JP2022024207A - Polyamino acid, block copolymer, and polymer particle composition - Google Patents

Abstract

To provide a delivery technique capable of improving the blood retention of 1-methyl-tryptophan and efficiently delivering it to a tumor.SOLUTION: A polyamino acid comprises at least one repeating unit derived from 1-methyl-tryptophan represented by the following formula (I). A block copolymer has a hydrophilic polymer segment and a hydrophobic polymer segment. Here, the hydrophobic polymer segment contains the polyamino acid. A polymer particle composition comprises the polyamino acid or the block copolymer.SELECTED DRAWING: None

Description

The present invention relates to polyamino acids and block copolymers containing repeating units derived from 1-methyl-tryptophan, and polymer particle compositions containing the polyamino acids or block copolymers.

In recent years, cancer immunotherapy has attracted attention, and it is expected that administration of antibodies and small molecule compounds will activate immune cells and increase antitumor effects. As one of such small molecule compounds, 1-methyl-D-tryptophan (MDT), which activates immune cells by inhibiting indoleamine-2,3-dioxygenase (IDO), which suppresses immunity, is being investigated. (For example, Non-Patent Document 1). However, a sufficient antitumor effect has not been obtained so far in the living body administration of MDT.

Nature Biotechnology, volume 33, pages 321-322 (2015)

One of the reasons why the antitumor effect of MDT is not sufficiently obtained by the above-mentioned living body administration is that the blood retention of MDT is low, and as a result, the tumor accumulation of MDT is low. The present invention has been made to solve this problem, and a main object thereof is to provide a technique for improving the blood retention of 1-methyl-tryptophan and efficiently delivering it to a tumor. ..

１つの実施形態において、上記１－メチル－トリプトファンが、１－メチル－Ｌ－トリプトファンを含む。
１つの実施形態において、上記ポリアミノ酸は、他のアミノ酸に由来する繰り返し単位をさらに含む。
本発明の別の局面によれば、親水性ポリマーセグメントと疎水性ポリマーセグメントとを有し、該疎水性ポリマーセグメントが上記ポリアミノ酸を含む、ブロックコポリマーが提供される。
本発明のさらに別の局面によれば、上記ポリアミノ酸又は上記ブロックコポリマーを含む、ポリマー粒子組成物が提供される。
１つの実施形態において、上記ポリマー粒子組成物は、薬物をさらに含む。 According to one aspect of the invention, a polyamino acid comprising at least one repeating unit derived from 1-methyl-tryptophan represented by the following formula (I) is provided.

In one embodiment, the 1-methyl-tryptophan is comprising 1-methyl-L-tryptophan.
In one embodiment, the polyamino acid further comprises repeating units derived from other amino acids.
According to another aspect of the present invention, there is provided a block copolymer having a hydrophilic polymer segment and a hydrophobic polymer segment, wherein the hydrophobic polymer segment contains the above polyamino acid.
According to yet another aspect of the present invention, there is provided a polymer particle composition comprising the polyamino acid or the block copolymer.
In one embodiment, the polymer particle composition further comprises a drug.

In the present invention, since a polyamino acid containing 1-methyl-tryptophan as a repeating unit is used, renal excretion is suppressed as compared with the case where it is administered as a small molecule compound, while 1-methyl is utilized by enzymatic degradation. -It is possible to release tryptophan slowly. In addition, by using a block copolymer in which the polyamino acid and the hydrophilic polymer are linked, it is possible to form a polymer micelle with the polyamino acid segment facing inward and the hydrophilic polymer segment facing outward, so that foreign matter recognition by immune cells can be formed. It can be expected that the blood retention will be improved and the accumulation in tumors will be expected.

It is a graph which shows the result of the enzymatic decomposition test of polymethyltryptophan (n = 1). It is a graph which shows the result of the inhibition test of indoleamine-2,3-dioxygenase (IDO). All results are shown as mean ± SD (n = 3). It is a graph which shows the result of the inhibition test of indoleamine-2,3-dioxygenase (IDO).

Hereinafter, preferred embodiments of the present invention will be described, but the present invention is not limited to these embodiments. Moreover, each embodiment can be combined as appropriate.

As used herein, the term amino acid means an organic compound having both functional groups of an amino group and a carboxyl group. Therefore, the amino acid includes α-amino acid, β-amino acid, γ-amino acid and δ-amino acid, and the α-amino acid may be either L-form or D-form. Further, the amino acid is not limited to the natural amino acid, and may be an amino acid derivative in which various groups are introduced into the side chain of the natural amino acid.

