This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anti-Cancer, Subject name: Pharmacology
[{'content': 'Antidote for methotrexate toxicity: \nSelect and explain. \nA. Folic acid, B. Folinic acid, C. Vitamin B, D. Thymine', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ref: Katzung 14th ed. pg. 957; KDT, 6th ed. pg. 823* The toxicity of Mtx can not be overcome by folic acid, because it will not be converted to the active coenzyme form. However, folinic acid rapidly reverses the effect.* Thymidine also counteracts the Mtx toxicity.METHOTREXATE (MTX)DHFA-DHFRaseTHFA* Methotrexate is a highly efficacious antineoplastic drug which inhibits dihydrofolate reductase (DHFRase) enzyme- blocking the conversion of dihydrofolic acid (DHFA) to tetrahydrofolic acid (THFA).* This conversion is essential for formation of an essential coenzyme required for one carbon transfer reactions in denovo purine synthesis and amino acid interconversions.* Methotrexate has cell cycle specific action kills cells in S phase; primarily inhibits DNA synthesis.Drug of choice for Mtx toxicity: FOLINIC ACID.', 'role': 'assistant'}]