Antibody polymer drug conjugates with increased drug to antibody ratio: CD38-targeting nanomedicines for innovative therapy of relapsed lymphomas.

The current frontline therapy for B-cell non-Hodgkin lymphomas (B-NHL), the most frequent hematologic malignancy in the Western hemisphere, is based on immunochemotherapy (ICT), i.e., a combination of genotoxic cytostatics and the anti-CD20 monoclonal antibody (mAb) rituximab. The treatment of relapsed or refractory (R/R) B-NHL remains an unmet medical need. Here, we developed and preclinically characterized a tailored hybrid mAb-polymer-drug conjugate (APDC) composed of the anti-CD38 mAb daratumumab (clinically approved for multiple myeloma therapy) and biocompatible N-(2-hydroxypropyl)methacrylamide (HPMA)-based copolymers conjugated with a cytotoxic payload monomethyl auristatine E (MMAE) via a Val-Cit-para-amino benzyl carbamate spacer cleavable by lysosomal enzymes. This innovative APDC design results in a significantly higher drug-to-antibody ratio (DAR) while maintaining a degree-of-conjugation (DOC) comparable to that of standard antibody-drug conjugates (ADCs). The enhanced anti-lymphoma efficacy of the new APDC nanotherapeutics, compared to standard ADCs, was confirmed in vivo using patient-derived lymphoma xenografts from a patient with R/R B-NHL. These APDC nanomedicines show promise as a personalized targeted chemotherapy approach.