WO2018172745A1

WO2018172745A1 - Combination therapy for treatment of cancer

Info

Publication number: WO2018172745A1
Application number: PCT/GB2018/050672
Authority: WO
Inventors: Sanjeev Krishna; Thomas Efferth
Original assignee: St George's Hospital Medical School
Priority date: 2017-03-21
Filing date: 2018-03-15
Publication date: 2018-09-27
Also published as: GB201704474D0

Abstract

The present invention relates to the treatment of colorectal cancer using a combination of artesunate and curcumin.

Description

COMBINATION THERAPY FOR TREATMENT OF CANCER

FIELD OF THE INVENTION

BACKGROUND TO THE INVENTION

Colorectal cancer, also known as bowel cancer, is the third most common cancer worldwide. Around 20% of patients with colorectal cancer will be found to have disease that has spread to other organs (cancer metastases) at diagnosis.

Patients are often treated with combination chemotherapy and targeted therapies, but their cancer eventually develops resistance to these treatments. For example, current standard of care includes combination chemotherapy with 5-fiuorouracil and oxaliplatin, with or without targeted monoclonal antibody therapy. Unfortunately up to 40% of inoperable metastatic colorectal cancers display chemo-resistance from the outset, with all cases eventually acquiring chemo-resistance. In chemo -refractory disease, median survival time is just five months. Metastatic disease is associated with significant morbidity.

Current chemotherapy and targeted therapy treatments are often associated with significant side effects and healthcare costs.

Consequently, there is an urgent need to develop more effective, well tolerated and affordable treatments to improve symptoms and survival rates for sufferers of this devastating disease.

SUMMARY OF THE PNVENTION

It has now been found that a combination of the compounds artesunate and curcumin can be used to treat colorectal cancer. It has also been found that such a combination may give rise to synergistic benefits compared with the effects conferred by the respective compounds alone.

The present invention thus provides:

[1] A pharmaceutical composition which comprises: (a) curcumin; and (b) artesunate; for use in treating colorectal cancer.

[2] Curcumin for use in treating colorectal cancer by co-administration with artesunate. [3] Artesunate for use in treating colorectal cancer by co-administration with curcumin.

[4] A method of treating a patient suffering from colorectal cancer, which method comprises co-administering to said patient curcumin and artesunate.

[5] A product comprising (a) curcumin, and (b) artesunate, as a combined preparation for simultaneous, concurrent, separate or sequential use in the treatment of a patient suffering from colorectal cancer.

[6] Use of curcumin in the manufacture of a medicament for the treatment of colorectal cancer by co-administration with artesunate.

[7] Use of artesunate in the manufacture of a medicament for the treatment of colorectal cancer by co-administration with curcumin.

[8] A pharmaceutical composition which comprises: (a) curcumin; and (b) artesunate.

[9] A kit which comprises: (a) a pharmaceutical composition comprising curcumin; and (b) a pharmaceutical composition comprising artesunate.

Further aspects of the present invention are outlined in detail below.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows the data points obtained in establishing the IC50 for curcumin and artesunate, respectively, for the HCT116 p53-wildtype cell line as described in Example 1. Y-axis: Mean% result on Tecan reader; X-axis: Concentration (μΜ) of curcumin (solid line) and artesunate (dotted line).

Figure 2 shows the isobologram for the curcumin-artesunate combination on the HCT116 p53-wildtype cell line as described in Example 1. Also shown are the point values for: 10 μΜ curcumin and ascorbic acid (filled circle); 20 μΜ curcumin and ascorbic acid (filled square); 30 μΜ curcumin and ascorbic acid (filled diamond); and 40 μΜ curcumin and ascorbic acid (unfilled circle).

Figure 3 shows the data points obtained in establishing the ICso for curcumin and artesunate, respectively, for the HCT-116 p53-knockout cell line as described in Example 1. Y-axis: Mean% result on Tecan reader; X-axis: Concentration (μΜ) of curcumin (solid line) and artesunate (dotted line).

