The Anti-Müllerian Hormone Receptor Type II (AMHR2): preliminary steps to unravel its potential as new non-gynaecological tumor antigen

In recent decades, interest in immunotherapy and the development of personalized cancer treatments has significantly increased. Monoclonal antibodies (mAbs) have emerged as powerful therapeutic tools due to their high specificity and ability to selectively recognize tumor-associated antigens (TAAs). The identification of novel membrane targets is therefore essential for improving targeted therapeutic strategies. In this context, this study investigated the anti-Müllerian hormone receptor type II (AMHR2), a member of the TGF-β superfamily, involved in the regulation of key cellular processes such as proliferation, differentiation, and apoptosis. Although its physiological expression is mainly restricted to reproductive tissues, recent evidence suggests its aberrant expression in several tumor types, including non-gynecological malignancies. We performed a preliminary meta-analysis (GEPIA2) confirming the non-gynecological AMHR2 expression in different tumor histotypes, with relevance in pancreatic adenocarcinoma (PDAC). These findings were experimentally in vitro validated, confirming receptor expression at the transcriptional and protein levels, including the presence of canonical and non-canonical isoforms. Cell viability assays using an anti-AMHR2 monoclonal antibody (mAb) demonstrated a concentration dependent reduction in proliferation in PDAC cell lines. This effect was accompanied by increased phosphorylation of SMAD1/5/9 proteins, indicating activation of the AMH/AMHR2 signaling pathway and supporting a potential anti proliferative role for AMHR2 targeting in this tumor context. Moreover, co immunoprecipitation experiments revealed the ability of AMHR2 to form macromolecular complexes at the plasma membrane, a feature of particular relevance for tumor associated antigens. Building on these premises and supported by evidence demonstrating the potential of AMHR2 as a diagnostic and clinical tool in melanoma, we generated an anti AMHR2 single chain variable fragment (scFv) derived from the pre existing full length mAb. This approach opens new perspectives for translational and preclinical applications and enables the exploration of innovative preclinical animal models. Among these, we considered the transgenic melanoma model of the medaka fish (Oryzias latipes), characterized by high conservation of the main neoplastic signaling pathways.