Polatuzumab Vedotin Enhances Intratumoral T‐Cell Infiltration and Demonstrates Combinatorial Efficacy With Anti‐CD20/CD3 Bispecific Antibody in a Syngeneic B‐Cell Malignancy Mouse Model

Introduction Polatuzumab vedotin (Pola) is an anti‐CD79b antibody‐drug conjugate. Clinical evidence supports the combination efficacy of Pola with mosunetuzumab or glofitamab, both anti‐CD20/CD3 bispecific antibodies (anti‐CD20/CD3 BsAbs). However, the influence of Pola on the tumor microenvironment and its impact on the efficacy of anti‐CD20/CD3 BsAb remains unclear. Results In a syngeneic mouse model, Pola significantly increased tumor‐infiltrating T cells and innate immune cells. Moreover, Pola also upregulated the levels of cytokine and chemokine involved in T‐cell infiltration. The Pola + anti‐CD20/CD3 BsAb combination showed superior anti‐tumor efficacy versus each monotherapy. Conclusion These findings suggest Pola enhances immune cell infiltration into tumors and could enhance the efficacy of anti‐CD20/CD3 BsAb. Trial Registration The authors have confirmed clinical trial registration is not needed for this submission