Figure 4 shows the isobologram for the curcumin-artesunate combination on HCT-

116 p53-knockout cell line as described in Example 1. Also shown are the point values for: 10 μΜ curcumin and ascorbic acid (filled circle); 20 μΜ curcumin and ascorbic acid (filled square); 30 μΜ curcumin and ascorbic acid (filled diamond); and 40 μΜ curcumin and ascorbic acid (unfilled circle).

Figure 5 shows the data points obtained in establishing the ICso for curcumin and artesunate, respectively, for the P-glycoprotein-expressing CaCo-2 cell line as described in Example 1. Y-axis: Mean% result on Tecan reader; X-axis: Concentration (μΜ) of curcumin (solid line) and artesunate (dotted line).

Figure 6 shows the isobologram for the curcumin-artesunate combination on the P- glycoprotein-expressing CaCo-2 cell line as described in Example 1. Also shown are the point values for: 10 μΜ curcumin and ascorbic acid (filled circle); 20 μΜ curcumin and ascorbic acid (filled square); 30 μΜ curcumin and ascorbic acid (filled diamond); and 40 μΜ curcumin and ascorbic acid (unfilled circle).

DETAILED DESCRIPTION

Artesunate

Artesunate is a well known compound that has been widely used as a medication the treatment of malaria. Its chemical structure is

Artesunate has a hemisuccinate group which confers substantial water-solubility and high oral bioavailability on the compound.

Artesunate is one of a number of well known derivatives of artemisinin, which itself has the structure

The active metabolite of artemisinin and all artemisinin derivatives

dihydroarteminisin (DHA), which has the formula

In the present invention, the artesunate can optionally be replaced by a "related compound" that is any of artemisinin, an artemisinin derivative other than artesunate (e.g., artemether, arteether, artelinic acid and artemotil) and dihydroarteminisin. Thus, references herein to artesunate can be substituted by artemisinin, an artemisinin derivative other than artesunate (e.g., artemether, arteether, artelinic acid and artemotil) and dihydroarteminisin, except insofar as context clearly dictates otherwise (such as in the working Examples).

In particular, the present invention extends to a pharmaceutical composition which comprises: (a) curcumin; and (b) artemisinin, an artemisinin derivative other than artesunate (e.g., artemether, arteether, artelinic acid and artemotil) or dihydroarteminisin; including such a composition for use in treating colorectal cancer. Similarly, the present invention extends to: (i) curcumin for use in treating colorectal cancer, by coadministration with artemisinin, an artemisinin derivative other than artesunate (e.g., artemether, arteether, artelinic acid and artemotil) or dihydroarteminisin; and (ii) artemisinin, an artemisinin derivative other than artesunate (e.g., artemether, arteether, artelinic acid and artemotil) or dihydroarteminisin for use in treating colorectal cancer, by co-administration with curcumin. Further, the present invention extends to a method of treating a patient suffering from colorectal cancer, which method comprises coadministering to said patient curcumin and artemisinin, an artemisinin derivative other than artesunate (e.g., artemether, arteether, artelinic acid and artemotil) or dihydroarteminisin. Still further, the present invention extends to a product comprising (a) curcumin, and (b) artemisinin, an artemisinin derivative other than artesunate (e.g., artemether, arteether, artelinic acid and artemotil) or dihydroarteminisin, as a combined preparation for simultaneous, concurrent, separate or sequential use in the treatment of a patient suffering from colorectal cancer. Additionally, the present invention extends to: (i) use of curcumin in the manufacture of a medicament for the treatment of colorectal cancer by

co-administration with artemisinin, an artemisinin derivative other than artesunate (e.g., artemether, arteether, artelinic acid and artemotil) or dihydroarteminisin; and (ii) use of artemisinin, an artemisinin derivative other than artesunate (e.g., artemether, arteether, artelinic acid and artemotil) or dihydroarteminisin in the manufacture of a medicament for the treatment of colorectal cancer by co-administration with curcumin. The present invention also extends to a kit which comprises: (a) a pharmaceutical composition comprising curcumin; and (b) a pharmaceutical composition comprising artemisinin, an artemisinin derivative other than artesunate (e.g., artemether, arteether, artelinic acid and artemotil) or dihydroarteminisin.

