(R)-HTS-3 (GLXC-25878) is a potent, selective, and cell-active inhibitor of lysophosphatidylcholine acyltransferase 3 (LPCAT3) with an IC50 of 0.09 µM, an enzyme critical for synthesizing C20:4-containing phospholipids. It reduces arachidonic acid-d8 incorporation into phospholipids and mitigates RSL3-induced ferroptosis in HT-1080 and 786-O cancer cells.