JP4972929B2 - Radiosensitizer - Google Patents

Description

  The present invention relates to a radiosensitizer that improves the success rate of radiotherapy for malignant tumors.

  Conventionally, radiotherapy has been performed together with surgical therapy, chemotherapy, immunotherapy, hyperthermia and the like as a treatment for malignant tumors such as leukemia, lymphoma, carcinoma, sarcoma and the like. Among these, radiation therapy shows a high local control rate in many malignant tumors, and is currently used as an effective treatment method. With recent advances in radiochemistry and radiobiology, drugs that enhance the effects of radiation have come to be used in the treatment of radiation resistant tumors. In cancer radiotherapy, the presence of cells that are resistant to radiation hinders the success rate of radiotherapy and causes cancer recurrence.

  Radiation therapy relies heavily on the choice of drugs that synergistically increase the biological effects of radiation, and in recent years there have been many reports on the development of radiosensitizers. For example, a radiosensitizer using texaphyrin (Patent Document 1), a radiosensitizer containing chlorin e6 (Patent Document 2), a radiosensitizer containing a nitro-5-deazaflavin derivative (Patent Document 3), 2 -A hypoxic cell radiosensitizer (Patent Document 4) containing a nitroimidazole derivative as an active ingredient, a radiosensitizer containing a boronated metalloporphyrin (Patent Document 5), and the like have been reported.

Special table hei 09-508616 JP-A-5-194268 JP 2000-212087 A JP-A-6-298739 Special table 2005-504012

  In recent years in cancer radiotherapy, hypoxic cancer cells resulting from the failure of blood vessel growth to catch up with tumor growth show resistance to radiation two to three times that of normobaric oxygen cancer cells. , Reduced cure rate, causing recurrence. There is a demand for the development of highly safe cell radiosensitizers that synergistically increase the biological effects of radiation and have no side effects such as the development of neurotoxicity due to accumulation.

  The inventors of the present invention have been studying an agent that increases the sensitivity to radiation, that is, a drug having a strong radiosensitization effect on cancer cells. It has been found that it has a radiosensitizing effect with high affinity for cells. Furthermore, the inventors have found that a compound having an iron element in the molecule exhibits a radiosensitizing action, and as a result of various studies based on these findings, the present inventors have completed the present invention.

That is, the present invention
(1) a radiosensitizer comprising an iron compound,
(2) The iron compound is an inorganic iron compound, or sugar-containing iron oxide, iron citrate, iron acetate, iron gluconate, chondroitin sulfate / iron colloid, sideferon, threonine iron, iron fumarate, iron pyrophosphate, porphyrin iron complex and The radiosensitizer according to (1) above, which is an organic iron compound selected from porphyrin-iron complex inclusion albumin compounds,
(3) The radiation sensitizer according to (2) above, wherein the inorganic iron compound is selected from iron chloride, iron oxide, iron hydroxide and iron sulfate,
(4) The iron compound is composed of sugar-containing iron oxide, iron citrate, iron gluconate, chondroitin sulfate / iron colloid, sideferon, threonine iron, iron fumarate, iron pyrophosphate, porphyrin iron complex and porphyrin iron complex inclusion albumin compound The radiosensitizer according to the above (1), which is an organic iron compound selected,
(5) The radiosensitizer according to the above (1), wherein the iron compound is sugar-containing iron oxide, chondroitin sulfate / iron colloid, porphyrin iron complex or porphyrin iron complex inclusion albumin compound,
(6) The radiosensitizer according to (4) or (5) above, wherein the iron of the porphyrin iron complex is divalent,
(7) The radiosensitizer according to (4) or (5) above, wherein the porphyrin iron complex does not have a phenyl group substituted with a substituent having a boron atom on the porphyrin ring and the porphyrin iron complex inclusion albumin compound.
(8) The radiosensitizer according to (4) or (5) above, wherein the porphyrin iron complex of the porphyrin iron complex and the porphyrin iron complex inclusion albumin compound is a non-borated porphyrin iron complex,
(9) The radiosensitizer according to the above (1), wherein the iron compound is a porphyrin iron complex inclusion albumin compound,
(10) The radiosensitizer according to (9) above, wherein the albumin is a recombinant albumin,
(11) A drug kit comprising the radiosensitizer and chemotherapeutic agent according to (1) above,
(12) The drug kit according to (11), wherein the radiosensitizer and the chemotherapeutic agent are individually packaged, and (13) the radiosensitization according to (1) within 1 hour after administration of the chemotherapeutic agent. The drug kit according to (11), wherein a sensitizer is administered and irradiated.

