Formulation Strategies and In Vitro Characterization of Talquetamab-Loaded Nanocarriers for Targeted Immunotherapy in Multiple Myeloma

Abstract

Background: Talquetamab is a first-in-class bispecific T-cell redirecting antibody that binds to the novel antigen, GPRC5D, which is highly expressed in multiple myeloma cells, and to CD3 on T cells, enabling T cells to mediate tumor cell lysis. Although it shows promising clinical effects, its stability, targeted delivery, and systemic distribution are still crucial factors in ensuring long-term therapeutic success. Objective: The purpose of this study is to design and test a new polymeric nanoparticle carrier for Talquetamab to improve its stability, tumor specificity, therapeutic efficacy and reduce off-target immunotoxicity. Methods: Talquetamab was formulated into PEGylated PLGA nanoparticles by the modified double-emulsion solvent evaporation technique. Folic acid was used to surface-functionalize the nanoparticles for improved tumor-targeting by receptor-mediated endocytosis. The characteristics of the system were determined by measuring particle size, zeta potential, encapsulation efficiency and in vitro release profile. The stability was evaluated in a simulated physiological condition. Internalization, cell death and T-cell redirection were assessed in GPRC5D+ RPMI 8226 multiple myeloma cells and CD3+ Jurkat T-cells by confocal microscopy, MTT and flow cytometry, respectively. Results: Talquetamab loaded nanoparticles formed in this study had a mean diameter of 142.6 ± 5.2 nm, zeta potential of – 28.3 mV, and the EE was 76.4%. In-vitro release studies revealed pH-responsive and sustained release up to 72 hrs. The functionalized nanoparticles demonstrated a considerable higher cellular uptake (3.6-fold) and cytotoxicity (p < 0.01) in GPRC5D+ cells in comparison to free antibody. Effective targeting and killing of T-cells was confirmed by flow cytometry. Conclusion: The folate-conjugated polymeric nanoparticle system significantly enhances the pharmacological properties of Talquetamab thanks to its stable, sustained, and tumor-specific delivery. This platform could be used to enhance the therapeutic window of bispecifics in the treatment of hematologic malignancies and could be applied to other types of T cell engagers.