23 July 2025, Shanghai—Abbisko Therapeutics Co., Ltd. (“Abbisko”) today announced that it has dosed the first patient in a Phase 1 clinical trial of ABSK131, an investigational and novel PRMT5*MTA inhibitor in patients with advanced or metastatic solid tumors with MTAP deficiency. In March 2025, ABSK131 received IND clearance from the Center for Drug Evaluation (CDE) of the China National Medical Products Administration (NMPA). In December 2024, ABSK131 received IND clearance from the U.S. Food and Drug Administration (FDA).

The ongoing clinical study is conducted under the title “A Phase 1, First-in-Human, Multicenter, Open-Label Study of ABSK131 to Assess Safety, Tolerability, Pharmacokinetics, and Preliminary Efficacy in Patients with Advanced/Metastatic Solid Tumors with MTAP deficiency."

Approximately 15% of solid tumors lack expression of methylthioadenosine phosphorylase (MTAP), a tumor suppressor gene ^[1]. Solid tumors with high rates of MTAP deficiency include non-small cell lung cancer (NSCLC) (15.7%), pancreatic cancer (21.7%), esophageal cancer (28.4%), mesothelioma (32.2%), and gastrointestinal cancer (10.4% of gastric and 1% of colorectal cancer)^[2], of which mesotheliomas and pancreatic cancers have no approved targeted therapies. Recent studies have demonstrated that selectively targeting PRMT5*MTA shows promise as a therapeutic strategy for MTAP-deficient cancers.

About ABSK131

ABSK131 is a novel, small molecule MTA-cooperative PRMT5 inhibitor in development by Abbisko Therapeutics. In preclinical studies, ABSK131 demonstrated excellent selectivity for MTAP-deleted cancer cells, as well as favorable drug metabolism and pharmacokinetic properties for oral dosing.

References:

1.Kalev P, Hyer ML, Gross S, et al. MAT2A Inhibition Blocks the Growth of MTAP-Deleted Cancer Cells by Reducing PRMT5-Dependent mRNA Splicing and Inducing DNA Damage. Cancer Cell. 2021;39(2):209-224.e11. doi:10.1016/j.ccell.2020.12.010

2.Bertino JR, Waud WR, Parker WB, Lubin M. Targeting tumors that lack  methylthioadenosine phosphorylase (MTAP) activity: current strategies. Cancer Biol Ther. 2011;11(7):627-632. doi:10.4161/cbt.11.7.14948.