HLA-A*02:01–Merkel cell polyomavirus peptide complex (HLA-A*02:01-MCPyV)

The HLA-A*02:01–Merkel cell polyomavirus (MCPyV) peptide complex is a specific molecular target consisting of the Human Leukocyte Antigen (HLA) allele A*02:01 presenting a peptide derived from the MCPyV T-antigen, typically the Large T-antigen (e.g., the KLLEIAPNC epitope). This complex is highly relevant in Merkel cell carcinoma (MCC), a rare and aggressive skin cancer where MCPyV is clonally integrated into the host genome in approximately 80% of cases. Because the viral proteins are foreign to the human proteome and are essential for tumor cell survival and proliferation, this peptide-MHC complex serves as an ideal tumor-specific neoantigen. Therapeutic interventions targeting this complex primarily involve adoptive cell therapies, such as T-cell receptor-engineered T-cells (TCR-T), which are designed to recognize the specific spatial configuration of the MCPyV peptide within the HLA-A*02:01 binding groove. Clinical trials have demonstrated that targeting this complex can induce regression in patients with metastatic MCC who are HLA-A*02:01 positive. The specificity of this interaction minimizes damage to healthy tissues, although challenges such as HLA loss and the immunosuppressive tumor microenvironment remain significant hurdles. This target represents a cornerstone of precision immunotherapy for virus-associated malignancies.

Other names

HLA-A*02:01-MCPyV T-antigen complexMHC-peptide complex (HLA-A*02:01/MCPyV)HLA-A2-MCPyV complexMerkel cell polyomavirus Large T-antigen/HLA-A*02:01 complex

Recognition by engineered T-cell receptors (TCRs) or bispecific molecules that bind specifically to the viral peptide presented in the HLA-A*02:01 groove, triggering cytotoxic T-lymphocyte mediated lysis of the target cell.