Neoantigen-targeted CD8+ T cell responses with PD-1 blockade therapy.

Neoantigens are peptides derived from non-synonymous mutations presented by human leukocyte antigens (HLAs), which are recognized by antitumour T cells1-14. The large HLA allele diversity and limiting clinical samples have restricted the study of the landscape of neoantigen-targeted T cell responses in patients over their treatment course. Here we applied recently developed technologies15-17 to capture neoantigen-specific T cells from blood and tumours from patients with metastatic melanoma with or without response to anti-programmed death receptor 1 (PD-1) immunotherapy. We generated personalized libraries of neoantigen-HLA capture reagents to single-cell isolate the T cells and clone their T cell receptors (neoTCRs). Multiple T cells with different neoTCR sequences (T cell clonotypes) recognized a limited number of mutations in samples from seven patients with long-lasting clinical responses. These neoTCR clonotypes were recurrently detected over time in the blood and tumour. Samples from four patients with no response to anti-PD-1 also demonstrated neoantigen-specific T cell responses in the blood and tumour to a restricted number of mutations with lower TCR polyclonality and were not recurrently detected in sequential samples. Reconstitution of the neoTCRs in donor T cells using non-viral CRISPR-Cas9 gene editing demonstrated specific recognition and cytotoxicity to patient-matched melanoma cell lines. Thus, effective anti-PD-1 immunotherapy is associated with the presence of polyclonal CD8+ T cells in the tumour and blood specific for a limited number of immunodominant mutations, which are recurrently recognized over time.

ERK mediates interferon gamma-induced melanoma cell death.

BACKGROUND: Interferon-gamma (IFNγ) exerts potent growth inhibitory effects on a wide range of cancer cells through unknown signaling pathways. We pursued complementary screening approaches to characterize the growth inhibition pathway. METHODS: We performed chemical genomics and whole genome targeting CRISPR/Cas9 screens using patient-derived melanoma lines to uncover essential nodes in the IFNγ-mediated growth inhibition pathway. We used transcriptomic profiling to identify cell death pathways activated upon IFNγ exposure. Live imaging experiments coupled with apoptosis assays confirmed the involvement of these pathways in IFNγ-mediated cell death. RESULTS: We show that IFNγ signaling activated ERK. Blocking ERK activation rescued IFNγ-mediated apoptosis in 17 of 23 (~ 74%) cell lines representing BRAF, NRAS, NF1 mutant, and triple wild type subtypes of cutaneous melanoma. ERK signaling induced a stress response, ultimately leading to apoptosis through the activity of DR5 and NOXA proteins. CONCLUSIONS: Our results provide a new understanding of the IFNγ growth inhibition pathway, which will be crucial in defining mechanisms of immunotherapy response and resistance.

Integrative systems biology reveals NKG2A-biased immune responses correlate with protection in infectious disease, autoimmune disease, and cancer.

Infection, autoimmunity, and cancer are principal human health challenges of the 21st century. Often regarded as distinct ends of the immunological spectrum, recent studies hint at potential overlap between these diseases. For example, inflammation can be pathogenic in infection and autoimmunity. T resident memory (TRM) cells can be beneficial in infection and cancer. However, these findings are limited by size and scope; exact immunological factors shared across diseases remain elusive. Here, we integrate large-scale deeply clinically and biologically phenotyped human cohorts of 526 patients with infection, 162 with lupus, and 11,180 with cancer. We identify an NKG2A+ immune bias as associative with protection against disease severity, mortality, and autoimmune/post-acute chronic disease. We reveal that NKG2A+ CD8+ T cells correlate with reduced inflammation and increased humoral immunity and that they resemble TRM cells. Our results suggest NKG2A+ biases as a cross-disease factor of protection, supporting suggestions of immunological overlap between infection, autoimmunity, and cancer.

Antitumor Immune Responses in B2M-Deficient Cancers.

