-7114-82) and IL-4-PE (BioLegend Cat. 504104) for 20 minutes at room temperature. Cells were washed once in 1X PermWash, once in PBS, then data were acquired on a LSRII flow cytometer. Gating was performed on CD45+CD3+CD44+CD4+ or CD45+CD3+CD44+CD8+ to determine the percentage of antigen (Ag)-specific cytokineproducing T cells. In Figs. 15-16 “AlumOH” refers to formulations comprising traditional aluminium hydroxide particles, whilst “nanoalum” refers to formulations comprising nano-sized aluminium hydroxide particles. Fig. 15 shows the percentage of antigen-specific CD4+ T cells induced following two immunisations with 0.1 pg or 1 pg HlaCP5 formulated with nanoalum or traditional aluminium hydroxide particles. The percentage of induced antigen-specific CD4+ T cells was equivalent between nanoalum and traditional aluminium hydroxide particles.

Fig. 16 shows the percentage of antigen-specific CD8+ T cells induced following two immunisations with 0.1 pg or 1 pg HlaCP5 formulated with nanoalum or traditional aluminium hydroxide particles. The percentage of induced antigen-specific CD8+ T cells was equivalent between nanoalum and traditional aluminium hydroxide particles.

REFERENCES

T. Fifis, A. Gamvrellis, B. Crimeen-lrwin, G.A. Pietersz, J. Li, P.L. Mottram, I.F.

McKenzie, M. Piebanski, Size-dependent immunogenicity: therapeutic and protective properties of nano-vaccines against tumors, J. Immunol. 173 (2004) 3148-3154.

Orr, M.T., Khandhar, A.P., Seydoux, E. et al. Reprogramming the adjuvant properties of aluminum oxyhydroxide with nanoparticle technology, npj Vaccines 4, 1 (2019) 1-10. Schartl, Light Scattering from Polymer Solutions and Nanoparticle Dispersions (2007).

X.R. Li, B.R. Sloat, N. Yanasarn, Z.R. Cui, Relationship between the size of nanoparticles and their adjuvant activity: data from a study with an improved experimental design, Eur. J. Pharm. Biopharm. 78 (2011) 107-116.

Vaccine Design (1995) eds. Powell & Newman. ISBN: 030644867X. Plenum.

Claims

43 Claims

1. An aqueous composition comprising particles, wherein the particles comprise aluminium hydroxide and the aqueous composition also comprises

(b) histidine.

2. The aqueous composition of claim 1, wherein the particles comprise aluminium hydroxide and the aqueous composition comprises

(b) histidine.

3. The composition according to either claim 1 or 2, wherein the particles have an average size of less than 300 nm.

4. The composition according to claim 3, wherein the particles have an average size of less than 250 nm.

5. The composition according to claim 4, wherein the particles have an average size of less than 200 nm.

6. The composition according to any one of claims 1 to 5, wherein the Pdl of the particles is 0.3 or less.

7. A method of maintaining or reducing the size of aluminium hydroxide particles in an aqueous composition comprising the step of adding to the aqueous composition

(b) histidine.

8. The method according to claim 7, wherein the average starting size of the particles is greater than 250 nm.

9. The method according to either claim 7 or 8, wherein the size of the particles is maintained for a period of no less than 76 days. 44

10. The method according to any one of claims 7 to 9, further comprising the step of sonicating the aqueous composition.

11. The method according to any one of claims 7 to 10, further comprising the step of centrifuging the aqueous composition.

12. The composition or method according to any one of claims 1 to 11, wherein the stabilising excipient is selected from octoxynol-9, polysorbate 20, sucrose, mannose, polyvinylpyrrolidone and glycine.

13. The composition or method according to claim 12, wherein the stabilising excipient is selected from octoxynol-9, polysorbate 20 and glycine.

14. The composition or method according to claim 13, wherein the stabilising excipient is polysorbate 20.

15. The composition or method according to any one of claims 1 to 14, wherein the pH of the composition comprising the stabilising excipient and/or histidine is 5.5 to 6.