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Totus Medicines Announces First Patient Dosed in Phase 1 Trial of TOS-358 for the Treatment Of Select Solid Tumors

TOS-358 is the first highly specific, potent inhibitor of PI3

EMERYVILLE, Calif. , April 13, 2023 — Totus Medicines, the drug discovery and development company committed to ending the era of untreatable disease, announced today the dosing of the first patient in a Phase 1 clinical trial of TOS-358, the company’s first-in-class covalent PI3Kα inhibitor for the treatment of numerous cancers with known PIK3CA mutations.

The Totus Accel Platform delivers the first biosearch technology that scans, maps, and decodes effective new drugs thousands of times faster than traditional drug discovery processes. As a result, Totus was able to file an Inves­tiga­tive New Drug application with the FDA in a mere 18 months after the TOS-358 program was discovered and developed. Totus uses proprietary molecular tags that track drug binding in individual cells to screen billions of drug molecules across thousands of genes in parallel. By combining this approach with break­through machine learning techniques, the company has developed the next generation of cellular analysis. The Totus Accel Platform is more effective, less costly, and thousands of times faster than legacy drug discovery methods, enabling the rapid translation of therapies to patients.

The Phase 1 clinical trial will evaluate the safety, toler­a­bility, phar­ma­co­ki­netics, and phar­ma­co­dy­namics of TOS-358 as a single agent in 241 trial partic­i­pants with select solid tumors. Trial partic­i­pants will have histo­log­i­cally confirmed diagnosis of colorectal cancer, gastric cancer, non-small cell lung cancer, human epidermal growth factor receptor 2 (HER2) negative breast cancer, squamous cell carcinoma of the head and neck, urothelial cancer, or select gynecologic cancers (ovarian cancer, cervical cancer, or endometrial cancer) with known PIK3CA mutations.

TOS-358 represents a promising new approach to the treatment of the root cause of nearly 15% of all cancers, and we are excited to be able to advance it into clinical development at such an accelerated rate,” said Neil Dhawan, PhD, CEO & co-founder, of Totus Medicines. 

This study will be conducted in two parts: a dose finding portion to determine the maximum tolerated dose, and recommended phase 2 dose of TOS-358 admin­is­tered orally on once a day and twice daily schedules; and a dose expansion portion to evaluate safety and toler­a­bility in tumor-specific cohorts admin­is­tered TOS-358 at the recommended phase 2 dose and schedule.

For more information on the Phase 1 trial of TOS-358, please visit

About Totus Medicines
Founded in 2019, Totus Medicines has developed the next generation of cellular analysis to create life-changing therapies to treat previously untreatable diseases. Totus’ platform uses proprietary molecular tags that track drug binding in individual cells to enable the screening of billions of molecules across any drug target. Totus is based in the Bay Area.

For more information, please visit and follow Totus on LinkedIn and Twitter.

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