Previous studies have posited that artemisinin and its derivatives (including artesunate) may have anti-cancer properties. The exact underlying mechanisms remain to be elucidated, but may include actions on cell cycle proteins that control transit through Gl restriction, induction of apoptosis, inhibition of NF-κΒ and antiangio genie and

antimetastatic effects. In a pilot study described in Krishna et ah, EBioMedicine 2(1): 82- 90 (2014), the effects of artesunate monotherapy in colorectal cancer were investigated, resulting in findings that artesunate has anti-proliferative properties and is generally well tolerated. Results from this pilot study in colorectal cancer patients provided the basis for a larger clinical trial investigating the effects of neoadjuvant artesunate on progression free survival and overall survival (the NeoART trial; recruiting participants at the time of filing of the present application).

Curcumin

Curcumin belongs to the polyphenols superfamily and is a derivative of the spice turmeric {Curcuma longa), typical to Asian cuisine.

Curcumin has previously been shown to possess anti-inflammatory, anti-oxidant and anti-neoplastic properties. Curcumin inhibits NF-κΒ and STAT3 signalling pathways, both of which play a key role in carcinogenesis and progression. The nuclear factor NF-KB, is a ubiquitous transcription factor involved in regulating a wide range of genes that are implicated inflammation, cell proliferation, carcinogenesis, and apoptosis. Curcumin has also been found to down-regulate other growth-regulatory molecules such as cyclin Dl and COX-2.

Some preclinical evidence has been reported of reductions in tumour volume and metastatic features when curcumin is combined with chemotherapy, as compared to either agent alone (see, for example: (i) Irving et ai, Best Pract Res Clin Gastroenterol. 2011 25:519-34; and (ii) Howells et al, Int J Cancer 2011; 129:476-86).

However, there are no known drug interactions between curcumin and artesunate. The effects of combined administration of curcumin and artesunate have not been reported to date.

Combination of active ingredients

The present invention involves the use of a combination of artesunate (or a related compound as described elsewhere herein) and curcumin. The artesunate (or a related compound as described elsewhere herein) and curcumin are herein referred to as "active ingredients".

In one aspect, the present invention provides a pharmaceutical composition that comprises: (a) curcumin; and (b) artesunate (or a related compound as described elsewhere herein); including for use in treating colorectal cancer. Pharmaceutical compositions according to the invention will typically further comprise one or more pharmaceutically acceptable excipients or carriers. The present invention extends to situations where the active ingredients discussed above are co-administered. When the active ingredients are co-administered they can be present either in a single pharmaceutical composition or in separate pharmaceutical compositions, including in separate pharmaceutical compositions optimized for administration either by the same mode or a different mode. For example, the active ingredients may both be administered orally, either in a single pharmaceutical composition or, more preferably, in separate pharmaceutical compositions.

For the avoidance of doubt, in the product comprising (a) curcumin and (b) artesunate (or a related compound as described elsewhere herein), as a combined preparation for simultaneous, concurrent, separate or sequential use, the product may comprise either a single pharmaceutical composition that comprises both (a) and (b) or alternatively, and preferably, a first pharmaceutical composition that comprises (a) and a second (i.e., separate) pharmaceutical composition that comprises (b).

Co-administration of the active ingredients according to the present invention includes simultaneous, separate and sequential administration.

In general, pharmaceutical compositions used in the invention may be suitable for oral, buccal, nasal, topical, ophthalmic or rectal administration. Preferably, the compositions are suitable for oral administration.

