JITC Digest February 2022

JITC Editor Picks

TIM-3 blockade enhances IL-12-dependent antitumor immunity by promoting CD8+ T cell and XCR1+ dendritic cell spatial co-localization

Alycia Gardner, Álvaro de Mingo Pulido, Kay Hänggi, Sarah Bazargan, Alexis Onimus, Agnieszka Kasprzak, Jose R Conejo-Garcia, Katarzyna A Rejniak, Brian Ruffell
Journal for ImmunoTherapy of Cancer 2022;10:e003571 (5 January 2022)
Research

Summary:

TIM-3 expression is a hallmark of terminally exhausted CD8⁺ T cells and a marker of resistance to anti-PD-(L)1 in certain solid tumors. Despite several ongoing efforts to develop anti-TIM-3 agents, the mechanisms by which TIM-3 blockade promote CD8⁺ T cell effector function are not completely understood. Alycia Gardner and colleagues describe a CXCL9-mediated spatial reorganization leading to increased proximity between effector T cells and conventional type 1 dendritic cells (cDC1s) in murine mammary tumors treated with anti-TIM-3 in combination with paclitaxel. TIM-3 blockade did not significantly alter antigen uptake by intratumoral myeloid cells (as assayed by ZsGreen uptake), but fewer lymph node cDCs were antigen-positive for reasons that remain unclear. Tumor control with anti-TIM-3 as well as the spatial shift leading to shorter distances between T cells and cDC1s both required CXCL9 expression in dendritic cells, but CXCL10 was dispensable for these phenotypes. Notably, TIM-3 blockade did not alter the density of infiltrating lymphocytes, nor alter the expression of CD69, CD44, PD-1, or Ki67 on intratumoral CD8⁺ T cells. However, proliferating (Ki67⁺) CD8⁺ T cells were found to be significantly closer to cDC1s in tumors from anti-TIM-3-treated mice. Expression of MHC-I by cDC1s was not required for activity of the TIM-3 plus paclitaxel combination, but selective depletion of IL-12-expressing dendritic cells eliminated the anti-tumor effects. The findings reveal new functions beyond antigen presentation for the anti-tumor activities of cDC1s and suggest investigation of strategies to enhance dendritic cell cytokine production to augment activity of anti-TIM-3.

Interrupting the nitrosative stress fuels tumor-specific cytotoxic T lymphocytes in pancreatic cancer

Research

Summary:

Pancreatic ductal adenocarcinoma (PDAC) is an immunologically cold tumor characterized by a low mutational load, robust infiltration by immunosuppressive cells, and exclusion of cytotoxic T lymphocytes. Francesco De Sanctis and colleagues identify reactive nitrogen species produced by myeloid cells as a major barrier contributing to the immune-excluded phenotype for PDAC and further demonstrate that administration of a novel nitrogen scavenger leads to effective tumor control with adoptive cell therapies in multiple murine models. Analysis of immune infiltrates in both orthotopic and spontaneous PDAC tumors at early and late time-points revealed a consistent accumulation of myeloid-derived suppressor cells (MDSCs) and MHC-II-low tumor associated macrophages associated with disease progression. Infiltrating CD11b⁺ myeloid cells expressed NOS2 and ARG1 at high levels and staining for the reactive nitrogen species marker 3-nitrotyrosine (N-Ty) was seen in large regions of the tumor at late time points. Notably, the distribution of cytotoxic T lymphocytes inversely correlated with N-Ty-positive regions of the tumor and “shields” of nitrosylation were observed around almost entirely T cell excluded tumor cores. Administration of the novel bioavailable nitrogen scavenger AT38 led to reduced N-Ty staining in the tumors, decreased MDSC accumulation, and, most notably, tumor control and prolonged survival when combined with telomerase-directed adoptive cell transfer. Samples from human PDAC tumors showed similar patterns of myeloid infiltration, N-Ty staining, and CD8⁺ T cell exclusion as was seen in the mice, in addition to expressing telomerase. The study offers new insight into mechanisms of immune exclusion, identifying nitrosative stress as a potential target to enhance the activity of immunotherapy in cold tumors.

