Characterization of the canine CD20 as a therapeutic target for comparative passive immunotherapy.

Anti-CD20 therapies have revolutionized the treatment of B-cell malignancies. Despite these advances, relapsed and refractory disease remains a major treatment challenge. The optimization of CD20-targeted immunotherapies is considered a promising strategy to improve current therapies. However, research has been limited by the scarcity of preclinical models that recapitulate the complex interaction between the immune system and cancers. The addition of the canine lymphoma (cNHL) model in the development of anti-CD20 therapies may provide a clinically relevant approach for the translation of improved immunotherapies. Still, an anti-CD20 therapy for cNHL has not been established stressing the need of a comprehensive target characterization. Herein, we performed an in-depth characterization on canine CD20 mRNA transcript and protein expression in a cNHL biobank and demonstrated a canine CD20 overexpression in B-cell lymphoma samples. Moreover, CD20 gene sequencing analysis identified six amino acid differences in patient samples (C77Y, L147F, I159M, L198V, A201T and G273E). Finally, we reported the use of a novel strategy for the generation of anti-CD20 mAbs, with human and canine cross-reactivity, by exploring our rabbit derived single-domain antibody platform. Overall, these results support the rationale of using CD20 as a target for veterinary settings and the development of novel therapeutics and immunodiagnostics.