the compound or pharmaceutically acceptable salt thereof represented by formula ( i ) according to the present invention can be produced by the method described in patent literature 1 . further , the compound or pharmaceutically acceptable salt thereof represented by formula ( ii ) according to the present invention can be produced by the method described in patent literature 2 . examples of the pharmaceutically acceptable salt include salts with inorganic acids , salts with organic acids , salts with inorganic bases , salts with organic bases , and salts with acidic or basic amino acids . preferred examples of the salts with inorganic acids include salts with hydrochloric acid , hydrobromic acid , sulfuric acid , nitric acid , phosphoric acid and the like . preferred examples of the salts with organic acids include salts with acetic acid , succinic acid , fumaric acid , maleic acid , tartaric acid , citric acid , lactic acid , stearic acid , benzoic acid , methanesulfonic acid , ethanesulfonic acid , p - toluenesulfonic acid and the like . preferred examples of the salts with inorganic bases include alkaline metal salts such as a sodium salt and a potassium salt ; alkaline earth metal salts such as a calcium salt and a magnesium salt ; an aluminum salt ; and an ammonium salt . preferred examples of the salts with organic bases include salts with diethylamine , diethanolamine , meglumine , n , n - dibenzylethylenediamine and the like . preferred examples of the salts with acidic amino acids include salts with aspartic acid , glutamic acid and the like . preferred examples of the salts with basic amino acids include salts with arginine , lysine , ornithine and the like . the antitumor agent of the present invention may be orally administered in the form of a solid formulation such as a tablet , granule , fine granule , powder or capsule , or in the form of a liquid , jelly , syrup or the like . further , the antitumor agent of the present invention may be parenterally administered in the form of an injection , suppository , ointment , cataplasm or the like . the dose of the compound or pharmaceutically acceptable salt thereof represented by formula ( i ) may be appropriately selected depending on the degrees of symptoms , age , sex and body weight of the patient , difference in sensitivity , route , time and interval of administration , type of pharmaceutical formulation , and / or the like . usually , in cases where oral administration is carried out for an adult ( 60 kg body weight ), the dose is 10 to 6000 mg , preferably 50 to 4000 mg per day . this may be administered at one time , or dividedly at 2 or 3 times per day . the dose of the compound or pharmaceutically acceptable salt thereof represented by formula ( ii ) may be appropriately selected as in the case described above . usually , in cases where oral administration is carried out for an adult ( 60 kg body weight ), the dose is 1 to 600 mg , preferably 4 to 400 mg , more preferably 4 to 200 mg per day . this may be administered at one time , or dividedly at 2 or 3 times per day . in cases where an oral solid formulation is prepared , a vehicle , and , as required , a binder , disintegrator , lubricant , coloring agent , flavoring agent and / or the like may be added to the principal component , that is , a compound or pharmaceutically acceptable salt thereof represented by formula ( i ), and a compound or pharmaceutically acceptable salt thereof represented by formula ( ii ), to prepare , thereafter , a tablet , granule , fine granule , powder , capsule or the like according to a conventional method . examples of the vehicle include lactose , corn starch , white soft sugar , glucose , sorbitol , crystalline cellulose and silicon dioxide . examples of the binder include polyvinyl alcohol , ethylcellulose , methylcellulose , gum arabic , hydroxypropylcellulose and hydroxypropylmethylcellulose . examples of the lubricant include magnesium stearate , talc and silica . examples of the coloring agent include titanium oxide , iron sesquioxide , yellow iron sesquioxide , cochineal , carmine and riboflavin . examples of the flavoring agent include cocoa powder , ascorbic acid , tartaric acid , peppermint oil , borneol and cinnamon powder . these tablets and granules may be coated as required . in cases where an injection is prepared , a ph adjustor , buffering agent , suspending agent , solubilizer , stabilizer , isotonic agent , preservative and / or the like may be added as required to the principal component , to prepare an intravenous , subcutaneous or intramuscular injection , or an intravenous drip infusion . as required , these may be prepared into lyophilized products by conventional methods . examples of the suspending agent include methylcellulose , polysorbate 80 , hydroxyethylcellulose , gum arabic , powdered tragacanth , sodium carboxymethylcellulose and polyoxyethylene sorbitan monolaurate . examples of the solubilizer include polyoxyethylene hydrogenated castor oil , polysorbate 80 , nicotinamide , polyoxyethylene sorbitan monolaurate , macrogol and glycerin fatty acid ester . examples of the stabilizer include sodium sulfite and sodium metabisulfite . examples of the preservative include methyl parahydroxybenzoate , ethyl parahydroxybenzoate , sorbic acid , phenol , cresol and chlorocresol . the antitumor agent of the present invention may be prepared by formulating a compound or pharmaceutically acceptable salt thereof represented by formula ( i ), and a compound or pharmaceutically acceptable salt thereof represented by formula ( ii ) separately , and the