# Totus Medicines

> Totus Medicines is a clinical-stage precision medicines company in Emeryville, California, building covalent small-molecule drugs against historically undruggable targets. Its AI-powered OmniDEL platform screens billions of DNA-encoded covalent candidates against thousands of targets inside living cells, surfacing molecules that older methods miss. Its lead program, TOS-358, is the first and only covalent PI3Ka inhibitor in clinical development, showing class-leading tolerability and strong disease control in breast, endometrial, and head & neck cancers.

- **Founded:** 2019
- **Headquarters:** Emeryville, California, United States
- **Founders:** Neil Dhawan (Co-Founder, founding CEO, now CSO & Head of R&D (Board of Directors))
- **Team size:** ~35 employees
- **Products:** OmniDEL Platform, TOS-358, Covalent IRF5 Inhibitor
- **Notable:** Built OmniDEL, an AI-powered DNA-encoded covalent library platform that screens drugs inside living cells, Advanced TOS-358, the first and only covalent PI3Ka inhibitor, into the clinic, Reported 100% disease control rate and 89% clinical benefit rate for TOS-358 + fulvestrant in HR+/HER2- breast cancer (Phase 1b)

## Products & services

- **OmniDEL Platform** — Proprietary AI-powered DNA-encoded covalent library technology that screens billions of drug candidates against thousands of targets simultaneously, inside their normal cellular environment, applying large-scale machine learning to map pharmacophore-target relationships across the proteome.
- **TOS-358** — Lead program - the first and only covalent PI3Ka selective inhibitor in clinical development, an oral small molecule for select solid tumors including breast, endometrial, and head & neck cancers.
- **Covalent IRF5 Inhibitor** — First-in-class covalent IRF5 inhibitor program for immunology/inflammation, with data presented at AAI IMMUNOLOGY2026.

## Achievements

- Built OmniDEL, an AI-powered DNA-encoded covalent library platform that screens drugs inside living cells
- Advanced TOS-358, the first and only covalent PI3Ka inhibitor, into the clinic
- Reported 100% disease control rate and 89% clinical benefit rate for TOS-358 + fulvestrant in HR+/HER2- breast cancer (Phase 1b)
- Demonstrated class-leading tolerability - 0% bone marrow, hepatic, renal, or ocular toxicity and zero discontinuations due to intolerance across 56 patients
- Raised $107M total, including a $66M Series B led by DCVC Bio
- Secured a drug-discovery partnership with Eli Lilly

## Latest updates

- **2026-05** — Presented early Phase 1b data showing 100% disease control rate and class-leading safety for TOS-358 + fulvestrant doublet therapy in HR+/HER2- breast cancer at ESMO Breast Cancer Annual Congress 2026.
- **2026-04** — Announced upcoming presentation of interim Phase 1b TOS-358 + fulvestrant data at ESMO Breast Cancer 2026.
- **2026-03** — Presented Phase 1a clinical data for TOS-358 at ESMO TAT 2026.
- **2026-01** — To present first-in-class covalent IRF5 inhibitor data at AAI IMMUNOLOGY2026.
- **2025-01** — Completed Phase 1 dose-escalation study, initiated expansion trial for TOS-358, and appointed Zelanna Goldberg as Chief Medical Officer.
- **2023-12** — Closed $66M Series B led by DCVC Bio; Nassim Usman, Ph.D., appointed President & CEO as co-founder Neil Dhawan moved to CSO & Head of R&D.

## Links

- Website: https://totusmedicines.com
- LinkedIn: https://www.linkedin.com/company/totusmedicines
- Twitter/X: https://twitter.com/Totus_Medicines

---

Profile page: https://yespress.io/totus-medicines
Published by YesPress — https://yespress.io
Last updated: 2026-06-08