Therapies in Refractory Metastatic Renal Cell Carcinoma

As the therapeutic landscape for metastatic clear cell renal cell carcinoma (mccRCC) expands to include vascular endothelial growth factor receptor tyrosine kinase inhibitors (VEGFR TKIs) and immunotherapies, new challenges are in place for evaluating and treating refractory disease. Assessing and managing refractory disease has several elements: (1) the mechanism(s) of front-line treatment, (2) timing of progressive disease, (3) rapidity and sites of progressing disease, (4) use of adjuvant therapy, and (5) incorporation of surgical and radiation techniques. These variables all have distinct impact on the biology of refractory or resistant mccRCC. A better understanding of the essential mechanisms of both primary and secondary immunotherapy resistance will inform biomarker development and therapeutic strategies in the refractory setting. This paper addresses the current understanding of treatment sequencing in refractory mccRCC, focusing on treatment options with prospective clinical trial data, considers refractory mccRCC after adjuvant immunotherapy, and incorporates radiation or surgical resection for oligoprogressive disease

Emerging Targets in Clear Cell Renal Cell Carcinoma

The dual immune checkpoint blockade targeting CTLA-4 and PD-1 (ipilimumab/nivolumab) or the IO combinations targeting PD-1 and anti-VEGF TKIs (pembrolizumab/axitinib, nivolumab/cabozantinib, pembrolizumab/lenvatinib) have demonstrated an overall survival benefit in advanced clear cell renal cell carcinoma (ccRCC). Despite this significant improvement in clinical outcomes in the frontline setting from IO/IO or the IO/TKI combinations, there is a subset of patients of advanced ccRCC that do not respond to such combinations or will lose the initial efficacy and have disease progression. Therefore, a remarkable unmet need exists to develop new therapeutics to improve outcomes. With an enhanced understanding of ccRCC biology and its interaction with the tumor microenvironment, several new therapies are under development targeting ccRCC metabolism, cytokine-signaling, alternative immune checkpoint proteins, and novel biological pathways. In addition, microbiome products enhancing IO response, antibody–drug conjugates, and targeted radionuclides are also being investigated. This review summarizes selected emerging agents that are under development in ccRCC

MRI of tumor T cell infiltration in response to checkpoint inhibitor therapy

Background Immune checkpoint inhibitors, the most widespread class of immunotherapies, have demonstrated unique response patterns that are not always adequately captured by traditional response criteria such as the Response Evaluation Criteria in Solid Tumors or even immune-specific response criteria. These response metrics rely on monitoring tumor growth, but an increase in tumor size and/or appearance after starting immunotherapy does not always represent tumor progression, but also can be a result of T cell infiltration and thus positive treatment response. Therefore, non-invasive and longitudinal monitoring of T cell infiltration are needed to assess the effects of immunotherapies such as checkpoint inhibitors. Here, we proposed an innovative concept that a sufficiently large influx of tumor infiltrating T cells, which have a smaller diameter than cancer cells, will change the diameter distribution and decrease the average size of cells within a volume to a degree that can be quantified by non-invasive MRI.Methods We validated our hypothesis by studying tumor response to combination immune-checkpoint blockade (ICB) of anti-PD-1 and anti-CTLA4 in a mouse model of colon adenocarcinoma (MC38). The response was monitored longitudinally using Imaging Microstructural Parameters Using Limited Spectrally Edited Diffusion (IMPULSED), a diffusion MRI-based method which has been previously shown to non-invasively map changes in intracellular structure and cell sizes with the spatial resolution of MRI, in cell cultures and in animal models. Tumors were collected for immunohistochemical and flow cytometry analyzes immediately after the last imaging session.Results Immunohistochemical analysis revealed that increased T cell infiltration of the tumors results in a decrease in mean cell size (eg, a 10% increase of CD3+ T cell fraction results a ~1 µm decrease in the mean cell size). IMPULSED showed that the ICB responders, mice with tumor volumes were less than 250 mm3 or had tumors with stable or decreased volumes, had significantly smaller mean cell sizes than both Control IgG-treated tumors and ICB non-responder tumors.Conclusions IMPULSED-derived cell size could potentially serve as an imaging marker for differentiating responsive and non-responsive tumors after checkpoint inhibitor therapies, a current clinical challenge that is not solved by simply monitoring tumor growth

