Background: Ozuriftamab vedotin (BA3021) is a conditionally active biologic (CAB) anti-receptor tyrosine kinase orphan receptor 2 (ROR2) humanized monoclonal antibody (IgG1) conjugated to monomethyl auristatin E (MMAE) using a cleavable linker (CAB ROR2 ADC) (Short, et al., 2014, Chang, et al. 2021). Conditional and reversible binding by CABs is designed to reduce off-tumor toxicity and immunogenicity, avoid tissue-mediated drug deposition, and improve pharmacokinetics (PK). ROR2 is a cell-surface transmembrane receptor protein tyrosine kinase highly expressed in several tumor types including head and neck squamous cell cancer (HNSCC). Increased ROR2 expression has been associated with tumor resistance to chemotherapy, programmed death-1 (PD-1) inhibitors, molecular targeted therapy, and radiation therapy. A pronounced unmet need exists as the majority of patients with recurrent or metastatic HNSCC experience disease progression with existing therapies (Chow 2020). Methods: BA3021-002 is a multi-center, open-label, single-arm Phase 2 study (n=40) designed to evaluate the efficacy and safety of BA3021 in patients previously treated with PD-(L)1 with ROR-2 expressing recurrent or metastatic HNSCC. Eligible patients include those with measurable disease by Response Evaluation Criteria in Solid Tumors (RECIST) Version 1.1 criteria. Failure to prior treatment is defined as documented disease progression after no more than one PD-1/L1 inhibitor either administered as monotherapy or in combination therapy. Pharmacokinetic (PK), pharmacodynamic (PD), immunogenicity, and biomarker assessments will be performed. Enrollment is ongoing (NCT05271604) References: Chang, H.W., Frey, G., Liu, H., Steinman, L., Boyle, W.J. and Short, J.M. Proc. Natl. Acad. Sci. 2021 Mar. 2; 118(9). Chow LQ. Head and neck cancer. N Engl J Med. 2020 Jan 2;382(1):60–72. doi: 10.1056/NEJMra1715715. Short, J.M. Nature Biotechnology 2014 Nov 8, 13(20). Clinical trial information: NCT05271604.