RS-5

RS-5 is a first-in-class Macrophage-Targeted Conjugate (MAC-TAC) being developed by Resolute Science for the treatment of various solid tumors. The drug utilizes a proprietary delivery platform designed to target tumor-associated macrophages (TAMs), which represent a significant portion of the solid tumor mass (30-50%). RS-5 carries a monomethyl auristatin E (MMAE) cytotoxic payload, a potent tubulin inhibitor, and leverages the natural biology of TAMs to deliver this payload deep into the tumor microenvironment. This mechanism aims to deplete or modulate the immunosuppressive TAM population while providing a localized cytotoxic effect against cancer cells. In preclinical studies, RS-5 has shown single-agent efficacy across multiple tumor models, including melanoma and lung cancer. The FDA granted RS-5 Orphan Drug Designation for soft tissue sarcomas in October 2025, and the drug is currently in the IND-enabling phase, with Phase 1 clinical trials expected to commence in 2026.

Other names

Macrophage-Targeted ConjugateMAC-TAC