Targeting mutant NPM1-expressing AML with T cell receptor-like antibodies

This study developed T cell receptor (TCR)-like antibodies targeting the intracellular neoantigen derived from the common NPM1 type A mutation (NPM1^mutA) in acute myeloid leukemia (AML), presented by HLA-A∗02:01. Hybridoma technology was employed to generate a murine monoclonal antibody (m2E2) specifically recognizing the NPM1^mutA _283-291-HLA-A∗02:01 complex. The lead antibody was humanized (hu2E2) and engineered into bispecific formats engaging CD3 or CD16, alongside an Fc-enhanced variant (hu2E2-GAALIE). In vitro, these antibodies mediated potent antibody-dependent cellular cytotoxicity (ADCC) against NPM1^mutA-positive AML cell lines, inducing apoptosis and cytokine release. In vivo, a single dose of hu2E2 variants significantly suppressed tumor growth in NCG mice engrafted with OCI-AML3-LUC cells. Fc silencing abolished antitumor efficacy, confirming FcγR-dependent mechanisms. Critically, m2E2 specifically bound to primary CD33⁺ blasts from HLA-A∗02:01-positive, NPM1-mutated AML patients. These findings demonstrate a potent immunotherapeutic strategy for targeting intracellular oncogenic peptides in AML and support further clinical development of TCR-like antibodies.