SunnyBay Biotech

SunnyBay Biotech is a private oncology biotechnology company developing first-in-class therapies that target human endogenous retrovirus K (HERV-K), a tumor-associated antigen expressed across a broad range of solid tumors. Its lead program, SBB001, is a HERV-K-targeting antibody-drug conjugate built from a fully humanized monoclonal antibody and evaluated with payloads including MMAE, SN38, and DXd. The company positions HERV-K as a differentiated target with low expression in normal adult tissues and potential utility across breast, lung, ovarian, pancreatic, colon, and melanoma tumors. Beyond its lead ADC, SunnyBay describes a broader platform spanning antibodies, cellular therapies, bispecific T-cell engagers, vaccines, and companion diagnostics. The company remains preclinical, with lead optimization completed for SBB001 and IND-enabling studies planned.