Immunosuppression in inflammatory melanoma: can it be resisted by adoptively transferred T cells?

Targeting STAT3 and STAT5 in Tumor-Associated Immune Cells to Improve Immunotherapy

Oncogene-induced STAT3-activation is central to tumor progression by promoting cancer cell expression of pro-angiogenic and immunosuppressive factors. STAT3 is also activated in infiltrating immune cells including tumor-associated macrophages (TAM) amplifying immune suppression. Consequently, STAT3 is considered as a target for cancer therapy. However, its interplay with other STAT-family members or transcription factors such as NF-κB has to be considered in light of their concerted regulation of immune-related genes. Here, we discuss new attempts at re-educating immune suppressive tumor-associated macrophages towards a CD8 T cell supporting profile, with an emphasis on the role of STAT transcription factors on TAM functional programs. Recent clinical trials using JAK/STAT inhibitors highlighted the negative effects of these molecules on the maintenance and function of effector/memory T cells. Concerted regulation of STAT3 and STAT5 activation in CD8 T effector and memory cells has been shown to impact their tumor-specific responses including intra-tumor accumulation, long-term survival, cytotoxic activity and resistance toward tumor-derived immune suppression. Interestingly, as an escape mechanism, melanoma cells were reported to impede STAT5 nuclear translocation in both CD8 T cells and NK cells. Ours and others results will be discussed in the perspective of new developments in engineered T cell-based adoptive therapies to treat cancer patients.

Preoperative NLR for predicting survival rate after radical resection combined with adjuvant immunotherapy with CIK and postoperative chemotherapy in gastric cancer

PURPOSE

The purpose of this study is to determine the efficacy of adjuvant immunotherapy with autologous cytokine-induced killer (CIK) for postoperative patients with gastric cancer and to investigate the impacts of the predictors on the efficacy of CIK immunotherapy.

PATIENTS AND METHODS

Ninety-two gastric cancer patients who have accepted radical resection were enrolled. The CIK and control groups were established by 1:1 matching on their baseline. As prognosis indicators, preoperative blood cell counts, the neutrophil/lymphocyte ratio (NLR) and platelet/lymphocyte ratio (PLR) were analyzed, respectively. Statistical analyses were done using IBM SPSS Statistics ver.19.0.

RESULTS

CIK treatment significantly prolonged disease-free survival (DFS) (p < 0.05) and there was a tendency of longer overall survival (OS) in the CIK group (p = 0.057). Preoperative NLR was an independent prognostic factor for DFS (p < 0.05). When patients were classified into low and high NLR groups using the cutoff value of 2.995, patients in the low NLR group had a better DFS (p < 0.05). Subset analysis showed that CIK immunotherapy significantly prolonged the DFS in the low NLR group (p = 0.017) but not in the high NLR group (p = 0.695) except that it did well clearly within 17 months. Compared to the low NLR group, lymphocyte decreased significantly, neutrophil increased steeply and white blood cell (WBC) elevated subsequently (p < 0.001in all cases) in the high NLR group.

CONCLUSION

Adjuvant immunotherapy with the CIK cells prolongs DFS in postoperative patients with gastric cancer and the preoperative NLR is an independent prognostic factor for DFS. Low NLR predicts significant benefits from the CIK immunotherapy while high NLR forebodes the requirement of more cycles of CIK treatment or other stronger immunotherapy to improve the survival rate of patients.

Distinct patterns of cytolytic T-cell activation by different tumour cells revealed by Ca2+ signalling and granule mobilization

Cancer-germline genes in both humans and mice have been shown to encode antigens susceptible to targeting by cytotoxic CD8 T effector cells (CTL). We analysed the ability of CTL to kill different tumour cell lines expressing the same cancer-germline gene P1A (Trap1a). We previously demonstrated that CTL expressing a T-cell receptor specific for the P1A_35-43 peptide associated with H-2L^d , although able to induce regression of P1A-expressing P815 mastocytoma cells, were much less effective against P1A-expressing melanoma cells. Here, we analysed parameters of the in vitro interaction between P1A-specific CTL and mastocytoma or melanoma cells expressing similar levels of the P1A gene and of surface H-2L^d . The mastocytoma cells were more sensitive to cytolysis than the melanoma cells in vitro. Analysis by video-microscopy of early events required for target cell killing showed that similar patterns of increase in cytoplasmic Ca²⁺ concentration ([Ca²⁺ ]i) were induced by both types of P1A-expressing tumour cells. However, the use of CTL expressing a fluorescent granzyme B (GZMB-Tom) showed a delay in the migration of cytotoxic granules to the tumour interaction site, as well as a partially deficient GZMB-Tom exocytosis in response to the melanoma cells. Among surface molecules possibly affecting tumour-CTL interactions, the mastocytoma cells were found to express intercellular adhesion molecule-1, the ligand for LFA-1, which was not detected on the melanoma cells.