  The radiosensitizer of the present invention is highly safe and excellent in the effect of enhancing radiosensitivity against hypoxic cancer cells that are resistant to radiotherapy, and as a radiosensitizer for radiotherapy for various malignant tumors. Useful. The radiosensitizer of the present invention is an excellent drug having high electron affinity and high affinity for cancer cells.

A radiosensitizer usually enhances radiosensitivity at the cellular level, but itself has no anticancer action, and the drug itself is not called an anticancer drug.
Examples of the iron compound used in the radiosensitizer of the present invention include inorganic or organic compounds having an iron ion (divalent or trivalent) in the molecule.
Examples of inorganic compounds having iron ions in the molecule include iron chloride, iron bromide, iron iodide, iron oxide, iron hydroxide, iron sulfate, iron nitrate, yellow iron oxide, yellow iron sesquioxide, and black iron oxide. , Iron sesquioxide, complex ions (eg, halogeno, cyano, thiocyanato, oxalato, etc.) and chelate compounds of iron ions and the like. Among these, iron chloride, iron oxide, iron hydroxide, and iron sulfate are preferable.

  Examples of organic compounds having iron (Fe) ions in the molecule include sugar-containing iron oxide, iron citrate, iron acetate, iron gluconate, chondroitin sulfate / iron colloid, sideferon, threonine iron, iron fumarate, pyrophosphate Iron, a porphyrin iron complex, a porphyrin iron complex albumin inclusion compound, etc. are mentioned. Among these, sugar-containing iron oxide, chondroitin sulfate / iron colloid, porphyrin iron complex, and porphyrin iron complex albumin inclusion compound are preferable. Particularly preferred is a porphyrin iron complex albumin inclusion compound. As the porphyrin in the porphyrin iron complex and the porphyrin iron complex albumin inclusion compound, non-borated porphyrin is desirably used.

  A macrocyclic tetrapyrrole ring (which may be referred to herein as a porphyrin ring), which is the basic skeleton of porphyrin, is represented by the following formula (additional numbering). Porphyrin is a macrocyclic compound in which four pyrrole rings are alternately bonded to four methine groups at the α position and derivatives thereof.

ポルフィリン鉄錯体の具体例としては、一般式（１）

As a specific example of the porphyrin iron complex, the general formula (1)

（式中、Ｒ₁ は１−メチル−１−シクロヘキシル基等の１−（飽和鎖状炭化水素基）−１−脂環式基、Ｒ₂ は置換基、ＭはＦｅイオン、Ｘ^- はハロゲンイオンを表わし、Ｘ^- の個数はＦｅイオンの価数から２を差し引いた数を示す）で表される化合物が挙げられる。

(Wherein R ₁ is a 1- (saturated chain hydrocarbon group) -1-alicyclic group such as 1-methyl-1-cyclohexyl group, R ₂ is a substituent, M is an Fe ion, and X ⁻ is a halogen. And the number of X ⁻ represents the number obtained by subtracting 2 from the valence of Fe ions.

  The compound represented by the general formula (1) is preferably the general formula (2).

（式中の記号は前記と同意義）で表される化合物である。

(Wherein the symbols are as defined above).

In the general formula (1), examples of R ₂ include general formula (3),

（式中、Ｒ₃ はＣ₁ 〜Ｃ₁₈のアルキル基を示す）で表される基、または一般式（４）、

(Wherein R ₃ represents a C _{1 to} C ₁₈ alkyl group), or a general formula (4),

（式中、Ｒ₄ はこれが結合しているイミダゾールの中心金属鉄への配位を阻害しない基、Ｒ₅ はアルキレン基を示す）で表される基が挙げられる。

(Wherein, R ₄ is a group that does not inhibit the coordination of the imidazole to which it is bonded to the central metal iron, and R ₅ is an alkylene group).

In the general formula (4), R ₄ is preferably hydrogen or a C ₁ -C ₃ alkyl group, and R ₅ is preferably a C ₁ -C ₁₀ alkylene group.

