WO2000004042A1

WO2000004042A1 - Peptide compounds

Info

Publication number: WO2000004042A1
Application number: PCT/JP1999/003820
Authority: WO
Inventors: Naoki Shinbara; Shinichiro Niwa
Original assignee: Sumitomo Electric Industries, Ltd.
Priority date: 1998-07-15
Filing date: 1999-07-15
Publication date: 2000-01-27

Abstract

Peptide compounds represented by general formula (I) or salts thereof, which exhibit immunological enhancement effects, wherein R?1 and R2¿ are each independently optionally substituted hydroxyl or optionally substituted amino; and X is C¿1?-C6 alkyl which may be substituted with -(CH2)2-COOH or the like.

Description

Peptide compounds Technical field

The present invention relates to a novel peptide compound having an immunostimulating activity. Background art

Newly generated cancer cells are suppressed by the foreign body elimination mechanism in the living body, but the immune system such as T-lymphocytes reacts mainly against cancer cells that have passed through this defense mechanism, resulting in genetic abnormalities. Recognize and eliminate cancer cells that have developed as non-self cells. The purpose of tumor immunity research is to find a method to cure cancer immunologically. As a means for achieving this goal, various methods have been proposed to enhance the immune responsiveness of a living body to cancer cells. ing.

Conventionally, effector cells that are difficult to activate in the living body are prepared in vitro, and the number of the effector cells is increased and adoptive transfer is performed; the effector is injected into the living body by injection of cytokine whose production is inhibited in the tumor-bearing organism. A method for activating the cells in the evening; a method for separating the cancer antigen peptide, which is expressed and incorporated into MHC, from the cancer cells to activate the immunity; or a method for introducing the cytokine gene into the cancer cells to immunize the host. Attempts have been made to improve response. However, these methods have many problems, such as poor protein stability due to the use of proteins, cells, etc., and the necessity of developing new administration methods due to high side effects in some cases. ing. For this reason, it has not yet been put to practical use in actual treatment.

On the other hand, endogenous antigens such as viruses and cancer antigens are localized in cells, and the biodegradation of these endogenous antigens is related to proteasome, an ATP-dependent protease. The decomposition is considered to go through the following process. That is, after endogenous antigens were multi-ubiquitinated by a number of ubiquitin proteins, It is roughly cleaved by a dumbbell-shaped proteasome called the proteasome. Thereafter, this fragment is ligated by a football-type proteasome (2OS proteasome) called PA28 (proteasome activator: hereinafter sometimes abbreviated as “PA28” in the present specification). Is further cut into fine peptides. The generated antigen peptide is taken into the endoplasmic reticulum via the TAP 1 / TAP 2 transport pump present in the endoplasmic reticulum membrane, associates with MHC class I molecules, is transported to the cell surface, and is then transported to the cell surface as CTL peptide. Presented and activates killer T cells. The activated killer T cells attack the cells displaying the CTL epitope on the surface and cause the cells to die.

PA28 has a function of quantitatively promoting the cleavage of peptides by the 20S proteasome (FEBS Letters, 366, pp. 37-42, 1995). It is known that proteasomes are activated by conical binding to both ends of the proteasome. PA28 is a hexamer, and it is known that there are three types of subunits (PA28, PA28 ?, and PA28a). Normally, PA28 is formed by associating 3 molecules of PA28 with 3 molecules of PA28, but it may be formed by associating 6 molecules of PA28a (The functions of the proteasome and PA28 are reviewed as a review. Adv. Immumo 1.64, pp. 1—38, 1997).

When carboxypeptidase is allowed to act on PA28, the above peptide-cleaving action of 20S proteasome is lost, so PA28 is considered to have an active domain on the C-terminal side (J. Biol. Chem., 268, pp. 22514-22519, 1993). It has also been suggested that oligopeptide compounds containing this moiety promote the peptide cleavage action of the 2OS proteasome (Molecular Biology Reports, 24, PP. 119-124, 1997). However, according to the study of the present inventors, these compounds are very poorly soluble in water, and have a problem that they cannot exhibit their effectiveness when administered to living bodies and the like. Disclosure of the invention

An object of the present invention is to provide a peptide compound having an immunostimulating activity. More specifically, an object of the present invention is to promote the cleaving function of 2OS proteasome for an endogenous antigen, and to produce an antigen-derived peptide fragment (killer T cell epitope: CTL ebitope). It is to provide a compound having an action of increasing the amount. Another object of the present invention is to provide a medicine containing a compound having the above characteristics as an active ingredient.

