Loss of Asf1a shows no significant effect on DNA damage and tumor cell proliferation

Primary clustering of tumor cells and immune cell populations

Alterations of myeloid populations in an orthotopic KP lung tumor model with short-term treatment

Immunotherapy has recently been shown to improve outcomes for advanced PD-L1-positive triple-negative breast cancer (TNBC) in the Impassion130 trial, leading to FDA approval of the first immune checkpoint inhibitor in combination with taxane chemotherapy. To further develop predictive biomarkers and improve therapeutic efficacy of the combination, interrogation of the tumor immune microenvironment before therapy as well as during each component of treatment is crucial. Here we use single-cell RNA sequencing (scRNA-seq) on tumor biopsies to assess immune cell changes from two patients with advanced TNBC treated in a prospective trial at predefined serial time points, before treatment, on taxane chemotherapy and on chemo-immunotherapy. Both patients (one responder and one progressor) received the trial therapy, in cycle 1 nab-paclitaxel given as single agent, in cycle 2 nab-paclitaxel in combination with pembrolizumab. Tumor core biopsies were obtained at baseline, 3 weeks (after cycle 1, chemotherapy alone) and 6 weeks (after cycle 2, chemo-immunotherapy). Single-cell RNA sequencing (scRNA-seq) of both cancer cells and infiltrating immune cells isolated were performed from fresh tumor core biopsy specimens by 10 × chromium sequencing. ScRNA-seq analysis showed significant baseline heterogeneity of tumor-infiltrating immune cell populations between the two patients as well as modulation of the tumor microenvironment by chemotherapy and immunotherapy. In the responding patient there was a population of PD-1high-expressing T cells which significantly decreased after nab-paclitaxel plus pembrolizumab treatment as well as a presence of tissue-resident memory T cells (TRM). In contrast, tumors from the patient with rapid disease progression showed a prevalent and persistent myeloid compartment. Our study provides a deep cellular analysis of on-treatment changes during chemo-immunotherapy for advanced TNBC, demonstrating not only feasibility of single-cell analyses on serial tumor biopsies but also the heterogeneity of TNBC and differences in on-treatment changes in responder versus progressor.

The emergence of immune checkpoint inhibitors has changed the treatment paradigm for NSCLC. Recently, immunotherapy in combination with chemotherapy was shown to be a promising first-line treatment strategy for patients with squamous cell lung cancer, where targeted therapy has had little efficacy due to the pathological driver mutations for this disease being poorly understood. However, for both adenocarcinoma and squamous cell NSCLC, use of such immune checkpoint inhibitors has shown to improve the outcome for only a subset of patients with advanced or metastatic disease. Understanding the diversity in the tumor immune microenvironment will be critical to not only advance immune oncology research but to also determine potential clinical distinctions that dictate therapeutic response. Here, we take a multifaceted approach to compare the tumor immune microenvironments of over 50 patients diagnosed with either adenocarcinoma or squamous cell NSCLC. To this end, we performed a comprehensive multicolor flow cytometry analysis to compare tumor immune infiltrates and expression of suppressive markers to adjacent normal lung tissue as well as peripheral blood immune cells from the same patient. This analysis showed differences in the CD4+ and CD8+ T cell, CD19+ B cell, NK cell, and CD14+/CD16+ myeloid cell populations between the tumor and matched tissue and blood. These immune profiles were then compared between adenocarcinoma and squamous cell carcinoma subtypes as well as early versus late stage disease. We then integrated these findings with multiplexed immunofluorescence analysis on a panel of immune cell markers. Finally, 10x genomics single-cell RNA sequencing (scRNAseq) data were used to analyze single-cell transcriptomes from both adenocarcinoma and squamous cell lung tumors. Our result showed great heterogeneity of immune infiltrates across different patient samples, including different subtypes and different disease stages. This detailed comparative analysis will help us further understand the involvement of tumor infiltrating immune cells for different subtypes of lung cancer. Citation Format: Kayla Harmeyer, Jiehui Deng, Suhagi Shah, Ece Bagdatlioglu, Aarif Ahsan, Christopher Reid, Aatish Thennavan, Charles Perou, Kwok-Kin Wong, Harvey Pass. Profiling the tumor immune microenvironment of adenocarcinoma and squamous cell NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4563.

Abstract Despite substantial progress in lung cancer immunotherapy, the overall response rate in patients with KRAS-mutant lung adenocarcinoma (LUAD) remains low. Combining standard immunotherapy with adjuvant approaches that enhance adaptive immune responses—such as epigenetic modulation of antitumor immunity—is therefore an attractive strategy. To identify epigenetic regulators of tumor immunity, we constructed an epigenetic-focused single guide RNA library and performed an in vivo CRISPR screen in a KrasG12D/Trp53−/− LUAD model. Our data showed that loss of the histone chaperone Asf1a in tumor cells sensitizes tumors to anti–PD-1 treatment. Mechanistic studies revealed that tumor cell–intrinsic Asf1a deficiency induced immunogenic macrophage differentiation in the tumor microenvironment by upregulating GM-CSF expression and potentiated T-cell activation in combination with anti–PD-1. Our results provide a rationale for a novel combination therapy consisting of ASF1A inhibition and anti–PD-1 immunotherapy. Significance: Using an in vivo epigenetic CRISPR screen, we identified Asf1a as a critical regulator of LUAD sensitivity to anti–PD-1 therapy. Asf1a deficiency synergized with anti–PD-1 immunotherapy by promoting M1-like macrophage polarization and T-cell activation. Thus, we provide a new immunotherapeutic strategy for this subtype of patients with LUAD. See related commentary by Menzel and Black, p. 179. This article is highlighted in the In This Issue feature, p. 161

Pancreatic ductal adenocarcinoma (PDA) is characterized by immune tolerance and immunotherapeutic resistance. We discovered upregulation of receptor-interacting serine/threonine protein kinase 1 (RIP1) in tumor-associated macrophages (TAMs) in PDA. To study its role in oncogenic progression, we developed a selective small-molecule RIP1 inhibitor with high in vivo exposure. Targeting RIP1 reprogrammed TAMs toward an MHCIIhiTNFα+IFNγ+ immunogenic phenotype in a STAT1-dependent manner. RIP1 inhibition in TAMs resulted in cytotoxic T cell activation and T helper cell differentiation toward a mixed Th1/Th17 phenotype, leading to tumor immunity in mice and in organotypic models of human PDA. Targeting RIP1 synergized with PD1-and inducible co-stimulator-based immunotherapies. Tumor-promoting effects of RIP1 were independent of its co-association with RIP3. Collectively, our work describes RIP1 as a checkpoint kinase governing tumor immunity.