Systemic administration of IL-33 induces a population of circulating KLRG1hi type 2 innate lymphoid cells and inhibits type 1 innate immunity against multiple myeloma.

Type 2 innate lymphoid cells (ILC2s) are important producers of type 2 cytokines whose role in hematological cancers remains unclear. ILC2s are a heterogeneous population encompassing distinct subsets with different tissue localization and cytokine responsiveness. In this study, we investigated the role of bone marrow (BM) ILC2s and interleukin (IL)-33-stimulated ILC2s in multiple myeloma, a plasma cell malignancy that develops in the BM. We found that myeloma growth was associated with phenotypic and functional alterations of BM ILC2s, characterized by an increased expression of maturation markers and reduced cytokine response to IL-2/IL-33. We identified a population of KLRG1hi ILC2s that preferentially accumulated in the liver and spleen of Il2rg-/- Rag2-/- mice reconstituted with BM ILC2s. A similar population of KLRG1hi ILC2s was observed in the blood, liver and spleen of IL-33-treated wild-type mice. The presence of KLRG1hi ILC2s in ILC2-reconstituted Il2rg-/- Rag2-/- mice or in IL-33-treated wild-type mice was associated with increased eosinophil numbers but had no effect on myeloma progression. Interestingly, while decreased myeloma growth was observed following treatment of Rag-deficient mice with the type 1 cytokines IL-12 and IL-18, this protection was reversed when mice received a combined treatment of IL-33 together with IL-12 and IL-18. In summary, our data indicate that IL-33 treatment induces a population of circulating inflammatory KLRG1hi ILC2s and inhibits type 1 immunity against multiple myeloma. These results argue against therapeutic administration of IL-33 to myeloma patients.

Concomitant or delayed anti-TNF differentially impact on immune-related adverse events and antitumor efficacy after anti-CD40 therapy.

BACKGROUND: Concomitant tumor necrosis factor (TNF) neutralization in combination with immune checkpoint inhibitors (ICIs) reduces clinical immune-related adverse events (irAEs) and appears to improve antitumor efficacy in preclinical tumor models. Agonistic antibodies targeting costimulatory receptors such as CD40 represent an additional strategy to boost antitumor immune response and potentiate the activity of ICIs. However, the dose-limiting toxicities observed in anti-CD40-treated cancer patients have hindered its clinical development. METHODS: We previously described a mouse model to assess both antitumor activity and irAEs induced by various effective combination immunotherapies. Using the BALB/c and C57BL/6 strains of FoxP3-GFP-DTR (FoxP3DTR) mice, transient depletion of T regulatory cells (Tregs) prior to immunotherapy with additional immunomodulatory antibodies, lowered immune self-tolerance, resulting in the development of a spectrum of physical and biochemical irAEs similar to that reported clinically. In MC38 and 4T1.2 tumor models, following transient Treg depletion, we evaluated the impact of anti-CD40 on antitumor efficacy and the development of irAEs and the impact of concomitant or delayed TNF blockade on both these parameters. Physical irAEs were scored and biochemical irAEs were measured in the serum (ALT and cytokine levels). Histopathological liver and colon tissue analysis were performed to assess immune cell infiltration and tissue damage. RESULTS: Similar to early clinical trials of CD40 agonists, in our tumor models we observed liver toxicities and rapid release of proinflammatory cytokines (TNF, interleukin 6, interferon-γ). In the BALB/c strain, anti-CD40 induced severe physical and biochemical irAEs. Concomitant anti-TNF treatment abrogated weight loss, liver damage and colitis, which consequently resulted in an improved clinical score. However, concomitant anti-TNF impaired antitumor response in a proportion of anti-CD40-treated C57BL/6 FoxP3DTR mice. Delaying TNF blockade in these mice reduced biochemical but not physical irAEs while preserving antitumor efficacy. CONCLUSIONS: Our results suggest concomitant rather than delayed anti-TNF is most effective in reducing biochemical and physical irAEs induced by anti-CD40, although it had the potential to negatively impact antitumor efficacy. Furthermore, our findings highlight the utility of our mouse model to assess the severity of irAEs induced by novel immunotherapeutic agents and evaluate whether their toxicity and antitumor efficacy can be uncoupled.

