AU5280790A

AU5280790A - Glycosylated insulins

Info

Publication number: AU5280790A
Application number: AU52807/90A
Authority: AU
Inventors: John Broberg Halstrom
Original assignee: Novo Nordisk AS
Current assignee: Novo Nordisk AS
Priority date: 1989-03-08
Filing date: 1990-03-06
Publication date: 1990-10-09
Anticipated expiration: 2010-03-06
Also published as: JPH04504117A; EP0462192A1; GR900100159A; NZ232808A; DD296933A5; IL93674A0; WO1990010645A1; HU902787D0; FI914226A0; GR1000604B; NO913517D0; ZA901737B; NO913517L; PT93366A; AU638701B2; CN1045586A; CS114290A3; DK111489D0; CA2049937A1; KR920701249A

Description

Glycosylated insulins.

The present invention relates to specifically glyco¬ sylated insulins and combinations thereof, pharmaceutical prep¬ arations containing such glycosylated compounds and a method for their preparation. In the recent years, several insulin analogues have been suggested for the treatment of diabetes ellitus. The pur¬ pose of developing such insulin analogues has been to improve the insulin replacement therapy by making available insulin analogues with either a more rapid or a more protracted insulin action compared to especially human insulin.

A problem in the development of insulin analogues by substituting one or more of the amino acid residues in native insulin is the potential im unogenicity of such compounds. Also unforeseeable solubility and stability problems may arise from such substitutions.

Although insulin has a very short half life time in circulating blood, it can not be excluded that a small amount of insulin is glycosylated in vivo not only in diabetic patients as postulated by Nakayama et al. (Nonenzymatic glyco- sylation of insulin in "Current topics in clinical and experi¬ mental aspects of diabetes mellitus" (1985), 201 - 204, Saka¬ moto, Min and Baba, Eds., Elsevier Science Publishers B.V.) but also in non-diabetics. It is therefore possible that the organ¬ ism has developed mechanisms to suppress the formation of anti- bodies against glycosylated insulin. It is furthermore possible that the conformational changes of the saccharide part will be able to camouflage the antigen.

The binding of glucose, mannose and certain oligo- saccharides to insulin has been the subject of numerous in vitro studies in the past with the purpose of investigating whether in vivo formation of glycosylated insulin might be re¬ sponsible for late complications in diabetic patients. Anzen- bacher et al. (Biochimica et Biophysica Acta 386 (1975), 60₃- 607) studied the binding of D-glucose to insulin by eguilibriu dialysis. The binding was not found to be very the specific and the average number of glucose molecules bound to the insulin molecule was found to be eight.

Interaction of insulin with glucose and mannose was studied by Dolhofer et al. (Febs Letters 100 (1979) , 133- 136) . The results indicated that both hexoses were covalently incorporated into the insulin molecule upon incubation in vitro at 37°C. Under the chosen reaction conditions, in average 3.6 ± 0.39 glucose and 5.0 ± 0.43 mannose residues were found to be taken up per molecule of insulin. A glucose controlled insulin delivery system was sug¬ gested by Brownlee & Cerami (Science 206 (1979) , 1190 - 1191, and Diabetes 3_2. (1983) , 499 - 505) by synthesizing glycosylated insulin derivatives which are able to compete with glucose for binding to lectins. In this study maltose and other oligo- saccharides were reacted with insulin.

Nakayama et al. (supra) investigated non-enzymatic glycosylation of insulin in vitro and in vivo (diabetic patients) and concluded that glucose was incorporated into the insulin molecule in vivo under pathological conditions. By the in vitro studies, 3 molecules of glucose were found to be in¬ corporated per molecule of insulin.

In 1988, Lapolla et al. (Diabetes 3_7 (1988), 787- 791) reported a reduced in vivo biological activity of in vitro glycosylated insulin. Insulin was glycosylated in ambient high glucose concentration according to Dolhofer (supra) in aqueous solution at 37"C for 17 hours at a pH value of 7.4. The incor¬ poration of glucose was found to be in average 2 mol glucose residue/mol insulin.

