CD8-Targeted IL2 Unleashes Tumor-Specific Immunity in Human Cancer Tissue by Reviving the Dysfunctional T-cell Pool.

Tumor-specific CD8+ T cells are key effectors of antitumor immunity but are often rendered dysfunctional in the tumor microenvironment. Immune-checkpoint blockade can restore antitumor T-cell function in some patients; however, most do not respond to this therapy, often despite T-cell infiltration in their tumors. We here explored a CD8-targeted IL2 fusion molecule (CD8-IL2) to selectively reactivate intratumoral CD8+ T cells in patient-derived tumor fragments. Treatment with CD8-IL2 broadly armed intratumoral CD8+ T cells with enhanced effector capacity, thereby specifically enabling reinvigoration of the dysfunctional T-cell pool to elicit potent immune activity. Notably, the revival of dysfunctional T cells to mediate effector activity by CD8-IL2 depended on simultaneous antigen recognition and was quantitatively and qualitatively superior to that achieved by PD-1 blockade. Finally, CD8-IL2 was able to functionally reinvigorate T cells in tumors resistant to anti-PD-1, underscoring its potential as a novel treatment strategy for patients with cancer. Significance: Reinvigorating T cells is crucial for response to checkpoint blockade therapy. However, emerging evidence suggests that the PD-1/PD-L1 axis is not the sole impediment for activating T cells within tumors. Selectively targeting cytokines toward specific T-cell subsets might overcome these barriers and stimulate T cells within resistant tumors. See related article by Moynihan et al., p. 1206 (32).

Addition of interleukin-2 overcomes resistance to neoadjuvant CTLA4 and PD1 blockade in ex vivo patient tumors.

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.

An ex vivo tumor fragment platform to dissect response to PD-1 blockade in cancer.

Inhibitors of the PD-1-PD-L1 axis have been approved as therapy for many human cancers. In spite of the evidence for their widespread clinical activity, little is known about the immunological alterations that occur in human cancer tissue after PD-1 blockade. We developed and employed a patient-derived tumor fragment platform to dissect the early immunological response of human tumor tissue to ex vivo PD-1 blockade. We observed that the capacity of immune cells to be reactivated ex vivo was predictive of clinical response, and perturbation analyses identified tumor-resident T cells as a key component of this immunological response. In addition, through combined analysis of baseline properties and immune response capacity, we identified a new subgroup of infiltrated tumors that lacks the capacity to respond to PD-1 blockade. Finally, the baseline presence of tertiary lymphoid structures and their components correlated with the capacity of cancers to undergo intratumoral immune cell reactivation.