The tetraphenylporphyrin iron complex represented by the general formula (1) is preferably a complex in which Fe of the central metal (M) is in a divalent state and one base is coordinated. 5) or represented by the general formula (6).
General formula (5)

（式中、Ｌは塩基（例えば、イミダール誘導体の窒素系軸配位子等）を、その他の記号は前記と同意義を示す）
一般式（６）

(In the formula, L is a base (for example, a nitrogen-based axial ligand of an imidazole derivative, etc.), and other symbols are as defined above).
General formula (6)

（式中の記号は、前記と同意義を示す）

(The symbols in the formula are as defined above.)

As the porphyrin iron complex, a tetraphenylporphyrin iron complex represented by the general formula (7) is particularly preferable.
General formula (7)

（式中、Ｍは鉄イオン、Ｒ₄ はこれが結合しているイミダゾール環内の窒素原子が中心鉄金属への配位を阻害しない基、Ｒ₅ はアルキレン基を示す）

(In the formula, M is an iron ion, R ₄ is a group in which the nitrogen atom in the imidazole ring to which it is bonded does not inhibit the coordination to the central iron metal, and R ₅ is an alkylene group)

Among the porphyrin iron complexes represented by the general formula (7), 2- [8- (2-methyl-1-imidazolyl) octanoyloxymethyl] -5,10,15,20 represented by the formula (8) -Tetrakis {[α, α, α, α-o- (1-methylcyclohexanoylamino)] phenyl} porfinato iron complex is particularly preferred.
Formula (8)

（式中、Ｍは鉄イオンを示す）
さらに、
式（９）

(In the formula, M represents an iron ion)
further,
Formula (9)

で表されるポルフィリン鉄錯体、
動植物に存在する公知のポルフィリン誘導体、例えばエチオポルフィリン、メソポルフィリン、プロトポルフィリン、ジューテロポルフィリン、ヘマトポルフィリン、コプロポルフィリン、ウロポルフィリン、テトラベンゾポルフィリン、ジベンゾ〔b,l〕ポルフィリン、シクロペンタ〔at〕ポルフィリンもしくは３Ｈ−ベンゾ〔at〕ポルフィリン等との鉄錯体、さらに特開２００４−２７７３２９号に記載のポルフィリン鉄錯体、特開２００４−１０４９５号に記載のポルフィリン鉄錯体、特開平６−２７１５７７号に記載のポルフィリン鉄錯体が用いられる。

Porphyrin iron complex represented by
Known porphyrin derivatives present in animals and plants such as ethioporphyrin, mesoporphyrin, protoporphyrin, deuteroporphyrin, hematoporphyrin, coproporphyrin, uroporphyrin, tetrabenzoporphyrin, dibenzo [b, l] porphyrin, cyclopenta [at] porphyrin or Iron complexes with 3H-benzo [at] porphyrin and the like, further porphyrin iron complexes described in JP-A No. 2004-277329, porphyrin iron complexes described in JP-A No. 2004-10495, and porphyrins described in JP-A No. 6-271777 An iron complex is used.

  The porphyrin iron complex inclusion albumin compound, that is, the inclusion compound of porphyrin iron complex and albumin described above, is one in which the porphyrin iron complex is embedded, fixed, and included in an internal hydrophobic region formed by albumin. The number of binding of porphyrin iron complex to 1 mol of albumin (for example, human serum albumin) is usually about 1-8. The number of porphyrin iron complexes included and bound to 1 mol of albumin is, for example, Scatchard plot (see C. J. Halfman, T. Nishida, Biochemistry 11, 3493 (1972)), etc. Can be determined by creating

The porphyrin iron complex used in the present invention can be easily prepared by a known method or a method known per se, for example, the production methods described in JP-A-6-271777, JP-A-2004-277329, JP-A-2004-10495, etc. Can be manufactured.
For example, the tetraphenylporphyrin iron complex represented by the general formula (1) is represented by 2- [8- (2-methyl-1-imidazolyl) octanoyloxymethyl] -5,10,15, represented by the formula (8). Method for producing 20-tetrakis {[α, α, α, α-o- (1-methylcyclohexanoylamino)] phenyl} porfinato iron complex (T. Komatsu et al. Bioconjugate Chemistry 13, 397-402 ( (2002)).