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, a tetrabeptide compound represented by the following formula has the effect of promoting the function of cleaving the 20S proteasome against an endogenous antigen. In addition, it can exert its promoting effect in vivo, and the above-mentioned peptide compound promotes the presentation of CTL peptide to the cell surface. It has been found that a therapeutic effect can be exhibited. The present invention has been completed based on these findings.

That is, the present invention provides the following formula (I):

(Wherein R ¹ and R ² each independently represent a hydroxyl group which may have a substituent or an amino group which may have a substituent; X represents an alkyl group which may have a substituent) Or a salt thereof. According to this inventions preferred embodiments, X is one or 1 2 or more C physician ₆ alkyl group (the alkyl group is a substituent other than a carboxyl group having a carboxyl group or two or more Or a salt thereof.

From another viewpoint, the present invention provides a medicine containing the compound represented by the above formula (I) or a physiologically acceptable salt thereof as an active ingredient. This medicament can be used, for example, as an immunostimulant and is useful for preventing and / or treating cancer. In still another aspect, there is provided a use of the compound represented by the above formula (I) or a physiologically acceptable salt thereof for the manufacture of the above medicament; a method for promoting immunity of mammals including human beings, A method comprising the step of administering an effective amount of the compound represented by the formula (I) or a physiologically acceptable salt thereof to an individual; a method for preventing and / or treating cancer, the method comprising: Administering a prophylactically and / or therapeutically effective amount of the compound or physiologically acceptable salt thereof to a mammal, including a human; and a 20S proteasome and / or killer in vivo in the mammal. A method for enhancing the action of a T cell, comprising the step of administering to a mammal, including a human, a prophylactically and / or therapeutically effective amount of a compound represented by the above formula (I) or a physiologically acceptable salt thereof. Including method Is provided. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows the results of analysis of the degradation products of Akt peptide by the 20S proteasome. In the figure, (A) shows the results of control without addition; (B) shows the results of Akt peptide degradation by PA28-20S proteasome; (C) shows the results of PSM A-5 at 30 M Fig. 2 shows the results of degradation by the 20S proteasome when added. Fig. 2 shows the cytotoxic activity promoting action of PSMA-5 (A in the figure) and the TNF-induced induction promoting action (B in the figure). FIG.

FIG. 3 is a graph showing the tumor-suppressing effect of PSMA-5 on transplanted cancer cells of a mouse individual. In the figure, A shows the results of the untreated control, and B shows the results of the PSMA-5 treated group (30 M).

FIG. 4 is a view showing the tumor-suppressing effect of PSMA_5 on transplanted cancer cells of a mouse individual. The results of the PSMA-5 treatment group (13 mg / kg subcutaneous administration) are shown. FIG. 5 is a graph showing the action of PSMA-5 to promote cytotoxic activity on ovalbumin antigen-presenting cells. In the figure, A shows the action of promoting cytotoxic activity, and B shows the action of promoting TNF-induction. BEST MODE FOR CARRYING OUT THE INVENTION

In the above formula (I), R ¹ and R ² each independently represent a hydroxyl group which may have a substituent or an amino group which may have a substituent. When the hydroxyl group or the amino group has a substituent, the type of the substituent is not particularly limited, but it is preferable to use a hydrophilic substituent so as not to impair the water solubility of the compound represented by the formula (I). Better. When the amino group has two substituents, they may be the same or different, and the two substituents may be bonded to each other to form a cyclic structure. Of these, an unsubstituted hydroxyl group or an unsubstituted amino group is preferable, and an unsubstituted hydroxyl group is more preferable.