Fine-tuned long-acting interleukin-2 superkine potentiates durable immune responses in mice and non-human primate

Rosemina Merchant, Carole Galligan, Manjunatha Ankathatti Munegowda, L Bruce Pearce, Peter Lloyd, Paul Smith, Fahar Merchant, Minh D To
Journal for ImmunoTherapy of Cancer 2022;10:e003155 (20 January 2022)
Research

Summary:

Recombinant human IL-2 (rhIL-2) has offered curative responses to a small subset of patients with metastatic melanoma and renal cell carcinoma, yet activation of regulatory T cells, a requirement for frequent, high-dose administration, and unacceptable toxicity have limited the cytokine’s utility as an immunotherapeutic agent. An engineered IL-2 superkine described by Rosemina Merchant et al demonstrated a favorable pharmacodynamic profile, therapeutic efficacy in three preclinical tumor models, and induction of a durable immune response in nonhuman primates, opening the door to a next-generation immunotherapy agent based on this cytokine. MDNA11 was engineered to strongly bind the CD122 and CD132 binding chains of the intermediate affinity IL-2 receptor that is expressed on natural killer (NK) and naïve T cells while minimally interacting with the CD25 binding chain that is constitutively expressed on regulatory T cells. In vitro, no binding between MDNA11 and CD25 was detected even up to 2000 nM concentrations and the EC50 for activation of regulatory T cells was 28-fold higher than the parent cytokine. Pharmacodynamic studies showed a 25-fold higher terminal half-life for MDNA11 compared to rhIL-2 attributed to the increased molecular size generated by fusion to albumin for the superkine. In BF16F10 melanoma tumors, significantly elevated CD8⁺ to regulatory T cell ratios were seen after MDNA11 treatment. The combination of MDNA11 and anti-PD-1 resulted in complete tumor regression in 100% of treated animals in the MC38 colon cancer model. Durable immune memory and protection from multiple rechallenges with CT26 colon tumors were observed when MDNA11 was combined with anti-CTLA-4. Studies in non-human primates demonstrated tolerable safety and increased proliferation of central memory and effector memory CD4⁺ and CD8⁺ T cells and NK cells with no appreciable effects on eosinophils. The pre-clinical portfolio could support future human investigation of MDNA11 as monotherapy or in combination with approved checkpoint inhibitors.

B cells imprint adoptively transferred CD8⁺ T cells with enhanced tumor immunity

Summary:

Toll-like receptor agonists such as CpG-ODNs have been demonstrated to induce anti-tumor responses in pre-clinical and clinical studies, however, systemic administration of these agents may be met with toxicity. Hypothesizing that ex vivo stimulation with a toll-like receptor agonist could enhance the potency of adoptively transferred cell therapy, Aubrey S Smith et al not only demonstrate improved anti-tumor efficacy for lymphocytes expanded from cultures treated with CpG-ODN but also uncover an essential role for B cells in imprinting potent T cell immunity. In Pmel-1 murine models of adoptive cell therapy for melanoma, expansion in the presence of CpG-ODN led to robust tumor control and prolonged survival. The proteomic profile of CD8⁺ T cells expanded in the presence of CpG-ODN displayed an enrichment for functions related to fatty acid oxidation and surface markers related to enhanced engraftment and function were highly expressed including IL-2alpha and ICOS. Decreased surface expression of markers of suppression or exhaustion such as CD39, PD-1, and LAG3 was also observed in the CpG-ODN-expanded CD8⁺ T cells, and TILs from human patients phenocopied the expression patterns on the murine T cells in vitro. Strikingly, however, TLR9 was not expressed in CD8⁺ T cells after expansion, and the addition of CpG-ODN after 3 days in culture (when antigen-presenting cells are depleted and CD8⁺ T cells predominate) led to an adoptive cell therapy product with similar surface marker profiles as vehicle-treated controls and minimal anti-tumor activity in vivo. Although numerous chemokines and cytokines were increased with CpG-ODN treatment, no supernatant transfer experiments recapitulated the phenotype of early-treated cultures, ruling out soluble factors. Depletion experiments revealed that B cells were necessary in the initial CpG-ODN-treated cultures for anti-tumor activity of the adoptively transferred CD8⁺ T cells and the addition of purified B cells alone to purified T cell cultures was sufficient for CpG-ODN to enhance potency. The study underscores the contribution of immune cells beyond CD8⁺ T cells in anti-tumor immunity and sets the stage for B cell-based culture strategies to enhance potency of adoptive cell therapies.

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