A Non-apoptotic Function of MCL-1 in Promoting Pluripotency and Modulating Mitochondrial Dynamics in Stem Cells

Summary: Human pluripotent stem cells (hPSCs) maintain a highly fragmented mitochondrial network, but the mechanisms regulating this phenotype remain unknown. Here, we describe a non-cell death function of the anti-apoptotic protein, MCL-1, in regulating mitochondrial dynamics and promoting pluripotency of stem cells. MCL-1 is induced upon reprogramming, and its inhibition or knockdown induces dramatic changes to the mitochondrial network as well as loss of the key pluripotency transcription factors, NANOG and OCT4. Aside from localizing at the outer mitochondrial membrane like other BCL-2 family members, MCL-1 is unique in that it also resides at the mitochondrial matrix in pluripotent stem cells. Mechanistically, we find MCL-1 to interact with DRP-1 and OPA1, two GTPases responsible for remodeling the mitochondrial network. Depletion of MCL-1 compromised the levels and activity of these key regulators of mitochondrial dynamics. Our findings uncover an unexpected, non-apoptotic function for MCL-1 in the maintenance of mitochondrial structure and stemness. : Gama and colleagues show that MCL-1 regulates mitochondrial network morphology in human pluripotent stem cells. MCL-1 downregulation resulted in loss of OCT4 and NANOG and an elongated mitochondrial network. MCL-1 associates with mitochondrial dynamics regulators; this association is disrupted by an MCL-1 small-molecule inhibitor. The results provide mechanistic insight into the connection between apoptosis, mitochondrial dynamics, and pluripotency. Keywords: apoptosis, MCL-1, pluripotent stem cells, mitochondria, DRP-1, OPA1, mitochondrial dynamics, pluripotenc

CD28 costimulation drives tumor-infiltrating T cell glycolysis to promote inflammation

Metabolic reprogramming dictates the fate and function of stimulated T cells, yet these pathways can be suppressed in T cells in tumor microenvironments. We previously showed that glycolytic and mitochondrial adaptations directly contribute to reducing the effector function of renal cell carcinoma (RCC) CD8(+) tumor-infiltrating lymphocytes (TILs). Here we define the role of these metabolic pathways in the activation and effector functions of CD8+ RCC TILs. CD28 costimulation plays a key role in augmenting T cell activation and metabolism, and is antagonized by the inhibitory and checkpoint immunotherapy receptors CTLA4 and PD-1. While RCC CD8(+) TILs were activated at a low level when stimulated through the T cell receptor alone, addition of CD28 costimulation greatly enhanced activation, function, and proliferation. CD28 costimulation reprogrammed RCC CD8(+) TIL metabolism with increased glycolysis and mitochondrial oxidative metabolism, possibly through upregulation of GLUT3. Mitochondria also fused to a greater degree, with higher membrane potential and overall mass. These phenotypes were dependent on glucose metabolism, as the glycolytic inhibitor 2-deoxyglucose both prevented changes to mitochondria and suppressed RCC CD8(+) TIL activation and function. These data show that CD28 costimulation can restore RCC CD8(+) TIL metabolism and function through rescue of T cell glycolysis that supports mitochondrial mass and activity

Neoadjuvant pazopanib and molecular analysis of tissue response in renal cell carcinoma

BACKGROUND Surgery remains the frontline therapy for patients with localized clear cell renal cell carcinoma (ccRCC); however, 20%–40% recur. Angiogenesis inhibitors have improved survival in metastatic patients and may result in responses in the neoadjuvant setting. The impact of these agents on the tumor genetic heterogeneity or the immune milieu is largely unknown. This phase II study was designed to evaluate safety, response, and effect on tumor tissue of neoadjuvant pazopanib.METHODS ccRCC patients with localized disease received pazopanib (800 mg daily; median 8 weeks), followed by nephrectomy. Five tumors were examined for mutations by whole exome sequencing from samples collected before therapy and at nephrectomy. These samples underwent RNA sequencing; 17 samples were available for posttreatment assessment.RESULTS Twenty-one patients were enrolled. The overall response rate was 8 of 21 (38%). No patients with progressive disease. At 1-year, response-free survival and overall survival was 83% and 89%, respectively. The most frequent grade 3 toxicity was hypertension (33%, 7 of 21). Sequencing revealed strong concordance between pre- and posttreatment samples within individual tumors, suggesting tumors harbor stable core profiles. However, a reduction in private mutations followed treatment, suggesting a selective process favoring enrichment of driver mutations.CONCLUSION Neoadjuvant pazopanib is safe and active in ccRCC. Future genomic analyses may enable the segregation of driver and passenger mutations. Furthermore, tumor infiltrating immune cells persist during therapy, suggesting that pazopanib can be combined with immune checkpoint inhibitors without dampening the immune response.FUNDING Support was provided by Novartis and GlaxoSmithKline as part of an investigator-initiated study

