Modified Hypoxia-Inducible Factor Expression in CD8+ T Cells Increases Antitumor Efficacy

Abstract

Adoptive transfer of antitumor cytotoxic T cells is an emerging form of cancer immunotherapy. A key challenge to expanding the utility of adoptive cell therapies is how to enhance the survival and function of the transferred T cells. Immune-cell survival requires adaptation to different microenvironments and particularly to the hypoxic milieu of solid tumors. The hypoxia-inducible factor (HIF) transcription factors are an essential aspect of this adaptation. In this study, we undertook experiments to define structural determinants of HIF that potentiate antitumor efficacy in cytotoxic T cells. We first created retroviral vectors to deliver ectopic expression of HIF1α and HIF2α in mouse CD8+ T cells, together or individually and with or without sensitivity to the oxygen-dependent HIFα inhibitors Von Hippel–Lindau and factor-inhibiting HIF (FIH). HIF2α, but not HIF1α, drove broad transcriptional changes in CD8+ T cells, resulting in increased cytotoxic differentiation and cytolytic function against tumor targets. A specific mutation replacing the hydroxyl group–acceptor site for FIH in HIF2α gave rise to the most effective antitumor T cells after adoptive transfer in vivo. In addition, codelivering an FIH-insensitive form of HIF2α with an anti-CD19 chimeric antigen receptor greatly enhanced cytolytic function of human CD8+ T cells against lymphoma cells both in vitro and in a xenograft adoptive transfer model. These experiments point to a means to increase the antitumor efficacy of therapeutic CD8+ T cells via ectopic expression of the HIF transcription factor. See related Spotlight on p. 364

Therapeutic Effects of Inhibition of Sphingosine-1-Phosphate Signaling in HIF-2α Inhibitor-Resistant Clear Cell Renal Cell Carcinoma

“…Given that HIF-2α inhibitors show encouraging results in clinical trials, in particular in the setting of treatment of VHL disease patients where long-term drug therapy is envisaged, it would be important to determine clinically whether this therapeutic intervention might also have specific inhibitory effects on anti-tumor immunity or cause more general immunosuppressive effects. Our pharmacological findings are consistent with a series of studies showing that HIF-α transcription factors are important for correct cytotoxic T cell differentiation and function in anti-tumor immunity [ 40 , 41 , 42 , 43 , 44 ] and it was recently shown that activated CD8 + liver T cells express high levels of HIF-2α and PT2385 suppressed the effector functions and survival of these cells [ 45 ]. While a phase I clinical trial of PT2385 together with nivolumab has been carried out [ 46 ], these findings also suggest that the combination of HIF-2α inhibition with immune checkpoint blockade is unlikely to be a viable therapeutic strategy.…”

Multifaceted Interplay between Hormones, Growth Factors and Hypoxia in the Tumor Microenvironment

“…Interestingly, they also reported that HypoxiCAR T-cells were not excluded from HIF-1-stabilized regions of the tumor (Figure 3). differentiation, and improving the rejection of primary and metastatic melanoma tumors [431]. [432].…”

“…Deletion of the transcription factor Nuclear Factor Erythroid 2-Related Factor 2 (Nrf2) impaired the enhancing effect of hypoxia. Another study showed that HIF-2α, but not HIF-1α, drove broad transcriptional changes in CD8 + T-cells, resulting in increased cytotoxic differentiation and cytolytic function against tumors [431]. Moreover, a HIF-2 form that is insensitive to FIH was delivered with anti-CD19 CAR T-cells.…”

“…These CAR T-cells showed enhanced cytolytic function in vitro and in a B-cell lymphoma xenograft ACT mouse model. Finally, genetic deletion of VHL and genes encoding for PHDs caused the accumulation of HIF-1 and HIF-2 in T-cells, enhancing their cytotoxic differentiation, and improving the rejection of primary and metastatic melanoma tumors [431].…”

NK Cells Under Hypoxia: The Two Faces of Vascularization in Tumor and Pregnancy

“…For instance, in a mouse melanoma model HIF-1α -/- CD8 + T cells show decreased expression of soluble factors including TNFα, IFNγ and granzyme B and tumor infiltration under hypoxia correlating with increased tumor growth ( 17 ). Moreover, ectopic expression of HIF-2α improved CD8+ T cell antitumor activity, revealing HIF-1α -/- CD8 + T cells as a potential adoptive cell therapy tool overcoming the harmful hypoxic TME ( 46 ). HIF-1α was also reported to enhance murine Treg differentiation ( 47 ).…”