Chemotherapy followed by anti-CD137 mAb immunotherapy improves disease control in a mouse myeloma model.

Immunotherapy holds promise for multiple myeloma (MM) patients but little is known about how MM-induced immunosuppression influences response to therapy. Here, we investigated the impact of disease progression on immunotherapy efficacy in the Vk*MYC mouse model. Treatment with agonistic anti-CD137 (4-1BB) mAbs efficiently protected mice when administered early but failed to contain MM growth when delayed more than three weeks after Vk*MYC tumor cell challenge. The quality of CD8+ T cell response to CD137 stimulation was not altered by the presence of MM, but CD8+ T cell numbers were profoundly reduced at the time of treatment. Our data suggest that an insufficient ratio of CD8+ T cells over MM cells (CD8/MM) accounts for the loss of anti-CD137 mAb efficacy. We established serum M-protein levels prior to therapy as a predictive factor of response. Moreover, we developed an in silico model to capture the dynamic interactions between CD8+ T cells and MM cells. Finally, we explored two methods to improve the CD8/MM ratio: anti-CD137 mAb immunotherapy combined with Treg-depletion or administered after chemotherapy treatment with cyclophosphamide or melphalan efficiently reduced MM burden and prolonged survival. Altogether, our data indicate that consolidation treatment with anti-CD137 mAbs might prevent MM relapse.

CD155 loss enhances tumor suppression via combined host and tumor-intrinsic mechanisms.

Critical immune-suppressive pathways beyond programmed death 1 (PD-1) and programmed death ligand 1 (PD-L1) require greater attention. Nectins and nectin-like molecules might be promising targets for immunotherapy, since they play critical roles in cell proliferation and migration and exert immunomodulatory functions in pathophysiological conditions. Here, we show CD155 expression in both malignant cells and tumor-infiltrating myeloid cells in humans and mice. Cd155-/- mice displayed reduced tumor growth and metastasis via DNAM-1 upregulation and enhanced effector function of CD8+ T and NK cells, respectively. CD155-deleted tumor cells also displayed slower tumor growth and reduced metastases, demonstrating the importance of a tumor-intrinsic role of CD155. CD155 absence on host and tumor cells exerted an even greater inhibition of tumor growth and metastasis. Blockade of PD-1 or both PD-1 and CTLA4 was more effective in settings in which CD155 was limiting, suggesting the clinical potential of cotargeting PD-L1 and CD155 function.

Anticancer immunotherapy by CTLA-4 blockade: obligatory contribution of IL-2 receptors and negative prognostic impact of soluble CD25.

The cytotoxic T lymphocyte antigen-4 (CTLA-4)-blocking antibody ipilimumab induces immune-mediated long-term control of metastatic melanoma in a fraction of patients. Although ipilimumab undoubtedly exerts its therapeutic effects via immunostimulation, thus far clinically useful, immunologically relevant biomarkers that predict treatment efficiency have been elusive. Here, we show that neutralization of IL-2 or blocking the α and ß subunits of the IL-2 receptor (CD25 and CD122, respectively) abolished the antitumor effects and the accompanying improvement of the ratio of intratumoral T effector versus regulatory cells (Tregs), which were otherwise induced by CTLA-4 blockade in preclinical mouse models. CTLA-4 blockade led to the reduction of a suppressive CD4(+) T cell subset expressing Lag3, ICOS, IL-10 and Egr2 with a concomitant rise in IL-2-producing effector cells that lost FoxP3 expression and accumulated in regressing tumors. While recombinant IL-2 improved the therapeutic efficacy of CTLA-4 blockade, the decoy IL-2 receptor α (IL-2Rα, sCD25) inhibited the anticancer effects of CTLA-4 blockade. In 262 metastatic melanoma patients receiving ipilimumab, baseline serum concentrations of sCD25 represented an independent indicator of overall survival, with high levels predicting resistance to therapy. Altogether, these results unravel a role for IL-2 and IL-2 receptors in the anticancer activity of CTLA-4 blockade. Importantly, our study provides the first immunologically relevant biomarker, namely elevated serum sCD25, that predicts resistance to CTLA-4 blockade in patients with melanoma.