ß2-microglobulin (B2M) is a critical component of the MHC class I molecule and is required to present tumor antigens to T cells. Its loss results in acquired resistance to immune checkpoint blockade (ICB) therapies. However, there have been well-documented cases of B2M-inactivated tumors responding to ICB, justifying investigation of how an antitumor immune response can be generated to tumors without surface MHC class I. We knocked out B2M in three murine models with varying baseline MHC class I expression and sensitivity to anti-programmed death receptor (PD-1) therapy and analyzed the immune responses. MC38 and YUMMER2.1 without B2M responded to anti-PD-1 alone or with an IL2 agonist, and this was mediated by CD4+ T cells and natural killer (NK) cells. The more aggressive B16 without B2M expression only partially responded to the IL2 agonist, and this was dependent on NK cells. When analyzing nearly 300 pretreatment biopsies from patients with melanoma receiving PD-1 blockade-based therapies, we found infrequent B2M mutations or homozygous loss but more frequent LOH or copy-number gains. B2M LOH was enriched in biopsies from patients without response to therapy, and these biopsies were more frequently infiltrated by activated NK cells. We conclude that in the absence of B2M, activation of CD4+ T cells and NK cells can mediate responses to murine models of PD-1 blockade therapy. In addition, in human melanoma, the intratumoral presence of activated NK cells upon partial B2M loss likely selects against tumor escape through low surface MHC class I expression.

An NKG2A biased immune response confers protection for infection, autoimmune disease, and cancer.

Infection, autoimmunity, and cancer are the principal human health challenges of the 21st century and major contributors to human death and disease. Often regarded as distinct ends of the immunological spectrum, recent studies have hinted there may be more overlap between these diseases than appears. For example, pathogenic inflammation has been demonstrated as conserved between infection and autoimmune settings. T resident memory (TRM) cells have been highlighted as beneficial for infection and cancer. However, these findings are limited by patient number and disease scope; exact immunological factors shared across disease remain elusive. Here, we integrate large-scale deeply clinically and biologically phenotyped human cohorts of 526 patients with infection, 162 with lupus, and 11,180 with cancer. We identify an NKG2A+ immune bias as associative with protection against disease severity, mortality, and autoimmune and post-acute chronic disease. We reveal that NKG2A+ CD8+ T cells correlate with reduced inflammation, increased humoral immunity, and resemble TRM cells. Our results suggest that an NKG2A+ bias is a pan-disease immunological factor of protection and thus supports recent suggestions that there is immunological overlap between infection, autoimmunity, and cancer. Our findings underscore the promotion of an NKG2A+ biased response as a putative therapeutic strategy.

A Pilot Study of Neoadjuvant Nivolumab, Ipilimumab, and Intralesional Oncolytic Virotherapy for HER2-negative Breast Cancer.

Purpose: Neoadjuvant combination immune checkpoint blockade and intralesional oncolytic virotherapy have the potential to activate antitumor responses in patients with breast cancer. Experimental Design: Eligibility for this pilot phase I trial included patients with localized HER2-negative breast cancer who received systemic nivolumab and ipilimumab and intratumor talimogene laherparepvec (T-VEC; NCT04185311). The primary objective was to evaluate the safety and adverse event profile of immunotherapy combined with T-VEC in patients with localized, HER2-negative breast cancer. Results: Six patients were enrolled, 4 having relapses after prior neoadjuvant chemotherapy and 2 who were previously untreated. Toxicities included 1 patient having grade 3 hypotension and type 1 diabetes mellitus, 3 patients with hypothyroidism, and all patients having constitutional symptoms known to be associated with the administration of T-VEC. One patient had a pathologic complete response, 3 patients had pathologic partial responses, 1 showed no significant response, and 1 had disease progression. Biopsies demonstrated increased immune cell infiltration in samples from patients who responded to therapy. Conclusions: This triple immunotherapy regimen provided responses in patients with advanced or relapsed HER2-negative breast cancer, at the expense of long-term toxicities. Significance: Systemic immune checkpoint blockade with a programmed death receptor 1 and a CTL antigen-4 blocking antibody, combined with intralesional oncolytic virotherapy, is a chemotherapy-free combination aimed at inducing an antitumor immune response locally and systemic immunity.

Prior anti-CTLA-4 therapy impacts molecular characteristics associated with anti-PD-1 response in advanced melanoma.

Immune checkpoint inhibitors (ICIs), including CTLA-4- and PD-1-blocking antibodies, can have profound effects on tumor immune cell infiltration that have not been consistent in biopsy series reported to date. Here, we analyze seven molecular datasets of samples from patients with advanced melanoma (N = 514) treated with ICI agents to investigate clinical, genomic, and transcriptomic features of anti-PD-1 response in cutaneous melanoma. We find that prior anti-CTLA-4 therapy is associated with differences in genomic, individual gene, and gene signatures in anti-PD-1 responders. Anti-CTLA-4-experienced melanoma tumors that respond to PD-1 blockade exhibit increased tumor mutational burden, inflammatory signatures, and altered cell cycle processes compared with anti-CTLA-4-naive tumors or anti-CTLA-4-experienced, anti-PD-1-nonresponsive melanoma tumors. We report a harmonized, aggregate resource and suggest that prior CTLA-4 blockade therapy is associated with marked differences in the tumor microenvironment that impact the predictive features of PD-1 blockade therapy response.