Examples of the substituent that binds to a hydroxyl group or an amino group include, for example, an alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and a cyclopropyl group (in the present specification, a substituent containing an alkyl group or an alkyl moiety; alkyl moiety of the linear, branched, cyclic, or may be either) a combination thereof; C _2, such as a vinyl group, Ariru group - ₆ alkenyl; C _2, such as propargyl group - ₆ alkynyl group Ci-6 alkanoyl group such as acetyl group; aroyl group such as benzoyl group; aralkyl group such as benzyl group; aryl group such as phenyl group; heteroaryl group such as pyridyl group; pyrrolidinyl group, piperazinyl group, morpholinyl group and the like. A heterocyclic group; or a rubamoyl group, but are not limited thereto. There is no.

The alkyl moiety of the substituent on the hydroxyl group or amino group specifically exemplified above may have one or more same or different substituents. Examples of such a group include a hydroxyCi-es alkyl group such as a hydroxyethyl group; a halogenated C alkyl group such as a trifluoromethyl group; In this case, it may be any of a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom); and a halogenated Ci-6 alkanol group such as a trifluoroacetyl group can be exemplified, but is not limited thereto. Never. Examples of the cyclic structure formed by combining two substituents present on an amino group with each other include a pyrrolidine ring, a piperazine ring, and a morpholine ring.

Further, one or more same or different substituents may be present on the aromatic ring of the substituent specifically exemplified above. For example, a substituted arylo group such as a P-cyclopentyl benzoyl group; a substituted aralkyl group such as a P-methoxybenzyl group; a substituted aryl group such as a tolyl group and a chlorophenyl group; a substituted heteroaryl group such as a nicotinyl group. The substituent on the ring is not limited to those exemplified above. In addition, one or two identical or different substituents may be present on the nitrogen atom of the carbamoyl group, and such substituents include, for example, those mentioned above for the amino group. Can be used.

X represents a C- ₆ alkyl group which may have a substituent. The number and substitution position of the substituents are not particularly limited, and when they have two or more substituents, they may be the same or different. The substituent on the alkyl group, for example, 1 ^ and 1 in ² for explanation mentioned as a substituent on a hydroxyl group or amino group monovalent other substituents, an amino group which may have a substituent (Amino As the substituent on the group, those exemplified above can be used); a hydroxyl group which may have a substituent (the above-described examples can be used as the substituent on the hydroxyl group); Group; a C-e alkoxycarbonyl group such as an ethoxycarbonyl group; a carbonyl group; and the like, but is not limited thereto.

Among them, X is preferably a C ^ 6 alkyl group having one or more carboxyl groups. When X represents an alkyl group having a carboxyl group, the number and substitution position of the carboxyl group are not particularly limited, but it is preferable that one carboxyl group is substituted at the terminal of the alkyl group. For example, X is -A-C00H (wherein A represents a linear alkylene group or a branched alkylene group). X is more preferably a group represented by — (CH ₂ ) _n —C00H (n is an integer of 1 to 6), and further preferably n is 2 in the above group. When X represents a C doctor ₆ alkyl group having a carboxyl group, the alkyl group may have a substituent other than Cal Bokishiru group one or more. Such substituents can be selected, for example, from those described above. X is preferably a hydrophilic substituent so as not to impair the water solubility of the compound represented by the formula (I).

Preferred compounds among the compounds of the present invention include:

(1) a compound wherein R ¹ and R ² are hydroxyl groups and X is-(CH ₂ ) ₂ -C00H;

(2) a compound wherein R i and R ² are an acetoxy group, and X is-(CH ₂ ) ₂ -C00H;

(3) a compound wherein R i is an acetoxyl group, and R ² is a hydroxyl group and X is-(CH ₂ ) ₂ -C00H;

(4) a compound wherein R ¹ and R ² are an amino group and X is-(CH ₂ ) ₂ -C00H;

(5) a compound wherein 1 ^ is an amino group, R ² is a hydroxyl group, and X is-(CH ₂ ) ₂ -C00H;

(6) The compound wherein 1 ^ is a carbamoyl group, R ² is a hydroxyl group, and X is-(CH ₂ ) ₂ -C00H;

(7) the compound wherein R i is a carbamoyl group, R ² is an acetoxy group, and X is-(C¾) ₂ -C00H;

(8) The compound wherein R ¹ and R ² are hydroxyl groups and X is a methyl group

The compounds of the present invention are not limited to these. Among these, the particularly preferred compound is the above-mentioned compound (1), and the production method and the physiological activity are specifically shown in Examples (this compound is sometimes referred to as “PSMA-5” in this specification). It has substantially the same or higher water solubility as the above compound (1), and has substantially the same or higher immunostimulating action as the parenthesis compound (for example, enhances the action of the 20S proteasome). The compound having action (1) is the most preferred embodiment of the present invention.