Taking into account that native insulin has three free primary amino groups viz. at position Bl (Phe) , Al (Gly) and B29 (Lys) , respectively, it is apparent that the above de¬ scribed glycosylated insulin preparations will all be inhomo- geneous mixtures of glycosylated insulin molecules.

Nobody has so far taken any steps to fractionate the above mixture into the individual components. Glycosylated insulin derivatives for self-regulating insulin delivery systems have been described by Kim et al. (Journal of Controlled Release 1 (1984), 57 - 66, and US patent specification Nos. 4,483,792; 4,478,830; 4,478,746 and 4,489,063). In these glycosylated insulins, glucose or mannose is coupled with insulin via a spacer group derived from di- carboxylic acids, acid anhydrides or phenyl amines or a combi¬ nation thereof.

European patent application No. 84200328 having pub- lication No. 119,650 relates to galactosyl insulins which like the glycosylated insulins described by Kim (supra) contain a spacer group.

It is the purpose of this invention to prepare insu¬ lin derivatives having improved properties. More specifically, it is the purpose of the present invention to develop non-im- munogenic insulin derivatives. It is furthermore the purpose of the present invention to develop insulin derivatives with a faster onset of insulin action than native insulin and to im¬ prove the solubility of less soluble insulins in order to allow the use of highly concentrated solutions, for example in insu¬ lin pumps. A still further purpose of this invention is to pre¬ pare insulin derivatives with an improved stability against fi¬ brillation.

The present invention provides specifically glyco- sylated insulins. Hereinafter the term specifically glycosy¬ lated insulins designates insulins having the carbohydrate sub- stituent in a specific position in the insulin molecule. Sur¬ prisingly, such specifically glycosylated insulins offer cer¬ tain therapeutical advantages as will be apparent from the fol- lowing description and examples.

In its broadest aspect the present invention provides specifically glycosylated insulins. In a narrower aspect the present invention provides insulin derivatives being either monoglycosylated in position Al, Bl or B29; diglycosylated in position Al and Bl; Al and B29; or Bl and B29 or triglycosy- lated in position Al, Bl and B29.

The glycosylated insulins described by Kim et al. and dealt with above are remote from the insulins of the present invention, which utilizes the aldehyde function of the sugar itself to form a covalent bond to insulin, without the use of artificial spacer groups. A further advantage of the present invention over the insulins of Kim et al. is the retention of the natural charge distribution of the insulin molecule. Thus, the amino groups involved which by the glycosylation reaction (see diagram) are converted into secondary amino groups are still capable of being protonated, as in normal insulin.

The present insulin derivatives may in each of the three positions contain a monosaccharide or an oligosaccharide with up to three sugar residues. Suitable monosaccharides are glucose, mannose and galactose. Suitable oligosaccharides are maltose, isomaltose, lactose, maltotriose, melibiose and cello- biose.

The specifically glycosylated insulin derivatives of this invention may be used as such for the treatment of dia- betes mellitus. With the purpose of monitoring the insulin therapy, selected mixtures of the individual specifically gly¬ cosylated compounds may however also be used.

As used herein, the expression insulins is meant to cover native forms of insulin such as human, bovine and porcine insulin, but also derivatives thereof wherein one or more amino acid residues have been substituted, added or deleted, compared with native insulin, for example as described in European patent applications having publication Nos. 0194864A and 0214826A. As mentioned above, native insulins have three poten¬ tial glycosylation sites, namely the two N-terminal amino acid residues in the A- and B-chain and the lysine residue in posi¬ tion B29. It is apparent that the number of potential glycosy¬ lation sites in insulin analogues of the above described type may be from two (the two N-terminal residues) and upwards de- pending on how many lysine residues are present in the modified insulin molecule, lysine being the only naturally occurring amino acid with a free primary amino group in the side chain.

The glycosylation schematically proceeds according to the following diagramme using D-glucose:

D-glucose D-glucose pyranose structure chain structure

The chain structure is the reactive component

NH-"insulin" + H₂N-"insulin"

~^~ insulin"

1 deoxy-D-fructosyl insulin (glucose insulin) "insulin" designates desamino insulin.

