Pharmaceutical composition for treating solid tumors

A method for treating a solid tumor while suppressing a gastrointestinal symptom, the method comprising:

• administering, to a human subject with the solid tumor, (6S,9aS)—N-benzyl-8-({6-[3-(4-ethylpiperazin-1-yl)azetidin-1-yl]pyridin-2-yl}methyl)-6-(2-fluoro-4-hydroxybenzyl)-4,7-dioxo-2-(prop-2-en-1-yl)hexahydro-2H-pyrazino [2,1-c][1,2,4]triazine-1(6H)-carboxamide represented by the formula (I) or a pharmaceutically acceptable salt thereof twice daily at a dose of about 10 mg to about 150 mg per dose of (6S,9aS)—N-benzyl-8-({6-[3-(4-ethylpiperazin-1-yl)azetidin-1-yl]pyridin-2-yl}methyl)-6-(2-fluoro-4-hydroxybenzyl)-4,7-dioxo-2-(prop-2-en-1-yl)hexahydro-2H-pyrazino [2,1-c][1,2,4]triazine-1(6H)-carboxamide;
• and
• administering an effective amount of a 5-HT3 receptor antagonist to suppress a gastrointestinal symptom in combination to the human subject with a solid tumor;
• wherein the gastrointestinal symptom is a gastrointestinal symptom associated with administration, to the human subject, of the (6S,9aS)—N-benzyl-8-({6-[3-(4-ethylpiperazin-1-yl)azetidin-1-yl]pyridin-2-yl}methyl)-6-(2-fluoro-4-hydroxybenzyl)-4,7-dioxo-2-(prop-2-en-1-yl)hexahydro-2H-pyrazino [2,1-c][1,2,4]triazine-1(6H)-carboxamide or the pharmaceutically acceptable salt thereof