Perturbations in the control of cellular arachidonic acid levels block cell growth and induce apoptosis in HL-60 cells

Our previous studies demonstrated that inhibitors of arachidonate-phospholipid remodeling [i.e. the enzyme CoA-independent transacylase (CoA-IT)] decrease cell proliferation and induce apoptosis in neoplastic cells. The goal of the current study was to elucidate the molecular events associated with arachidonate-phospholipid remodeling that influence cell proliferation and survival. Initial experiments revealed the essential nature of cellular arachidonate to the signaling process by demonstrating that HL-60 cells depleted of arachidonate were more resistant to apoptosis induced by CoA-IT inhibition. In cells treated with CoA-IT inhibitors a marked increase in free arachidonic acid and AA-containing triglycerides were measured. TG enrichment was likely due to acylation of arachidonic acid into diglycerides and triglycerides via de novo glycerolipid biosynthesis. To determine the potential of free fatty acids to affect cell proliferation, HL-60 cells were incubated with varying concentrations of free fatty acids; exogenously provided 20-carbon polyunsaturated fatty acids caused a dose-dependent inhibition of cell proliferation, whereas oleic acid was without effect. Blocking 5-lipoxygenase or cyclooxygenases had no effect on the inhibition of cell proliferation induced by arachidonic acid or CoA-IT inhibitors. An increase in cell-associated ceramides (mainly in the 16:0-ceramide fraction) was measured in cells exposed to free arachidonic acid or to CoA-IT inhibitors. This study, in conjunction with other recent studies, suggests that perturbations in the control of cellular arachidonic acid levels affect cell proliferation and survival.

Durvalumab plus tremelimumab in advanced or metastatic soft tissue and bone sarcomas: a single-centre phase 2 trial

BACKGROUND

Few standard treatment options are available for patients with metastatic sarcomas. We did this trial to evaluate the efficacy, safety, and changes in the tumour microenvironment for durvalumab, an anti-PD-L1 drug, and tremelimumab, an anti-CTLA-4 drug, across multiple sarcoma subtypes.

METHODS

In this single-centre phase 2 trial, done at The University of Texas MD Anderson Cancer Center (Houston, TX USA), patients aged 18 years or older with advanced or metastatic sarcoma with an Eastern Cooperative Oncology Group performance status of 0 or 1 who had received at least one previous line of systemic therapy were enrolled in disease subtype-specific groups (liposarcoma, leiomyosarcoma, angiosarcoma, undifferentiated pleomorphic sarcoma, synovial sarcoma, osteosarcoma, alveolar soft-part sarcoma, chordoma, and other sarcomas). Patients received 1500 mg intravenous durvalumab and 75 mg intravenous tremelimumab for four cycles, followed by durvalumab alone every 4 weeks for up to 12 months. The primary endpoint was progression-free survival at 12 weeks in the intention-to-treat population (all patients who received at least one dose of treatment). Safety was also analysed in the intention-to-treat population. This trial is registered with ClinicalTrials.gov, NCT02815995, and is completed.

FINDINGS

Between Aug 17, 2016, and April 9, 2018, 62 patients were enrolled, of whom 57 (92%) received treatment and were included in the intention-to-treat population. With a median follow-up of 37·2 months (IQR 1·8-10·1), progression-free survival at 12 weeks was 49% (95% CI 36-61). 21 grade 3-4 treatment-related adverse events were reported, the most common of which were increased lipase (four [7%] of 57 patients), colitis (three [5%] patients), and pneumonitis (three [5%] patients). Nine (16%) patients had a treatment related serious adverse event. One patient had grade 5 pneumonitis and colitis.

INTERPRETATION

The combination of durvalumab and tremelimumab is an active treatment regimen for advanced or metastatic sarcoma and merits evaluation in specific subsets in future trials.

FUNDING

AstraZeneca.

The RNA-binding Protein MEX3B Mediates Resistance to Cancer Immunotherapy by Downregulating HLA-A Expression