The Transcription Factor Bhlhe40 Programs Mitochondrial Regulation of Resident CD8+ T Cell Fitness and Functionality

Tissue-resident memory CD8(+) T (Trm) cells share core residency gene programs with tumor-infiltrating lymphocytes (TILs). However, the transcriptional, metabolic, and epigenetic regulation of Trm cell and TIL development and function is largely undefined. Here, we found that the transcription factor Bhlhe40 was specifically required for Trm cell and TIL development and polyfunctionality. Local PD-1 signaling inhibited TIL Bhlhe40 expression, and Bhlhe40 was critical for TIL reinvigoration following anti-PD-L1 blockade. Mechanistically, Bhlhe40 sustained Trm cell and TIL mitochondria! fitness and a functional epigenetic state. Building on these findings, we identified an epigenetic and metabolic regimen that promoted Trm cell and TIL gene signatures associated with tissue residency and polyfunctionality. This regimen empowered the anti-tumor activity of CD8(+) T cells and possessed therapeutic potential even at an advanced tumor stage in mouse models. Our results provide mechanistic insights into the local regulation of Trm cell and TIL function

A Phase 1/2 Study to Evaluate the Safety and Activity of Nivolumab in Combination With Vorolanib, a Vascular Endothelial Growth Factor Tyrosine Kinase Inhibitor, in Patients With Refractory Thoracic Tumors

Introduction: Targeting the tumor microenvironment may enhance response to immunotherapy (immune checkpoint inhibitors) and improve outcomes for patients. This study tested the safety and efficacy of vorolanib, a novel tyrosine kinase inhibitor of vascular endothelial growth factor, platelet-derived growth factor, and c-KIT, in combination with programmed cell death protein 1 blockade using nivolumab for refractory thoracic malignancies. Methods: This single-arm multicenter study enrolled patients with extensive-stage SCLC, thymic carcinoma, and NSCLC, either naive or had progressed on previous chemotherapy or immune checkpoint inhibitors (either primary or acquired resistance). The primary objective of phase 1 was to determine the maximum tolerated dose, and the primary end point for each dose-expansion cohort was the objective response rate. Results: A total of 88 patients were enrolled in phase 1 (n = 11) and dose expansion (n = 77) cohorts. Transaminitis was dose-limiting and expansion proceeded with oral vorolanib 200 mg daily combined with intravenous nivolumab 240 mg every 2 weeks. The objective response rate per cohort were as follows: NSCLC naive 33% (five of 15, 95% confidence interval [CI]: 13%–60%), NSCLC primary refractory 5.9% (one of 17, 95% CI: 0%–17.6%), NSCLC acquired resistance 11.1% (two of 18, 95% CI: 0%–27.8%); SCLC 0% (zero of 18), and thymic carcinoma 11% (one of nine, 95% CI: 0%–33%). Disease control rate ranged from 11.1% in SCLC (two of 18, 0%–27.8%) to 66.7 % in thymic carcinoma (six of nine, 95% CI: 33.3%–100%). The most common adverse events were fatigue (32%), aspartate transaminase (27%) and alanine transaminase elevation (25%), and diarrhea (19%). Transaminitis was more common in patients with thymic carcinoma than other tumors. Conclusions: Vorolanib plus nivolumab had a manageable safety profile and may have clinical benefits in various thoracic malignancies. The disease control rate in thymic malignancies warrants further assessment

The Transcription Factor Bhlhe40 Programs Mitochondria! Regulation of Resident CD8(+) T Cell Fitness and Functionality

10.1016/j.immuni.2019.08.013IMMUNITY513491-50