Ipilimumab with or without nivolumab in PD-1 or PD-L1 blockade refractory metastatic melanoma: a randomized phase 2 trial.

In this randomized phase 2 trial, blockade of cytotoxic T-lymphocyte protein 4 (CTLA-4) with continuation of programmed death protein 1 (PD-1) blockade in patients with metastatic melanoma who had received front-line anti-PD-1 or therapy against programmed cell death 1 ligand 1 and whose tumors progressed was tested in comparison with CTLA-4 blockade alone. Ninety-two eligible patients were randomly assigned in a 3:1 ratio to receive the combination of ipilimumab and nivolumab, or ipilimumab alone. The primary endpoint was progression-free survival. Secondary endpoints included the difference in CD8 T cell infiltrate among responding and nonresponding tumors, objective response rate, overall survival and toxicity. The combination of nivolumab and ipilimumab resulted in a statistically significant improvement in progression-free survival over ipilimumab (hazard ratio = 0.63, 90% confidence interval (CI) = 0.41-0.97, one-sided P = 0.04). Objective response rates were 28% (90% CI = 19-38%) and 9% (90% CI = 2-25%), respectively (one-sided P = 0.05). Grade 3 or higher treatment-related adverse events occurred in 57% and 35% of patients, respectively, which is consistent with the known toxicity profile of these regimens. The change in intratumoral CD8 T cell density observed in the present analysis did not reach statistical significance to support the formal hypothesis tested as a secondary endpoint. In conclusion, primary resistance to PD-1 blockade therapy can be reversed in some patients with the combination of CTLA-4 and PD-1 blockade. Clinicaltrials.gov identifier: NCT03033576 .

Spatial profiling reveals association between WNT pathway activation and T-cell exclusion in acquired resistance of synovial sarcoma to NY-ESO-1 transgenic T-cell therapy.

BACKGROUND: Genetically engineered T-cell immunotherapies for adoptive cell transfer (ACT) have emerged as a promising form of cancer treatment, but many of these patients develop recurrent disease. Furthermore, delineating mechanisms of resistance may be challenging since the analysis of bulk tumor profiling can be complicated by spatial heterogeneity. METHODS: Tumor samples were collected from a patient with synovial sarcoma who developed acquired resistance to ACT targeting NY-ESO-1. Biopsies (primary, progressive metastasis, and recurrence) were subjected to bulk tumor DNA and RNA sequencing, as well as high-dimensional spatial profiling of RNA and protein targets. Untreated and progressive lesions were compared with identified patterns associated with acquired resistance to ACT. RESULTS: Gene expression patterns due to immune activity and infiltration were diluted in bulk tumor sequencing. The metastasis was enriched for tumor regions with increased CTNNB1 (encoding beta-catenin), which were negatively associated with the expression of T-cell surface proteins and antigen presentation machinery. Spatial profiling was most highly concordant with bulk sequencing in the lesions with decreased spatial heterogeneity. CONCLUSIONS: Complementary use of bulk and spatial profiling enables more accurate interrogation of tumor specimens, particularly to address complex questions regarding immunotherapeutic mechanisms. Our study uses this approach to demonstrate a mechanism of T-cell exclusion and resistance to cellular immunotherapy in synovial sarcoma.

Remodeling of the tumor microenvironment through PAK4 inhibition sensitizes tumors to immune checkpoint blockade.

PAK4 inhibition can sensitize tumors to immune checkpoint blockade (ICB) therapy, however, the underlying mechanisms remain unclear. We report that PAK4 inhibition reverses immune cell exclusion by increasing the infiltration of CD8 T cells and CD103+ dendritic cells (DCs), a specific type of DCs that excel at cross-presenting tumor antigens and constitute a source of CXCL10. Interestingly, in melanoma clinical datasets, PAK4 expression levels negatively correlate with the presence of CCL21, the ligand for CCR7 expressed in CD103+ DCs. Furthermore, we extensively characterized the transcriptome of PAK4 knock out (KO) tumors, in vitro and in vivo, and established the importance of PAK4 expression in the regulation of the extracellular matrix, which can facilitate immune cell infiltration. Comparison between PAK4 wild type (WT) and KO anti-PD-1 treated tumors revealed how PAK4 deletion sensitizes tumors to ICB from a transcriptomic perspective. In addition, we validated genetically and pharmacologically that inhibition of PAK4 kinase activity is sufficient to improve anti-tumor efficacy of anti-PD-1 blockade in multiple melanoma mouse models. Therefore, this study provides novel insights into the mechanism of action of PAK4 inhibition and provides the foundation for a new treatment strategy that aims to overcome resistance to PD-1 blockade by combining anti-PD-1 with a small molecule PAK4 kinase inhibitor.