The inclusion compound of porphyrin iron complex and albumin can be produced according to a known method (described in T. Komatsu et al. Bioconjugate Chemistry Vol. 13, pages 397-402 (2002)) or a method known per se. . Further, the clathrate compound can be produced, for example, by the following method.
First, a porphyrin iron complex is dissolved in a solvent (for example, ethanol), and an aqueous solution of albumin (for example, human serum albumin) (for example, water, phosphate buffer (pH 5-9), physiological saline, And shake gently. The obtained aqueous dispersion was concentrated to about 10% of the total amount by ultrafiltration (for example, using an ultrafiltration membrane having an ultramolecular weight of 20,000 to 40,000), and then again water, phosphate buffer ( When the operation of performing ultrafiltration is repeated until pH 5-9), physiological saline, Krebs-Ringer solution, etc. are added and the ethanol concentration in the dispersion is 100 ppm or less, a porphyrin iron complex-albumin inclusion compound is obtained. . This dispersion is stable with no precipitation or aggregation even after storage at 4-35 ° C. for several months.

The porphyrin iron complex can reduce central iron from trivalent to divalent by a conventional method such as adding a reducing agent (for example, an aqueous solution of sodium dithionite, ascorbic acid or the like).
This reduction reaction can be performed not only by addition of a reducing agent but also by palladium carbon / hydrogen gas. For example, the central iron can be reduced by dissolving a porphyrin iron (trivalent) complex in dry dichloromethane, benzene, toluene or the like, adding a small amount of palladium carbon, and then sufficiently blowing hydrogen gas at room temperature. After the reduction, the palladium carbon can be filtered off and the filtrate can be used after vacuum drying. This reduction reaction is preferably performed before the inclusion reaction with albumin.

  The albumin used in the present invention is not limited in its origin such as human serum albumin, recombinant human serum albumin, bovine serum albumin and the like. When considering application to humans, human serum albumin or human serum albumin produced by gene recombination technology (hereinafter referred to as recombinant human serum albumin) is preferred, and recombinant human serum albumin is particularly preferred.

  In recent years, with the development of genetic recombination technology, high-purity recombinant human serum albumin having the same structure, composition and physicochemical characteristics as human serum albumin has been developed (K. Kobayashi et al., Therapeutic Apheresis, 2 (4), 257-262 (1998)), a porphyrin iron complex-recombinant human serum albumin clathrate compound comprising this recombinant human serum albumin and a substituted porphyrin iron complex is Since it can be provided as a total synthesis system, production on an industrial scale is relatively easy.

In radiation therapy, cancer cell DNA is not only directly damaged by radiation, but also by the generation of reactive oxygen species such as hydroxy radicals. Since iron catalyzes the Fenton reaction that generates hydroxy radicals, this catalytic action provides an excellent radiosensitizing action.
The iron compound used in the preparation of the present invention can be prepared by various methods such as injections, suppositories, tablets, powders, granules, capsules, pills, ointments, solutions, patches, vapours, aerosols, etc. Can be made into a dosage form. When manufacturing an injection, add an appropriate solvent, if necessary, pH adjuster, buffer, stabilizer, suspension, solubilizer, carrier, etc. Can do.

  As the stabilizer, sodium sulfite, sodium metasulfite and the like are used. As the suspending agent, for example, methylcellulose, polysorbate 80, gum arabic and the like are used. As the solubilizer, polyoxyethylene hydrogenated castor oil, nicotinamide, polyoxyethylene sorbitan monolaurate, or the like is used.

The injection is prepared by, for example, dissolving, dispersing, emulsifying, etc., an iron compound in an aqueous carrier such as physiological saline for injection in advance, or by dissolving it in a powder for injection, dissolving, dispersing, emulsifying, etc. at the time of use. can do.
When using a porphyrin iron complex inclusion albumin compound as an iron compound, it is preferable to use it dispersed in a physiologically acceptable aqueous medium, for example, physiological saline such as phosphate buffered saline.

Examples of the administration method of the injection include intravenous administration, intraarterial administration, intraportal administration, intramuscular administration, intraperitoneal administration, subcutaneous administration, and intralesional direct administration.
Solid preparations such as tablets, powders, granules, capsules, pills, suppositories, or liquids such as syrups are excipients, binders, disintegrants, lubricants, coloring agents, flavoring agents for iron compounds. , Flavoring agents, extenders, coating agents and the like can be added and produced according to conventional methods. For example, when a porphyrin iron complex is used as the iron compound, it may be formulated into tablets, powders, granules, capsules, pills, and syrups according to conventional methods and administered orally.
An ointment, liquid, patch, buccal, and aerosol can be produced from an iron compound and an appropriate carrier by a conventional method, and may be directly applied to a lesion site as an external preparation. The radiosensitizers of the present invention may be used alone or in combination of two or more.

