CSF1R⁺ myeloid-monocytic cells drive CAR-T cell resistance in aggressive B cell lymphoma

Despite the improvement, approximately 60% of patients with relapsed or refractory (r/r) aggressive B cell lymphoma (B-NHL) do not achieve durable benefit from CAR-T cell therapy. To elucidate factors associated with CAR-T therapy resistance, we conducted high-dimensional analyses of pre- and post-CAR-T cell specimens. In patients with non-durable response, we identified a prognostically relevant lymphoma-associated myeloid-monocytic (LAMM) gene signature. In-depth profiling revealed a distinct CSF1R⁺CD14⁺CD68⁺ LAMM cell population in both human and murine B-NHL that inhibits CAR-T cell function and correlates with poor outcome. Cell-cell inference analysis uncovered that LAMM cells impair CAR-T cell function through a direct LAMM-T cell interaction via the PGE₂-EP2/EP4 axis. In an autochthonous lymphoma mouse model, combined anti-CD19 CAR-T cell therapy with CSF1R blockade exhibited synergistic effects and improved survival. These findings provide strong rationale for combining anti-CD19 CAR-T cells with CSF1R inhibitors in treating r/r aggressive B-NHL patients.