Abstract 4363: Loss of PTEN promotes resistance to T cell-mediated immunotherapy

CD8+ T Cell-Based Molecular Classification With Heterogeneous Immunogenomic Landscapes and Clinical Significance of Clear Cell Renal Cell Carcinoma

The tumor microenvironment (TME) exerts a high impact on tumor biology and immunotherapy. The heterogeneous phenotypes and the clinical significance of CD8⁺ T cells in TME have not been fully elucidated. Here, a comprehensive immunogenomic analysis based on multi-omics data was performed to investigate the clinical significance and tumor heterogeneity between CD8⁺ T cell-related molecular clusters. We identified two distinct molecular clusters of ccRCC (C1 and C2) in TCGA and validated in E-MTAB-1980 cohorts. The C1 cluster was characterized by unfavorable prognosis, increased expression levels of CD8⁺ T cell exhaustion markers, high immune infiltration levels as well as more immune escape mechanisms. The C2 cluster was featured by favorable prognosis, elevated expression levels of CD8⁺ T cell effector markers, low load of copy number loss and low frequency of 9p21.3 deletion. Moreover, the effect of molecular classifications on Nivolumab therapeutic efficacy in the CheckMate 025 cohort was examined, and the C2 cluster exhibited a better prognosis. Taken together, we determine two CD8⁺ T cell-related molecular clusters in ccRCC, and provide new insights for evaluating the functions of CD8⁺ T cells. Our molecular classification is a potential strategy for prognostic prediction and immunotherapeutic guidance for ccRCC patients.

Biomarkers of Immune Checkpoint Blockade Response in Triple-Negative Breast Cancer

OPINION STATEMENT

Immune checkpoint blockade (ICB) has revolutionized the treatment landscape across multiple solid tumor types. In triple-negative breast cancer (TNBC), clinical benefit for the addition of ICB to chemotherapy has been shown in both the metastatic and early stage disease settings. A minority of patients with TNBC will truly benefit from ICB, with many tumors unlikely to respond, and ICB can cause additional toxicities for patients to incur. In clinical practice, ICB-based regimens are emerging as standard-of-care treatment options in TNBC subpopulations. Atezolizumab in combination with nab-paclitaxel is recommended as first-line treatment for patients with PD-L1-positive metastatic TNBC. Clinical trials are needed to confirm this benefit and evaluate if additional biomarkers may allow for improved patient selection. Trials investigating ICB in early-stage breast cancer show promise for the benefit of combination ICB with neoadjuvant chemotherapy. However, longer follow-up is required before ICB can be considered as standard-of-care treatment in the early stage setting. In both metastatic and early stage TNBC, novel biomarkers to improve patient selection are now under investigation. These include multiplex IHC to profile immune cell subtypes (such as tumor infiltrating lymphocytes) or RNA gene expression profiling to detect signatures suggestive of a T-cell-inflamed microenvironment. Detecting somatic mutations through tumor next-generation DNA sequencing may predict resistance mechanisms or suggest sensitivity to ICB monotherapy or in combination with other forms of systemic therapy. These biomarker platforms may allow for a more granular analysis of immune activity and should be further investigated in prospective studies with the aim of personalizing ICB-focused therapies in TNBC.

Hepatocellular Carcinoma Immune Landscape and the Potential of Immunotherapies

Hepatocellular carcinoma (HCC) is the most common liver tumor and among the deadliest cancers worldwide. Advanced HCC overall survival is meager and has not improved over the last decade despite approval of several tyrosine kinase inhibitors (TKi) for first and second-line treatments. The recent approval of immune checkpoint inhibitors (ICI) has revolutionized HCC palliative care. Unfortunately, the majority of HCC patients fail to respond to these therapies. Here, we elaborate on the immune landscapes of the normal and cirrhotic livers and of the unique HCC tumor microenvironment. We describe the molecular and immunological classifications of HCC, discuss the role of specific immune cell subsets in this cancer, with a focus on myeloid cells and pathways in anti-tumor immunity, tumor promotion and immune evasion. We also describe the challenges and opportunities of immunotherapies in HCC and discuss new avenues based on harnessing the anti-tumor activity of myeloid, NK and γδ T cells, vaccines, chimeric antigen receptors (CAR)-T or -NK cells, oncolytic viruses, and combination therapies.

In Vivo Priming of Peritoneal Tumor-Reactive Lymphocytes With a Potent Oncolytic Virus for Adoptive Cell Therapy

Adoptive cell therapy (ACT) using autologous tumor infiltrating lymphocytes (TIL) achieves durable clinical benefit for patients from whom these cells can be derived in advanced metastatic melanoma but is limited in most solid tumors as a result of immune escape and exclusion. A tumor microenvironment (TME) priming strategy to improve the quantity and quality of TIL represents an important tactic to explore. Oncolytic viruses expressing immune stimulatory cytokines induce a potent inflammatory response that may enhance infiltration and activation of T cells. In this study, we examined the ability of an attenuated oncolytic vaccinia virus expressing IL15/IL15Rα (vvDD-IL15/Rα) to enhance recovery of lavage T cells in peritoneal carcinomatosis (PC). We found that intraperitoneal (IP) vvDD-IL15/Rα treatment of animals bearing PC resulted in a significant increase in cytotoxic function and memory formation in CD8⁺ T cells in peritoneal fluid. Using tetramers for vaccinia virus B8R antigen and tumor rejection antigen p15E, we found that the expanded population of peritoneal CD8⁺ T cells are specific for vaccinia or tumor with increased tumor-specificity over time, reinforced with viral clearance. Application of these vvDD-IL15/Rα induced CD8⁺ T cells in ACT of a lethal model of PC significantly increased survival. In addition, we found in patients with peritoneal metastases from various primary solid tumors that peritoneal T cells could be recovered but were exhausted with infrequent tumor-reactivity. If clinically translatable, vvDD-IL15/Rα in vivo priming would greatly expand the number of patients with advanced metastatic cancers responsive to T cell therapy.

