Immunosuppressive milieu of high-risk localized prostate cancer

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Background: The immune factors that modulate the aggressiveness of localized treatment-naïve prostate cancer remain poorly understood. Methods: Fresh tumor and peripheral blood were collected at the time of radical prostatectomy in patients with localized prostate cancer. We evaluated the immune cell composition of 22 patient samples employing multi-parametric flow cytometry. Samples were grouped by histological grade into intermediate (INTPCA) and high-grade (HIGHPCA) prostate cancers based on standard NCCN criteria and immune cell abundances were quantified by mean +/- SEM. Statistical significance was assessed using the Mann-Whitney test. Results: INTPCA and HIGHPCA tumors harbored a similar increase in CD8+ T cells ( p < 0.0005 and p < 0.05, respectively) and CD11b+CD68-CD16+ myeloid-derived cells (p < 0.05) relative to the peripheral blood. Other cell types were similarly decreased in both INTPCA and HIGHPCA, including CD11b+CD68+CD14+ ( p < 0.005 and p < 0.05, respectively). By contrast, regulatory T cells were the only cell type in our analysis to be uniquely enriched in HIGHPCA rather than INTPCA ( p < 0.05). The most unique feature found in phenotypic profiling of the immune repertoire of HIGHPCA relative to INTPCA was an increase in the immune inhibitory receptor ligand, PD-L1, in the tumor associated macrophages (CD11b+CD68+CD14+) compared to the periphery (p < 0.05). Conclusions: Collectively, our findings reveal that HIGHPCA harbors a distinct immunological landscape. Although effector CD8+ T cells are preferentially expressed in the tumor, these are met with an increased proportion of regulatory T cells as well as PD-L1 expressing macrophages that contribute to the inert tumor microenvironment. These are key features of aggressive prostate cancer that may serve as potential biomarkers and therapeutic targets.

Use of Ex Vivo Patient-Derived Tumor Organotypic Spheroids to Identify Combination Therapies for HER2 Mutant Non-Small Cell Lung Cancer

PURPOSE

Evaluating drug responses using primary patient-derived cells ex vivo represents a potentially rapid and efficient approach to screening for new treatment approaches. Here, we sought to identify neratinib combinations in HER2 mutant non-small cell lung cancer (NSCLC) patient xenograft-derived organotypic spheroids (XDOTS) using a short-term ex vivo system.

EXPERIMENTAL DESIGN

We generated two HER2-mutant NSCLC PDX models [DFCI359 (HER2 exon19 755_757LREdelinsRP) and DFCI315 (HER2 exon20 V777_G778insGSP)] and used the PDX tumors to generate XDOTS. Tumor spheroids were grown in a microfluidic device and treated ex vivo with neratinib-based drug combinations. Live/dead quantification was performed by dual-labeling deconvolution fluorescence microscopy. The most efficacious ex vivo combination was subsequently validated in vivo using the DFCI359 and DFCI315 PDXs and a HER2 ^YVMA genetically engineered mouse model.

RESULTS

Both neratinib and afatinib, but not gefitinib, induced cell death in DFCI359 XDOTS. The combinations of neratinib/trastuzumab and neratinib/temsirolimus enhanced the therapeutic benefit of neratinib alone in DFCI315 and DFCI359. The combination of neratinib and trastuzumab in vivo was more effective compared with single-agent neratinib or trastuzumab and was associated with more robust inhibition of HER2 and downstream signaling.

CONCLUSIONS

The XDOTS platform can be used to evaluate therapies and therapeutic combinations ex vivo using PDX tumors. This approach may accelerate the identification and clinical development of therapies for targets with no or few existing models and/or therapies.

Activation of Oxidative Stress Response in Cancer Generates a Druggable Dependency on Exogenous Non-essential Amino Acids

Rewiring of metabolic pathways is a hallmark of tumorigenesis as cancer cells acquire novel nutrient dependencies to support oncogenic growth. A major genetic subtype of lung adenocarcinoma with KEAP1/NRF2 mutations, which activates the endogenous oxidative stress response, undergoes significant metabolic rewiring to support enhanced antioxidant production. We demonstrate that cancers with high antioxidant capacity exhibit a general dependency on exogenous non-essential amino acids (NEAAs) that is driven by the Nrf2-dependent secretion of glutamate through system x_c^- (XCT), which limits intracellular glutamate pools that are required for NEAA synthesis. This dependency can be therapeutically targeted by dietary restriction or enzymatic depletion of individual NEAAs. Importantly, limiting endogenous glutamate levels by glutaminase inhibition can sensitize tumors without alterations in the Keap1/Nrf2 pathway to dietary restriction of NEAAs. Our findings identify a metabolic strategy to therapeutically target cancers with genetic or pharmacologic activation of the Nrf2 antioxidant response pathway by restricting exogenous sources of NEAAs.

