TwoStep Therapeutics has raised $62.5m in an oversubscribed Series A financing round to support its lead peptide-drug conjugate, TS-104, for the treatment of solid tumours.
Insight Partners and Medical Excellence Capital led the round, with additional investment from Pfizer Ventures and M Ventures, the corporate venture capital arm of Merck KGaA, all joining as co-lead investors.
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Previous backers NFX and 2048 Ventures also participated, alongside Stanford University, where the company’s core scientific platform originated before it launched in 2024.
TwoStep’s total capital raised now stands at $71.2m.
The company also received investigational new drug (IND) application clearance for TS-104 from the US Food and Drug Administration (FDA).
This approval enables a first-in-human Phase I study of TS-104, with patient enrolment expected to commence later this year.
TwoStep Therapeutics co-founder and CEO Caitlyn Miller said: “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 I 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.”
TwoStep said that most existing tumour-targeted therapies rely on the presence of a single cell-surface target, which may not be uniformly expressed across all patients or tumour cells.
Its approach uses a polyspecific integrin-binding peptide (PIP), designed to bind five tumour-associated integrins found across a variety of solid tumours.
The company’s TS-104 conjugates the PIP to Monomethyl auristatin E (MMAE), a cytotoxic payload.
In connection with the fundraising, TwoStep appointed Insight Partners vice-president Matias Porras Paniagua, Medical Excellence Capital CEO John Prufeta, M Ventures biotechnology investment associate Oliver Lyth, and Pfizer Ventures operations head Rana Al-Hallaq to the company’s board. Existing members include Miller and NFX general partner Omri Amirav-Drory.