The above reaction will proceed in an analogous manner with other monosaccharides or oligosaccharides having a free aldehyde group.

Specific examples of the present glycosylated insu- lins are:

Phe(Bl) glucose human insulin, Phe(Bl) mannose human insulin. Gly(Al) mannose human insulin, Lys(B29) mannose human insulin, Phe(Bl) galactose human insulin, Gly(Al) galactose human insulin, Lys(B29) galactose human insulin, Phe(Bl) maltose human insulin, Phe(Bl) lactose human insulin, Gly(Al) glucose human insulin, Gly(Al) maltose human insulin, Gly(Al) lactose human insulin, Lys(B29) glucose human insulin, Lys(B29) maltose human insulin, Lys(B29) lactose human insulin, Gly(Al) ,Phe(Bl) diglucose human insulin, Gly(Al) ,Lys(B29) diglucose human insulin, Phe(Bl) ,Lys(B29) diglucose human insulin, Phe(Bl) isomaltose human insulin, Gly(Al) isomaltose human insulin, Lys(B29) isomaltose human insulin, Phe(Bl) maltotriose human insulin, Gly(Al) maltotriose human insulin, Lys(B29) maltotriose human insulin, Gly(Al) ,Phe(Bl) dimaltose human insulin, Gly(Al) ,Lys(B29) dimaltose human insulin, Phe(Bl) ,Lys(B29) dimaltose human insulin, Gly(Al) ,Phe(Bl) dilactose human insulin, Gly(Al) ,Lys(B29) dilactose human insulin, Phe(Bl) ,Lys(B29) dilactose human insulin, Gly(Al) ,Phe(Bl) dimaltotriose human insulin, Gly(Al) ,Lys(B29) dimaltotriose human insulin, Phe(Bl) ,Lys(B29) dimaltotriose human insulin, Phe(Bl) ,Gly(Al) dimannose human insulin, Phe(Bl) ,Lys(B29) dimannose human insulin, Gly(Al) ,Lys(B29) dimannose human insulin, Phe(Bl) ,Gly(Al) digalactose human insulin, Phe(Bl) ,Lys(B29) digalactose human insulin, Gly(Al) ,Lys(B29) digalactose human insulin, Phe(Bl) ,Gly(Al) diisomaltose human insulin, Phe(Bl) ,Lys(B29) diisomaltose human insulin, Gly(Al) ,Lys(B29) diisomaltose human insulin,

Gly(Al) ,Phe(Bl) ,Lys(B29) triglucose human insulin, Gly(Al) ,Phe(Bl) ,Lys(B29) trimaltose human insulin, Gly(Al) ,Phe(Bl) ,Lys(B29) trilactose human insulin, Gly(Al) ,Phe(Bl) ,Lys(B29) trimaltotriose human insulin. Gly(Al) ,Phe(Bl) ,Lys(B29) trimannose human insulin, Gly(Al) ,Phe(Bl) ,Lys(B29) trigalactose human insulin, Gly(Al) ,Phe(Bl) ,Lys(B29) triisomaltose human insulin, Phe(Bl) glucose [Asp^B1°] human insulin, Gly(Al) ,Phe(Bl) diglucose [Asp^B1°] human insulin.

Also, specifically glycosylated insulins from other species such as porcine are interesting.

The present glycosylated insulins may be prepared by reacting insulin or an insulin analogue with an excess of the selected monosaccharide or oligosaccharide in a suitable or¬ ganic or aqueous medium. The temperature may vary from 20 to 60°C. As organic solvents lower carboxylic acids, for example acetic acid and propionic acid, lower aliphatic alcohols, for example methanol, ethanol and 2-propanol, ethylene glycol and propylene glycol may be used. However, phenols may also be used.

The duration of the reaction and the composition of the reaction mixture will depend on whether a mono-, di- or triglycosylated end product is desired. The reaction may con- veniently be followed by reversed phase high pressure liquid chromatography (hereinafter designated RP HPLC) to determine the point of maximum formation of each of the individual glyco¬ sylated products.