Purpose: Cancer immunotherapy has shown promising clinical outcomes in many patients. However, some patients still fail to respond, and new strategies are needed to overcome resistance. The purpose of this study was to identify novel genes and understand the mechanisms that confer resistance to cancer immunotherapy.Experimental Design: To identify genes mediating resistance to T-cell killing, we performed an open reading frame (ORF) screen of a kinome library to study whether overexpression of a gene in patient-derived melanoma cells could inhibit their susceptibility to killing by autologous tumor-infiltrating lymphocytes (TIL).Results: The RNA-binding protein MEX3B was identified as a top candidate that decreased the susceptibility of melanoma cells to killing by TILs. Further analyses of anti-PD-1-treated melanoma patient tumor samples suggested that higher MEX3B expression is associated with resistance to PD-1 blockade. In addition, significantly decreased levels of IFNγ were secreted from TILs incubated with MEX3B-overexpressing tumor cells. Interestingly, this phenotype was rescued upon overexpression of exogenous HLA-A2. Consistent with this, we observed decreased HLA-A expression in MEX3B-overexpressing tumor cells. Finally, luciferase reporter assays and RNA-binding protein immunoprecipitation assays suggest that this is due to MEX3B binding to the 3' untranslated region (UTR) of HLA-A to destabilize the mRNA.Conclusions: MEX3B mediates resistance to cancer immunotherapy by binding to the 3' UTR of HLA-A to destabilize the HLA-A mRNA and thus downregulate HLA-A expression on the surface of tumor cells, thereby making the tumor cells unable to be recognized and killed by T cells. Clin Cancer Res; 24(14); 3366-76. ©2018 AACRSee related commentary by Kalbasi and Ribas, p. 3239.

Characterization of the Immune Landscape of EGFR-Mutant NSCLC Identifies CD73/Adenosine Pathway as a Potential Therapeutic Target

INTRODUCTION

Lung adenocarcinomas harboring EGFR mutations do not respond to immune checkpoint blockade therapy and their EGFR wildtype counterpart. The mechanisms underlying this lack of clinical response have been investigated but remain incompletely understood.

METHODS

We analyzed three cohorts of resected lung adenocarcinomas (Profiling of Resistance Patterns of Oncogenic Signaling Pathways in Evaluation of Cancer of Thorax, Immune Genomic Profiling of NSCLC, and The Cancer Genome Atlas) and compared tumor immune microenvironment of EGFR-mutant tumors to EGFR wildtype tumors, to identify actionable regulators to target and potentially enhance the treatment response.

RESULTS

EGFR-mutant NSCLC exhibited low programmed death-ligand 1, low tumor mutational burden, decreased number of cytotoxic T cells, and low T cell receptor clonality, consistent with an immune-inert phenotype, though T cell expansion ex vivo was preserved. In an analysis of 75 immune checkpoint genes, the top up-regulated genes in the EGFR-mutant tumors (NT5E and ADORA1) belonged to the CD73/adenosine pathway. Single-cell analysis revealed that the tumor cell population expressed CD73, both in the treatment-naive and resistant tumors. Using coculture systems with EGFR-mutant NSCLC cells, T regulatory cell proportion was decreased with CD73 knockdown. In an immune-competent mouse model of EGFR-mutant lung cancer, the CD73/adenosine pathway was markedly up-regulated and CD73 blockade significantly inhibited tumor growth.

CONCLUSIONS

Our work revealed that EGFR-mutant NSCLC has an immune-inert phenotype. We identified the CD73/adenosine pathway as a potential therapeutic target for EGFR-mutant NSCLC.

Persistence of adoptively transferred T cells with a kinetically engineered IL-2 receptor agonist

Interleukin-2 (IL-2) is a component of most protocols of adoptive cell transfer (ACT) therapy for cancer, but is limited by short exposure and high toxicities. NKTR-214 is a kinetically-engineered IL-2 receptor βγ (IL-2Rβγ)-biased agonist consisting of IL-2 conjugated to multiple releasable polyethylene glycol chains resulting in sustained signaling through IL-2Rβγ. We report that ACT supported by NKTR-214 increases the proliferation, homing and persistence of anti-tumor T cells compared to ACT with IL-2, resulting in superior antitumor activity in a B16-F10 murine melanoma model. The use of NKTR-214 increases the number of polyfunctional T cells in murine spleens and tumors compared to IL-2, and enhances the polyfunctionality of T and NK cells in the peripheral blood of patients receiving NKTR-214 in a phase 1 trial. In conclusion, NKTR-214 may have the potential to improve the antitumor activity of ACT in humans through increased in vivo expansion and polyfunctionality of the adoptively transferred T cells.

Distinct tumor-infiltrating lymphocyte landscapes are associated with clinical outcomes in localized non-small-cell lung cancer

BACKGROUND

Despite the importance of tumor-infiltrating T lymphocytes (TILs) in cancer biology, the relationship between TIL phenotypes and their prognostic relevance for localized non-small-cell lung cancer (NSCLC) has not been well established.

PATIENTS AND METHODS

Fresh tumor and normal adjacent tissue was prospectively collected from 150 patients with localized NSCLC. Tissue was comprehensively characterized by high-dimensional flow cytometry of TILs integrated with immunogenomic data from multiplex immunofluorescence, T-cell receptor sequencing, exome sequencing, RNA sequencing, targeted proteomics, and clinicopathologic features.

