– Lometrexol hydrate (DDATHF hydrate) is an antipurine antifolate compound that inhibits glycinamide ribonucleotide formyltransferase (GARFT) activity without inducing detectable DNA strand breaks. It further disrupts de novo purine synthesis, leading to abnormal cell proliferation, apoptosis, and cell cycle arrest, exhibiting anticancer activity [1] [2]. Additionally, it acts as a potent inhibitor of human Serine hydroxymethyltransferase1/2 (h SHMT1/2) [3].