Patent Description:
Tumors that had emerged in the human body are removed by the ordinarily inherent immune mechanism before they proliferate to an extent that they have harmful effects on the human body. The following phenomenon is known as this mechanism. Namely, a protein (tumor antigen) specific to cancer cells binds to a protein called class I MHC molecule in cancer cells, and is presented on the cell surface. When this class I MHC and the tumor antigen binds to the TCR (T Cell Receptor) protein on the surface of T cells which are responsible for immunity, the T cell recognizes this cell as a cancer cell. The T cell which recognized the cancer cell initiates proliferation, and damages the cancer cell presenting the tumor antigen.

However, it is known that when the cancer cell was expressing a membrane protein called PD-L1 together with class I MHC, by binding with a membrane protein called PD-<NUM> which is being expressed in the T cell, the activation of the above T cell is suppressed. Because this cancer cell which has acquired the immunological escape mechanism which is normally for suppressing excess immunity continues to proliferate, inhibition of the binding between PD-L1 and PD-<NUM> has been focused as the target for a new anticancer agent (Patent Literature <NUM>). Note that PD-L1 is also expressed in "professional antigen-presenting cells" such as dendritic cells which specialize in presenting antigens to T cells. In recent years, anti-PD-<NUM> antibodies nivolumab (Opdivo®) and pembrolizumab (Keytruda®) have been developed and put to practical use as anticancer agents, and anti-PD-L1 antibodies atezolizumab, durvalumab, avelumab (Bavencio™), and the like have also been developed and put to practical use.

On the other hand, in the antigen presentation of cancer cells (or professional antigen-presenting cells) to T cells, other mechanisms to suppress immune reaction (immune checkpoints) are also known, a representative of which is a combination of the B7 family molecule on the antigen-presenting side and CTLA4 on the T cell side, and pharmaceuticals such as ipilimumab (Yervoy®) and tremelimumab have been developed. In addition, CD137L-CD137, MHC-LAG-<NUM>/KIR, CD48-CD244, GAL9-TIM3, HVEM-BTLA/CD160, CD40L-CD40, OX40L-OX40, GITRL-GITR, and the like are known (in all of which the former is the molecule on the antigen-presenting side) (Non-Patent Literatures <NUM> and <NUM>).

Recently, there has been a report that the antitumor effect by an anti-PD-<NUM> antibody is related to the generation of reactive oxygen in T cells, and that the said antitumor effect is enhanced by intracellular signal transduction and mitochondrial activation by addition of a reactive oxygen generator at a low concentration. Moreover, it is reported at the same time that the antitumor effect of an anti-PD-<NUM> antibody is also enhanced in pharmaceuticals that mimics this intracellular signal transduction (Non-Patent Literature <NUM>).

The present inventors have found that an ALA or a derivative thereof is effective for cancer therapy by a presumed mechanism which enhances the heme or cytochrome in the mitochondria of a cancer cell or a cell almost becoming a cancer cell having formed an abnormality in the nucleus, improves mitochondrial activities such as the electron transport chain and the TCA cycle, and calls up the Bax and Bak systems to cause a caspase IX-type apoptosis when there is an abnormality in the nucleus that cannot be restored (Patent Literature <NUM>).

On the other hand, ALA together with an arbitrary sodium ferrous citrate (SFC) becomes a heme in the body, and this heme is degradated by an enzyme called a heme oxygenase <NUM> (HO-<NUM>) to change into bilirubin and carbon monoxide (Non-Patent Literature <NUM>). It is known that this bilirubin and carbon monoxide has a high antioxidant action and can directly/indirectly erase reactive oxygen species (ROS) (Non-Patent Literature <NUM>).

Patent Literature <NUM> and <NUM> report compositions comprising an aminolevulinic acid derivative and sodium ferrous citrate for use in the treatment of cancer.

