Addition of interleukin-2 overcomes resistance to neoadjuvant CTLA4 and PD1 blockade in ex vivo patient tumors
Paulien Kaptein, Célia Jacoberger-Foissac, Petros Dimitriadis, Paula Voabil, Marjolein de Bruijn, Simone Brokamp, Irene L. M. Reijers, Judith M. Versluis, Gahyathiri Nallan, Hannah Triscott, Elizabeth S. McDonald, Joshua Tay, Georgina V. Long, Christian U. Blank, Daniela S. Thommen, Michele W.L. Teng
Abstract
Neoadjuvant immunotherapy with anti-cytotoxic T lymphocyte–associated protein 4 (CTLA4) + anti–programmed cell death protein 1 (PD1) monoclonal antibodies has demonstrated remarkable pathological responses and relapse-free survival in ~80% of patients with clinically detectable stage III melanoma. However, about 20% of the treated patients do not respond. In pretreatment biopsies of patients with melanoma, we found that resistance to neoadjuvant CTLA4 + PD1 blockade was associated with a low CD4/interleukin-2 (IL-2) gene signature. Ex vivo, addition of IL-2 to CTLA4 + PD1 blockade induced T cell activation and deep immunological responses in anti-CTLA4 + anti-PD1–resistant human tumor specimens. In the 4T1.2 breast cancer mouse model of neoadjuvant immunotherapy, triple combination of anti-CTLA4 + anti-PD1 + IL-2 cured almost twice as many mice as compared with dual checkpoint inhibitor therapy. This improved efficacy was due to the expansion of tumor-specific CD8 + T cells and improved proinflammatory cytokine polyfunctionality of both CD4 + and CD8 + T effector cells and regulatory T cells. Depletion studies suggested that CD4 + T cells were critical for priming of CD8 + T cell immunity against 4T1.2 and helped in the expansion of tumor-specific CD8 + T cells early after neoadjuvant triple immunotherapy. Our results suggest that the addition of IL-2 can overcome resistance to neoadjuvant anti-CTLA4 + anti-PD1, providing the rationale for testing this combination as a neoadjuvant therapy in patients with early-stage cancer.