For oral administration, the pharmaceutical compositions of the present invention may take the form of, for example, tablets, lozenges or capsules prepared by conventional means with pharmaceutically acceptable excipients such as binding agents (e.g.

pregelatinised maize starch, polyvinylpyrrolidone or hydroxypropyl methyl cellulose); fillers (e.g. lactose, microcrystalline cellulose or calcium hydrogenphosphate); lubricants (e.g. magnesium stearate, talc or silica); disintegrants (e.g. potato starch or sodium glycolate); or wetting agents (e.g. sodium lauryl sulphate). The tablets may be coated by methods well known in the art. Liquid preparations for oral administration may take the form of, for example, solutions, syrups or suspensions, or they may be presented as a dry product for constitution with water or other suitable vehicle before use. Such liquid preparations may be prepared by conventional means with pharmaceutically acceptable additives such as suspending agents, emulsifying agents, non-aqueous vehicles or preservatives. The preparations may also contain buffer salts, flavouring agents, colouring agents or sweetening agents, as appropriate. For ophthalmic administration the pharmaceutical compositions of the present invention may be conveniently formulated as micronized suspensions in isotonic, pH- adjusted sterile saline, either with or without a preservative such as a bactericidal or fungicidal agent, for example phenylmercuric nitrate, benzylalkonium chloride or chlorhexidine acetate. Alternatively, for ophthalmic administration compounds may be formulated in an ointment such as petrolatum.

For rectal administration the pharmaceutical compositions of the present invention may be conveniently formulated as suppositories. These can be prepared by mixing the active component with a suitable non-irritating excipient which is solid at room

temperature but liquid at rectal temperature and so will melt in the rectum to release the active component. Such materials include, for example, cocoa butter, beeswax and polyethylene glycols.

For topical administration the pharmaceutical compositions of the present invention may take the form of any formulation normally used for topical administration, in particular solutions, lotions, emulsions of liquid consistency, emulsions of semi-liquid consistency, emulsions of semi-solid consistency, emulsions of solid consistency, creams, gels or ointments. The emulsions are obtained by dispersion of an oil phase in water (O/W) or a water phase in oil (W/O). For example, some pharmaceutical compositions for topical administration contain an oil phase. Such pharmaceutical compositions may, for example, be water-in-oil emulsions (i.e. emulsions wherein the water is the dispersed phase and the oil in the dispersion medium) or be substantially non-aqueous.

Compositions for topical use in accordance with the invention may also contain one or more emollients, emulsifiers, thickeners and/or preservatives. The emollients are typically long chain alcohols, such as cetyl alcohol, stearyl alcohol and cetearyl alcohol; hydrocarbons such as petrolatum and light mineral oil; or acetylated lanolin. The total amount of emollient in the formulation is preferably about 5% to about 30%, and more preferably about 5% to about 10% by weight based on the total weight of the formulation. The emulsifier is typically a nonionic surface active agent, e.g., polysorbate 60 (available from Sigma Aldrich), sorbitan monostearate, polyglyceryl-4 oleate, and

polyoxyethylene(4)lauryl ether or trivalent cationic. Generally the total amount of emulsifier is preferably about 2% to about 14%, and more preferably about 2% to about 6% by weight based on the total weight of the formulation. Pharmaceutically acceptable thickeners, such as Veegum.TM.K (available from R. T. Vanderbilt Company, Inc.), and long chain alcohols (i.e. cetyl alcohol, stearyl alcohol or cetearyl alcohol) can be used. The total amount of thickener present is preferably about 3% to about 12% by weight based on the total weight of the formulation. Preservatives such as methylparaben, propylparaben and benzyl alcohol can be present in the formulation.

Optionally, an additional solubilizing agent such as benzyl alcohol, lactic acid, acetic acid, stearic acid or hydrochloric acid can be included in the formulation. If an additional solubilizing agent is used, the amount present is preferably about 1% to about 12% by weight based on the total weight of the cream.

Optionally, the formulation can contain a humectant such as glycerin and skin penetration enhancers such as butyl stearate.