Roles of the Dynamic Tumor Immune Microenvironment in the Individualized Treatment of Advanced Clear Cell Renal Cell Carcinoma

Immune checkpoint inhibitors (ICIs) are currently a first-line treatment option for clear cell renal cell carcinoma (ccRCC). However, recent clinical studies have shown that a large number of patients do not respond to ICIs. Moreover, only a few patients achieve a stable and durable response even with combination therapy based on ICIs. Available studies have concluded that the response to immunotherapy and targeted therapy in patients with ccRCC is affected by the tumor immune microenvironment (TIME), which can be manipulated by targeted therapy and tumor genomic characteristics. Therefore, an in-depth understanding of the dynamic nature of the TIME is important for improving the efficacy of immunotherapy or combination therapy in patients with advanced ccRCC. Here, we explore the possible mechanisms by which the TIME affects the efficacy of immunotherapy and targeted therapy, as well as the factors that drive dynamic changes in the TIME in ccRCC, including the immunomodulatory effect of targeted therapy and genomic changes. We also describe the progress on novel therapeutic modalities for advanced ccRCC based on the TIME. Overall, this review provides valuable information on the optimization of combination therapy and development of individualized therapy for advanced ccRCC.

The Resistance Mechanisms of Lung Cancer Immunotherapy

Immunotherapy has revolutionized lung cancer treatment in the past decade. By reactivating the host’s immune system, immunotherapy significantly prolongs survival in some advanced lung cancer patients. However, resistance to immunotherapy is frequent, which manifests as a lack of initial response or clinical benefit to therapy (primary resistance) or tumor progression after the initial period of response (acquired resistance). Overcoming immunotherapy resistance is challenging owing to the complex and dynamic interplay among malignant cells and the defense system. This review aims to discuss the mechanisms that drive immunotherapy resistance and the innovative strategies implemented to overcome it in lung cancer.

The Role of GSK3β in T Lymphocytes in the Tumor Microenvironment

Immunotherapy options for patients with cancer have emerged following decades of research on immune responses against tumors. Most treatments in this category harness T cells with specificity for tumor associated antigens, neoantigens, and cancer-testis antigens. GSK3β is a serine-threonine kinase with the highest number of substrates and multifaceted roles in cell function including immune cells. Importantly, inhibitors of GSK3β are available for clinical and research use. Here, we review the possible role of GSK3β in the immune tumor microenvironment, with goal to guide future research that tests GSK3β inhibition as an immunotherapy adjunct.

Toward Systems Biomarkers of Response to Immune Checkpoint Blockers

Immunotherapy with checkpoint blockers (ICBs), aimed at unleashing the immune response toward tumor cells, has shown a great improvement in overall patient survival compared to standard therapy, but only in a subset of patients. While a number of recent studies have significantly improved our understanding of mechanisms playing an important role in the tumor microenvironment (TME), we still have an incomplete view of how the TME works as a whole. This hampers our ability to effectively predict the large heterogeneity of patients' response to ICBs. Systems approaches could overcome this limitation by adopting a holistic perspective to analyze the complexity of tumors. In this Mini Review, we focus on how an integrative view of the increasingly available multi-omics experimental data and computational approaches enables the definition of new systems-based predictive biomarkers. In particular, we will focus on three facets of the TME toward the definition of new systems biomarkers. First, we will review how different types of immune cells influence the efficacy of ICBs, not only in terms of their quantification, but also considering their localization and functional state. Second, we will focus on how different cells in the TME interact, analyzing how inter- and intra-cellular networks play an important role in shaping the immune response and are responsible for resistance to immunotherapy. Finally, we will describe the potential of looking at these networks as dynamic systems and how mathematical models can be used to study the rewiring of the complex interactions taking place in the TME.

Akt Inhibition Is Associated With Favorable Immune Profile Changes Within the Tumor Microenvironment of Hormone Receptor Positive, HER2 Negative Breast Cancer

Background: The PI3K/Akt/mTOR pathway in part impacts tumorigenesis through modulation of host immune activity. To assess the effects of Akt inhibition on the tumor micro-environment (TME), we analyzed tumor tissue from patients with operable hormone receptor positive, HER2 negative breast cancer (BC) treated on a presurgical trial with the Akt inhibitor MK-2206. Methods: Quantitative multiplex immunofluorescence (qmIF) was performed using CD3, CD8, CD4, FOXP3, CD68, and pancytokeratin on biopsy and surgical specimens of MK-2206 and untreated, control patients. nanoString was performed on surgical specimens to assess mRNA expression from MK-2206-treated vs. control patients. Results: Increased CD3+CD8+ density was observed in post vs. pre-treatment tissue in the MK-2206-treated vs. control patients (87 vs. 0.2%, p < 0.05). MK-2206 was associated with greater expression of interferon signaling genes (e.g., IFI6, p < 0.05) and lower expression of myeloid genes (CD163, p < 0.05) on differential expression and gene set enrichment analyses. Greater expression of pro-apoptotic genes (e.g., BAD) were associated with MK-2206 treatment (p < 0.05). Conclusion: Akt inhibition in operable BC was associated with a favorable immune profile in the TME, including increased CD3+CD8+ density and greater expression of interferon genes. Additional studies are warranted, as this may provide rationale for combining Akt inhibition with immunotherapy.