TwoStep Therapeutics, a biotechnology company developing multi-specific targeted therapies for solid tumors, has achieved two significant milestones. The company closed an oversubscribed $62.5 million Series A financing and received clearance from the U.S. Food and Drug Administration for its Investigational New Drug application for TS-104. This decision allows TwoStep to initiate a first-in-human Phase 1 clinical trial of its lead peptide-drug conjugate, with patient enrollment expected to begin later this year.
Financing and Regulatory Milestone
The Series A round was led by Insight Partners and Medical Excellence Capital. M Ventures, the strategic corporate venture capital arm of Merck KGaA, and Pfizer Ventures joined as co-lead investors, while existing backers NFX and 2048 Ventures also participated. Additional support came from Stanford University, where the company's foundational science originated before its 2024 launch, and the financing brings total capital raised to $71.2 million.
Platform Science
Most tumor-targeted therapies depend on high and relatively uniform expression of a single cell-surface target. In solid tumors, target expression can vary widely across tumor types, between patients, and even among cells within the same tumor. TwoStep addresses this challenge with a polyspecific integrin-binding peptide known as PIP that targets five tumor-associated integrins, and this multi-targeting strategy is designed to deliver broader and more consistent tumor recognition despite heterogeneity.
Lead Candidate and Pipeline
The company's lead candidate, TS-104, couples PIP to the clinically validated cytotoxic payload MMAE. The small size and rapid internalization of PIP support flexible conjugation chemistry and enable targeted drug delivery with the same scaffold paired to different payloads. Beyond TS-104, the financing will support advancement of a radioligand program and expansion into next-generation peptide conjugates.
Clinical Development Plans
FDA clearance of the IND enables TwoStep to begin the first clinical evaluation of its multi-specific targeting approach in oncology. The Phase 1 trial will assess the safety and early efficacy of TS-104 in patients with solid tumors. Positive results could validate the broader applicability of the company's peptide-drug conjugate platform in heterogeneous cancers.
Leadership and Board Expansion
TwoStep was co-founded by Chief Executive Officer Caitlyn Miller in collaboration with Stanford faculty members Jennifer Cochran, Nobel laureate Carolyn Bertozzi, and Ronald Levy. In connection with the financing, the company expanded its board of directors. New appointments include Matias Porras Paniagua from Insight Partners, John Prufeta from Medical Excellence Capital, Oliver Lyth from M Ventures, and Rana Al-Hallaq from Pfizer Ventures.
Investor Commentary
Matias Porras Paniagua of Insight Partners noted that TwoStep is tackling a central challenge in solid-tumor drug development. He said the company's approach has the potential to broaden the reach of targeted therapies across tumor types and patient populations. John Prufeta of Medical Excellence Capital added that the caliber of the investor syndicate reflects confidence in the company's scientific foundation and long-term potential.
Strategic Significance
The combined announcement positions TwoStep to advance a differentiated oncology pipeline with both financial and regulatory momentum. The company's modular platform could support multiple therapeutic programs beyond its initial clinical candidate. This flexibility may enable TwoStep to potentially address a wider range of solid tumors more effectively than traditional single-target approaches.
TwoStep Therapeutics now enters a pivotal period as it moves TS-104 into clinical testing with a strengthened balance sheet and expanded board. The company's multi-specific targeting technology could offer a meaningful alternative to conventional therapies that depend on a single tumor antigen. With enrollment expected later this year, TwoStep is well positioned to generate early clinical data and advance its broader pipeline of peptide conjugates and radioligand therapies.