# Targeting CD39 in combination with IL-2/anti-IL-2 complexes enhances cytotoxic immunity and limits tumor progression

## TL;DR

Blocking CD39 and combining it with IL-2/anti-IL-2 complexes boosts T cell activity and reduces tumor growth in mice.

## Contribution

A novel combinatorial immunotherapy strategy using CD39 blockade and IL-2cx to enhance antitumor immunity.

## Key findings

- CD39 deficiency in mice reduced tumor growth and increased PD-1High CD8+ T cell infiltration.
- Combining CD39 blockade with IL-2cx treatment enhanced cytotoxic T cell accumulation and improved tumor control.
- The strategy increased activated NK cells and reduced immunosuppressive M-MDSCs in the tumor microenvironment.

## Abstract

Immunotherapies revolutionized cancer treatment, yet their efficacy remains constrained by the tumor’s immunosuppressive microenvironment. Here, we evaluated whether combining CD39 blockade with other modalities of immunotherapy such as IL-2/anti-IL-2 complexes (IL-2cx) administration could further enhance T cell-mediated antitumor responses and improve tumor control. We demonstrated that CD39 deficiency in MC38 tumor-bearing CD39KO (Entpd1 null) mice decreases tumor growth. This better tumor growth control was associated with increased infiltration of PD-1High CD8+ T cells, expressing elevated levels of exhaustion markers and transcription factors such as TOX. This PD-1High CD8+ T cell subset also exhibited a higher frequency of IFN-γ-producing and cytotoxic (Granzyme B+, Perforin+) cells. In contrast, the less immunogenic B16F10-OVA model did not show significant differences in tumor growth; however, CD39KO mice displayed an increased frequency of antigen-specific, pre-exhausted (PD-1Int) CD8+ T cells, a population recognized as a key target of immunotherapy. Pharmacological CD39 blockade with POM-1, when combined with IL-2cx treatment to redirect IL-2 activity, enhanced the accumulation of pre-exhausted CD8+ T cells with cytotoxic potential, thereby improving tumor control. This combinatorial strategy also reshaped the tumor immune landscape by increasing activated NK cells, elevating Granzyme B expression in CD4+ T cells, and decreasing immunosuppressive M-MDSCs expressing CD39, CD38, and CD73. Collectively, our findings demonstrate that integrating purinergic pathway inhibition with IL-2–based immunotherapies can coordinately reprogram lymphoid and myeloid compartments, attenuate immunosuppressive mechanisms within the tumor microenvironment, and amplify antitumor immunity, providing a strong rationale for advancing this strategy toward clinical translation.