The reaction is stopped by cooling, for example to -20°C, and the reaction mixture is concentrated to dryness whereupon the major components of the reaction mixture are iso¬ lated and purified by preparative RP HPLC. After desalting, the products are characterized by fast atom bombardment mass spec- trometry (hereinafter designated FAB-MS) , quantitative amino acid analysis after borohydride reduction and bioassays.

The present glycosylated insulins and mixtures there¬ of may be substituted for the human or porcine insulin in the insulin preparations heretofore known in the art to prepare novel insulin preparations. Such novel insulin preparations will contain the glycosylated insulin or a pharmaceutically acceptable salt thereof in an aqueous solution, preferably at a neutral pH value. Preferably, the aqueous medium is made isoto- nic, for example with sodium chloride, sodium acetate or gly- cerol. Furthermore, the aqueous medium may contain zinc ions, buffer components such as acetate or phosphate and a preserva¬ tive such as m-cresol, methylparaben or phenol. The pH value of the preparation may be adjusted to the desired value and the preparation can be sterilized by filtration.

The insulin preparation of the present invention can be used similarly to the use of the known insulin preparations.

EXPERIMENTAL PART

Example 1 Phe(Bl) glucose human insulin

Human insulin (0.1 mmol) was suspended in methanol (30 ml) and glacial acetic acid (5 ml) was added at ambient temperature. The mixture was gently stirred until the insulin had dissolved. Then, a further quantity of methanol (35 ml) was added and after addition of D-glucose (2.2 mmol), the mixture was gently stirred at 40°C for 8 hours, by which the title com¬ pound became the main component.

The solution was concentrated almost to dryness on a rotatory evaporator. The residue was dissolved in water and fractionated by preparative RP HPLC. Column: 16 x 250 mm with 7 μm 100 A C₁₈ particles. Temperature 30°C. Mobile phase. A: 0.04 M phosphoric acid, 0.2 M sodium sulphate, 10% acetonitrile, pH value adjusted to 2.5 with ethanol amine. B: 50% acetonitrile. The fraction corresponding to the central part of the major peak was desalted and lyophilized. The yield was 0.02 mmol. The product was characterized by FAB-MS and quantitative amino acid analysis after borohydride reduction. The amino acid analysis showed the presence of two phenylalanine residues (i.e. one less phenylalanine residue compared to human insulin) proving substitution in Phe(Bl) . The molecular weight was found to be 5970 (calculated: 5970) .

Example 2

Phe(Bl) .Gly(Al) diσlucose human insulin

The above compound was prepared as described in Example 1 with the exception that the reaction time was 16 hours instead of 8 hours, by which the title compound became the main component.

The yield was 0.06 mmol.

The amino acid analysis showed the presence of one less Phe and one less Gly residue proving a substitution in po- sition Al and Bl.

The molecular weight measured was 6132 (calculated: 6132) .

The subcutaneous absorption was measured in pigs by injection of ¹²⁵l labelled Phe(Bl) ,Gly(Al) diglucose insulin prepared using the iodate method essentially as described (Jør- gensen et al., Diabetologia JL9 (1980), 546 - 554). The absorp- tion rate after subcutaneous injection into pigs of 1 ^J-2^<"5^Jχ human insulin and 125I Phe(Bl) ,Gly(Al) diglucose human insulin is shown in Table 1, below. The T₇₅, T₅₀ and T ₅ values given in Table 1 are the time (in hours) elapsed from the moment of in- 10

jection of the sample until the radioactivity measured at the site of injection has decreased to 75%, 50% and 25%, respecti¬ vely, of the initial value. It appears from Table 1 that the glycosylated insulin has a significantly faster absorption than human insulin.

TABLE 1

^•75 T50 ^•25

human insulin 1.12 2.33 3.69 diglucose human insulin 0.65 1.47 2.76

The blood glucose lowering effect of human insulin (Actrapid™) and Gly(Al) ,Phe(Bl) diglucose human insulin by subcutaneous injection in pigs (mean of 5 animals) in an amount of 0.1 U/kg appears from Table 2, below. Table 2 gives the values for glucose in mmol/1.