Moreover, ALA, together with an arbitrary SFC, is known to have an immunological tolerance effect which suppresses immunity. This mechanism is thought to be where, in a dendritic cell which is the antigen-presenting cell, the above-described HO-<NUM> (or bilirubin and carbon monoxide) changes (differentiates) the dendritic cell into a cell called a tolerogenic dendritic cell. A tolerogenic cell is known to highly express PD-L1 and to perform specific immunological tolerance (immunosuppression) on the antigen presented on the T cell, and in fact, a rise in the mRNA of PD-L1 has been observed in a cell that is recognized as a dendritic cell by administration of ALA and SFC (Non-Patent Literature <NUM>).

Patent Literature <NUM> and <NUM> disclose compositions comprising an aminolevulinic acid derivative and an immune checkpoint inhibitor for use in the treatment of cancer.

Patent Literature <NUM> and Non-Patent Literature <NUM> set forth compositions comprising an aminolevulinic acid derivative for use, alone or together with a further anticancer agent, in the treatment of cancer.

As described above, cancer therapy agents that comprise an anti-PD-<NUM> antibody or an anti-PD-L1 antibody as the active ingredient have been created, and further, a combination therapy method of these cancer therapy agents and preexisting pharmaceuticals has been drawing attention. In fact, a clinical trial of the combination of pharmaceuticals that mimic the above signal transduction (lipid-lowering drug bezafibrate that activates the transcription factor PPARs) and an anti-PD-<NUM> antibody has been planned. Namely, there is a demand for the search or creation of a medicament or a pharmaceutical composition which has high correlation with immune checkpoint inhibitors such as an anti-PD-<NUM> antibody or an anti-PD-L1 antibody and which may enhance the antitumor effect by an immune checkpoint inhibitor.

Accordingly, the object of the present invention is to provide a pharmaceutical composition for enhancing the antitumor effect by immune checkpoint inhibitors such as an anti-PD-<NUM> antibody or an anti-PD-L1 antibody.

As a result of repeated extensive investigation in order to solve the above problem, the present inventors found that systemically administered <NUM>-aminolevulinic acid (ALA) in combination with sodium ferrous citrate can significantly enhance the antitumor effect by an immune checkpoint inhibitor selected from an anti-PD-L1 antibody or an anti-PD-<NUM> antibody. As above, although ALA itself may be useful for cancer therapy, in consideration of the high antioxidant action by bilirubin and carbon monoxide (CO) resulting from administration of ALA or the immunological tolerance effect by ALA, when ALA is administered during cancer therapy by immune check inhibitors selected from an anti-PD-<NUM> antibody or an anti-PD-L1 antibody, it was rather thought that the effect of the immune checkpoint inhibitor will be counteracted due to ALA causing increase of PD-L1-expressing dendritic cells or reactive oxygen in T cells being removed by bilirubin and CO, and thus this result was surprising.

Namely, the present invention relates to a compound shown by the following Formula (I):
[Chemical Formula <NUM>].

R<NUM>-NHCH<NUM>COCH<NUM>CH<NUM>COOR<NUM>     (I).

The compound can be administered at the same time or at different times as the immune checkpoint inhibitor.

In particularly preferred embodiments, R<NUM> and R<NUM> are hydrogen atoms.

The present invention will now be described in detail.

The present invention relates to a compound for use in the treatment of cancer as defined in claims <NUM> to <NUM>. Additional aspects described in this document are provided for illustrative purposes. Any references to methods of medical treatment should be understood to mean that it is not the method per se that forms part of the invention, but the compound for use in such a method.

An "immune checkpoint inhibitor" is an anticancer agent that suppresses the proliferation of cancer by binding to an immune checkpoint molecule which suppresses T cell activity due to presentation of antigen, and inhibiting its signal transduction. Immune checkpoint molecules may include both receptors and ligands which function as immune checkpoints.

According to the present invention, an "immune checkpoint inhibitor" is an anti-PD-L1 antibody or an anti-PD-<NUM> antibody.

