Dual mechanisms of novel CD73-targeted antibody and antibody-drug conjugate in inhibiting lung tumor growth and promoting antitumor immune-effector function.

While the tyrosine kinase inhibitor (TKI) therapy and immunotherapy have significantly improved lung cancer management, many patients do not benefit or become resistant to treatment, highlighting the need for novel treatments. We found elevated CD73 expression to be prevalent in non-small cell lung cancer (NSCLC) including those harboring the RAS- or RTK (EGFR, EML4-ALK) oncogenes. CD73 expression is enriched closely with the transcriptome signature of epithelial-mesenchymal transition and immune-tolerant tumor microenvironment, which are increasingly relevant for disease progression and therapy resistance. We developed two novel series of CD73 antibody Ab001/Ab002 and humanized version Hu001/Hu0002, which demonstrated high CD73 binding affinity, potent enzyme inhibition and efficiently protected effector T lymphocyte function from adenosine/cancer-imposed toxicity. Hu001/Hu002 inhibited growth of RAS-mutant NSCLC tumors in mice via enhanced ADCC and multifaceted remodeling of tumor immune-environment reflecting diminished levels of tumor-associated macrophages, myeloid-derived suppressor cells and tumor vasculature. A novel MMAE-conjugated CD73-ADC (Hu001-MMAE) elicited potent cytotoxicity against CD73-high expressing tumor cells (IC50