It is known to those skilled in the art that a single ingredient can perform more than one function in a composition, i.e., cetyl alcohol can serve both as an emollient and as a thickener.

The pharmaceutical composition of the invention optionally comprises an oil phase.

In this case, typically the amount of oil in the composition is at least 10 wt. %, preferably at least 30 wt. %, more preferably at least 50 wt. %, more preferably at least 80 wt. %, based on the total weight of the composition. As used herein an oil phase is typically a liquid or solid phase which is substantially immiscible with water. More typically, an oil phase as used herein has a solubility in water at 25°C of less than or equal to 1 mg/L, preferably less than 0.1 mg/L.

The oil phase in an emulsion may be any oil phase normally used in emulsions for topical administration. Such oil phases include, for example, hydrocarbon bases such as such as hard paraffin, soft paraffin, ceresine and microcrystalline wax, absorption bases such as lanolin and beeswax, emulsifying bases such as emulsifying wax and cetrimide, and vegetable oils such as olive oil, coconut oil, sesame oil, almond oil and peanut oil. Other oil phases useful in accordance with the invention are mineral oil, liquid petroleum, sorbitan monostearate, polysorbate 60, cetyl esters wax, cetearyl alcohol, benzyl alcohol and 2 octyldodecanol.

Those skilled in the art will understand that by varying the ratio of water to oil in an emulsion, the result could be deemed a lotion, a cream, or an ointment, by order of increasing proportion of oil. An emulsion comprising similar proportions of oil phase and water phase is usually deemed a cream, whereas an ointment will generally contain a substantially higher proportion of oil phase compared to water phase, for example greater than 60 wt. % oil phase, preferably greater than 70 wt. % oil phase, more preferably greater than 80 wt. % oil phase, based on the total weight of the oil phase and the water phase. A lotion will generally contain a lower proportion of oil phase than a cream, for example under 25 wt. % oil phase, under 20 wt. % oil phase, under 15 wt. % oil phase, under 10 wt. % oil phase or under 5 wt. % oil phase, based on the total weight of the oil phase and the water phase.

Generally, a cream for use according to the invention comprises an oil phase and a water phase mixed together to form an emulsion. Preferably, the amount of water present in a cream of the invention is about 45% to about 85% by weight based on the total weight of the cream, more preferably about 45 wt. % to about 65 wt. %, even more preferably about 45 wt. % to about 55 wt. %.

Where the composition is an ointment a pharmaceutically acceptable ointment base will be used. Examples of ointment bases include hydrocarbon bases such as such as hard paraffin, soft paraffin, ceresine and microcrystalline wax, absorption bases such as lanolin and beeswax, water-soluble bases such as polyethylene glycols (e.g. polyethylene glycol 200, 300, 400, 3350, 4000 or 6000), propylene glycol and polypropylene glycols, emulsifying bases such as emulsifying wax and cetrimide, and vegetable oils such as olive oil, coconut oil, sesame oil, almond oil and peanut oil. Mixtures of ointment bases can of course be used. The amount of ointment base present in an ointment of the invention is preferably about 60% to about 95% by weight based on the total weight of ointment, more preferably about 70 wt. % to about 90 wt. %>, still more preferably about 75 wt. % to about 85 wt. %.

The pharmaceutical composition for use in accordance with the present invention may also be a lotion containing the active component suspended or dissolved in one or more pharmaceutically acceptable carriers. Particular carriers include, for example, mineral oil, sorbitan monostearate, polysorbate 60, cetyl esters wax, cetearyl alcohol, benzyl alcohol, 2-octyldodecanol and water.

Suitable dosages of the active ingredients may be determined by a skilled medical practitioner. Actual dosage levels of the active ingredients may be varied so as to obtain an amount of the active ingredient which is effective to achieve the desired therapeutic response for a particular patient, composition, and mode of administration, without being toxic to the patient. Thus, the dosage is typically an effective or therapeutically effective dosage.