Neuropeptide Levels as well as Neprilysin Activity Decrease in Renal Cell Carcinoma

Calcitonin Gene-related Peptide (CGRP), Vasoactive Intestinal Peptide (VIP) and Substance P (SP) are sensory neuropeptides which may alter cancer growth through modulation of chronic inflammation. We recently reported that SP suppresses breast cancer growth and metastasis through neuroimmune modulation. These neuropeptides are hydrolyzed by Neprilysin (NEP) to bioactive fragments. Decreased activity of NEP was reported in clear cell and chromophobe type renal cell carcinoma (RCC). It is however not known how the levels of neuropeptides hydrolyzed with NEP changes in RCC. Decrease activity of SP and CGRP containing sensory nerve endings was previously reported to increase cancer metastasis in animal models. It is however not known how peptidergic nerve endings are altered in RCC. Hence we here evaluated the levels of neuronal and non-neuronal neuropeptides and NEP activity in RCC including papillary type as well as neighboring uninvolved kidney. A cross-sectional study was conducted in 57 patients undergoing radical nephrectomy and diagnosed with RCC. NEP activity, levels and expression were determined using flourogenic substrate, western blot and qPCR respectively in freshly-frozen tissues. Immunohistochemical analyses were also performed. Neuronal and non-neuronal levels of CGRP, SP and VIP levels were determined using two-step acetic acid extraction. Levels and activity of NEP were markedly decreased in RCC regardless of subtype. Similar levels of VIP were detected in first and second extractions. VIP levels were higher in clear cell and papillary RCC compared to nearby kidney tissue. VIP levels of neighboring kidney tissue of papillary type RCC was significantly lower compared to kidney samples from clear cell RCC. CGRP levels were higher in second extraction. Similar to VIP levels, CGRP levels of neighboring kidney tissue from clear cell and chromophobe type RCC was significantly lower compared to corresponding tumor samples, an effect observed in the second extraction. VIP and CGRP levels of nearby kidney tissue varied subtype dependently demonstrating that different subtypes of RCC alter their local environment differently. Furthermore NEP-induce hydrolysis of VIP creates selective VPAC-1 receptor agonist which has anti-proliferative and anti-inflammatory effects. Hence loss of NEP activity may prevent anti-tumoral effects of VIP on RCC.

Molecular profiling of CD8 T cells in autochthonous melanoma identifies Maf as driver of exhaustion

T cells infiltrating neoplasms express surface molecules typical of chronically virus-stimulated T cells, often termed "exhausted" T cells. We compared the transcriptome of "exhausted" CD8 T cells infiltrating autochthonous melanomas to those of naïve and acutely stimulated CD8 T cells. Despite strong similarities between transcriptional signatures of tumor- and virus-induced exhausted CD8 T cells, notable differences appeared. Among transcriptional regulators, Nr4a2 and Maf were highly overexpressed in tumor-exhausted T cells and significantly upregulated in CD8 T cells from human melanoma metastases. Transduction of murine tumor-specific CD8 T cells to express Maf partially reproduced the transcriptional program associated with tumor-induced exhaustion. Upon adoptive transfer, the transduced cells showed normal homeostasis but failed to accumulate in tumor-bearing hosts and developed defective anti-tumor effector responses. We further identified TGFβ and IL-6 as main inducers of Maf expression in CD8 T cells and showed that Maf-deleted tumor-specific CD8 T cells were much more potent to restrain tumor growth in vivo. Therefore, the melanoma microenvironment contributes to skewing of CD8 T cell differentiation programs, in part by TGFβ/IL-6-mediated induction of Maf.