In Vivo Epigenetic CRISPR Screen Identifies Asf1a as an Immunotherapeutic Target in Kras-Mutant Lung Adenocarcinoma

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 Kras G12D/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.

CDK7 Inhibition Potentiates Genome Instability Triggering Anti-tumor Immunity in Small Cell Lung Cancer

Cyclin-dependent kinase 7 (CDK7) is a central regulator of the cell cycle and gene transcription. However, little is known about its impact on genomic instability and cancer immunity. Using a selective CDK7 inhibitor, YKL-5-124, we demonstrated that CDK7 inhibition predominately disrupts cell-cycle progression and induces DNA replication stress and genome instability in small cell lung cancer (SCLC) while simultaneously triggering immune-response signaling. These tumor-intrinsic events provoke a robust immune surveillance program elicited by T cells, which is further enhanced by the addition of immune-checkpoint blockade. Combining YKL-5-124 with anti-PD-1 offers significant survival benefit in multiple highly aggressive murine models of SCLC, providing a rationale for new combination regimens consisting of CDK7 inhibitors and immunotherapies.

Treatment-Induced Tumor Dormancy through YAP-Mediated Transcriptional Reprogramming of the Apoptotic Pathway

Eradicating tumor dormancy that develops following epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) treatment of EGFR-mutant non-small cell lung cancer, is an attractive therapeutic strategy but the mechanisms governing this process are poorly understood. Blockade of ERK1/2 reactivation following EGFR TKI treatment by combined EGFR/MEK inhibition uncovers cells that survive by entering a senescence-like dormant state characterized by high YAP/TEAD activity. YAP/TEAD engage the epithelial-to-mesenchymal transition transcription factor SLUG to directly repress pro-apoptotic BMF, limiting drug-induced apoptosis. Pharmacological co-inhibition of YAP and TEAD, or genetic deletion of YAP1, all deplete dormant cells by enhancing EGFR/MEK inhibition-induced apoptosis. Enhancing the initial efficacy of targeted therapies could ultimately lead to prolonged treatment responses in cancer patients.

Elevated serum rheumatoid factor, anti-citrullinated protein antibodies and active rheumatoid arthritis disease are not associated with chronic periodontitis

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease of the joints with the involvement of other systems. Previous studies have demonstrated its association with chronic periodontitis (CP), a chronic inflammatory disease of tooth-supporting tissues. Positive rheumatoid factor (RF) and anti-citrullinated protein antibody (ACPA) in RA patients have been found to be associated with CP. The aim of this study is to determine the prevalence of CP in RA patients, and to investigate the association of ACPA, RF status and RA disease activity with CP and non-CP RA patients.

MATERIALS AND METHODS

A comparative cross-sectional study involving 98 RA patients was conducted at Hospital Universiti Sains Malaysia, Kubang Kerian, Malaysia. Clinical oral examination was carried out to determine the CP status of RA patients. RF, ACPA and erythrocyte sedimentation rate (ESR) were measured, and the 28-joint Disease Activity Score (DAS-28) was assessed.

RESULTS

Forty-five patients (45.9%) were found to have CP (95% CI: 0.36-0.56). No significant difference was observed in the prevalence of positive RF (p=0.989) or ACPA (p=0.431) in CP and non-CP RA patients. There was also no significant association between active RA disease (DAS-28 score ≥3.2) and RF positivity in CP (p=0.927) and non-CP (p=0.431) RA patients as well as ACPA positivity in CP (p=0.780) and non-CP (p=0.611) RA patients.

CONCLUSION

In our cohort of RA patients, we did not find significant associations between elevated RF, ACPA, or active RA disease with the presence of CP. There were also no significant associations between elevated RF or ACPA with active RA disease.