Radiotherapy using a radiosensitizer containing an iron compound is usually used after reducing cancer cells with a chemotherapeutic agent. Therefore, the radiosensitizer of the present invention may be a combined preparation of a chemotherapeutic agent and a kit type. In the case of a kit type combination preparation, both may be parenteral preparations, one may be a parenteral preparation, the other may be an oral preparation, and both may be oral preparations.
Examples of chemotherapeutic agents include anticancer agents generally used for cancer treatment, for example, anti-cancer alkylating agents such as cyclophosamide, ifosfamide and melphalan, methotrexate, gemcitabine, and 5-fluorouracil (5-FU). Anticancer antimetabolite such as actinomycin D (dactinomycin), doxorubicin (adriamycin), daunorubicin (daunomycin), epirubicin and other anticancer antibiotics, plant-derived anticancer such as vincristine, etoposide, docetaxel, paclitaxel Agents, anticancer camptothecin derivatives such as camptothecin, anticancer platinum compounds such as cisplatin, carboplatin and oxaliplatin, anticancer tyrosine kinase inhibitors such as gefitinib, biological responses such as krestin and picibanil Agent (Biological Response Modifier) and the like are used. These anticancer agents can be administered according to a known method, but when administering a drug having a radiosensitizing action such as gemcitabine, paclitaxel, carboplatin, etc., the dose of the radiosensitizer of the present invention is appropriately reduced. Can be administered.

The dose of the radiosensitizer of the present invention varies depending on the age, weight, sex, administration method, and symptoms of the patient, but usually 1 to 150 mg of iron as a parenteral dose per day per adult, and 10 as an oral dose. ˜250 mg is suitable. Usually, irradiation is performed within 12 hours after administration of the radiosensitizer of the present invention, but it is more desirable to receive irradiation within 1 hour.
The LD ₅₀ value after intravenous administration of chondroitin sulfate / iron colloid for intravenous injection is 250 mg / kg or more as iron (Fujimoto et al., Pharmaceutical Journal, Vol. 87, 677-681 (1967)). high.

Hereinafter, the present invention will be described more specifically with reference to examples.
In the examples, the radiosensitizing effect of porphyrin iron complex-albumin inclusion compound, sugar-containing iron oxide and chondroitin sulfate / iron colloid was examined by intra-arterial administration of 1.7 mg / kg as iron.

  2- [8- (2-Methyl-1-imidazolyl) octanoyloxymethyl] -5,10,15,20-tetrakis {[α, α, α, α-o- (1 -Methylcyclohexanoylamino)] phenyl} porfinato iron complex was prepared by the method described in T. Komatsu et al. Bioconjugate Chemistry 13, 397-402 (2002).

Production Example 1 Production of Albumin Inclusion Body of Porphyrin Iron Complex Under a carbon monoxide atmosphere, 2- [8- (2-methyl-1-imidazolyl) octanoyloxymethyl] -5,10,15,20-tetrakis { [Α, α, α, α-o- (1-methylcyclohexanoylamino)] phenyl} porphinatoiron complex 1.5 L of ethanol solution 1.5 L is added to 1.5 L of 0.6 M L-ascorbic acid aqueous solution Then, this solution was added to 6.5 L of a phosphate buffer aqueous solution (pH 7.4, 1/30 mM) containing 0.27 mmol of recombinant human serum albumin (hereinafter, rHSA) and stirred. Constant volume ultrafiltration dialysis using an ultrafiltration device (Millipore ultrafiltration membrane: ultramolecular weight 30,000) while adding 60 L of a phosphate buffer aqueous solution (pH 7.4, 1/30 mM) to the mixture. The ethanol contained in the mixed solution was removed. This mixture is concentrated to 300 mL, and then prepared using a phosphate buffer aqueous solution (pH 7.4, 1/30 mM) so that the rHSA concentration becomes a final concentration of 0.75 mM (5 w / v%). A dispersion of the complex-albumin inclusion compound (hereinafter abbreviated as rHSA-FecycP) was obtained.
An experiment was carried out using Experimental Example 1 in which rHSA-FecycP was irradiated with light for 20 minutes using a 500 W halogen lamp under oxygen gas (100%) ventilation. In addition, rHSA manufactured by Baifa Corporation (25% preparation) was used.