The selected dosage level will depend upon a variety of pharmacokinetic factors including the activity of the particular compositions of the present invention employed, the route of administration, the time of administration, the rate of excretion of the particular compound being employed, the duration of the treatment, other drugs, compounds and/or materials used in combination with the particular compositions employed, the age, sex, weight, condition, general health and prior medical history of the patient being treated, and like factors well known in the medical arts.

Dosage regimens may be adjusted to provide the optimum desired response. For example, a single dose may be administered (e.g. a single dose daily), several divided doses may be administered over time or the dose may be proportionally reduced or increased as indicated by the exigencies of the therapeutic situation. Dosage unit form as used herein refers to physically discrete units suited as unitary dosages for the subjects to be treated; each unit contains a predetermined quantity of active compound calculated to produce the desired therapeutic effect in association with the required pharmaceutical carrier.

In the compositions and products according to the invention, the active ingredients may each, for example, be present at a concentration of between 0.001 and 20% by weight, relative to the total weight of the composition or product, preferably between 0.01 and 10%, more preferably between 0.02 and 5% by weight, and more preferably still between 1 and 4% by weight. In a particular embodiment, each of the two active ingredients is present at a concentration of between 1 and 3% by weight.

In one currently preferred aspect, the artesunate (or related compound) is formulated for administration at 50 to 500 mg (more preferably 100 to 300 mg such as about 200 mg) daily. Preferably, the artesunate (or related compound) is formulated for oral administration. Preferably the artesunate is administered for a period of 3 to 30 days, more preferably 10 to 20 days, such as about 14 days. This period may correspond to a cycle of treatment in an administration regime that comprises multiple such cycles of treatment (e.g. at least two, three, four, five, six, or more cycles, for example with such cycles continuing until the desired therapeutic results have been achieved). Each cycle of treatment may be separated by a break in artesunate (or related compound) administration; such a break may, for example, allow for bone marrow recovery. The break in

administration may comprise not administering the artesunate (or related compound) for a period of 3 to 14 days, more preferably 5 to 10 days, such as about 7 days.

In one exemplary such aspect, the artesunate (or related compound) is administered at about 200 mg daily for a cycle of treatment of two weeks, with each cycle being followed by a one week break.

In a currently preferred aspect, the curcumin is formulated for administration at 0.5 to 10 g (more preferably 1 to 5 g such as about 2 g) daily. Preferably, the curcumin is formulated for oral administration. Preferably the artesunate is administered at this daily dosing amount substantially continuously over the duration of the combination treatment, i.e. both during the administration of the artesunate (or related compound) as well as during any "breaks" in the administration of the artesunate (or related compound).

In one exemplary such aspect, the curcumin is administered at about 2 mg daily both during cycles of treatment with the artesunate (or related compound) and during breaks in the cycles of treatment with the artesunate (or related compound).

In the kit of the present invention, the pharmaceutical compositions (a) and (b) are typically presented as separate pharmaceutical compositions. Thus, the kit comprises: a pharmaceutical composition comprising curcumin; and, separately, (b) a pharmaceutical composition comprising artesunate.

Treatment of colorectal cancer

Typically the patient to be treated is a mammal. Preferably the patient is a human. Colorectal cancer includes colon cancer and rectal cancer.

The colorectal cancer to be treated may be metastatic or non-metastatic and may be resectable or unresectable. The colorectal cancer may also be refractory to conventional chemotherapy. For example, the colorectal cancer may be refractory to one or more of fluorouracil, capecitabine, oxaliplatin, irinotecan and UFT (Tegafur-uracil).

Treatment may be curative or palliative in nature, i.e. it may aim at curing the patient, achieving complete or partial remission, alleviating or managing symptoms and/or side effects of the disease (without curing the patient) and/or increasing life expectancy. The treatment may be an adjuvant therapy or a neo-adjuvant therapy, for example being combined with surgery, other chemotherapy strategies and/or radiotherapy.

The present invention is explained in more detail in the following by referring to the Examples, which are not to be construed as limitative.

