MTAP Deletion as a Therapeutic Vulnerability in Cancer: From Molecular Mechanism to Clinical Targeting

The MTAP (methylthioadenosine phosphorylase) gene, located on chromosome 9p21, plays a crucial role in the methionine salvage pathway and is frequently co-deleted with CDKN2A in various malignancies. Loss of MTAP expression leads to the accumulation of methylthioadenosine (MTA), which selectively inhibits protein arginine methyltransferase 5 (PRMT5) and creates a unique metabolic vulnerability in MTAP-deficient tumors. These alterations have emerged as promising therapeutic targets in precision oncology. Recent advances highlight the potential of exploiting MTAP loss through synthetic lethality approaches using PRMT5 and methionine adenosyltransferase 2A (MAT2A) inhibitors. Preclinical and early clinical data indicate that targeting these pathways can selectively impair tumor growth while sparing MTAP-proficient cells. Moreover, MTAP deletion has been associated with specific molecular and immunologic profiles that may influence treatment response and tumor microenvironment characteristics. This review summarizes current knowledge on the biological functions of MTAP, the mechanisms linking its loss to oncogenesis, and the evolving landscape of therapeutic strategies targeting MTAP-deficient cancers. Understanding these molecular dependencies offers novel opportunities for the development of precision-based therapies across diverse tumor types.