TwoStep Therapeutics Raises $62.5M to Move TS-104 Into Phase 1

Solid tumors create a targeting problem before a drug delivers its payload: the marker that makes one cancer cell visible may appear weakly or not at all on the cell beside it. TwoStep Therapeutics is financing a five-integrin answer and taking it into the clinic.

TwoStep has closed an oversubscribed $62.5M Series A and announced FDA clearance of the Investigational New Drug application for TS-104, its lead peptide-drug conjugate. Insight Partners and Medical Excellence Capital led the September 9, 2026 financing, with M Ventures and Pfizer Ventures joining as co-lead investors. Returning backers NFX and 2048 Ventures participated alongside Stanford University and other investors.

The financing and regulatory milestone put money and permission on the same clinical calendar. TwoStep expects to begin enrolling patients in a first-in-human Phase 1 study later in 2026. That study will be the first human test of a targeting strategy designed to recognize five tumor-associated integrins rather than depend on high, uniform expression of a single antigen.

What TwoStep Therapeutics Announced

The $62.5M Series A brings TwoStep’s company-reported total capital raised to $71.2M. The company launched publicly in 2024 with a $6.5M Seed led by NFX, with 2048 Ventures, Alexandria Venture Investments, GC&H Investments, and the family office of the founder of Arcadia Investment Partners participating.

A January 2026 SEC Form D described a $62.21M Series A preferred-stock offering and included shares issued on conversion of existing convertible notes. The filing was an interim snapshot, showing $21.11M sold at the time, while the September announcement reports the completed, oversubscribed round at $62.5M. TwoStep did not disclose valuation, ownership, investor check sizes, or the full bridge between its prior Seed and stated lifetime capital.

The financing also changed the board around the program. Matias Porras Paniagua of Insight Partners, John Prufeta of Medical Excellence Capital, Oliver Lyth of M Ventures, and Rana Al-Hallaq of Pfizer Ventures joined existing directors Caitlyn Miller and Omri Amirav-Drory of NFX. That group now has direct visibility into the clinical, manufacturing, and portfolio decisions behind TS-104 and TwoStep’s radioligand work.

Why Solid Tumors Complicate Targeted Delivery

Many targeted cancer therapies depend on a single surface marker being present at a sufficiently high and consistent level. TwoStep’s scientific thesis begins with the opposite reality: target expression can vary across tumor types, from one patient to another, and among cells within the same tumor. A delivery system can recognize its intended marker accurately while still leaving target-low or target-negative cells outside its useful reach.

TwoStep’s answer is PIP, an engineered, ultra-stable knottin peptide that binds five tumor-associated integrins. The company says the small peptide preferentially recognizes integrin conformations found in tumor tissue, internalizes rapidly, and can be joined to different therapeutic payloads. Those properties are designed to broaden tumor recognition and support a pipeline across peptide-drug conjugates and radioligand therapies, but the breadth, specificity, and safety claims remain preclinical until human evidence arrives.

TS-104 joins PIP to monomethyl auristatin E, or MMAE, a cytotoxic payload used in approved antibody-drug conjugates. The payload is familiar; the experimental question sits in the targeting scaffold. TwoStep now has to learn whether one peptide engaging five integrins can produce useful exposure across heterogeneous tumors without narrowing the therapeutic window through off-tumor effects.

From Stanford Research to a Clinical Company

TwoStep’s platform grew from work spanning bioengineering, chemical biology, and oncology at Stanford. Jennifer Cochran’s lab engineered the PIP targeting peptide. During doctoral and postdoctoral work, Caitlyn Miller helped connect the scaffold to therapeutic payloads, then led the spinout through the Stanford Innovative Medicines Accelerator.

Miller is now CEO and Co-Founder alongside Stanford faculty Jennifer Cochran, Carolyn Bertozzi, and Ronald Levy. Bertozzi, a 2022 Nobel laureate in chemistry, contributed chemical-biology and drug-conjugate expertise; Levy brought decades of oncology and cancer-immunotherapy experience. The company was legally formed in 2023 and launched publicly in 2024, turning a multidisciplinary academic foundation into a San Carlos biotechnology company.

The current TwoStep leadership roster reflects the work required for that transition. Joy Geallis serves as VP, Clinical; Nicolas Salem leads radiopharmaceutical clinical development; Kevin Roland leads CMC; and Yash Agarwal directs R&D operations. No current CTO appears on the official team page or financing announcement, so the record should not manufacture one to complete an executive template.

What the Series A Has to Deliver

TwoStep says the proceeds will move TS-104 through Phase 1 development, advance its radioligand program, and expand into next-generation peptide conjugates. The company expects enrollment in the first TS-104 study to begin later in 2026, but it has not disclosed the protocol, trial sites, patient count, tumor indications, dose plan, runway, or timing for initial data.

FDA guidance makes the next work plain. An IND allows clinical research to begin; it is not commercial approval and does not establish that a medicine works. Phase 1 oncology studies focus on safety, tolerability, dose, pharmacokinetics, and early signs of activity in people with cancer, creating the evidence needed to design later studies.

The investor roster brings more than financial capacity. M Ventures is the corporate venture arm of Merck KGaA, and Pfizer Ventures operates inside a global drug company with extensive oncology development experience. Their participation can contribute pattern recognition and strategic access, while TwoStep’s own clinical and CMC team remains responsible for turning those advantages into a well-run study and a reproducible product.

The Clinical Handoff Now Begins

The Series A arrives at a more consequential moment than a standard platform financing. TwoStep has a lead program, an IND that the company says is cleared, a board expanded around the round, and a stated path into human testing. The central scientific proposition can finally meet the variability it was designed to address.

That makes the next milestones narrower and more useful than a broad claim about targeted oncology. Investigators need to learn where TS-104 travels, how patients tolerate it, which dose produces workable exposure, and whether early tumor signals support the multi-integrin design. The radioligand and next-generation conjugate programs can widen the pipeline later, but TS-104 carries the first clinical burden of proof.

The $62.5M Series A gives Caitlyn Miller’s team the operating runway to put PIP in front of the biology that matters. From here, TwoStep’s record will advance dose by dose, as investigators learn whether heterogeneous tumors present enough common ground for a five-target peptide to hold.