The compound for use of the present invention is characterized in that it has ALA shown by the following Formula (I) or a salt thereof (hereinafter also simply referred to as "ALAs") as the active ingredient.

An ALA as used herein means <NUM>-aminolevulinic acid. ALA is also referred to as δ-aminolevulinic acid, and is a type of amino acid.

In Formula (I), R<NUM> represents a hydrogen atom or an acyl group, and R<NUM> represents a hydrogen atom, a linear or branched alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group. Note that in Formula (I), ALA corresponds to when R<NUM> and R<NUM> are hydrogen atoms. [Chemical Formula <NUM>].

ALAs may act as an active ingredient in vivo in the form of the ALA of Formula (I) or a derivative thereof, and can also be administered as a prodrug (precursor) that is degradated by an in vivo enzyme.

The acyl group in R<NUM> of Formula (I) can include a linear or branched alkanoyl group having <NUM>-<NUM> carbons such as formyl, acetyl, propionyl, butyryl, isobutyryl, valeryl, isovaleryl, pivaloyl, hexanoyl, octanoyl, and benzylcarbonyl groups, or an aroyl group having <NUM> - <NUM> carbons such as benzoyl, <NUM>-naphthoyl, <NUM>-naphthoyl groups.

The alkyl group inR<NUM> of Formula (I) can include a linear or branched alkyl group having <NUM> - <NUM> carbons such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, pentyl, isopentyl, neopentyl, hexyl, heptyl, and octyl groups.

The cycloalkyl group in R<NUM> of Formula (I) can include a cycloalkyl group having <NUM> - <NUM> carbons which may be saturated or have partially unsaturated bonds, such as cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclododecyl, and <NUM>-cyclohexenyl groups.

The aryl group in R<NUM> of Formula (I) can include an aryl group having <NUM> - <NUM> carbons such as phenyl, naphthyl, anthryl, and phenanthryl groups.

The aralkyl group in R<NUM> of Formula (I) can be exemplified with the same aryl groups as above as the aryl moiety and the same alkyl groups as above as the alkyl moiety, and can specifically include an aralkyl group having <NUM> - <NUM> carbons such as benzyl, phenethyl, phenylpropyl, phenylbutyl, benzhydryl, trityl, naphthylmethyl, and naphthylethyl groups.

Preferred ALA derivatives include compounds where R<NUM> is a formyl group, an acetyl group, a propionyl group, a butyryl group, and the like. Moreover, preferred ALA derivatives also include compounds where the above R<NUM> is a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, and the like. Moreover, preferred ALA derivatives also include compounds where the combination of the above R<NUM> and R<NUM> is each combination of (formyl and methyl), (acetyl and methyl), (propionyl and methyl), (butyryl and methyl), (formyl and ethyl), (acetyl and ethyl), (propionyl and ethyl), and (butyryl and ethyl).

Among ALAs, a salt thereof can include a pharmaceutically acceptable acid addition salt, a metal salt, an ammonium salt, an organic amine addition salt, and the like. Acid addition salts can be exemplified by e.g. each of inorganic acid salts such as a hydrochloride salt, a hydrobromide salt, a hydroiodide salt, a phosphate salt, a nitrate salt, and a sulfate salt, and each of organic acid addition salts such as a formate salt, an acetate salt, a propionate salt, a toluenesulfate salt, a succinate salt, an oxalate salt, a lactate salt, a tartrate salt, a glycolate salt, a methanesulfonate salt, a butyrate salt, a valerate salt, a citrate salt, a fumarate salt, a maleate salt, and a malate salt. Metal salts can be exemplified by each of alkali metal salts such as a lithium salt, a sodium salt, and a potassium salt, each of alkaline earth metal salts such as a magnesium salt and a calcium salt, and each of metal salts such as aluminum and zinc. Ammonium salts can be exemplified by e.g. ammonium salts and alkyl ammonium salts such as a tetramethylammonium salt. Organic amine salts can be exemplified by each of salts such as a triethylamine salt, a piperidine salt, a morpholine salt, and a toluidine salt. Note that these salts can also be employed as a solution at the time of use.