EXAMPLES

Example 1

A series of experiments and isobologram analyses were conducted of combined artesunate-curcumin preparations in P-glycoprotein-expressing CaCo-2 colorectal cancer cell lines, HCT116 p53-wildtype and HCT-116 p53-knockout colorectal cancer cell lines. The P-glycoprotein-expressing line is more resistant to some conventional anticancer therapies.

Materials

Materials used were artesunate, curcumin, Resazurin reagent, Tecan microplate reader and a range of colorectal cancer cell lines (namely, P-glycoprotein-expressing CaCo-2 colorectal cancer cell lines, HCT116 p53-wildtype and HCT-116 p53-knockout colorectal cancer cell lines).

Method

1. Evaluations were based on three independent experiments per cell line.

2. IC50 values for curcumin and artesunate were obtained separately for each of the colon cancer cell lines.

3. From the IC50 values obtained, values lower than that of the IC50 for curcumin were selected, i.e. IC50 of 10, 20, 30 and 40 μΜ. These concentrations were then combined with varied concentrations of artesunate.

4. Each combination of curcumin and artesunate was then run on a 96-well plate and incubated for 72hrs before adding the Resazurin reagent. After a further incubation of 4hrs the plate was read on a Tecan reader.

5. The IC50 from the results obtained from the Tecan reader was then calculated. 6. The IC50 value for each combination was then divided by the IC50 of artesunate to obtain the y-axis value, and the four selected concentrations of the curcumin were also divided by the individual ICso of curcumin to obtain the x-axis value for the data plots.

7. X- and y-axis values were then plotted against each other to produce the isobologram curves.

Results

The isobolograms derived from these studies indicate that there is a synergy between the two drugs in the studied colorectal cancer cell lines.

Raw data for the separate curcumin and artesunate studies on each of the cell lines

(as per method step 2 above) are shown in Table 1.

Table

Table 2 shows the data obtained on the HCT116 p53-wildtype cell line.

ICso combi (cur-art) Cur (μΜ) X y

34.20 10 0.242718 0.708173 ± 0.54

12.06 20 0.485437 0.249749 ± 0.64

5.783794 30 0.728155 0.119747 ± 0.18

0.651417 40 0.970874 0.013487 ± 0.26 Table 2 - data obtained for HCT116 p53-wildtype cell line

FIG. 1 shows the data points obtained in establishing the IC50 for curcumin and artesunate, respectively, for the HCT116 p53-wildtype cell line. The ICso for curcumin was found to be 41.20 ± 0.6 μΜ, while the IC50 for artesunate was found to be 48.30 ± 0.3 μΜ. FIG. 2 shows the isobologram for the curcumin-artesunate combination on the HCT116 p53-wildtype cell line.

Table 3 shows the data obtained on the HCT-116 p53-knockout cell line.

FIG. 3 shows the data points obtained in establishing the IC50 for curcumin and artesunate, respectively, for the HCT-116 p53-knockout cell line. The IC50 for curcumin was found to be 48.60 ± 0.3 μΜ, while the IC50 for artesunate was found to be 50.50 ± 0.2 μΜ. FIG. 4 shows the isobologram for the curcumin-artesunate combination on the HCT- 116 p53-knockout cell line.

Table 4 shows the data obtained on the P-glycoprotein-expressing CaCo-2 cell line.

Table 4 - data obtained for P-glycoprotein-expressing CaCo-2 cell line

FIG. 5 shows the data points obtained in establishing the IC50 for curcumin and artesunate, respectively, for the P-glycoprotein-expressing CaCo-2 cell line. The IC50 for curcumin was found to be 49.80 ± 0.1 μΜ, while the ICso for artesunate was found to be 50.10 ± 0.2 μΜ. FIG. 6 shows the isobologram for the curcumin-artesunate combination on the P-glycoprotein-expressing CaCo-2 cell line. Example 2

Phase I/II open label prospective study of Artesunate and Curcumin in Metastatic

Colorectal Cancer (Met-ArtCu)

Patients are recruited who have developed progressive disease following conventional chemotherapy treatment or who are not fit for chemotherapy. Each treatment cycle consists of three weeks whereby patients are prescribed oral artesunate 200mg for two weeks followed by a one week treatment break and continuous daily curcumin.