RESULTS

While neither the magnitude of TIL infiltration nor specific TIL subsets were significantly prognostic alone, the integration of high-dimensional flow cytometry data identified two major immunotypes (IM1 and IM2) that were predictive of recurrence-free survival independent of clinical characteristics. IM2 was associated with poor prognosis and characterized by the presence of proliferating TILs expressing cluster of differentiation 103, programmed cell death protein 1, T-cell immunoglobulin and mucin-domain containing protein 3, and inducible T-cell costimulator. Conversely, IM1 was associated with good prognosis and differentiated by an abundance of CD8⁺ T cells expressing cytolytic enzymes, CD4⁺ T cells lacking the expression of inhibitory receptors, and increased levels of B-cell infiltrates and tertiary lymphoid structures. While increased B-cell infiltration was associated with good prognosis, the best prognosis was observed in patients with tumors exhibiting high levels of both B cells and T cells. These findings were validated in patient tumors from The Cancer Genome Atlas.

CONCLUSIONS

Our study suggests that although the number of infiltrating T cells is not associated with patient survival, the nature of the infiltrating T cells, resolved in distinct TIL immunotypes, is prognostically relevant in NSCLC and may inform therapeutic approaches to clinical care.

Combined Analysis of Antigen Presentation and T-cell Recognition Reveals Restricted Immune Responses in Melanoma

The quest for tumor-associated antigens (TAA) and neoantigens is a major focus of cancer immunotherapy. Here, we combine a neoantigen prediction pipeline and human leukocyte antigen (HLA) peptidomics to identify TAAs and neoantigens in 16 tumors derived from seven patients with melanoma and characterize their interactions with their tumor-infiltrating lymphocytes (TIL). Our investigation of the antigenic and T-cell landscapes encompassing the TAA and neoantigen signatures, their immune reactivity, and their corresponding T-cell identities provides the first comprehensive analysis of cancer cell T-cell cosignatures, allowing us to discover remarkable antigenic and TIL similarities between metastases from the same patient. Furthermore, we reveal that two neoantigen-specific clonotypes killed 90% of autologous melanoma cells, both in vitro and in vivo, showing that a limited set of neoantigen-specific T cells may play a central role in melanoma tumor rejection. Our findings indicate that combining HLA peptidomics with neoantigen predictions allows robust identification of targetable neoantigens, which could successfully guide personalized cancer immunotherapies.Significance: As neoantigen targeting is becoming more established as a powerful therapeutic approach, investigating these molecules has taken center stage. Here, we show that a limited set of neoantigen-specific T cells mediates tumor rejection, suggesting that identifying just a few antigens and their corresponding T-cell clones could guide personalized immunotherapy. Cancer Discov; 8(11); 1366-75. ©2018 AACR. This article is highlighted in the In This Issue feature, p. 1333.

PD-1 and BTLA and CD8(+) T-cell "exhaustion" in cancer: "Exercising" an alternative viewpoint

The elevated expression of PD-1, BTLA, and other co-inhibitory molecules on T cells from cancer patients has become an accepted signature for a state called T-cell “exhaustion” that has emerged almost as dogma in the field. However, here we propose that in some cases this “exhausted” T-cell phenotype may instead be an indicator of T cells that are in a more heightened state of T-cell activation more susceptible to negative regulation rather than being “exhausted.” This alternative interpretation fits in line with the view that CD8⁺ T-cell activation in cancer results from a continuum of signals regulating their differentiation towards potent effector cells.

The Effect of Topoisomerase I Inhibitors on the Efficacy of T-Cell-Based Cancer Immunotherapy

Background

Immunotherapy has increasingly become a staple in cancer treatment. However, substantial limitations in the durability of response highlight the need for more rational therapeutic combinations. The aim of this study is to investigate how to make tumor cells more sensitive to T-cell-based cancer immunotherapy.

Methods

Two pairs of melanoma patient-derived tumor cell lines and their autologous tumor-infiltrating lymphocytes were utilized in a high-throughput screen of 850 compounds to identify bioactive agents that could be used in combinatorial strategies to improve T-cell-mediated killing of tumor cells. RNAi, overexpression, and gene expression analyses were utilized to identify the mechanism underlying the effect of Topoisomerase I (Top1) inhibitors on T-cell-mediated killing. Using a syngeneic mouse model (n = 5 per group), the antitumor efficacy of the combination of a clinically relevant Top1 inhibitor, liposomal irinotecan (MM-398), with immune checkpoint inhibitors was also assessed. All statistical tests were two-sided.