As used herein, a polyamino acid means a compound in which two or more amino acids are linked via a peptide bond.

A. Polyamino acid The polyamino acid in one embodiment of the present invention may be referred to as a repeating unit derived from 1-methyl-tryptophan represented by the following formula (I) (hereinafter, referred to as "1-methyl-tryptophan residue"). The same applies to other amino acids). In the conventional drug delivery system (DDS), the drug is carried by covalently or non-covalently binding the DDS carrier and the drug, or by encapsulating or dispersing the drug in the DDS carrier. In the embodiment, the polymer 1-methyl-tryptophan itself, which is a drug, can be used as a carrier. As a result, 1-methyl-tryptophan can be sustained-release to improve blood retention without the need to prepare a separate carrier. In addition, the dose can be easily increased or decreased by adjusting the degree of polymerization.

The number of 1-methyl-tryptophan residues contained in the polyamino acid is 1 or more, typically 2 or more, for example, 5 to 300, preferably 10 to 200, more preferably 15 to 150, and further. It can be preferably 20 to 100.

The 1-methyl-tryptophan represented by the above formula (I) is 1-methyl-D-tryptophan represented by the following formula (Ia), 1-methyl-L-tryptophan represented by the following formula (Ib), or these. Can include both. From the viewpoint of preferably releasing the drug by undergoing proteolysis by a protease or proteasome, the 1-methyl-tryptophan represented by the above formula (I) preferably contains 1-methyl-L-tryptophan, and 1-methyl-tryptophan is preferable. More preferably, it is L-tryptophan.

The polyamino acid may further contain amino acid residues other than 1-methyl-tryptophan, depending on the purpose. The other amino acids are not limited as long as the effects of the present invention are obtained, and any suitable natural or non-natural amino acids, for example, amino acids used in DDS carriers including conventional polyamino acids are used. be able to. Specific examples include amino acids having a hydrophilic group in the side chain, amino acids having a hydrophobic group in the side chain, and amino acids having a functional group in the side chain. Further, other amino acids are not limited to natural or non-natural amino acids used as DDS carriers to the extent that 1-methyl-tryptophan can be released from polyamino acids.

Examples of the amino acid having a hydrophilic group or a functional group in the side chain include an amino acid having a hydroxyl group, a carboxyl group, an amino group, an amide group, a maleimide group, a hydrazide group, a thiol group and the like in the side chain. These hydrophilic groups or functional groups may be unique to amino acids or may be additionally introduced. Examples of amino acids having a unique hydrophilic group or functional group include serine, threonine, tyrosine, aspartic acid, glutamic acid, lysine, ornithine, arginine, histidine, asparagine, glutamine, cysteine and the like. Of these, aspartic acid, glutamic acid, lysine, ornithine and arginine are preferable. Amino acids into which a functional group has been additionally introduced include a derivative in which aminopentane (AP) is introduced into the side chain carboxylic acid of aspartic acid or glutamic acid, and diethylenetriamine (DET: H ₂ ) to the side chain carboxylic acid of aspartic acid or glutamic acid. Examples thereof include derivatives into which NCH ₂ CH ₂ NH-CH ₂ CH ₂ NH ₂ ) have been introduced. By using an amino acid having a hydrophilic group in the side chain, a polyamino acid having increased solubility in an aqueous medium can be obtained. Further, by using an amino acid having a functional group in the side chain, a drug (drug other than 1-methyl-tryptophan), a cross-linking agent, or the like can be bound to the side chain of the polyamino acid.

Examples of the amino acid having a hydrophobic group in the side chain include amino acids having a solubility of 5 g or less, more preferably 4 g or less, in 100 g of water at 25 ° C. Examples of such amino acids include non-polar natural amino acids such as leucine, isoleucine, phenylalanine, methionine, and tryptophan, and derivatives in which a hydrophobic group is introduced into the side chain of the natural amino acid. The derivative preferably includes a derivative in which a hydrophobic group is introduced into the side chain of an acidic amino acid such as aspartic acid or glutamic acid. As the hydrophobic group to be introduced, a saturated or unsaturated linear or branched aliphatic hydrocarbon group having 6 to 27 carbon atoms, an aryl group having 6 to 27 carbon atoms, an aralkyl group or a cholesterol residue is preferable. Can be exemplified. By using an amino acid having a hydrophobic group in the side chain, the degree of hydrophobicity of the polyamino acid is increased, and as a result, the block copolymer containing the polyamino acid described in Item B as one block component more preferably forms a polymer micelle. be able to.