both may be administered either at the same time or separately . further , the two formulations may be placed in a single package , to provide the so called kit formulation . further , the both compounds may be contained in a single formulation . the type of the tumor to be treated with the antitumor agent of the present invention is not restricted , and examples thereof include fibroma , adipoma , myxoma , chondroma , osteoma , angioma , lymphoma , myeloma , melanoma , myoma , neuroma , glioma , osteosarcoma , myosarcoma , fibrosarcoma , papilloma , adenoma , brain tumor , and cancers such as cervical cancer , esophagus cancer , tongue cancer , lung cancer , breast cancer , pancreatic cancer , gastric cancer , small intestinal cancer in duodenum , jejunum , ileum and the like , large bowel cancer in colon , caecum , rectum and the like , bladder cancer , renal cancer , liver cancer , gallbladder cancer , prostate cancer , uterine cancer , ovarian cancer , thyroid cancer and pharyngeal cancer ; and mixed tumors thereof . the present invention is described in more detail by way of examples below . a combined effect of compound a and compound b in a model animal to which human malignant melanoma cell line ( seki ) was transplanted the human malignant melanoma cell line seki ( jcrb cell bank ) was cultured using a 10 % fbs - containing rpm 1640 medium ( sigma ) in a 5 % co 2 incubator under the condition of 37 ° c . when the cells reached a state of approximately 80 % confluency , the cells were collected using trypsin - edta . to these cells , a hanks &# 39 ; balanced salt solution containing 50 % matrigel was added to prepare a suspension at 5 . 0 × 10 7 cells / ml . the cell suspension thus obtained was subcutaneously transplanted at the lateral side of the body of a nude mouse ( cann . cg - foxn1nu / crlcrlj , charles river laboratories japan , inc .) in an amount of 0 . 1 ml , where each group contained six mice . from 11 days after the transplantation , compound a ( 10 mg / kg , once daily , for 17 days ) and compound b ( 100 mg / kg , once daily , for 17 days ) were orally administered , either individually or both in a row . setting the initial day of administration at day 0 , the major axis and the minor axis of a tumor developed in each mouse were measured using digimatic caliper ( mitsutoyo corporation ) thereafter on day 3 , 7 , 10 , 14 , and 17 . the tumor volume and the relative tumor volume were calculated according to the equations below . the results of rtv were summarized in table 1 and fig1 . the numbers in the table indicate an average value ± standard deviation ( the same will apply to the following tables ). compared to cases where compound a and compound b were each administered individually , the combined use of compound a and compound b exhibited a remarkably excellent antitumor effect . also , as a result of performing two - way anova with respect to log - transformed rtv by setting compound a and compound b as the factors , rtv on day 17 was found to be statistically significant ( p & lt ; 0 . 05 ), whereby the synergistic effect of compound a and compound b was confirmed . a combined effect of compound a and compound b in a model animal to which human pancreatic cancer cell line ( kp - 4 ) was transplanted the human pancreatic cancer cell line kp - 4 ( acquired from national hospital organization kyushu cancer center ) was cultured using a 10 % fbs - containing rpmi 1640 medium ( sigma ) in a 5 % co 2 incubator under the condition of 37 ° c . when the cells reached a state of approximately 80 % confluency , the cells were collected using trypsin - edta . to these cells , a hanks &# 39 ; balanced salt solution containing 50 % matrigel was added to prepare a suspension at 5 . 0 × 10 7 cells / ml . the cell suspension thus obtained was subcutaneously transplanted at the lateral side of the body of a nude mouse ( cann . cg - foxn1nu / crlcrlj , charles river laboratories japan , inc .) in an amount of 0 . 1 ml , where each group contained six mice . from 11 days after the transplantation , compound a ( 10 mg / kg , once daily , for 17 days ) and compound b ( 100 mg / kg , once daily , for 17 days ) were orally administered , either individually or both in a row . setting the initial day of administration at day 0 , the major axis and the minor axis of a tumor developed in each mouse were measured using digimatic caliper ( mitsutoyo corporation ) thereafter on day 3 , 7 , 10 , 14 , and 17 . the tumor volume and the relative tumor volume were calculated according to the equations below . the results of rtv were summarized in table 2 and fig2 . compared to cases where compound a and compound b were each administered individually , the combined use of compound a and compound b exhibited a remarkably excellent antitumor effect . also , as a result of performing two - way anova with respect to log - transformed rtv by setting compound a and compound b as the factors , rtv on day 17 was found to be statistically significant ( p & lt ; 0 . 05 ), whereby the synergistic effect of compound a and compound b was confirmed . a combined effect of compound a and compound b in a model animal to which human gastric cancer cell line ( im95m ) was transplanted the human gastric cancer cell line im95m ( health science research resources bank ) was cultured using a dmem medium ( wako pure chemical industries , ltd ) containing 4500 mg / ml glucose , 10 % fbs , and 10 μg / ml insulin in a 5 % co 2 incubator under the condition of 37 ° c . when the cells reached a state of approximately 80 % confluency , the cells were collected using trypsin - edta . to these cells , a hanks &# 39 ; balanced salt solution containing 50 % matrigel was added to prepare a suspension at 1 . 