Results

We found that Top1 inhibitors increased the sensitivity of patient-derived melanoma cell lines (n = 7) to T-cell-mediated cytotoxicity (P < .001, Dunnett’s test). This enhancement is mediated by TP53INP1, whose overexpression increased the susceptibility of melanoma cell lines to T-cell cytotoxicity (2549 cell line: P = .009, unpaired t test), whereas its knockdown impeded T-cell killing of Top1 inhibitor–treated melanoma cells (2549 cell line: P < .001, unpaired t test). In vivo, greater tumor control was achieved with MM-398 in combination with α-PD-L1 or α-PD1 (P < .001, Tukey’s test). Prolonged survival was also observed in tumor-bearing mice treated with MM-398 in combination with α-PD-L1 (P = .002, log-rank test) or α-PD1 (P = .008, log-rank test).

Conclusions

We demonstrated that Top1 inhibitors can improve the antitumor efficacy of cancer immunotherapy, thus providing the basis for developing novel strategies using Top1 inhibitors to augment the efficacy of immunotherapy.

Elucidation of Tumor-Stromal Heterogeneity and the Ligand-Receptor Interactome by Single-Cell Transcriptomics in Real-world Pancreatic Cancer Biopsies

PURPOSE

Precision medicine approaches in pancreatic ductal adenocarcinoma (PDAC) are imperative for improving disease outcomes. With molecular subtypes of PDAC gaining relevance in the context of therapeutic stratification, the ability to characterize heterogeneity of cancer-specific gene expression patterns is of great interest. In addition, understanding patterns of immune evasion within PDAC is of importance as novel immunotherapeutic strategies are developed.

EXPERIMENTAL DESIGN

Single-cell RNA sequencing (scRNA-seq) is readily applicable to limited biopsies from human primary and metastatic PDAC and identifies most cancers as being an admixture of previously described epithelial transcriptomic subtypes.

RESULTS

Integrative analyses of our data provide an in-depth characterization of the heterogeneity within the tumor microenvironment, including cancer-associated fibroblast subclasses, and predicts for a multitude of ligand-receptor interactions, revealing potential targets for immunotherapy approaches.

CONCLUSIONS

Our analysis demonstrates that the use of de novo biopsies from patients with PDAC paired with scRNA-seq may facilitate therapeutic prediction from limited biopsy samples.

T-cell Homing Therapy for Reducing Regulatory T Cells and Preserving Effector T-cell Function in Large Solid Tumors

Purpose: Infused autologous tumor-infiltrating lymphocytes (TIL) and tumor-targeted chimeric antigen receptor (CAR) T cells typically surround malignant lesions or penetrate small tumor nodules but fail to penetrate large solid tumors, significantly compromising their antitumor impact. Strategies to overcome this primary challenge are largely required.Experimental Design: We tested the effects of IL12 plus doxorubicin on T-cell penetration and efficacy in solid tumors in a murine lung cancer model, a murine breast carcinoma lung metastasis model, and two human xenograft tumor models bearing large tumors (>10 mm).Results: Intriguingly, this simple approach increased the numbers, the distribution, and the depth of penetration of infused CD8+ T cells in these tumors, including both TILs and CAR T cells. This combined treatment halted tumor progression and significantly extended survival time. Studies of the underlying mechanism revealed multiple effects. First, the combined treatment maintained the high ratios of immune-stimulatory receptors to immune-inhibitory receptors on infiltrated CD8+ T cells, reduced the accumulation of immunosuppressive regulatory T cells, and enhanced the numbers of T-bet+ effector T cells in the tumors. Second, doxorubicin induced chemokines CXCL9 and CXCL10, which may attract NKG2D+CD8+ T cells to tumors, and this effect was boosted by IL12-induced IFNγ accumulation in tumors, promoting the penetration of NKG2D+CD8+ T cells.Conclusions: The deep penetration of infused T cells associated with combined IL12 plus doxorubicin yielded striking therapeutic effects in murine and human xenograft solid tumors. This approach might broaden the application of T-cell therapy to a wider range of solid tumors. Clin Cancer Res; 24(12); 2920-34. ©2018 AACRSee related commentary by Berraondo et al., p. 2716.

Neoadjuvant Chemotherapy Increases Cytotoxic T Cell, Tissue Resident Memory T Cell, and B Cell Infiltration in Resectable NSCLC

INTRODUCTION

The combination of programmed cell death protein-1 or programmed death-ligand 1 immune checkpoint blockade and chemotherapy has revolutionized the treatment of advanced NSCLC, but the mechanisms underlying this synergy remain incompletely understood. In this study, we explored the relationships between neoadjuvant chemotherapy and the immune microenvironment (IME) of resectable NSCLC to identify novel mechanisms by which chemotherapy may enhance the effect of immune checkpoint blockade.