（式中、
Ｒ^１は、水酸基、オキシベンジル基、－Ｏ－Ｒ^１ａ又は‐ＮＨ－Ｒ^１ｂ基を表し、ここでＲ^１ａ又はＲ^１ｂはそれぞれ独立して、未置換又は置換された直鎖もしくは分枝の炭素数１～１２アルキル基を表し、
Ｒ^２は、水素原子、未置換又は置換された直鎖もしくは分枝の炭素数１～１２のアルキル基あるいは未置換又は置換された直鎖もしくは分枝の炭素数１～２４のアルキルカルボニル基を表し、
Ｒ^３ａ、Ｒ^３ｂ、Ｒ^４ａ及びＲ^４ｂは、相互に独立して、メチレン基又はエチレン基を表し、
Ｒ^５ａ及びＲ^５ｂは、相互に独立して、－Ｏ－又はＮＨ－を表し、
Ｒ^６ａ及びＲ^６ｂは、相互に独立して、水素原子又は疎水性有機基を表し；
Ｒ^７ａ及びＲ^７ｂは、相互に独立して、下記の基：
－ＮＨ－（ＣＨ_２）_ｐ１－〔ＮＨ－（ＣＨ_２）_ｑ１－〕_ｒ１ＮＨ_２ （ｉ）；
－ＮＨ－（ＣＨ_２）_ｐ２－Ｎ〔－（ＣＨ_２）_ｑ２－ＮＨ_２〕_２ （ｉｉ）；
－ＮＨ－（ＣＨ_２）_ｐ３－Ｎ｛〔－（ＣＨ_２）_ｑ３－ＮＨ_２〕〔－（ＣＨ_２）_ｑ４－ＮＨ－〕_ｒ２Ｈ｝ （ｉｉｉ）；
－ＮＨ－（ＣＨ_２）_ｐ４－Ｎ｛－（ＣＨ_２）_ｑ５－Ｎ〔－（ＣＨ_２）_ｑ６－ＮＨ_２〕_２｝_２ （ｉｖ）；及び
－ＮＨ－（ＣＨ_２）_ｐ５－ＮＨ_２ （ｖ）
からなる群の同一もしくは異なる基から選ばれ、
ここで、ｐ１～ｐ５、ｑ１～６、及びｒ１～ｒ２は、それぞれ相互に独立して、１～５の整数であり、
Ｒ^８は、リシン、オルニチン、アルギニン、ホモアルギニン、及びヒスチジンからなる群より選択されるアミノ酸の側鎖を表し、
ａ、ｂ、ｃ、ｄ、及びｅは、それぞれ独立して、０～２００の整数であり；
ｆは、１～３００の整数を表し；
ただし、２≦ａ＋ｂ＋ｃ＋ｄ＋ｅ＋ｆ≦４００の関係を満たし；
上記各アミノ酸残基の結合順は任意であり；
Ｒ^６ａ、Ｒ^６ｂ、Ｒ^７ａ、Ｒ^７ｂ及びＲ^８は、ポリマー分子内のアミノ酸残基毎に任意に選択可能である。） In one embodiment, the polyamino acid can be represented by the following formula (II).

(During the ceremony,
R ¹ represents a hydroxyl group, an oxybenzyl group, -OR ^1a or -NH-R ^1b group, where R ^1a or R ^1b are independently unsubstituted or substituted linear or branched. Represents an alkyl group with 1 to 12 carbon atoms
R ² is a hydrogen atom, an unsubstituted or substituted linear or branched alkyl group having 1 to 12 carbon atoms, or an unsubstituted or substituted linear or branched alkyl carbonyl group having 1 to 24 carbon atoms. Represent,
R ^3a , R ^3b , R ^4a and R ^4b independently represent a methylene group or an ethylene group.
R ^5a and R ^5b represent -O- or NH- independently of each other.
R ^6a and R ^6b represent hydrogen atoms or hydrophobic organic groups independently of each other;
R ^7a and R ^7b are independent of each other and have the following groups:
-NH- (CH ₂ ) _p1- [NH- (CH ₂ ) _q1- ] _r1 NH ₂ (i);
-NH- (CH ₂ ) _p2 -N [-(CH ₂ ) _q2 -NH ₂ ] ₂ (ii);
-NH- (CH ₂ ) _p3 -N {[-(CH ₂ ) _q3 -NH ₂ ] [-(CH ₂ ) _q4 -NH-] _r2 H} (iii);
-NH- (CH ₂ ) _p4 -N {-(CH ₂ ) _q5 -N [-(CH ₂ ) _q6- NH ₂ ] ₂ } ₂ (iv); and -NH- (CH ₂ ) _p5 -NH ₂ ( v)
Selected from the same or different groups of groups consisting of
Here, p1 to p5, q1 to 6, and r1 to r2 are integers of 1 to 5 independently of each other.
^R8 represents the side chain of an amino acid selected from the group consisting of lysine, ornithine, arginine, homoarginine, and histidine.
a, b, c, d, and e are independently integers from 0 to 200;
f represents an integer from 1 to 300;
However, the relationship of 2≤a + b + c + d + e + f≤400 is satisfied;
The order of binding of each of the above amino acid residues is arbitrary;
R ^6a , R ^6b , R ^7a , R ^7b and R ⁸ can be arbitrarily selected for each amino acid residue in the polymer molecule. )