0 × 10 8 cells / ml . the cell suspension thus obtained was subcutaneously transplanted at the lateral side of the body of a nude mouse ( cann . cg - foxn1nu / crlcrlj , charles river laboratories japan , inc .) in an amount of 0 . 1 ml , where each group contained six mice . from 13 days after the transplantation , compound a ( 10 mg / kg , once daily , for 21 days ) and compound b ( 100 mg / kg , once daily , for 21 days ) were orally administered continuously , either individually or both in a row . setting the initial day of administration at day 0 , the major axis and the minor axis of a tumor developed in each mouse were measured using digimatic caliper ( mitsutoyo corporation ) thereafter on day 4 , 7 , 11 , 14 , 18 and 21 . the tumor volume and the relative tumor volume were calculated according to the equations below . the results of rtv were summarized in table 3 and fig3 . compared to cases where compound a and compound b were each administered individually , the combined use of compound a and compound b exhibited a remarkably excellent antitumor effect . although no statistical significance was shown by two - way anova , an effect of complete inhibition of tumor proliferation was confirmed by the combined use of compound a and compound b . a combined effect of compound a and compound b in a model animal to which human ovarian cancer cell line ( a2780 ) was transplanted the human ovarian cancer cell line a2780 ( atcc ) was cultured using a 10 % fbs - containing rpmi 1640 medium ( sigma ) in a 5 % co 2 incubator under the condition of 37 ° c . when the cells reached a state of approximately 80 % confluency , the cells were collected using trypsin - edta . to these cells , a hanks &# 39 ; balanced salt solution containing 50 % matrigel was added to prepare a suspension at a concentration of 5 . 0 × 10 7 cells / ml . the cell suspension thus obtained was subcutaneously transplanted at the lateral side of the body of a nude mouse ( cann . cg - foxn1nu / crlcrlj , charles river laboratories japan , inc .) in an amount of 0 . 1 ml , where each group contained six mice . compound a ( 10 mg / kg , once daily , for 10 days ) and compound b ( 100 mg / kg , once daily , for 10 days ) were orally administered , either individually or both in a row . setting the initial day of administration at day 0 , the major axis and the minor axis of a tumor developed in each mouse were measured using digimatic caliper ( mitsutoyo corporation ) thereafter on day 3 , 5 , 8 , and 10 . the tumor volume and the relative tumor volume were calculated according to the equations below . the results of rtv were summarized in table 4 and fig4 . compared to cases where compound a and compound b were each administered individually , the combined use of compound a and compound b exhibited a remarkably excellent antitumor effect . also , as a result of performing two - way anova with respect to log - transformed rtv by setting compound a and compound b as the factors , rtv on day 10 was found to be statistically significant ( p & lt ; 0 . 05 ), whereby the synergistic effect of compound a and compound b was confirmed . the human glioblastoma cell line ( u87mg ) ( atcc ) was cultured using a 10 % fbs - containing e - mem medium ( sigma ) in a 5 % co 2 incubator under the condition of 37 ° c . when the cells reached a state of approximately 80 % confluency , the cells were collected using trypsin - edta . to these cells , a hanks &# 39 ; balanced salt solution containing 50 % matrigel was added to prepare a suspension at a concentration of 5 . 0 × 10 7 cells / ml . the cell suspension thus obtained was subcutaneously transplanted at the lateral side of the body of a nude mouse ( cann . cg - foxn1nu / crlcrlj , charles river laboratories japan , inc .) in an amount of 0 . 1 ml , where each group contained six mice . compound a ( 10 mg / kg , once daily , for 21 days ) and compound b ( 100 mg / kg , once daily , for 21 days ) were orally administered , either individually or both in a row . setting the initial day of administration at day 0 , the major axis and the minor axis of a tumor developed in each mouse were measured using digimatic caliper ( mitsutoyo corporation ) thereafter on day 2 , 5 , 7 , 9 , 12 , 14 , 16 , 19 , and 21 . the tumor volume and the relative tumor volume were calculated according to the equations below . the results of rtv were summarized in table 5 and fig5 . compared to cases where compound a and compound b were each administered individually , the combined use of compound a and compound b exhibited a remarkably excellent antitumor effect . also , although no statistical significance was shown by two - way anova performed with respect to log - transformed rtv by setting compound a and compound b as the factors , an effect of complete inhibition of tumor proliferation was confirmed by the combined use of compound a and compound b .
an antitumor agent for combined use of a compound or pharmaceutically acceptable salt thereof represented by formula and a compound or pharmaceutically acceptable salt thereof represented by formula exhibits an excellent antitumor effect compared to cases where these are individually used , and exhibits antitumor effects against various cancer types : wherein r 1 is azetidinyl and the like , r 2 to r 5 is a hydrogen atom or a halogen atom , r 6 is c 3 - 8 cycloalkyl and the like , r 7 is a hydrogen atom and the like , and r 8 is a halogen atom and the like .