Plamotamab (CD20 x CD3)
CD20 x CD3 bispecific T-cell engager to be evaluated in patients with multi-drug resistant rheumatoid arthritis
Xencor plans to initiate a Phase 1b/2a proof-of-concept study for plamotamab in multi-drug resistant rheumatoid arthritis (MDR-RA) in the first half of 2025 (Press Release, September 9, 2024). The Phase 1b portion of the study will select a priming and step-up dose regimen based on the regimen established in oncology, and will assess the initial safety, efficacy, and biomarkers of plamotamab in patients with MDR-RA. The selected dose regimen will then be evaluated in the randomized Phase 2a portion, with efficacy determined at week 24.
Xencor previously completed a Phase 1 clinical study of plamotamab in hematologic cancers, completing enrollment in late 2023. Results from the study showed favorable tolerability and comparable preliminary efficacy data, when cross compared to results from studies of a competitor molecule within the class, with similar patient baseline characteristics. Based on these clinical outcomes, significant B-cell depletion observed in preclinical studies, and the emergent biology supportive of B-cell targeted T cell engagers for the treatment of patients with autoimmune diseases, Xencor plans to evaluate plamotamab in MDR-RA, in which patients progressed through two prior lines of therapy.