Experimental example 1
(Method) About 1.0 × 10 ⁶ cells of tumor cells (Assites hepatoma LY80) subcultured intraperitoneally in Donryu rats were transplanted directly under the right femoral fascia of the same strain of rats. Six days after tumor implantation, 10% / kg of 5% (w / v%, hereinafter the same) rHSA, rHSA-FecycP, sugar-containing iron oxide solution or chondroitin sulfate / iron colloid solution was administered into the common iliac artery (Group 6). (However, chondroitin sulfate / iron colloid solution is 3 animals per group). The rHSA-FecycP, the sugar-containing iron oxide solution, and the chondroitin sulfate / iron colloid solution were each adjusted to 3 mM as the iron concentration. Immediately after administration, the tumor transplantation site was irradiated with X-ray 20 Gy. For comparison, an untreated group that was not irradiated with X-rays and an rHSA-FecycP-administered group were provided (6 mice per group).
The day of tumor transplantation was defined as day 0, and survival was observed up to 60 days later. The survival days of each group are represented by a box mustache diagram, and the logarithmic test (significance level 5%) was performed as a significant difference test.
In addition, rHSA is manufactured by Baifa Co., Ltd. (25% preparation), and sugar-containing iron oxide is Fejin [trade name, manufactured by Nippon Pharmaceutical Co., Ltd. (currently renamed Nichi-Iko Co., Ltd.)], chondroitin sulfate The iron colloid used was bull tar (trade name, manufactured by Dainippon Pharmaceutical Co., Ltd. (currently renamed Dainippon Sumitomo Pharma Co., Ltd.)).
(result)
The obtained results are shown in FIG.
Moreover, the tumor major axis and minor axis were measured 6, 7, 9, 12, 15, 20, 25, 32, 39, 46, 53 and 60 after tumor transplantation, and the tumor weight was calculated according to the following formula.
Tumor weight (g) = major axis (mm) × <minor axis (mm)> ² ÷ 2 ÷ 1000
The tumor weight of each group was expressed as an average value ± standard deviation, and the significant difference test was performed by Tukey-Kramer multiple comparison test (significance level 5%). The obtained results are shown in FIG.

The median survival time for the untreated group was 21.5 days. The rHSA-FecycP administration group (no irradiation) did not prolong the survival days compared to the untreated group, but the survival days significantly increased in all the groups irradiated with X-rays. In addition, the survival time was not prolonged in the rHSA administration + irradiation group compared with the irradiation group, but in the rHSA-FecycP administration + irradiation group, the sugar-containing iron oxide administration + irradiation group and the chondroitin sulfate / iron colloid solution administration + irradiation group. The days were further significantly extended. In the rHSA-FecycP administration + irradiation group and the sugar-containing iron oxide administration + irradiation group, one and two cases survived 60 days after transplantation, respectively.
Tumor weight increased daily in the untreated group, and the rHSA-FecycP administration group (no irradiation) showed the same transition as the untreated group. On the other hand, in the group irradiated with X-rays, the tumor weight was significantly reduced compared to the untreated group. No difference was seen in rHSA administration + irradiation group compared to irradiation group, but tumor weight in rHSA-FecycP administration + irradiation group, sugar-containing iron oxide administration + irradiation group and chondroitin sulfate / iron colloid solution administration + irradiation group Was significantly reduced. In the rHSA-FecycP administration + irradiation group and the sugar-containing iron oxide administration + irradiation group, tumor disappearance was observed 12 to 20 days after transplantation in an example of surviving 60 days after transplantation.

  From the above, it has been clarified that rHSA-FecycP alone does not show an antitumor effect, but when used in combination with X-rays, the life extension and tumor reduction effect by X-ray irradiation are enhanced. In addition, this effect was also observed in sugar-containing iron oxide and chondroitin sulfate / iron colloid containing the same concentration of iron, indicating that common iron in the chemical structural formula is involved in the enhancement. It is clear that iron-containing compounds are useful as radiation enhancers.

Production Example 2 Metholization of Albumin Inclusion Body of Porphyrin Iron Complex (Fe ²⁺ → Fe ³⁺ )
rHSA-FecycP was irradiated with light for 20 minutes using a 500 W halogen lamp under oxygen gas (100%) ventilation, and after oxygenation, it was kept at 37 ° C. for about 5 days, and then metotheized by auto-oxidation (Fe ²⁺ → Fe ³⁺ Emil L. Smith et al., Biochemistry, 7th edition [II] -Mammalian biochemistry-see pages 668-689, Yodogawa Shoten, Tokyo (1990)) to obtain rHSA-FecycP (hereinafter, Met- rHSA-FecycP). In addition, the formation of rHSA-FecycP was confirmed by a decrease in absorbance at an absorption maximum wavelength λmax of 539.0 nm.

