Raltitrexed

Raltitrexed (Tomudex, TDX, ZD 1694) is an antimetabolite drug used in cancer chemotherapy. It is an inhibitor of thymidylate synthase, and is manufactured by AstraZeneca.

Uses
Used in treatment of colorectal cancer since 1998.

Mechanism of action
Raltitrexed is chemically similar to folic acid and is in the class of chemotherapy drugs called folate antimetabolites, which inhibit one or more of three enzymes that use folate and deriavtives as substrates: DHFR, GARFT and Thymidine synthase. Raltitrexed is fully active after polyglutamylation, which allows cellular retention of the drug.

By inhibiting Thymidine synthase (TS), thus formation of precursor pyrimidine nucleotides, raltitrexed prevents the formation of DNA and RNA, which are required for the growth and survival of both normal cells and cancer cells.

Inhibition of L1210 cell growth in culture IC50 = 9 nM, is one of the strongest antimetabolites in use.

Structure and phase I clinical trial described in 1986.