Antibody-Fc/FcR Interaction on Macrophages as a Mechanism for Hyperprogressive Disease in Non-Small Cell Lung Cancer Subsequent to PD-1/PD-L1 Blockade

PURPOSE: Hyperprogression (HP), a paradoxical boost in tumor growth, was described in a subset of patients treated with immune checkpoint inhibitors (ICI). Neither clinico-pathological features nor biological mechanisms associated with HP have been identified. EXPERIMENTAL DESIGN: Among 187 patients with non-small cell lung cancer (NSCLC) treated with ICI at our Institute, cases with HP were identified according to clinical and radiological criteria. Baseline histological samples from patients treated with ICI were evaluated by immunohistochemistry (IHC) for myeloid and lymphoid markers. T-cell deficient mice, injected with human lung cancer cells and patient-derived xenografts (PDXs) belonging to specific mutational subsets, were assessed for tumor growth after treatment with antibodies against mouse and human programmed death receptor-1 (PD-1). The immune microenvironment was evaluated by flow cytometry and IHC. RESULTS: Among 187 patients, 152 were evaluable for clinical response. We identified 4 categories: 32 cases were defined as Responders (21%), 42 patients with Stable Disease (27.7%), 39 cases defined as Progressors (25.7%) and 39 patients with HP (25.7%). Pre-treatment tissue samples from all patients with HP showed tumor-infiltration by M2-like CD163+CD33+PD-L1+ clustered epithelioid macrophages. Enrichment by tumor-associated macrophages (TAM) was observed, even in tumor nodules from immunodeficient mice injected with human lung cancer cells and with PDXs. In these models, tumor growth was enhanced by treatment with anti-PD-1, but not by anti-PD-1 F(ab)2-fragments. CONCLUSIONS: These results suggest a crucial role of TAM reprogramming, upon Fc receptor engagement by ICI, eventually inducing HP and provide clues on a distinctive immunophenotype potentially able to predict HP.