Experimental example 2
(Method) About 1.0 × 10 ⁶ cells of tumor cells (Assites hepatoma LY80) subcultured intraperitoneally in Donryu rats were transplanted directly under the right femoral fascia of the same strain of rats. Six days after tumor implantation, 5% rHSA or Met-rHSA-FecycP was administered into the common iliac artery at 10 mL / kg (6 mice per group). Met-rHSA-FecycP was adjusted to 3 mM as the iron concentration. Immediately after administration, the tumor transplantation site was irradiated with X-ray 20 Gy. For comparison, an untreated group not irradiated with X-rays and a Met-rHSA-FecycP-administered group were provided (one group of 6 animals).
The tumor transplantation date is taken as day 0, and the tumor major and minor diameters are measured after 6, 7, 9, 12, 15, 20, 25, 32, 39, 46, 53, and 60 days after tumor implantation. Was calculated.
Tumor weight (g) = major axis (mm) × <minor axis (mm)> ² ÷ 2 ÷ 1000
The tumor weight of each group was expressed as an average value ± standard deviation, and the significant difference test was performed by Tukey-Kramer multiple comparison test (significance level 5%). The obtained results are shown in FIG.

  The tumor weight increased with time in the untreated group, and the Met-rHSA-FecycP administration group (no irradiation) showed almost the same transition as the untreated group. On the other hand, in the group irradiated with X-rays, the tumor weight was significantly reduced. The tumor weight was significantly reduced in the Met-rHSA-FecycP administration + irradiation group compared to the rHSA + irradiation group. In the Met-rHSA-FecycP administration + irradiation group, one patient survived 60 days after transplantation. In this surviving case, the tumor disappeared 15 days after transplantation. Therefore, it has been clarified that Met-rHSA-FecycP enhances the tumor reduction effect by X-ray irradiation of the tumor tissue.

  From the above, it can be seen that the combined use of X-rays with Met-rHSA-FecycP enhances the tumor shrinking effect by X-ray irradiation as well as rHSA-FecycP and sugar-containing iron oxide containing the same concentration of iron. Therefore, the iron in the chemical structural formula is enhanced in radiosensitivity regardless of whether it is divalent (the iron valence of rHSA-FecycP) or trivalent (the iron valence of sugar-containing iron oxide and Met-rHSA-FecycP). It turns out that there is an effect, and it is clear that iron-containing compounds are useful as radiation enhancers.

  The radiosensitizer of the present invention exhibits a high radiosensitization effect and is stable with low toxicity. Useful as a radiosensitizer in cancer chemotherapy.

(1) Combined use of rHSA-FecycP and X-ray, (2) Combined use of sugar-containing iron oxide and X-ray, (3) Combined use of chondroitin sulfate / iron colloid and X-ray, and (4) No treatment (5) RHSA-FecycP single administration only, (6) X-ray irradiation only, (7) Survival days of rats in case of combined use of rHSA and X-rays. (1) Combined use of rHSA-FecycP and X-ray, (2) Combined use of sugar-containing iron oxide and X-ray, (3) Combined use of chondroitin sulfate / iron colloid and X-ray, and (4) No treatment (5) It is the figure which compared the reduction effect of the tumor weight of a rat in the case of only rHSA-FecycP single administration, (6) X-ray irradiation only, and (7) Combination of rHSA and X-ray. (1) Combined use of Met-rHSA-FecycP and X-ray, (2) No treatment as control, (3) Only administration of Met-rHSA-FecycP, (4) Rat in combination of rHSA administration and X-ray It is the figure which compared the reduction effect of the tumor weight of each.

Claims (4)

A radiosensitizer comprising a sugar-containing iron oxide comprising trivalent iron . A drug kit comprising the radiosensitizer and the chemotherapeutic agent according to claim 1 . The drug kit according to claim 1, wherein the radiosensitizer and the chemotherapeutic agent are individually packaged. Pharmaceutical kit according to claim 1, characterized in that the administered irradiation radiosensitizers according to claim 1 within 1 hour after administration of the chemotherapeutic agent.
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