METHODS

Genomic, transcriptomic, and immune profiling data of 511 patients treated with neoadjuvant chemotherapy followed by surgery (NCT) versus upfront surgery (US) were compared with determined differential characteristics of the IMEs derived from whole-exome sequencing (NCT = 18; US = 73), RNA microarray (NCT = 45; US = 202), flow cytometry (NCT = 17; US = 39), multiplex immunofluorescence (NCT = 10; US = 72), T-cell receptor sequencing (NCT = 16 and US = 63), and circulating cytokines (NCT = 18; US = 73).

RESULTS

NCT was associated with increased infiltration of cytotoxic CD8⁺ T cells and CD20⁺ B cells. Moreover, NCT was associated with increases in CD8⁺CD103⁺ and CD4⁺CD103⁺PD-1⁺TIM3^- tissue resident memory T cells. Gene expression profiling supported memory function of CD8⁺ and CD4⁺ T cells. However, NCT did not affect T-cell receptor clonality, richness, or tumor mutational burden. Finally, NCT was associated with decreased plasma BDNF (TrkB) at baseline and week 4 after surgery.

CONCLUSIONS

Our study supports that, in the context of resectable NSCLC, neoadjuvant chemotherapy promotes antitumor immunity through T and B cell recruitment in the IME and through a phenotypic change toward cytotoxic and memory CD8⁺ and CD4⁺ memory helper T cells.

Selective inhibition of autoimmune exacerbation while preserving the anti-tumor clinical benefit using IL-6 blockade in a patient with advanced melanoma and Crohn's disease: a case report

BACKGROUND

Novel immunotherapies, or checkpoint inhibitors, targeting programmed cell death protein-1 (PD-1) and cytotoxic T lymphocyte-associated antigen-4 (CTLA-4) have significantly improved outcomes for patients with numerous different cancer types. However, owing to their exclusion from clinical trials and risk for autoimmune exacerbation on these treatments, the impact on safety and degree of toxicity of these potentially life-prolonging therapies is not well characterized in patients with an underlying autoimmune disease or previous organ transplant.

CASE PRESENTATION

We report a case of a patient with advanced melanoma and refractory Crohn's disease who was treated concurrently with pembrolizumab (anti-PD-1 antibody) and tocilizumab (anti-interluekin-6 receptor antibody). This novel treatment strategy was well tolerated and did not result in Crohn's disease exacerbation for at least 16 weeks. Importantly, this treatment resulted in marked, durable antitumor responses.

CONCLUSIONS

This outcome suggests that targeted immunosuppression combined with checkpoint inhibitors may hold promise as a treatment strategy for this unique patient population and may warrant additional study.

BTLA marks a less-differentiated tumor-infiltrating lymphocyte subset in melanoma with enhanced survival properties

In a recent adoptive cell therapy (ACT) clinical trial using autologous tumor-infiltrating lymphocytes (TILs) in patients with metastatic melanoma, we found an association between CD8⁺ T cells expressing the inhibitory receptor B- and T-lymphocyte attenuator (BTLA) and clinical response. Here, we further characterized this CD8⁺BTLA⁺ TIL subset and their CD8⁺BTLA⁻ counterparts. We found that the CD8⁺ BTLA⁺ TILs had an increased response to IL-2, were less-differentiated effector-memory (T_EM) cells, and persisted longer in vivo after infusion. In contrast, CD8⁺BTLA⁻ TILs failed to proliferate and expressed genes associated with T-cell deletion/tolerance. Paradoxically, activation of BTLA signaling by its ligand, herpes virus entry mediator (HVEM), inhibited T-cell division and cytokine production, but also activated the Akt/PKB pathway thus protecting CD8⁺BTLA⁺ TILs from apoptosis. Our results point to a new role of BTLA as a useful T-cell differentiation marker in ACT and a dual signaling molecule that curtails T-cell activation while also conferring a survival advantage for CD8⁺ T cells. These attributes may explain our previous observation that BTLA expression on CD8⁺ TILs correlates with clinical response to adoptive T-cell therapy in metastatic melanoma.

Interaction of low molecular weight group IIA phospholipase A2 with apoptotic human T cells: role of heparan sulfate proteoglycans

Human group IIA phospholipase A2 (hIIA PLA2) is a 14 kDa secreted enzyme associated with inflammatory diseases. A newly discovered property of hIIA PLA2 is the binding affinity for the heparan sulfate proteoglycan (HSPG) glypican-1. In this study, the binding of hIIA PLA2 to apoptotic human T cells was investigated. Little or no exogenous hIIA PLA2 bound to CD3-activated T cells but significant binding was measured on activated T cells induced to undergo apoptosis by anti-CD95. Binding to early apoptotic T cells was greater than to late apoptotic cells. The addition of heparin and the hydrolysis of HSPG by heparinase III only partially inhibited hIIA PLA2 binding to apoptotic cells, suggesting an interaction with both HSPG and other binding protein(s). Two low molecular weight HSPG were coimmunoprecipitated with hIIA PLA2 from apoptotic T cells, but not from living cells. Treatment of CD95-stimulated T cells with hIIA PLA2 resulted in the release of arachidonic acid but not oleic acid from cells and this release was blocked by heparin and heparinase III. Altogether, these results suggest a role for hIIA PLA2 in the release of arachidonic acid from apoptotic cells through interactions with HSPG and its potential implication in the progression of inflammatory diseases.

