The cytokines IL-2 and IFN-α received FDA approval three decades ago. Although efficacious in a subset of cancer patients, widespread usage of these treatments has been limited by toxicity.
We are developing cytokine drugs that are only active following binding to a specified target. Targeted, locally activated cytokine drugs will be more effective than systemically active native or attenuated cytokines.
PD-1-Dependent IL-2 will target PD-1+ tumor-specific T-cells while remaining inactive on the majority of T-cells in the periphery, which do not express PD-1.
PD-1 expression identifies activated tumor-reactive T cells, whereas it is absent on the majority of T cells in circulation. Directing IL-2 activity specifically to PD-1+ T cells has the potential to stimulate the anti-tumor T cell response while minimizing systemic toxicity.
IL-2 promotes the growth and differentiation of activated T-cells and natural killer (NK) cells. High-dose IL-2 is approved for the treatment of cancer, but its clinical usage is limited by toxic side effects.