Our Science

Most tumor-targeted therapies rely on a single target, which can limit the tumors they can treat and the patients who may benefit. To address these limitations, TwoStep uses a unique multi-specific binder, “PIP,” as the targeting component for its therapies.

About PIP

PIP is an engineered, ultra-stable knottin peptide that binds five tumor-associated integrins expressed across a broad range of solid tumors. By engaging multiple integrins through a single binder, TwoStep’s approach has the potential to address target heterogeneity within tumors and broaden targeted drug delivery across tumor types. PIP preferentially binds to integrin conformations abundant in tumor tissue, enhancing specificity and safety.

MOA animations by Visual Science

One peptide unlocks a pipeline of cancer therapies

Targeted Drug Conjugates

Targeted Radioligand Therapy

Targeted Drug Conjugates

Drug conjugates combine a tumor-targeting molecule with a cytotoxic drug payload, helping direct the payload to tumors while limiting exposure to healthy tissues.

PIP’s rapid, target-mediated internalization makes it a powerful vehicle for delivering cytotoxic payloads directly into cancer cells. TwoStep’s lead peptide-drug conjugate is TS-104, which uses PIP to deliver the clinically validated cytotoxic payload, MMAE.

View our 2025 scientific poster to learn more.

Targeted Radioligand Therapy

Radioligand therapies pair a tumor-targeting molecule with a therapeutic radioisotope, concentrating radiation at tumor sites while reducing exposure elsewhere in the body.

PIP’s small size makes it uniquely suited for delivery of radiopharmaceuticals – it clears rapidly from the blood while its multi-specific integrin binding enables robust tumor delivery across cancer types. The same construct can be paired with different types of radioisotopes: diagnostic isotopes for tumor imaging or therapeutic isotopes for targeted radiotherapy.