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Totus Medicines Launches Phase I Trial of PI3Kα Inhibitor in Biomarker-Defined Solid Tumors

NEW YORK – Totus Medicines on Thursday said it began a Phase I trial of its covalent PI3Kα inhibitor in patients with PIK3CA-mutated cancer.

In the trial, investigators will test the safety, tolerability, pharmacokinetics, and pharmacodynamics of TOS-358 in 241 patients with certain solid tumors with known PIK3CA mutations. Researchers are particularly interested in enrolling patients with colorectal, gastric, non-small cell lung, HER2-negative breast, urothelial, squamous cell head and neck, and gynecologic cancers. The aim of the trial will be to determine a maximum tolerated dose for TOX-358, a recommended Phase II dose, and safety and tolerability at the recommended Phase II dose.

The drug, TOS-358, was developed on Totus' Accel Platform, which combines a library of covalent chemistries with high-throughput cell-based screening and machine learning to evaluate billions of small molecule compounds against thousands of targets. In 2021, the Emeryville, California-based company raised $40 million in Series A financing to further develop its drug discovery platform and advance TOS-358 into the clinic.