TABLE 2

Time. Human Dicrlucose human hours insulin insulin -0.33 5.30 5.24

0 5.36 5.32

0.33 4.78 4.76

0.67 4.72 4.06

1 4.12 3.34

1.5 3.60 2.98

2 3.24 2.84

2.5 3.28 2.96

3 3.18 3.14

4 3.34 3.96 Table 2 shows the fast action of diglucose insulin compared with human insulin.

The immune responses in rabbits (mean values for 10 animals) of human insulin, bovine insulin and Gly(Al) ,Phe(Bl) diglucose human insulin appear from Table 3, below, giving values for percentage binding in rabbit serum. (Method: Schlichtkrull et al. (Horm. Metab. Res. Suppl. ser. 5_ (1974), 134 - 143) ) .

TABLE 3

Time. Human Bovine Diσlucose human days insulin insulin insulin

0 1.9 -0.4 1.2

13 2.3 0.6 1.3

27 3.0 28.5 1.5

41 3.2 29.7 1.4

55 4.3 30.7 1.1

69 3.9 32.7 2.2

83 2.4 30.1 1.1

97 2.0 32.6 1.5

It appears from Table 3 that diglucose human insulin has a surprisingly low immune response which corresponds to that of human insulin.

Example 3

The following compounds were prepared analogously.

The molecular weight measured by FAB-MS or plasma desorption mass spectroscopy, together with the calculated molecular weight, is given for each of the compounds. Molecular weight

Compound Measured Calcu' lated

Phe(Bl) galactose human insulin 5956 5970

Phe(Bl) maltose human insulin 6119 6132

Phe(Bl) lactose human insulin 6125 6132

Phe(Bl) maltotriose human insulin 6288 6294

Gly(Al) ,Phe(Bl) dimaltose human insulin 6444 6456

Gly(Al) ,Phe(Bl) dilactose human insulin 6446 6456

Gly(Al) ,Phe(Bl) dimaltotriose human insulin L 6771 6780

Gly(Al) ,Phe(Bl) ,Lys(B29) triglucose human insulin 6294 6294

Gly(Al) ,Phe(Bl) diglucose [Asp^B1°] human insulin 6112 6110

The location of the bound sugar residues was confirmed by boro- hydride reduction followed by quantitative amino acid analysis.

Claims

1. Specifically glycosylated insulins containing one or more monosaccharide groups or one or more oligosaccharide groups with up to three sugar units.

2. Glycosylated insulin according to claim l con¬ taining one monosaccharide group or one oligosaccharide group with up to three sugar units.

3. Glycosylated insulin according to claim 1 con- taining two monosaccharide groups or two oligosaccharide groups with up to three sugar units.

4. Glycosylated insulin according to claim l con¬ taining three monosaccharide groups or three oligosaccharide groups with up to three sugar units.

5. Glycosylated insulin according to claim 2 being monoglycosylated in position Al, Bl or B29.

6. Glycosylated insulin according to claim 3 being diglycosylated in position Al and Bl; Al and B29; or Bl and B29.

7. Glycosylated insulin according to claim 4 being triglycosylated in position Al, Bl and B29.

8. Glycosylated insulin according to any one of the preceding claims containing Asp in position BIO.

9. Glycosylated insulin according to any one of the preceding claims, characterized in that the parent insulin species are human.

10. Phe(Bl) glucose human insulin.

11. Phe(Bl) ,Gly(Al) diglucose human insulin.

12. A composition containing at least 90%, preferably at least 95%, most preferred at least 99%, of a specifically glycosylated insulin according to any one of the preceding claims.

13. Pharmaceutical preparations containing a speci¬ fically glycosylated insulin according to any of the previous claims or a pharmaceutically acceptable salt thereof optionally together with pharmaceutically acceptable adjuvants and additives and preservatives.

14. A process for the preparation of specifically glycosylated insulins according to any of the previous claims 1 - 11 wherein the appropriate insulin is reacted in an aqueous or organic medium with a monosaccharide with a free aldehyde group or an oligosaccharide with a free aldehyde group and with up to three sugar units whereupon the desired product is iso¬ lated from the reaction mixture.

15. Any novel feature or combination of features de¬ scribed herein.

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