In the above formula (II), the linear or branched alkyl group having 1 to 12 carbon atoms defined by the groups of R ^1a , R ^1b and R ² is, for example, a methyl group, an ethyl group or n-propyl. Examples include a group, an isopropyl group, an n-butyl group, a sec-butyl group, a tert-butyl group, an n-hexyl group, a decyl group, an undecyl group and the like.

The linear or branched alkyl moiety having 1 to 12 carbon atoms in the linear or branched alkylcarbonyl group having 1 to 24 carbon atoms defined by the group of ^R2 can be referred to the above-mentioned example. Examples of the alkyl moiety having 13 or more carbon atoms include a tridecyl group, a tetradecyl group, a pentadecyl group, a nonadecil group, a docosanyl group and a tetracosyl group.

With respect to the above alkyl group or alkyl moiety, the substituent when "substituted" is not limited, but is limited to C _1-6 alkoxy group, aryloxy group, arylC _1-3 oxy group, cyano group, carboxyl. Group, amino group, C _1-6 alkoxycarbonyl group, C _2-7 acylamide group, tri-C _1-6 alkyl syroxy group, syroxy group, silyl amino group or acetalized formyl group, formyl group, chlorine or Halogen atoms such as fluorine can be mentioned. Here, for example, a display such as C _1-6 means 1 to 6 carbon atoms.

When both R ^3a and R ^3b represent an ethylene group, they typically represent a polyamino acid having b = 0 or a = 0. The former represents, for example, poly-α-glutamic acid obtained by polymerization of N-carboxylic acid anhydride of glutamic acid γ-benzyl ester, and the latter represents, for example, a strain of the bacterium Bacillus including Bacillus natto. Represents the poly-γ-glutamic acid produced. On the other hand, when both R ^3a and R ^3b represent a methylene group, it is understood that each repeating unit having these groups can coexist. The same applies to R ^4a and R ^4b .

The hydrophobic organic group defined by the groups of R ^6a and R ^6b is, for example, a saturated or unsaturated linear or unsaturated aliphatic hydrocarbon group having 6 to 27 carbon atoms and an aryl having 6 to 27 carbon atoms. A residue derived from a group, an aralkyl group, or a sterol. Specific examples include a phenyl group, a naphthyl group, a tolyl group, a xylyl group, a benzyl group, a phenethyl group and the like. Further, by using the groups of R ^6a and R ^6b as hydrogen atoms, the hydrophilicity of the polyamino acid can be increased. In this case, R ^5a and R ^5b are preferably oxygen atoms.

The groups of R ^7a and R ^7b are preferably the groups of the formula (i) or (v) independently of each other. In formula (i), p1 and q1 are preferably 2 or 3 independently of each other, and more preferably 2. On the other hand, r1 is preferably an integer of 1 to 3.

The group of ^R8 is preferably a side chain of lysine or ornithine.

F, which represents the number of repetitions of the 1-methyl-tryptophan residue, is typically an integer of 2 or more, for example, an integer of 5 to 300, preferably an integer of 10 to 200, and more preferably an integer of 15 to 150. More preferably, it is an integer of 20 to 100. The 1-methyl-tryptophan residue is preferably a 1-methyl-L-tryptophan residue.

A, b, c, d, and e, which represent the number of repetitions of other amino acid residues, are independently, preferably an integer of 0 to 150, and more preferably an integer of 0 to 100, respectively. The degree of polymerization of the polyamino acid (a + b + c + d + e + f) is, for example, an integer of 5 to 300, preferably an integer of 10 to 250, and more preferably an integer of 15 to 200.