The method for producing the compound of the present invention is not particularly limited. Good. For example, a method in which four peptides are sequentially bonded by an ordinary peptide solid phase method using amino acids appropriately protected as necessary is suitable. In the examples of the present specification, a method for producing the compound of the present invention by applying a general peptide synthesis method is specifically shown.Thus, those skilled in the art can refer to the starting compound and Any of the compounds of the present invention encompassed by the formula (I) can be easily produced by appropriately changing the reagents and, if necessary, by appropriately modifying or altering the method.

Among the four amino acids constituting the compound represented by the above formula (I), the configuration of three amino acids except glycine is not particularly limited, but it is preferable that they are L-amino acids. In addition, the compound represented by the above formula (I) may further have an asymmetric carbon depending on the type of the substituent, but their configuration is not particularly limited. Any stereoisomers such as optically active isomers and diastereoisomers, any mixtures of stereoisomers, racemates and the like are all included in the scope of the present invention. When the compound of the present invention contains one or more double bonds, any geometrical isomers are included in the scope of the present invention.

The compound of the present invention represented by the formula (I) may exist as an acid addition salt or a base addition salt depending on the type of the substituent. Examples of the acid addition salt include mineral salts such as hydrochloride, sulfate, nitrate, and phosphate; or P-toluenesulfonate, methanesulfonate, citrate, oxalate, maleate, and the like. Organic salts such as tartrate can be mentioned. Examples of the base addition salt include metal salts such as sodium salt, potassium salt, calcium salt and magnesium salt; ammonium salts; organic ammonium salts such as methyl ammonium salt and triethyl ammonium salt. They may form salts with amino acids such as glycine, and they may also form counterions in the molecule. Further, the compound represented by the formula (I) or a salt thereof may exist as a hydrate or a solvate. It goes without saying that all of these substances are included in the scope of the present invention.

The compound of the present invention represented by the formula (I) or a physiologically acceptable salt thereof is represented by 2 It has the effect of promoting the cleavage function of the 20 S proteasome against endogenous antigen cleaved by the 6 S proteasome, and produces antigen-derived peptide fragments (epitopes of killer T cells: CTL epitopes). Has the effect of increasing In addition, as a result of promoting the process in which the CTL ebitope associates with the MHC class I molecule and is presented on the cell surface, it is possible to promote the cytotoxic activity of killer T cells in response to the epitope, and to enhance the immunity of the individual. Performance can be enhanced.

Therefore, the compound of the present invention or a physiologically acceptable salt thereof is useful as an active ingredient of a medicament such as an immunostimulant, and an enhancer of 20S proteasome action, an enhancer of killer T cell action, etc. Is useful as an active ingredient of a medicament. Pharmaceuticals provided by the present invention include cancers involving endogenous antigens, for example, stomach cancer, esophageal cancer, oral cancer, intestinal cancer, hepatic cancer, liver cancer, kidney cancer, bladder cancer, breast cancer, uterine cancer, lung cancer It is useful for the prevention and / or treatment of solid tumors such as brain tumors, skin cancers and bone cancers, or non-solid cancers such as leukemias and malignant lymphomas, but the use of the medicament of the present invention is not limited to these. There is no. It can be easily confirmed that the compound of the present invention or a salt thereof increases the amount of CTL peptide produced by the method specifically shown in Example 2 of the present specification. Further, the fact that the compound of the present invention or a salt thereof promotes the activity of killer T cells can be measured by measuring the cytotoxic activity shown in Example 3 of the present specification, or by producing TNF-producing cells produced by killer T cells. Easily confirmed by measuring the amount

The medicament of the present invention generally comprises an active ingredient selected from the group consisting of a compound represented by the formula (I) and a physiologically acceptable salt thereof, and a hydrate and a solvate thereof. And a pharmaceutically acceptable excipient for a pharmaceutical preparation. The above-mentioned substances or additives for pharmaceuticals as active ingredients may be used alone or in combination of two or more. The type of substance that is the active ingredient of the medicament of the present invention can be appropriately selected from the viewpoints of efficacy, water solubility, pharmacokinetics such as absorption and excretion, and / or stability. It is particularly preferred to use