Patients are followed up closely every 3 weeks with clinic reviews and blood tests.

Patients have CT scans once every 12 weeks to assess their response to treatment. The study drug is stopped if patients experience intolerable side effects or significant disease progression on CT imaging criteria.

Recruitment is in two phases. In Phase I of the study between 3-6 patients are recruited to assess safety and feasibility of this treatment approach in a traditional Phase I safety-response model. Provided this approach is found to be safe and well tolerated expansion is undertaken to a Phase II study, recruiting a further 30 patients to assess if this combination treatment approach leads to disease response or disease stabilisation whilst improving patient quality of life and survival.

Trial Design

Prospective open label pilot study of oral artesunate and curcumin in patients with metastatic colorectal cancer and chemo-refractory disease or patients not fit for

conventional chemotherapy.

Aim

To confirm the efficacy and safety of combined artesunate and curcumin treatment in the treatment of chemo-refractory metastatic colorectal cancer (CRC). Methods

Phase I of the study uses a traditional escalation response model (3 + 3). Three patients meeting the inclusion criteria receive oral artesunate 200mg daily for two weeks followed by a 1 week break to allow bone marrow recovery, and continuous daily curcumin for up to 4 cycles. After a 12 week enhanced early monitoring phase and in the absence of artesunate associated dose-limiting toxicity (DLT) in three consecutive patients, Phase II of the study is commenced. In the event of a DLT attributable to artesunate or curcumin, the participant ceases involvement in the trial and a further three participants are recruited at that dose level. If a participant withdraws for a reason unrelated to curcumin, only that participant is replaced. An Independent Data Monitoring committee is convened prior to commencement of Phase II to ensure patient safety.

In Phase II patients receive artesunate 200mg daily for two weeks followed by a one week break per cycle and curcumin 2g daily till disease progression on CT (according to RECIST Version 1.1 criteria) or drug intolerability. Patients are monitored closely for side effects with monthly clinic reviews, blood tests and restaging CT scans every 3 months.

Outcome measures

Phase I

Primary outcome measure: Safety and tolerability of combined artesunate and curcumin therapy for up to 4 cycles in patients with metastatic colorectal cancer.

Phase II

Primary outcome measures:

Number (%) of patients with clinical benefit in Phase II based on the following:

• Partial or complete response at any time in the study based on imaging criteria

• Stable disease at 12 weeks (4 cycles)

• Reduction of validated tumour biomarker Carcinoma Embryonic Antigen (CEA) levels Secondary outcome measures:

• Drug tolerability

• Quality of Life • Time to disease progression

• Progression free survival

• Overall survival

Claims

A pharmaceutical composition which comprises:

(a) curcumin; and

(b) artesunate;

for use in treating colorectal cancer.

Curcumin for use in treating colorectal cancer by co-administration with artesunate.

Artesunate for use in treating colorectal cancer by co-administration with curcumin.

A method of treating a patient suffering from colorectal cancer, which method comprises co-administering to said patient curcumin and artesunate.

A product comprising (a) curcumin, and (b) artesunate, as a combined preparation for simultaneous, concurrent, separate or sequential use in the treatment of a patient suffering from colorectal cancer.

Use of curcumin in the manufacture of a medicament for the treatment of colorectal cancer by co-administration with artesunate.

Use of artesunate in the manufacture of a medicament for the treatment of colorectal cancer by co-administration with curcumin.

A pharmaceutical composition which comprises:

(a) curcumin; and

(b) artesunate.

A kit which comprises:

(a) a pharmaceutical composition comprising curcumin; and

(b) a pharmaceutical composition comprising artesunate.