The polyamino acid represented by the formula (II) may be N-carboxylic acid anhydride (NCA) of 1-methyl-tryptophan and optionally another amino acid NCA (eg, β), starting with, for example, n-butylamine or the like. -Polyamino acids are synthesized by polymerizing protected amino acids such as benzyl-L-aspartate, γ-benzyl-L-glutamate, and Nε-Z-L-lysine (N-carboxylic acid anhydride) to synthesize polyamino acids, if necessary. Therefore, it can be produced by deprotecting the side chain of the obtained polyamino acid and optionally introducing the groups (i) to (v).

In the process of the above synthesis, a structural change (for example, formation of an imide ring by dealcoholization of the amino acid ester residue) may occur in a part of the amino acid ester residue due to the nucleophilic attack of the amine. In this book, polyamino acids containing residues that have undergone such structural changes are also included in the above formula (II). In this case, the residues that have undergone the structural change are not included in the number of amino acid residues. In addition, some NH groups and NH ₂ groups in cationic amino acid residues may become salts (mainly hydrochloride) due to the use of acid (mainly hydrochloric acid) in the synthesis process. In this book, polyamino acids containing such structures are also included in the above formula (II). That is, some NH groups and NH ₂ groups in the groups of R ^7a , R ^7b , and R ⁸ may be salts (for example, hydrochloride).

B. Block Copolymer The block copolymer according to one embodiment of the present invention has a hydrophilic polymer segment and a hydrophobic polymer segment, and the hydrophobic polymer segment contains the polyamino acid according to the above item A. The block copolymer is typically a block copolymer in which a hydrophilic polymer segment and the polyamino acid according to the above item A are bonded in series.

Examples of the polymer constituting the hydrophilic polymer segment include polyethylene glycol, polypropylene glycol, poly (2-oxazoline), polysaccharide, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylamide, polymethacrylamide, polyacrylic acid ester, and polymethacrylic acid ester. Etc., polyethylene glycol can be preferably used. The hydrophilic polymer segment may be linear or branched chain.

When the polymer constituting the hydrophilic polymer segment is polyethylene glycol, the number of repetitions of polyethylene glycol (in the case of a branched chain, the number of repetitions in each chain) is, for example, 20 to 2,000, preferably 200 to 1,500. possible.

（上記式（ＩＩＩ）又は（ＩＶ）において、
Ｒ^１～Ｒ^８、ａ、ｂ、ｃ、ｄ、ｅ及びｆについては、上記式（ＩＩ）について定義したのと同義であり、
Ｌ^１及びＬ^３は、連結基を表し、
Ｒ^９及びＲ^１０は、相互に独立して、水素原子あるいは未置換もしくは置換された炭素数１～１２の直鎖又は分枝状のアルキル基を表し、
ｋは、２０～２，０００の整数を表す。） In one embodiment, the block copolymer can be represented by formula (III) or (IV):

(In the above formula (III) or (IV)
^R1 to R8, a, b, c, d, e and f are synonymous with the definition of the above formula ⁽ II).
L ¹ and L ³ represent a linking group.
R ⁹ and R ¹⁰ independently represent a hydrogen atom or an unsubstituted or substituted linear or branched alkyl group having 1 to 12 carbon atoms.
k represents an integer of 20 to 2,000. )

L ¹ and L ³ are linking moieties of the hydrophilic polymer segment and the polyamino acid segment and may be any suitable linking group. The linking groups represented by L ¹ are, for example, -NH-, -O-, -OL ² -NH-, -CO-, -CH _2- , and OL ² -SL ² -NH. -(Here, L ² is an alkylene group having 1 to 6 carbon atoms independently) can be a linking group selected. L ³ can be, for example, a linking group selected from -OCO-L ⁴ -CO- and NHCO-L ⁴ -CO- (where L ⁴ is an alkylene group having 1 to 6 carbon atoms).

Examples of the linear or branched alkyl group having 1 to 12 carbon atoms defined by the groups of R ⁹ and R ¹⁰ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group and sec. -Butyl group, tert-butyl group, n-hexyl group, decyl group, undecyl group and the like can be mentioned. Further, the substituent in the case of "substituted" may be the same as the substituent exemplified for the groups of ^R1 and ^R2 in the above formula (II). Alternatively, the groups of R ⁹ and R ¹⁰ may be substituted with a group containing a target binding site. By introducing a target binding site at the end of the hydrophilic polymer segment, reachability to the desired target site can be improved.