The administration route of the medicament of the present invention is not particularly limited, and it may be administered orally or parenterally. And it is possible. Formulations suitable for oral administration include, for example, tablets, powders, capsules, granules, fine granules, syrups, and suspensions.Formulations suitable for parenteral administration include, for example, Intravenous, intramuscular or subcutaneous injections, drops, suppositories, external preparations, eye drops, nasal drops, ear drops, inhalants, transdermal absorbents, ointments, creams, patches And the like, but the form of the preparation is not limited to these.

The method for producing these preparations is not particularly limited as long as it can be used by those skilled in the art.The person skilled in the art selects one or more appropriate additives for pharmaceutical preparations in the manufacture of the preparation. Can be used. The use of a pharmaceutical composition in which the active ingredient is encapsulated in ribosomes or a pharmaceutical composition to which an antibody or the like is bound may improve the affinity and selectivity for the target organ. The administration route and dosage can be appropriately selected according to the type of disease to be applied, the purpose of treatment or prevention, the type of affected part, the condition of the patient, etc., and are suitable for each administration route and dosage. It goes without saying that a suitable formulation form can be appropriately selected. The dose can be selected, for example, from the range of about 0.111 to about 1,000 mg per adult per day. Example

Hereinafter, the present invention will be described more specifically with reference to Examples, but the scope of the present invention is not limited to the following Examples.

Example 1 Title of the peptide compound of the present invention (a compound in which R ¹ and R ² are hydroxyl groups and X is — (CH ₂ ) ₂ —C00H: hereinafter referred to as “PSMA-5” in the examples). Was prepared with an automatic peptide synthesizer (Nippon Perceptive Co., Ltd., Mode 19U50) using Fmoc-amino acid. The amino acid derivatives used were Fmoc-Tyr (t-Bu) -Wang PEG resin (manufactured by Watanabe Chemical), Fm0c-Met-OH (manufactured by NOVA BI OCHEM), FmocI1e-OH (NOVA BI OCHEM) and Z—Gly—OH (NOVA BIOC HEM). The outline of the synthesis program is as follows. Washing: dimethylformamide (DMF) (9 min); Deprotection: 20% piperidine / DMF (6 111; 111); Washing: 0 ^ 1 (9 min); Condensation: 10% diisopropylethylamine ( DI EA) / DMF (6 Omin); and Wash :: DMF (9 min).

Deprotection was carried out by the following procedure in order to remove the protective group on the side chain of the obtained protective peptide and further remove the bond between the resin and the peptide. The dried synthetic resin was washed 2-3 times with methanol and dried overnight. m-Cresol: triisopropane virsilane: thioanisole: TFA = 1: 1.8: 6: 43 (volume ratio) The mixture was mixed with 15 ml and treated under ice cooling for 1 hour. After filtering the mixture, the supernatant was collected and concentrated to 1 Oml or less under a nitrogen atmosphere. About 100 ml of getyl ether was added to the residue, and the mixture was stirred at room temperature for 1 hour. The white precipitate of the peptide was centrifuged, and the obtained precipitate was dissolved again in cold ether, and then left on ice to precipitate the peptide, followed by centrifugation to collect the precipitate. This operation was repeated four times, and the obtained peptide was air-dried, dissolved in 10 to 20 ml of 0.1% TFA, and filtered through a 0.45 μm filter.

OD of the obtained peptide. Separation and purification were performed using an acetonitrile gradient using a column (C18 column, Nomura Chemical Co., 4.6 x 25 mm). The conditions of the gradient are as follows. Buffer A: 0.1% trifluoroacetic acid (TFA), Buffer B: 0.075% trifluoroacetic acid + 80% acetonitrile, gradient: 0-3 Omin, buffer B (5-65%). The obtained main beak was measured using a mass spectrometer MALD I-TOF mass spectrometer (manufactured by Perseptive), and a fraction having a target molecular weight was collected and dried to obtain a final purified product. .