Unleashing antitumor T-cell activation without ensuing autoimmunity: the case for A20-deletion in adoptive CD8+ T-cell therapy

Mechanisms controlling immune reactivity prevent excessive inflammation and autoimmunity, but generally dampen antitumor activity. We recently showed that adoptively transferred antitumor CD8⁺ T cells harboring a deletion of A20/Tnfaip3, a molecule controlling NF-κB activation, possessed heightened antitumor activity in vivo. The boosted immunity of A20-deleted CD8⁺ T cells correlated with a heightened capacity to produce IFNγ and TNFα while expressing reduced levels of the immune checkpoint molecule PD-1.

The tumor necrosis factor alpha-induced protein 3 (TNFAIP3, A20) imposes a brake on antitumor activity of CD8 T cells

The transcription factor NF-κB is central to inflammatory signaling and activation of innate and adaptive immune responses. Activation of the NF-κB pathway is tightly controlled by several negative feedback mechanisms, including A20, an ubiquitin-modifying enzyme encoded by the tnfaip3 gene. Mice with selective deletion of A20 in myeloid, dendritic, or B cells recapitulate some human inflammatory pathology. As we observed high expression of A20 transcripts in dysfunctional CD8 T cells in an autochthonous melanoma, we analyzed the role of A20 in regulation of CD8 T-cell functions, using mice in which A20 was selectively deleted in mature conventional T cells. These mice developed lymphadenopathy and some organ infiltration by T cells but no splenomegaly and no detectable pathology. A20-deleted CD8 T cells had increased sensitivity to antigen stimulation with production of large amounts of IL-2 and IFNγ, correlated with sustained nuclear expression of NF-κB components reticuloendotheliosis oncogene c-Rel and p65. Overexpression of A20 by retroviral transduction of CD8 T cells dampened their intratumor accumulation and antitumor activity. In contrast, relief from the A20 brake in NF-κB activation in adoptively transferred antitumor CD8 T cells led to improved control of melanoma growth. Tumor-infiltrating A20-deleted CD8 T cells had enhanced production of IFNγ and TNFα and reduced expression of the inhibitory receptor programmed cell death 1. As manipulation of A20 expression in CD8 T cells did not result in pathologic manifestations in the mice, we propose it as a candidate to be targeted to increase antitumor efficiency of adoptive T-cell immunotherapy.

Active STAT5 regulates T-bet and eomesodermin expression in CD8 T cells and imprints a T-bet-dependent Tc1 program with repressed IL-6/TGF-β1 signaling

In adoptive therapy, CD8 T cells expressing active STAT5 (STAT5CA) transcription factors were found to be superior to unmanipulated counterparts in long-term persistence, capacity to infiltrate autochthonous mouse melanomas, thrive in their microenvironment, and induce their regression. However, the molecular mechanisms sustaining these properties were undefined. In this study, we report that STAT5CA induced sustained expression of genes controlling tissue homing, cytolytic granule composition, type 1 CD8 cytotoxic T cell-associated effector molecules granzyme B(+), IFN-γ(+), TNF-α(+), and CCL3(+), but not IL-2, and transcription factors T-bet and eomesodermin (Eomes). Chromatin immunoprecipitation sequencing analyses identified the genes possessing regulatory regions to which STAT5 bound in long-term in vivo maintained STAT5CA-expressing CD8 T cells. This analysis identified 34% of the genes differentially expressed between STAT5CA-expressing and nonexpressing effector T cells as direct STAT5CA target genes, including those encoding T-bet, Eomes, and granzyme B. Additionally, genes encoding the IL-6R and TGFbRII subunits were stably repressed, resulting in dampened IL-17-producing CD8 T cell polarization in response to IL-6 and TGF-β1. The absence of T-bet did not affect STAT5CA-driven accumulation of the T cells in tissue or their granzyme B expression but restored IL-2 secretion and IL-6R and TGFbRII expression and signaling, as illustrated by IL-17 induction. Therefore, concerted STAT5/T-bet/Eomes regulation controls homing, long-term maintenance, recall responses, and resistance to polarization towards IL-17-producing CD8 T cells while maintaining expression of an efficient type 1 CD8 cytotoxic T cell program (granzyme B(+), IFN-γ(+)).