The group containing the target binding site can be any suitable group as long as it has directivity or functionality toward the target tissue, for example, an antibody or a fragment thereof, or other functionality or target orientation. It can be a group derived from a physiologically active substance such as a protein, a peptide, an aptamer, a sugar such as lactose, or a folic acid, and a derivative thereof.

K, which represents the number of iterations of ethylene glycol, can be preferably an integer of 200 to 1,500.

The block copolymer can be formed, for example, by purifying the polyamino acid and the hydrophilic polymer as they are or, if necessary, so as to narrow the molecular weight distribution, and then coupling them by a known method. Further, for example, in the block copolymer of the general formula (III), a polyethylene glycol chain is formed by performing anionic living polymerization using an initiator capable of imparting ^R9 , and then an amino group is introduced on the growth terminal side thereof. N-Carboxylic Acid Anhydrous (NCA) of 1-methyl-tryptophan from the amino terminal and optionally other amino acids NCA (eg β-benzyl-L-aspartate, γ-benzyl-L-glutamate, Nε-Z- It is produced by polymerizing (N-carboxylic acid anhydride) of a protected amino acid such as L-lysine, deprotecting it if necessary, and optionally introducing the groups (i) to (v). Can be done. The introduction of the groups (i) to (v) can be carried out, for example, by aminolysis or transesterification.

C. Polymer particle composition The polymer particle composition according to one embodiment of the present invention comprises the polyamino acid according to the above item A or the block copolymer according to the item B. The polyamino acids and block copolymers can associate in an aqueous medium to preferably form polymer particles. For example, the block copolymer can form polymer micelles with the polyamino acid segment facing inward and the hydrophilic polymer segment facing outward. In the present invention, an aggregate in which a plurality of molecules are aggregated in the form of particles is also included in the particles, and such an aggregate is also referred to as a polymer particle.

The average particle size of the polymer particles is, for example, 1000 nm or less, preferably 400 nm or less, 200 nm or less, 150 nm or less, 100 nm or less or 80 nm or less, and for example, 20 nm or more or 30 nm or more. The average particle size of the particles can be measured using a commercially available dynamic light scattering (DLS) measuring device.

The polymer particle composition may contain polymers other than the polyamino acid according to item A and the block copolymer according to item B, to the extent that the effects of the present invention can be obtained. Examples of such other polymers include block copolymers having a hydrophilic polymer segment and a hydrophobic polymer segment. Since such block copolymers can be suitably associated in an aqueous medium to form stable polymer particles (for example, polymer micelles), the coexistence of these can provide a polymer particle composition having excellent stability. Can be. Such effects may be particularly preferably exerted in polymer particle compositions containing polyamino acids that do not have hydrophilic polymer chain segments. Examples of the other block copolymers include the polymers described in WO2007 / 09660, WO2007 / 099661, WO2010 / 093036, WO2012 / 0963399, WO2014 / 133172, WO2015 / 170757 and the like.

In the polymer particle composition, for example, an aqueous medium such as water or a buffer is added to the polymer of interest and stirred to give ultrasonic waves, pressure, shearing force, or physical energy in combination thereof, to obtain the polymer of interest. After dissolving in a volatile organic solvent, the organic solvent is volatilized to dry, and the above-mentioned aqueous medium is added thereto to give the above-mentioned physical energy or the like. Alternatively, it can also be prepared by adding a water-soluble organic solvent capable of dissolving the polymer to the target polymer, dissolving the polymer, and dialyzing the aqueous medium. Here, examples of the volatile organic solvent include methanol, ethanol, acetone, chloroform, acetonitrile, tetrahydrofuran, dichloromethane and the like. Examples of the water-soluble organic solvent include methanol, ethanol, acetonitrile, dimethyl sulfoxide, N, N-dimethylformamide, N, N-dimethylacetamide and the like.

The polymer particle composition may further comprise a drug other than 1-methyl-tryptophan. The drug is preferably carried (eg, encapsulated) in polymer particles. By carrying a drug other than 1-methyl-tryptophan on the polymer particles, combination therapy using two or more drugs can be preferably performed.

As the above-mentioned drug, any suitable drug can be used depending on the purpose, and an anticancer drug is preferably used. The anticancer agent may be a cytotoxic compound used for chemotherapy, a molecular target drug using a low molecular weight compound or an antibody, or a nucleic acid drug such as siRNA or antisense nucleic acid. Further, the anti-cancer agent may be an antibody or the like that can activate immunity against cancer by inhibiting an immune checkpoint. In one embodiment, anti-cancer agents that induce immunogenicity, such as paclitaxel and doxorubicin, are used. In another embodiment, an anticancer agent such as imiquimod that activates an immune response is used.

