Preclinical assessment of MAGE-A4-specific TCR-NK cells against solid tumors

T cell (Tc) receptor (TCR)-based cell therapies have shown clinical efficacy across many cancer types and represent an attractive strategy for targeting solid tumors. However, the immunosuppressive tumor microenvironment, downregulation of target antigen and HLA, and the need for an autologous source limit the efficacy and the accessibility of TCR-Tc therapies. Early clinical trials have shown the potential of natural killer cells (NKs) as a therapy to treat hematological and solid cancers. Allogeneic NKs, engineered to express a TCR, represent a novel and promising strategy overcoming the limitations of T and NKs therapies. Here we describe the development of a product consisting of NKs engineered to express an affinity-enhanced TCR recognizing MAGE-A4, a clinically validated tumor antigen expressed across several solid tumors. The introduction of the TCR does not disrupt the innate functionality of NKs and adds TCR-mediated specific killing of antigen-positive targets. In fact, the innate potential of the NKs appears to be enhanced by the presence of the CD3-TCR complex, creating NKs with increased potency. TCR-NKs are faster, more potent than TCR-Tc and retain killing activity in the absence of TCR target antigen thus potentially overcoming tumor heterogeneity and/or antigen loss. Lastly, TCR-NKs are not activated when co-cultured with normal cells, displaying a safe profile. Combining the innate cytotoxicity of NKs with MAGE-A4-specific targeting of an affinity-enhanced TCR, results in a potent and safe cellular product representing a promising and novel therapeutic off-the-shelf paradigm for the treatment of many solid cancers.