Reducing Skin Toxicities from EGFR Inhibitors with Topical BRAF Inhibitor Therapy.

Treatment of cancer with EGFR inhibitors is limited by on-target skin toxicities induced by inhibition of the MAPK pathway. BRAF inhibitors are known to paradoxically activate the MAPK downstream of EGFR, which we confirmed using human skin keratinocytes. We then conducted a phase I clinical trial testing the hypothesis that topical therapy with the BRAF inhibitor LUT014 could improve skin toxicities induced by EGFR inhibitors. Ten patients with metastatic colorectal cancer who had developed acneiform rash while being treated with cetuximab or panitumumab were enrolled in three cohorts. LUT014 was well tolerated, and there were no dose-limiting toxicities. The acneiform rash improved in the 6 patients who started with grade 2 rash in the low and intermediate cohorts. We conclude that topical LUT014 is safe and efficacious in improving rash from EGFR inhibitors, consistent with the mechanism of action inducting paradoxical MAPK activation. SIGNIFICANCE: BRAF inhibitor topical therapy could avoid dose reductions of EGFR inhibitors, locally treating the main dose-limiting skin toxicity of this class of agents.This article is highlighted in the In This Issue feature, p. 2113.

Melanoma dedifferentiation induced by IFN-γ epigenetic remodeling in response to anti-PD-1 therapy.

Melanoma dedifferentiation has been reported to be a state of cellular resistance to targeted therapies and immunotherapies as cancer cells revert to a more primitive cellular phenotype. Here, we show that, counterintuitively, the biopsies of patient tumors that responded to anti-programmed cell death 1 (anti-PD-1) therapy had decreased expression of melanocytic markers and increased neural crest markers, suggesting treatment-induced dedifferentiation. When modeling the effects in vitro, we documented that melanoma cell lines that were originally differentiated underwent a process of neural crest dedifferentiation when continuously exposed to IFN-γ, through global chromatin landscape changes that led to enrichment in specific hyperaccessible chromatin regions. The IFN-γ-induced dedifferentiation signature corresponded with improved outcomes in patients with melanoma, challenging the notion that neural crest dedifferentiation is entirely an adverse phenotype.

PAK4 inhibition improves PD-1 blockade immunotherapy.

Lack of tumor infiltration by immune cells is the main mechanism of primary resistance to programmed cell death protein 1 (PD-1) blockade therapies for cancer. It has been postulated that cancer cell-intrinsic mechanisms may actively exclude T cells from tumors, suggesting that the finding of actionable molecules that could be inhibited to increase T cell infiltration may synergize with checkpoint inhibitor immunotherapy. Here, we show that p21-activated kinase 4 (PAK4) is enriched in non-responding tumor biopsies with low T cell and dendritic cell infiltration. In mouse models, genetic deletion of PAK4 increased T cell infiltration and reversed resistance to PD-1 blockade in a CD8 T cell-dependent manner. Furthermore, combination of anti-PD-1 with the PAK4 inhibitor KPT-9274 improved anti-tumor response compared with anti-PD-1 alone. Therefore, high PAK4 expression is correlated with low T cell and dendritic cell infiltration and a lack of response to PD-1 blockade, which could be reversed with PAK4 inhibition.

Conserved Interferon-γ Signaling Drives Clinical Response to Immune Checkpoint Blockade Therapy in Melanoma.

We analyze the transcriptome of baseline and on-therapy tumor biopsies from 101 patients with advanced melanoma treated with nivolumab (anti-PD-1) alone or combined with ipilimumab (anti-CTLA-4). We find that T cell infiltration and interferon-γ (IFN-γ) signaling signatures correspond most highly with clinical response to therapy, with a reciprocal decrease in cell-cycle and WNT signaling pathways in responding biopsies. We model the interaction in 58 human cell lines, where IFN-γ in vitro exposure leads to a conserved transcriptome response unless cells have IFN-γ receptor alterations. This conserved IFN-γ transcriptome response in melanoma cells serves to amplify the antitumor immune response. Therefore, the magnitude of the antitumor T cell response and the corresponding downstream IFN-γ signaling are the main drivers of clinical response or resistance to immune checkpoint blockade therapy.