The GMIY peptide was dissolved in 0.1 M NaCl and the pH of the solution was adjusted to 8.0 with a 0.5 M sodium bicarbonate solution. While maintaining the temperature of the solution at 15 ° C., 15-fold molar amount of succinic anhydride which was finely divided as a solid was added little by little under stirring to progress the reaction. After adding succinic anhydride, adjust the reaction mixture to pH 4 Extracted with chill. The solid obtained by concentrating this extract under reduced pressure was washed with ether. The PSMA-5 thus obtained was eluted as a single peak with a retention time of 48 minutes in HPLC under the conditions of Example 2 (3). Example 2: Effect of the compound of the present invention on the degradation of tumor rejection antigen peptide

The promoting effect of PSMA-15 on the processing of the endogenous antigen peptide of the 20 S proteasome was examined using a synthetic peptide containing the tumor rejection antigen, CTL epitope, and the compound PSMA-5 obtained in Example 1. Was. As the synthetic peptide, a 29-residue peptide containing a mouse leukemia tumor rejection antigen, CTL peptide (J. Exp. Med., 180, pp. 1599-1607, 1994) was used.

(1) Synthesis of tumor rejection antigen Akt peptide

A 29-mer peptide consisting of the amino acid sequence AYREETL SII PGLPLSLGATDTMNDVAI V containing the leukemia tumor rejection antigen peptide (SII PGLPLSL) (in the examples, sometimes referred to as “Akt peptide”) was converted to an automatic peptide synthesizer, Mode 1431 ( It was synthesized by F—Moc method using Perkin Elmer (manufactured by Perkin Elmer). The synthesized peptide was purified by reversed-phase high-performance liquid chromatography (LC10AS, manufactured by Shimadzu), and it was confirmed that the purity was 90% or more. MALD I—TOF mass spectrometry analysis (Perceptive (P ers eptive) and HPLC.

(2) Purification of proteasome and PA28

Rat 20S proteasome was purified using various chromatography methods in the presence of 20% glycerol by the method of Tanaka et al. (J. Biol. Chem., 263, pp. 16 209-16217, 1988). Purification of rat PA28 and preparation of a complex of 20S protesome and PA28 were carried out by a method such as a shelf bridge (Genetocels, 2, pp. 195-211, 1997).

(3) Effect of the compound of the present invention on Akt peptide degradation by proteinome 29mer synthetic peptide (AYREETLSI IPGLPLSLGATDT MNDVAIV) 20〃M and 5nM (a) 20S proteasome, (b) PA28-20S proteasome complex, and (c) 20S proteasome SMA-5 at 30〃M the added system, the final volume lml (50 mM T ris -HC 1 (p H 7. 8), 5mM MgCl 2, 1 mM d ithiothre it ol, 2m M ATP) to be the For 24 hours at 37 ° C. The degradation products were separated by an acetonitrile gradient using an ODC column (Waters, C18 column, 2.1 x 150 mm). The conditions of the gradient are as follows. Buffer A; 0.1% trifluoroacetic acid (TFA), Buffer B; 0.09% trifluoroacetic acid + 80% acetonitrile, 0-60 min 2.0--37.5%, 60-90min 37.5-75% _s 90-105 min 75—98%. The amino acid sequence of the degradation product was determined using a peptide sequencer Mode 1492 (Perkin Elmer) and a mass spectrometer MALD I-TOF Mass Spectrometer (Perceptive). Figure 1 (A) shows the results of analysis of Akt peptide degradation products by 20S proteasome. As a result of mass spectrometry, five types of peptides were detected. From the results of peptide sequencing and TOF-ASS analysis, it was found that the amino acid sequence of the degradation product was as follows. Peptide 1: AYREETL, Peptide 2: GATDTMN DVA IV, Peptide 3: SI IPGLPLSL, Peptide 4: SI IPGLP LSLGATDTMNDVAIV, Peptide 5: AYREETLS II PGLP LSL. Of these, Peptide 3 was a precursor peptide containing a CTL levitope peptide. It is known that this precursor peptide is trimmed by another peptide in the cytoplasm, and finally generates a CTL peptide of IPGLPLSL.