ALAs esters can include, but are not limited to, methyl esters, ethyl esters, propyl esters, butyl esters, pentyl esters, and the like.

Among the above ALAs, the most favorable are ALA and various esters such as an ALA methyl ester, an ALA ethyl ester, an ALA propyl ester, an ALA butyl ester, and an ALA pentyl ester, as well as hydrochloride salts, phosphate salts, and sulfate salts thereof. In particular, ALA hydrochloride salts and ALA phosphate salts can be exemplified as particularly favorable.

The above ALAs can be manufactured by e.g. well-known methods such as chemical synthesis, production by microorganisms, and production by enzymes. Moreover, the above ALAs may also form a hydrate or a solvate, and ALAs can be employed alone or in an appropriate combination of two or more.

When the above ALAs are to be prepared as an aqueous solution, attention must be paid so that the aqueous solution will not become alkaline in order to prevent degradation of ALAs. In the case it becomes alkaline, degradation can be prevented by removing oxygen.

In the present invention, the compound of formula (I) is combined with sodium ferrous citrate (SFC).

The dosage of sodium ferrous citrate to a subject may be <NUM> - <NUM> folds by molar ratio to the dosage of ALA to the subject, desirably <NUM> - <NUM> folds, and more desirably <NUM> - <NUM> folds.

ALAs and sodium ferrous citrate for use according to the present invention can be administered as a composition comprising ALAs and sodium ferrous citrate or each can be administered alone, although it is preferred that even when administering each alone, they are administered at the same time. Same time here means not only administering simultaneously, but also even if not simultaneously, administering without substantial interval between each other so that the administration of ALAs and sodium ferrous citrate can exert additive effect, preferably synergistic effect.

The administration route of ALAs and sodium ferrous citrate in the present invention is systemic administration. Administration routes can include, for example, oral administration including sublingual administration, or parenteral administration such as inhalation administration, intravenous administration including infusion, transdermal administration by e.g. patches, suppository, or administration by forced enteral nutrition employing nasogastric tube, nasointestinal tube, gastrostomy tube, or enterostomy tube. Moreover, as described above, ALAs and the metal-containing compound may be administered from separate routes.

The dosage form of the compound for use of the present invention may be appropriately determined depending on the said administration route, and can include, but is not limited to, injections, infusions, tablets, capsules, fine granules, powders, liquids, solutions dissolved in syrups etc., patches, suppositories, and the like.

Other optional ingredients such as other medicinal ingredients, nutrients, and carriers can be added as necessary. For example, as optional ingredients, various compounding ingredients for preparation of drugs such as pharmaceutically acceptable ordinary carriers e.g. crystalline cellulose, gelatin, lactose, starch, magnesium stearate, talc, vegetable and animal fat, oil, gum, and polyalkylene glycol, binders, stabilizers, solvents, dispersion mediums, expanders, excipients, diluents, pH buffers, disintegrants, solubilizers, solubilizing agents, and isotonic agents.

The administration subject of the compound for use according to the present invention is a subject to which an immune checkpoint inhibitor is administered or being administered, namely a subject suffering from cancer. The type of cancer to be the therapeutic subject may change depending on the immune checkpoint inhibitor used.

The dosage of ALAs to be administered, depending on the height, weight, age, and the symptom of the subject, can be administered in the range of <NUM> - <NUM>,<NUM>, preferably <NUM> - <NUM>, more preferably <NUM> - <NUM>, further preferably <NUM> - <NUM> per kg of subject body weight, when converted into ALA (i.e. converted into mass of when R<NUM> and R<NUM> are hydrogen atoms in Formula (I)).