Multifaceted Role of BTLA in the Control of CD8+ T-cell Fate after Antigen Encounter

Purpose: Adoptive T-cell therapy using autologous tumor-infiltrating lymphocytes (TIL) has shown an overall clinical response rate 40%-50% in metastatic melanoma patients. BTLA (B-and-T lymphocyte associated) expression on transferred CD8⁺ TILs was associated with better clinical outcome. The suppressive function of the ITIM and ITSM motifs of BTLA is well described. Here, we sought to determine the functional characteristics of the CD8⁺BTLA⁺TIL subset and define the contribution of the Grb2 motif of BTLA in T-cell costimulation.Experimental Design: We determined the functional role and downstream signal of BTLA in both human CD8⁺ TILs and mouse CD8⁺ T cells. Functional assays were used including single-cell analysis, reverse-phase protein array (RPPA), antigen-specific vaccination models with adoptively transferred TCR-transgenic T cells as well as patient-derived xenograft (PDX) model using immunodeficient NOD-scid IL2Rgammanull (NSG) tumor-bearing mice treated with autologous TILs.Results: CD8⁺BTLA^- TILs could not control tumor growth in vivo as well as their BTLA⁺ counterpart and antigen-specific CD8⁺BTLA^- T cells had impaired recall response to a vaccine. However, CD8⁺BTLA⁺ TILs displayed improved survival following the killing of a tumor target and heightened "serial killing" capacity. Using mutants of BTLA signaling motifs, we uncovered a costimulatory function mediated by Grb2 through enhancing the secretion of IL-2 and the activation of Src after TCR stimulation.Conclusions: Our data portrays BTLA as a molecule with the singular ability to provide both costimulatory and coinhibitory signals to activated CD8⁺ T cells, resulting in extended survival, improved tumor control, and the development of a functional recall response. Clin Cancer Res; 23(20); 6151-64. ©2017 AACR.

4-1BB-Enhanced Expansion of CD8+ TIL from Triple-Negative Breast Cancer Unveils Mutation-Specific CD8+ T Cells

Triple-negative breast cancer (TNBC) highly infiltrated with CD8⁺ tumor-infiltrating lymphocytes (TIL) has been associated with improved prognosis. This observation led us to hypothesize that CD8⁺ TIL could be utilized in autologous adoptive cell therapy for TNBC, although this concept has proven to be challenging, given the difficulty in expanding CD8⁺ TILs in solid cancers other than in melanoma. To overcome this obstacle, we used an agonistic antibody (urelumab) to a TNFR family member, 4-1BB/CD137, which is expressed by recently activated CD8⁺ T cells. This approach was first utilized in melanoma and, in this study, led to advantageous growth of TILs for the majority of TNBC tumors tested. The agonistic antibody was only added in the initial setting of the culture and yet favored the propagation of CD8⁺ TILs from TNBC tumors. These expanded CD8⁺ TILs were capable of cytotoxic functions and were successfully utilized to demonstrate the presence of immunogenic mutations in autologous TNBC tumor tissue without recognition of the wild-type counterpart. Our findings open the way for a successful adoptive immunotherapy for TNBC. Cancer Immunol Res; 5(6); 439-45. ©2017 AACR.

Single-Cell Sequencing Reveals Trajectory of Tumor-Infiltrating Lymphocyte States in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) has few effective treatments. Immunotherapy, an attractive alternative strategy, remains challenging with the lack of knowledge on the tumor-infiltrating lymphocyte (TIL) landscape in PDAC. To generate a reference of T-cell subpopulations, we profiled 80,000 T cells from 57 PDAC samples, 22 uninvolved/normal samples, and cultured TIL using single-cell transcriptomic and T-cell receptor analysis. These data revealed 20 cell states and heterogeneous distributions of TIL populations. The CD8+ TIL contained a putative transitional GZMK+ population based on T-cell receptor clonotype sharing, and cell-state trajectory analysis showed similarity to a GZMB+PRF1+ cytotoxic and a CXCL13+ dysfunctional population. Statistical analysis suggested that certain TIL states, such as dysfunctional and inhibitory populations, often occurred together. Finally, analysis of cultured TIL revealed that high-frequency clones from effector populations were preferentially expanded. These data provide a framework for understanding the PDAC TIL landscape for future TIL use in immunotherapy for PDAC.