Figure 1 (B) shows the results of the degradation of Ak peptide by PA28-20S proteasome. The amount of peptide 3 (CTL ebitope) produced increased about 2.0 times as compared with the case without addition (FIG. 1 (A)). Figure 1 (C) shows the addition of 30〃M PSMA-5 This is the result of degradation by the 20 S proteasome. The amount of peptide 3 (CTL epitope peptide) produced increased about 1.8-fold compared to the case without the addition. This result indicates that the compound PSMA-5 of the present invention increases the production of the CTL epitope top precursor peptide. Example 3 Effect of Compound of the Invention on CTL Tumor Cytotoxic Activity

We examined whether PSMA-5 promotes the cytotoxic activity of killer T cells on cancer cells. A cytotoxic activity assay was performed using RL cells derived from mouse leukemia and killer T cells that recognize them. The RL 1 cells labeled with ⁵¹ Cr to measure the amount of liberated ⁵¹ Cr in killer T cells were destroyed, killer - T cells secreted recognize target cancer cells TNF- non-producing amount Kira one It was measured as an indicator of the cytotoxic activity of T cells.

(1) Preparation of target tumor cells (evening-get cells)

RL 1 cells (Proc. Natl. Acad. Sci. USA, 76, 3486) at a concentration of ⁵ × 10 ⁵ cells / ml in RPMI medium + fetal calf serum 10% (FBS) + 2-mercapto It was prepared in a medium containing ⁵ × 10 ⁵ M ethanol. At this time, PSMA-5 was not added or added at various concentrations (10, 30, 50〃M) and cultured for 24 hours.

(2) Killer T cells (effector cell preparation)

Killer T cell (CTL) clone B—24 that recognizes H- 2 L ^d- restricted IPGLPL SL peptide expressed on RL1 cells (J. Exp. Med. ヽ 180, 1599– 1607) (1994) in a similar medium. These CTL cells are! ^ 認識 It is known to recognize cytochrome (IPGL PLSL) bound to molecules on cells and have cytotoxic activity.

(3) ⁵¹ Cr release activity measurement

Step (1) obtained in RLc ^ l cells.. - the (evening get cells) were washed with ^{PBS, 2x 10 5 ce 11 s} / 0 placed in RPM I medium at _{^{_{2 ml, Na 2 51 Cr0 4}}} l 85 The cells were cultured for 1.5 hours with MBq added. The cells ^{5x 1 0 4 ce 11 s /} ml and such so that the prepared (0. lml), Kira one T cell B- 24 cultured in step (2) 1. 25 xl 0 ⁵ cells / ml Prepared and added 100%. This resulted in an E / T (effector cell / evening-get cell) ratio of 2.5: 1. In this state, the cells were cultured for 3 hours, and ⁵¹ Cr released into the culture supernatant was measured with an a counter. (4) Measurement of TNF production

RL1 cells (evening-get cells) cultured in step (1) were adjusted to 5 × 10 ⁴ / ml and 100 1 was added. To this was 100 1 added to prepare a CTL clone B- 24 cultured in ⁵ xl 0 5 cells / ml in step (2). This resulted in an E / T (effector cell / evening-gate cell) ratio of 10: 1. After culturing for 6 hours, the cells were mixed well and the culture supernatant was collected by centrifugation. The amount of TNF-produced by ELISA was measured by an ordinary ELISA method using a measurement kit manufactured by Amersham. FIG. 2A shows the cytotoxic activity when PSMA-5 was used, and FIG. 2B shows the amount of TNF-producing when PSMA-5 was used. It was found that killer T cell cytotoxic activity and TNF production were maximized when PSMA-5 was used at a concentration of 30 M. Example 4: Tumor-suppressing effect of the compound of the present invention on transplanted cancer cells of mouse individuals

When the target tumor cells are implanted intradermally on the back of the mouse, the diameter of the tumor becomes more than 30 mm in about one month, and most mice die. Therefore, it was first examined whether tumor suppression was observed by treating target cancer cells with PSMA-5 and then transplanting them intradermally on the back of mice. 3 x 1 0 ^six Ba lb / c mouse leukemia cell RLd ^ l cells were added to the PB S of 0. 2 ml, was injected intraperitoneally into Ba lb / c mice. Ί-10 days later, ascites was collected, washed well with PBS, and RL1 cells were diluted to 2 × 10 ⁶ / ml. PSMA-5 was added to this cell solution to a final concentration of 30 μM, and the cells were cultured for 12 hours.