Improved mouse models to assess tumour immunity and irAEs after combination cancer immunotherapies.

The current excitement surrounding cancer immunotherapy stems particularly from clinical data involving agents mediating immune checkpoint receptor blockade, which have induced unprecedented efficacy against a range of tumours compared with previous immunotherapeutic approaches. However, an important consideration in targeting checkpoint receptors has been the emergence of associated toxicities termed immune-related adverse events (irAEs). In light of the clinical benefits observed after co-blockade of checkpoint receptors and data from preclinical mouse models, there is now a strong rationale to combine different checkpoint receptors together, with other immunotherapies or more conventional therapies to assess if clinical benefits to cancer patients can be further improved. However, one may predict the frequency and severity of irAEs will increase with combinations, which may result in premature therapy cessation, thus limiting the realization of such an approach. In addition, there is a limit to how many different combination therapies that can be tested in a timely manner given the legal, regulatory and budgetary issues associated with conducting clinical trials. Thus, there is a need to develop preclinical mouse models that more accurately inform us as to which immunotherapies might combine best to provide the optimal therapeutic index (maximal anti-tumour efficacy and low level irAEs) in different cancer settings. In this review we will discuss the irAEs observed in patients after checkpoint blockade and discuss which mouse models of cancer can be appropriate to assess the development of tumour immunity and irAEs following combination cancer immunotherapies.

Co-blockade of immune checkpoints and adenosine A2A receptor suppresses metastasis.

Immunosuppressive pathways active within the tumor microenvironment must be targeted in combination to sufficiently bolster antitumor immune defenses. Inhibition of A2A adenosine receptor signaling in combination with immune checkpoint blockade enhances CD8+ T and NK cell anti-metastatic activity. This results in reduced metastatic burden and improved survival in pre-clinical models.

Differential potency of regulatory T cell-mediated immunosuppression in kidney tumors compared to subcutaneous tumors.

In many cancers, regulatory T cells (Treg) play a crucial role in suppressing the effector immune response thereby permitting tumor development. Indeed, in mouse models, their depletion can promote the regression of tumors of various origins, including renal cell carcinoma when located subcutaneous (SC). In the present study, we aimed to assess the importance of Treg immunosuppression in the physiologic context of metastatic renal carcinoma (Renca) disease. To that purpose we inoculated renal tumors orthotopically, intra-kidney (IK), in mice. Treg depletions were performed using anti-CD4 antibody in wild type mice or diphtheria toxin (DT) in Foxp3DTR transgenic mice. Our main observation was that Treg were not the key immunosuppressive component of the IK tumoral microenvironment, compared to the same tumors located SC. We demonstrated that the CD8+ effector immune response was still suppressed in IK tumors when compared to SC tumors, following Treg depletion. Furthermore, the level of program cell death protein (PD)-1 was increased on the surface of CD4+ T cells infiltrating IK tumors compared to SC tumors. Finally, the Treg-independent immunosuppression, occurring in IK tumors, was potent enough to inhibit regression of concomitant SC tumors, normally responsive to Treg depletion. Our findings provide further insight into the immunosuppressive nature of the immune response generated in the kidney microenvironment, suggesting that it can have additional mechanisms in addition to Treg. These observations might help to identify better targets from the kidney tumor microenvironment for future cancer therapies.