SIGNIFICANCE

To improve the efficacy of immunotherapy in PDAC, there is a great need to understand the PDAC TIL landscape. This study represents a reference of PDAC TIL subpopulations and their relationships and provides a foundation upon which to base future immunotherapeutic efforts. This article is highlighted in the In This Issue feature, p. 2221.

Parallel profiling of immune infiltrate subsets in uveal melanoma versus cutaneous melanoma unveils similarities and differences: A pilot study

The low response rates to immunotherapy in uveal melanoma (UM) sharply contrast with reputable response rates in cutaneous melanoma (CM) patients. To characterize the mechanisms responsible for resistance to immunotherapy in UM, we performed immune profiling in tumors from 10 metastatic UM patients and 10 metastatic CM patients by immunohistochemistry (IHC). Although there is no difference in infiltrating CD8⁺ T cells between UM and CM, a significant decrease in programmed death-1 (PD-1)-positive lymphocytes was observed and lower levels of programmed death ligand-1 (PD-L1) in UM metastases compared with CM metastases. Tumors from metastatic UM patients showed a lower success rate of tumor-infiltrating lymphocyte (TIL) growth compared with metastatic CM (45% vs. 64% success), with a significantly lower quantity of UM TIL expanded overall. These studies suggest that UM and CM are immunologically distinct, and provide potential explanation for the impaired success of immunotherapy in UM.

4-1BB Agonist Focuses CD8+ Tumor-Infiltrating T-Cell Growth into a Distinct Repertoire Capable of Tumor Recognition in Pancreatic Cancer

Purpose: Survival for pancreatic ductal adenocarcinoma (PDAC) patients is extremely poor and improved therapies are urgently needed. Tumor-infiltrating lymphocyte (TIL) adoptive cell therapy (ACT) has shown great promise in other tumor types, such as metastatic melanoma where overall response rates of 50% have been seen. Given this success and the evidence showing that T-cell presence positively correlates with overall survival in PDAC, we sought to enrich for CD8+ TILs capable of autologous tumor recognition. In addition, we explored the phenotype and T-cell receptor repertoire of the CD8+ TILs in the tumor microenvironment.Experimental Design: We used an agonistic 4-1BB mAb during the initial tumor fragment culture to provide 4-1BB costimulation and assessed changes in TIL growth, phenotype, repertoire, and antitumor function.Results: Increased CD8+ TIL growth from PDAC tumors was achieved with the aid of an agonistic 4-1BB mAb. Expanded TILs were characterized by an activated but not terminally differentiated phenotype. Moreover, 4-1BB stimulation expanded a more clonal and distinct CD8+ TIL repertoire than IL2 alone. TILs from both culture conditions displayed MHC class I-restricted recognition of autologous tumor targets.Conclusions: Costimulation with an anti-4-1BB mAb increases the feasibility of TIL therapy by producing greater numbers of these tumor-reactive T cells. These results suggest that TIL ACT for PDAC is a potential treatment avenue worth further investigation for a patient population in dire need of improved therapy. Clin Cancer Res; 23(23); 7263-75. ©2017 AACR.

Metastatic Melanoma Patient Had a Complete Response with Clonal Expansion after Whole Brain Radiation and PD-1 Blockade

We report here on a patient with metastatic melanoma who had extensive brain metastases. After being treated with the sequential combination of whole brain radiation therapy followed by the PD-1-inhibitory antibody, pembrolizumab, the patient had a durable complete response. Retrospective laboratory studies of T cells revealed that, after treatment with anti-PD-1 commenced, effector CD8⁺ T cells in the blood expanded and the ratio of CD8⁺:Treg T cells increased. A CD8⁺ T-cell clone present in the initial brain metastases was expanded in the blood after anti-PD-1 treatment, which suggested an antitumor role for this clone. Immunohistochemical analysis confirmed the presence of CD8⁺ T cells and low PD-L1 expression in the brain metastases before immunotherapy initiation. This sequence of therapy may provide an option for melanoma patients with unresponsive brain metastases. Cancer Immunol Res; 5(2); 100-5. ©2017 AACR.

