TwoStep Therapeutics has raised an oversubscribed $62.5 million Series A and received FDA clearance for the Investigational New Drug application for TS-104, its lead multi-specific peptide-drug conjugate for solid tumors.
The IND clearance allows TwoStep to begin a first-in-human Phase 1 clinical trial of TS-104, with patient enrollment expected to start later in 2026.
The financing was led by Insight Partners and Medical Excellence Capital, with M Ventures, the strategic corporate venture arm of Merck KGaA, and Pfizer Ventures serving as co-lead investors.
Existing investors NFX and 2048 Ventures also participated, along with additional investors including Stanford University.
The round brings TwoStep’s total capital raised to $71.2 million.
TwoStep was launched in 2024 and was co-founded by CEO Caitlyn Miller, Ph.D., in collaboration with Stanford faculty members Jennifer Cochran, Carolyn Bertozzi and Ronald Levy. The foundational research underlying the company was developed at Stanford.
TwoStep is developing therapies intended to overcome a challenge with traditional targeted cancer treatments. Many existing approaches depend on high and relatively uniform expression of a single target on tumor cells, but target levels can vary substantially among tumor types, patients and individual cells.
Instead, TwoStep uses a polyspecific integrin-binding peptide, or PIP, that targets five tumor-associated integrins found across a broad range of solid tumors.
By targeting multiple integrins rather than one antigen, the company aims to recognize heterogeneous tumors more consistently and potentially treat broader patient populations.
The peptide’s small size, rapid internalization and conjugation chemistry allow TwoStep to pair the same targeting scaffold with multiple therapeutic payloads.
The company’s lead candidate, TS-104, combines PIP with the clinically validated cytotoxic payload MMAE. TwoStep is also using the platform to develop radioligand therapies and additional next-generation peptide conjugates.
The Series A proceeds will fund Phase 1 development of TS-104 while supporting the company’s radioligand program and additional peptide-conjugate programs.
In connection with the financing, TwoStep added Matias Porras Paniagua of Insight Partners, John Prufeta of Medical Excellence Capital, Oliver Lyth of M Ventures and Rana Al-Hallaq of Pfizer Ventures to its board.
KEY QUOTES:
“This financing, together with FDA clearance of the IND, marks an important inflection point for TwoStep and positions us to advance TS-104, our lead peptide-drug conjugate, through Phase 1 clinical development in oncology. This trial will provide the first clinical evaluation of the multi-specific targeting approach at the heart of TwoStep and begin to assess its potential to broaden the reach of targeted therapies. Beyond TS-104, the proceeds will enable us to advance our radioligand program and expand into next-gen peptide conjugates.”
Caitlyn Miller, Ph.D., Co-Founder and Chief Executive Officer of TwoStep Therapeutics
“TwoStep is addressing one of the central challenges in solid-tumor drug development: identifying a targeting approach that can reach meaningful numbers of patients without relying on a single, uniformly expressed tumor target. By engaging multiple tumor-associated integrins through a small and rapidly internalizing targeting agent, TwoStep’s approach has the potential to broaden the reach of targeted therapies across tumor types and patient populations. As TS-104 enters clinical development, we look forward to seeing that potential realized in practice.”
Matias Porras Paniagua, Ph.D., Vice President at Insight Partners
“MEC is proud to lead the Series A financing. TwoStep truly exemplifies the characteristics we seek in leading transformative biotechnology investments: highly differentiated science, rigorous execution, and a management team dedicated to translating innovation into meaningful clinical impact for patients. Reaching an FDA-cleared IND for TS-104 is a significant accomplishment. Moreover, the caliber of this investor syndicate reflects confidence in the company’s scientific foundation as well as its long-term potential. We look forward to supporting Caitlyn and the outstanding TwoStep team to build a leading precision oncology company as they advance this potentially transformational program into the clinic.”
John Prufeta, Founder and General Partner of Medical Excellence Capital