Appropriate number of administrations and the administration frequency for the compound for use of the present invention can be suitably determined by those skilled in the art in consideration of the administration conditions of the immune checkpoint inhibitor used in combination (the administration interval, the number of administrations, and the duration of administration). In one embodiment of the present invention, the compound for use according to the present invention is provided for administration every day from before administration of, at the time of administration of, or after administration of the immune checkpoint inhibitor.

In the present invention, the effective amount of each of the compound for use of the present invention and the immune checkpoint inhibitor can be administered to a subject at the same time or at different times, continuously or with intervals. The compound for use of the present invention and the immune checkpoint inhibitor may be administered to a tumor patient in the same administration cycle, or each may be administered in different administration cycles. In one embodiment of the present invention, each of the compound for use of the present invention and the immune checkpoint inhibitor are administered in different administration cycles.

The administration of the compound for use of the present invention to a subject can be initiated before the administration of the immune checkpoint inhibitor is initiated. For example, the compound for use of the present invention can be administered every day from one week before the administration of the immune checkpoint inhibitor is initiated.

The administration of the compound for use of the present invention to a subject can be initiated on the same day as the administration of the immune checkpoint inhibitor. For example, the compound for use of the present invention can be administered every day from the day the administration of the immune checkpoint inhibitor is initiated. When the compound for use of the present invention and the immune checkpoint inhibitor are simultaneously administered, they may be prepared and administered as a single formulation, or may be simultaneously administered in separate administration routes.

Further, the administration of the compound for use of the present invention to a subject can be initiated after the administration of the immune checkpoint inhibitor. For example, the compound for use of the present invention can be administered every day after the administration of the immune checkpoint inhibitor. As long as the antitumor effect by the immune checkpoint inhibitor can be enhanced, the time point of initiating the compound for use of the present invention is not particularly limited, and it is preferred that an extended period of time, for example one month or longer, preferably three weeks or longer, more preferably two weeks of longer, and more preferably ten days or longer has not elapsed since the time point of initiating the immune checkpoint inhibitor.

The terms used herein, except for those that are particularly defined, are employed for describing particular embodiments, and do not intend to limit the invention.

Moreover, the term "comprising" as used herein, unless the content clearly indicates to be understood otherwise, intends the presence of the described items (such as components, steps, elements, and numbers), and does not exclude the presence of other items (such as components, steps, elements, and numbers).

Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meanings as those broadly recognized by those skilled in the art of the technology to which the present invention belongs. The terms used herein, unless explicitly defined otherwise, are to be construed as having meanings consistent with the meanings herein and in related technical fields, and shall not be construed as having idealized or excessively formal meanings.

The present invention will now be described in further detail with reference to Examples. However, the present invention can be embodied by various aspects, and shall not be construed as being limited to the Examples described herein.

To C57BL/<NUM> mice, <NUM> × <NUM><NUM> of mouse melanoma cell strain B16F10 were inoculated in the flank, and the tumor was allowed to grow for <NUM> days. On Day <NUM> and Day <NUM> from inoculation, <NUM>µg/head of anti-mouse PD-L1 antibody (Clone: MIH5) was intraperitoneally administered for the PD-L1 antibody only administration group, the anti-PD-L1 antibody + ALA administration group, and the anti-PD-L1 antibody + ALA + SFC administration group (<FIG>). For the anti-PD-L1 antibody + ALA + SFC administration group, <NUM>/kg of ALA hydrochloride salt (from neo ALA CO. ) and <NUM>/kg of sodium ferrous citrate (SFC; from KOMATSUYA CORPORATION) were orally administered once a day from Day <NUM> to Day <NUM> from inoculation. Moreover, for the anti-PD-L1 antibody + ALA administration group, <NUM>/kg of ALA hydrochloride salt (from neo ALA CO. ) was orally administered once a day from Day <NUM> to Day <NUM> from inoculation. The group with no treatment after inoculation was placed as the control group.