Cells (1 x 1 0 ⁶ cells) after incubation were washed with PB S (0. 2 ml), Ba 1 b / c mice were implanted intradermally on the back of 10 mice. At this time, untreated RLc-1 cells were similarly transplanted to 10 Balb / c mice as a control. Tumor diameter on the back was measured weekly for one month. As shown in Fig. 3A, in mice without PSMA-5 treatment, the tumor grew to a diameter of 10 cm or more after 3 weeks, and all mice died at 4 weeks. However, in the PSMA-5 treatment group (30 zM ), 8 animals survived one month later, and 4 of them had tumor regression effects (Fig. 3B). Example 5: Tumor-suppressing effect of the compound of the present invention in mouse individuals

According to the method of Example 4, the tumor-suppressing effect of subcutaneous administration of PSMA-5 was examined. The administration was performed at 400 g / animal (13 gm / kg) daily for 2 weeks from day 1 after transplantation of untreated RL1 cells. As shown in FIG. 4, a tumor regression effect was observed in 5 out of 10 mice. Example 6: Promotion of cytotoxic activity of PSMA-5 on ovalbumin antigen presenting cells and effect of modified peptide

It was examined whether PSMA-5 exhibited efficacy on antigen-presenting cells other than Example 3. EG-7-OVA cells (Ce 11, 54, pp. 777-785, 1998), which express a peptide derived from ovalbumin (OVA) (SI INFEEKL) in an H—2 ^Kb- restricted manner, were used as target cells. Recognized 0 VA-specific CTLs were used as effector cells. The measurement of the amount of TNF-hi production was performed in the same manner as in Example 3 above. Fig. 5 shows the results. As is evident from these results, PSMA-5 also had an excellent cytotoxic activity promoting effect on ovalbumin antigen-presenting cells. Industrial applicability

The compound of the present invention has an immunostimulating effect and is useful as an active ingredient of a medicament such as an agent for preventing and / or treating cancer.

Claims

Scope of Claim Formula (I) below

(Wherein, R ¹ and R ² each independently represent a hydroxyl group which may have a substituent or an amino group which may have a substituent; X represents C ^ -alkyl which may have a substituent Or a salt thereof.

2. X is a Ci-6 alkyl group having one or more carboxyl groups (the alkyl group may have one or more substituents other than a carboxyl group). 2. The compound according to item 1 or a salt thereof.

3. The compound or a salt thereof according to claim 2, wherein X is a group represented by -A-C00H (wherein, A represents a linear alkylene group or an alkylene group having a branched chain).

4. The compound or a salt thereof according to claim 3, wherein X is a group represented by — (CH ₂ ) ₂ —C00H.

5. The compound or a salt thereof according to any one of claims ^{1 to} 4, wherein R ¹ and R ² are a hydroxyl group.

6. The compound or a salt thereof according to any one of claims ^{1 to 4,} wherein R ¹ and R ² are each independently an alkanoyloxy group.

7. The compound or a salt thereof according to claim 6, wherein R ¹ and R ² are an acetyl group.

8. The compound or a salt thereof according to any one of claims ¹ to 4, wherein R ¹ is an acetyl group and R ² is a hydroxyl group.

9. The compound or a salt thereof according to any one of claims ¹ to 4, wherein R ¹ is an amino group, and R ² is a hydroxyl group.

10. The compound or a salt thereof according to any one of claims ^{1 to 4,} wherein R ¹ and R ² are an amino group.

11. A medicament comprising the compound according to any one of claims 1 to 10 or a physiologically acceptable salt thereof as an active ingredient.

12. The medicament according to claim 11, which is an immunostimulant.

13. The medicament according to claim 11 or 12, which is a prophylactic and / or therapeutic agent for cancer.

14.20 S proteasome action enhancer comprising as an active ingredient the compound according to any one of claims 1 to 10 or a physiologically acceptable salt thereof.

15. An agent for enhancing the activity of killer T cells, comprising the compound according to any one of claims 1 to 10 or a physiologically acceptable salt thereof as an active ingredient.