Examples of the method for carrying the drug on the polymer particles include a method of preparing the polymer particle composition in the presence of the drug, a method of preparing the polymer particle composition, and a method of adding the drug to the polymer particle composition and mixing the mixture. Can be mentioned. For example, by forming polymer micelles using block copolymers in the presence of a drug, polymer micelles containing a drug can be obtained.

D. Usage The polyamino acid according to item A, the block copolymer according to item B, or the polymer particle composition according to item C requires, for example, suppression of indoleamine 2.3-dioxygenase (IDO) activity. Can be administered to an individual. In one embodiment, the individual in need of suppression of IDO activity is an individual suffering from cancer.

Examples of the individual to be administered include humans and non-human mammals. The administration method is preferably parenteral administration, and examples thereof include subcutaneous administration, intramuscular administration, intravenous administration, intraperitoneal administration, and intrathecal administration. It may also be locally administered to intratumoral or peritumor tissues.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.

[Production Example 1] Synthesis of 1-methyl-L-tryptophan-N-carboxylic acid anhydride (MLT-NCA) 1-Methyl-L-tryptophan (5 g) was dried under reduced pressure for 24 hours, and triphosgene (3.5 g) was dried. ) Was added, and the mixture was stirred in tetrahydrofuran (THF, 100 mL) at 0 ° C. for 30 minutes. The powder was completely dissolved by heating at 40 ° C. for 30 minutes, and after stirring for 1 hour, the reaction solution was added to hexane (200 mL) to obtain MLT-NCA. The resulting powder was crystallized overnight at −20 ° C. and recrystallized with THF and hexanes. ¹³ The chemical structure of the compound obtained by the C-NMR and FT-IR methods was analyzed, and it was confirmed that the desired compound was obtained.

[Production Example 2] Synthesis of 1-methyl-D-tryptophan-N-carboxylic acid anhydride (MDT-NCA) 1-methyl-D-tryptophan (5 g) is used instead of 1-methyl-L-tryptophan (5 g). MDT-NCA was obtained in the same manner as in Production Example 1 except that it was used. The resulting powder was crystallized overnight at −20 ° C. and recrystallized with THF and hexanes. ¹³ The chemical structure of the compound obtained by the C-NMR and FT-IR methods was analyzed, and it was confirmed that the desired compound was obtained.

[Production Example 3] Synthesis of Homo-PMLT Homo-PMLT was synthesized by the reaction scheme shown below.

Specifically, MLT-NCA (80 mg) was dissolved in DMF (10 mL) and added to n-butylamine (8 μL) dissolved in DMF (1 mL). After the reaction at 35 ° C. for 48 hours, the reaction solution was added to pure water to obtain Homo-PMLT. When the degree of polymerization of the PMLT chain was calculated from the absorbance of UV at 220 nm, the degree of polymerization was 5.

[Production Example 4] Synthesis of Homo-PMDT Homo-PMDT was obtained in the same manner as in Production Example 3 except that MDT-NCA (80 mg) was used instead of MLT-NCA (80 mg). When the degree of polymerization of the PMDT chain was calculated from the absorbance of UV at 220 nm, the degree of polymerization was 5.

≪Enzyme decomposition test≫
Homo-PMLT or Homo-PMDT (2 mg) was dissolved in N-methyl-2-pyrrolidone (NMP, 200 μL) and 20 mM Hepes buffer (20 mL) containing 10 mM CaCl was added. Chymotrypsin (1 mg / mL, 0.5 mL) was added to the solution and incubated at 37 ° C. for 48 hours. The amount of the polymer decomposed by chymotrypsin was measured by the HPLC method. The results are shown in FIG.

As shown in FIG. 1, the release rate of Homo-PMLT after 48 hours was more than 25%, whereas the release rate of Homo-PMDT after 48 hours was less than 2%. From this, it can be seen that Homo-PMLT is easily decomposed by chymotrypsin and Homo-PMDT is not easily decomposed by chymotrypsin. It is known that chymotrypsin mainly hydrolyzes the carboxyl-terminal side of aromatic amino acids, but there has been no report on the degradation of 1-methyl-tryptophan, and it is not possible to have high selectivity for PMLT. This is the first finding obtained this time.

