Rethinking Oncologic Treatment Strategies with Interleukin-2

High-dose recombinant human IL-2 (rhIL-2, aldesleukin) emerged as an important treatment option for selected patients with metastatic melanoma and metastatic renal cell carcinoma, producing durable and long-lasting antitumor responses in a small fraction of patients and heralding the potential of cancer immunotherapy. However, the adoption of high-dose rhIL-2 has been restricted by its severe treatment-related adverse event (TRAE) profile, which necessitates highly experienced clinical providers familiar with rhIL-2 administration and readily accessible critical care medicine support. Given the comparatively wide-ranging successes of immune checkpoint inhibitors and chimeric antigen receptor T cell therapies, there have been concerted efforts to significantly improve the efficacy and toxicities of IL-2-based immunotherapeutic approaches. In this review, we highlight novel drug development strategies, including biochemical modifications and engineered IL-2 variants, to expand the narrow therapeutic window of IL-2 by leveraging downstream activation of the IL-2 receptor to selectively expand anti-tumor CD8-positive T cells and natural killer cells. These modified IL-2 cytokines improve single-agent activity in solid tumor malignancies beyond the established United States Food and Drug Administration (FDA) indications of metastatic melanoma and renal cell carcinoma, and may also be safer in rational combinations with established treatment modalities, including anti-PD-(L)1 and anti-CTLA-4 immunotherapy, chemotherapies, and targeted therapy approaches.

Automated summary

High-dose rhIL-2 has shown promise in treating metastatic melanoma and metastatic renal cell carcinoma, but its severe adverse effects have limited its adoption. Efforts have been made to improve the efficacy and safety of IL-2-based immunotherapies, including through biochemical modifications and engineered IL-2 variants. These modified IL-2 cytokines have shown improved activity in solid tumors beyond the FDA-approved indications and can be combined with other treatment modalities.