Tilsotolimod with Ipilimumab Drives Tumor Responses in Anti-PD-1 Refractory Melanoma

Many patients with advanced melanoma are resistant to immune checkpoint inhibition. In the ILLUMINATE-204 phase I/II trial, we assessed intratumoral tilsotolimod, an investigational Toll-like receptor 9 agonist, with systemic ipilimumab in patients with anti-PD-1- resistant advanced melanoma. In all patients, 48.4% experienced grade 3/4 treatment-emergent adverse events. The overall response rate at the recommended phase II dose of 8 mg was 22.4%, and an additional 49% of patients had stable disease. Responses in noninjected lesions and in patients expected to be resistant to ipilimumab monotherapy were observed. Rapid induction of a local IFNα gene signature, dendritic cell maturation and enhanced markers of antigen presentation, and T-cell clonal expansion correlated with clinical response. A phase III clinical trial with this combination (NCT03445533) is ongoing. SIGNIFICANCE: Despite recent developments in advanced melanoma therapies, most patients do not experience durable responses. Intratumoral tilsotolimod injection elicits a rapid, local type 1 IFN response and, in combination with ipilimumab, activates T cells to promote clinical activity, including in distant lesions and patients not expected to respond to ipilimumab alone.This article is highlighted in the In This Issue feature, p. 1861.

Pilot Clinical Trial of Perioperative Durvalumab and Tremelimumab in the Treatment of Resectable Colorectal Cancer Liver Metastases

PURPOSE

Despite the prognostic importance of immune infiltrate in colorectal cancer, immunotherapy has demonstrated limited clinical activity in refractory metastatic proficient mismatch-repair (pMMR) colorectal cancer. This study explores combining anti-CTLA-4 and an anti-PD-L1 therapy in the preoperative management of resectable colorectal cancer liver metastases with the intent to improve immune responses in this disease setting.

PATIENTS AND METHODS

Patients with resectable colorectal cancer liver-only metastases received one dose of tremelimumab and durvalumab preoperatively followed by single-agent durvalumab postoperatively. Primary objectives were to determine feasibility and safety.

RESULTS

A total of 24 patients were enrolled between November 2016 and November 2019. Twenty-three patients received treatment [21 pMMR and 2 deficient mismatch-repair (dMMR)] and subsequently 17 (74%; 95% CI: 53%-88%) underwent surgical resection. Grade 3/4 treatment-related immune toxicity and postoperative grade 3/4 toxicity were seen in 5/23 (22%; 95% CI: 10%-44%) and 2/17 (12%; 95% CI: 2%-38%) patients. The median relapse-free survival (RFS) was 9.7 (95% CI: 8.1-17.8) months, and overall survival was 24.5 (95% CI: 16.5-28.4) months. Four patients demonstrated complete pathologic response, two dMMR patients and two POLE mutation patients. Pre- and post-tumor tissue analysis by flow cytometry, immunofluorescence, and RNA sequencing revealed similar levels of T-cell infiltration, but did demonstrate evidence of CD8⁺ and CD4⁺ activation posttreatment. An increase in B-cell transcriptome signature and B-cell density was present in posttreatment samples from patients with prolonged RFS.

CONCLUSIONS

This study demonstrates the safety of neoadjuvant combination tremelimumab and durvalumab prior to colorectal cancer liver resection. Evidence for T- and B-cell activation following this therapy was seen in pMMR metastatic colorectal cancer.

A Novel Method to Generate and Expand Clinical-Grade, Genetically Modified, Tumor-Infiltrating Lymphocytes

Following the clinical success achieved with the first generation of adoptive cell therapy (ACT) utilizing in vitro expanded tumor-infiltrating lymphocytes (TILs), the second and third generations of TIL ACT are evolving toward the use of genetically modified TIL. TIL therapy generally involves the transfer of a high number of TIL, ranging from 10⁹ to 10¹¹ cells. One of the technical difficulties in genetically modifying TIL, using a retroviral vector, is the ability to achieve large expansion of transduced TIL, while keeping the technique suitable to a Good Manufacturing Practices (GMP) environment. Consequently, we developed and optimized a novel method for the efficient production of large numbers of GMP-grade, gene-modified TIL for the treatment of patients with ACT. The chemokine receptor CXCR2 was used as the gene of interest for methodology development. The optimized procedure is currently used in the production of gene-modified TIL for two clinical trials for the treatment of metastatic melanoma at MD Anderson Cancer Center.

Advances in the development of cancer immunotherapies

Manipulating the immune system in order to induce clinically relevant responses against cancer is a longstanding goal. Interventions to enhance tumor-specific immunity through vaccination, sustaining effector T cell activation, or increasing the numbers of tumor-specific T cells using ex vivo expansion, have all resulted in clinical successes. Here, we examine recent clinical advances and major ongoing studies in the field of cancer immunotherapy. Single agents have so far benefited a limited proportion of patients, and future studies combining different types of immunotherapies and other therapeutic modalities, such as drugs against specific signaling pathways driving cancer cell growth, are needed to pave the way for the development of effective anticancer treatments causing durable responses.