<< Indoleamine-2,3-dioxygenase (IDO) inhibition test >>
Macrophage-like cells (RAW264.7) were seeded on culture plates. After 24 hours, lipopolysaccharide (LPS, 1 μg / mL) and chymotrypsin-treated Homo-PMLT (70 μg / mL) were added, and after 24 hours, the amount of kynurenine in the supernatant was measured by the HPLC method. The control was the one to which nothing was added. In addition, as a negative control, one to which only lipopolysaccharide (LPS, 1 μg / mL) was added was used, and as a positive control, one to which lipopolysaccharide (LPS, 1 μg / mL) and MLT (70 μg / mL) were added was used. board. The results are shown in FIG.

As shown in FIG. 2, IDO was induced to produce kynurenine by stimulation with lipopolysaccharide, and chymotrypsin-treated Homo-PMLT suppressed the production of kynurenine at almost the same level as MLT.

[Production Example 5] Synthesis of polyethylene glycol-poly (1-methyl-L-tryptophan) (PEG-PMLT) PEG-PMLT was synthesized by the reaction scheme shown below.

Specifically, MLT-NCA (200 mg) was dissolved in DMF (2 mL) and added to PEG-NH ₂ (100 mg, PEG molecular weight: 12 kDa) dissolved in DMF (1 mL). After reacting at 35 ° C. for 48 hours, the reaction solution was added to diethyl ether (150 mL) to obtain PEG-PMLT. When the degree of polymerization of the PMLT chain was calculated from the absorbance of UV at 220 nm, the degree of polymerization was 55.

[Production Example 6] Synthesis of polyethylene glycol-poly (1-methyl-D-tryptophan) (PEG-PMDT) Production Example 5 except that MDT-NCA (200 mg) was used instead of MLT-NCA (200 mg). Similarly, PEG-PMDT was obtained. When the degree of polymerization of the PMDT chain was calculated from the absorbance of UV at 220 nm, the degree of polymerization was 61.

[Production Example 7] Preparation of Polymer Micelles PEG-PMLT or PEG-PMDT was dissolved in N, N-dimethylacetamide (DMAc, 1 mg / mL) and stirred at room temperature for 1 hour. Then, the polymer solution was dialyzed against pure water for 24 hours, and the prepared micelle solution was purified by a filter (0.22 μm). The average particle size and polydispersity (PDI) of the prepared micelles were measured by a dynamic light scattering (DLS) method. The results are shown in Table 1.

[Production Example 8] Preparation of imiquimod-encapsulating polymer micelles Imiquimod was dissolved in DMAc (0.5 mg / mL) by dissolving PEG-PMLT in N, N-dimethylacetamide (DMAc, 1 mg / mL). Added. After stirring overnight at 40 ° C., the solution was dialyzed against pure water for 24 hours, and the prepared micelle solution was purified by a filter (0.22 μm). As a result of the measurement by the dynamic light scattering (DLS) method, the average particle size and the polydispersity (PDI) of the obtained micelles were 70 nm and 0.13, respectively.

<< Indoleamine-2,3-dioxygenase (IDO) inhibition test >>
Macrophage-like cells (RAW264.7) were seeded on culture plates. After 24 hours, lipopolysaccharide (LPS, 1 μg / mL), free (free) imikimod (5 μg / mL), empty polymer micelles (PEG-PMLT polymer micelles prepared in Production Example 7, 10 μg / mL), Empty polymer micelles (10 μg / mL) and free imiquimod (5 μg / mL), or imiquimod-encapsulating polymer micelles (imikimod concentration: 5 μg / mL) prepared in Production Example 8 were added, and 24 hours a day. The amount of quinurenin in the supernatant after 48 hours and 72 hours was measured by the HPLC method. The results are shown in FIG.

As shown in FIG. 3, imiquimod-encapsulating polymer micelles promoted the release of kynurenine from macrophages as compared to the case where imiquimod or high molecular weight micelles were administered alone or in combination. This suggests that macrophages were activated by encapsulating the drug in high molecular weight micelles.

The present invention can be suitably used in the field of DDS, for example.

Claims (6)

A polyamino acid containing at least one repeating unit derived from 1-methyl-tryptophan represented by the following formula (I).

The polyamino acid according to claim 1, wherein the 1-methyl-tryptophan comprises 1-methyl-L-tryptophan. The polyamino acid according to claim 1 or 2, further comprising a repeating unit derived from another amino acid. A block copolymer having a hydrophilic polymer segment and a hydrophobic polymer segment, wherein the hydrophobic polymer segment contains the polyamino acid according to any one of 1 to 3. A polymer particle composition comprising the polyamino acid according to any one of claims 1 to 3 or the block copolymer according to claim 4. The polymer particle composition of claim 5, further comprising a drug.

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