12. A product containing Pemetrexed disodium, vitamin B 12 or a pharmaceutical derivative thereof said pharmaceutical derivative of vitamin
B12 being hydroxocobalamin, cyano-1-0-chlorocobalamin, aquocobalamin perchlorate, aquo-10-chlorocobalamin perchlorate, azidocobalamin,
chlorocobalamin or cobalamin, and, optionally, a folic binding protein binding agent selected from the group consisting of folic acid, (6R)-5-methyl-
5,6,7,8-tetrahydro folic acid and (6R)-5-formyl-5,6,7,8-tetrahydro folic acid, or a physiologically available salt or ester thereof, as a combined
preparation for the simultaneous, separate or sequential use in inhibiting
tumor growth."