The tumor diameter was measured every two days, and v wherein v = (minor axis, mm)<NUM> × (major axis, mm)/<NUM> was recorded as the tumor volume (mm<NUM>). The values of N were <NUM> mice for the control group (<NUM> mice were alive on Day <NUM>), <NUM> mice for the anti-PD-L1 antibody only group (<NUM> mice were alive on Day <NUM>), <NUM> mice for the anti-PD-L1 antibody + ALA administration group (all mice were alive on Day <NUM>), and <NUM> mice for the anti-PD-L1 antibody + ALA + SFC administration group (all mice were alive on Day <NUM>).

On Day <NUM> from inoculation, the anti-PD-L1 antibody + ALA administration group had clearly smaller tumor volumes compared to the anti-PD-L1 antibody only group (<FIG>). Moreover, the effect by the anti-PD-L1 antibody was more significant when ALA was added and SFC was further administrated (the anti-PD-L1 antibody + ALA + SFC administration group). This result indicates that the antitumor effect of the anti-PD-L1 antibody is enhanced by the combination use of ALA + SFC, and it is expected to contribute to further extension of mouse survival rates.

To C57BL/<NUM> mice, <NUM> × <NUM><NUM> of mouse melanoma cell strain B16F10 were inoculated in the flank, and the tumor was allowed to grow for <NUM> days. On Day <NUM> and Day <NUM> from inoculation, <NUM>µg/mouse of anti-mouse PD-<NUM> antibody (Clone: RMP1-<NUM>) was intraperitoneally administered for the PD-<NUM> antibody only administration group, the anti-PD-<NUM> antibody + ALA administration group, and the anti-PD-<NUM> antibody + ALA + SFC administration group (<FIG>). For the anti-PD-<NUM> antibody + ALA + SFC administration group, <NUM>/kg of ALA hydrochloride salt (from neo ALA CO. ) and <NUM>/kg of sodium ferrous citrate (SFC; from KOMATSUYA CORPORATION) were orally administered once a day from Day <NUM> to Day <NUM> from inoculation. The group with no treatment after inoculation was placed as the control group.

The tumor diameter was measured every two days, and v wherein v = (minor axis, mm)<NUM> × (major axis, mm)/<NUM> was recorded as the tumor volume (mm<NUM>). The values of N were <NUM> mice for the control group (<NUM> mice were alive on Day <NUM>), <NUM> mice for the anti-PD-<NUM> antibody only group (all mice were alive on Day <NUM>), and <NUM> mice for the anti-PD-<NUM> antibody + ALA + SFC administration group (<NUM> mice were alive on Day <NUM>).

On Day <NUM> from inoculation, the anti-PD-<NUM> antibody + ALA + SFC administration group had clearly smaller tumor volumes compared to the anti-PD-<NUM> antibody only group (<FIG>). This result indicates that the antitumor effect of the anti-PD-<NUM> antibody is enhanced by the combination use of ALA + SFC, and it is expected to contribute to further extension of mouse survival rates.

According to the present invention, a pharmaceutical composition for enhancing the antitumor effect by an immune checkpoint inhibitor is provided. Accordingly, by using an immune checkpoint inhibitor and the pharmaceutical composition according to the present invention in combination, it is expected to lead to extension of life and increase of remission rate for cancer patients.

Claim 1:
A compound shown by the following Formula (I):
[Chemical Formula I]

        R<NUM>-NHCH<NUM>COCH<NUM>CH<NUM>COOR<NUM>     (I)

wherein R<NUM> represents a hydrogen atom or an acyl group, and R<NUM> represents a hydrogen atom, a linear or branched alkyl group, a cycloalkyl group, an aryl group, or an aralkyl group or a salt thereof, for use in the treatment of cancer, wherein the compound is used in combination with an immune checkpoint inhibitor, and in combination with sodium ferrous citrate, and is systemically administered
wherein the immune checkpoint inhibitor is an anti-PD-L1 antibody or an anti-PD-<NUM> antibody.