To provide more specificity to the site of action of the broadly stimulating cytokine IL-2, Quijano-Rubio et al. re-engineered the 4-helix-bundle IL-2 mimetic Neoleukin-2/15 (a fusion of IL-2 and IL-15) into separate 3- and 1-helix fragments (split Neo-2/15), which can associate to restore activity. Targeting each fragment to tumor cell surface receptors (e.g., HER2 and EGFR separately, or both to PD-L1) using binding domains restored trans activity locally and enhanced tumor control in vivo. Split Neo-2/15 targeting of CD8 stimulated T cells in cis and slowed growth of B16 melanoma. Targeting to two surface receptors on CD19-CAR T cells enhanced tumor control and overall survival.
Contributed by Ed Fritsch
ABSTRACT: The therapeutic potential of recombinant cytokines has been limited by the severe side effects of systemic administration. We describe a strategy to reduce the dose-limiting toxicities of monomeric cytokines by designing two components that require colocalization for activity and that can be independently targeted to restrict activity to cells expressing two surface markers. We demonstrate the approach with a previously designed mimetic of cytokines interleukin-2 and interleukin-15-Neoleukin-2/15 (Neo-2/15)-both for trans-activating immune cells surrounding targeted tumor cells and for cis-activating directly targeted immune cells. In trans-activation mode, tumor antigen targeting of the two components enhanced antitumor activity and attenuated toxicity compared with systemic treatment in syngeneic mouse melanoma models. In cis-activation mode, immune cell targeting of the two components selectively expanded CD8+ T cells in a syngeneic mouse melanoma model and promoted chimeric antigen receptor T cell activation in a lymphoma xenograft model, enhancing antitumor efficacy in both cases.