Gain-of-Function RHOA Mutations Promote Focal Adhesion Kinase Activation and Dependency in Diffuse Gastric Cancer

Diffuse gastric cancer (DGC) is a lethal malignancy lacking effective systemic therapy. Among the most provocative recent results in DGC has been that of highly recurrent missense mutations in the GTPase RHOA. The function of these mutations has remained unresolved. We demonstrate that RHOA^Y42C, the most common RHOA mutation in DGC, is a gain-of-function oncogenic mutant, and that expression of RHOA^Y42C with inactivation of the canonical tumor suppressor Cdh1 induces metastatic DGC in a mouse model. Biochemically, RHOA^Y42C exhibits impaired GTP hydrolysis and enhances interaction with its effector ROCK. RHOA ^Y42C mutation and Cdh1 loss induce actin/cytoskeletal rearrangements and activity of focal adhesion kinase (FAK), which activates YAP-TAZ, PI3K-AKT, and β-catenin. RHOA^Y42C murine models were sensitive to FAK inhibition and to combined YAP and PI3K pathway blockade. These results, coupled with sensitivity to FAK inhibition in patient-derived DGC cell lines, nominate FAK as a novel target for these cancers. SIGNIFICANCE: The functional significance of recurrent RHOA mutations in DGC has remained unresolved. Through biochemical studies and mouse modeling of the hotspot RHOA^Y42C mutation, we establish that these mutations are activating, detail their effects upon cell signaling, and define how RHOA-mediated FAK activation imparts sensitivity to pharmacologic FAK inhibitors.See related commentary by Benton and Chernoff, p. 182.This article is highlighted in the In This Issue feature, p. 161.

The KDM5A/RBP2 histone demethylase represses NOTCH signaling to sustain neuroendocrine differentiation and promote small cell lung cancer tumorigenesis

More than 90% of small cell lung cancers (SCLCs) harbor loss-of-function mutations in the tumor suppressor gene RB1 The canonical function of the RB1 gene product, pRB, is to repress the E2F transcription factor family, but pRB also functions to regulate cellular differentiation in part through its binding to the histone demethylase KDM5A (also known as RBP2 or JARID1A). We show that KDM5A promotes SCLC proliferation and SCLC's neuroendocrine differentiation phenotype in part by sustaining expression of the neuroendocrine transcription factor ASCL1. Mechanistically, we found that KDM5A sustains ASCL1 levels and neuroendocrine differentiation by repressing NOTCH2 and NOTCH target genes. To test the role of KDM5A in SCLC tumorigenesis in vivo, we developed a CRISPR/Cas9-based mouse model of SCLC by delivering an adenovirus (or an adeno-associated virus [AAV]) that expresses Cre recombinase and sgRNAs targeting Rb1, Tp53, and Rbl2 into the lungs of Lox-Stop-Lox Cas9 mice. Coinclusion of a KDM5A sgRNA decreased SCLC tumorigenesis and metastasis, and the SCLCs that formed despite the absence of KDM5A had higher NOTCH activity compared to KDM5A ^+/+ SCLCs. This work establishes a role for KDM5A in SCLC tumorigenesis and suggests that KDM5 inhibitors should be explored as treatments for SCLC.

Pan-Cancer Landscape and Analysis of ERBB2 Mutations Identifies Poziotinib as a Clinically Active Inhibitor and Enhancer of T-DM1 Activity

We characterized the landscape and drug sensitivity of ERBB2 (HER2) mutations in cancers. In 11 datasets (n = 211,726), ERBB2 mutational hotspots varied across 25 tumor types. Common HER2 mutants yielded differential sensitivities to eleven EGFR/HER2 tyrosine kinase inhibitors (TKIs) in vitro, and molecular dynamics simulations revealed that mutants with a reduced drug-binding pocket volume were associated with decreased affinity for larger TKIs. Overall, poziotinib was the most potent HER2 mutant-selective TKI tested. Phase II clinical testing in ERBB2 exon 20-mutant non-small cell lung cancer resulted in a confirmed objective response rate of 42% in the first 12 evaluable patients. In pre-clinical models, poziotinib upregulated HER2 cell-surface expression and potentiated the activity of T-DM1, resulting in complete tumor regression with combination treatment.

CTA in preoperative planning for DIEP breast reconstruction: what the reconstructive surgeon wants to know. A modified Delphi study

AIM

To gather expert reconstructive surgical opinion to define and rank the surgically most important anatomy and provide guidance for report content to radiologists when reading a preoperative computed tomography angiography (CTA).

MATERIALS AND METHODS

A modified Delphi approach was used, involving a panel of 13 microsurgery experts across North America. Data from three consecutive online surveys were collected and returned to the respondents in the subsequent survey, allowing each respondent to see the range of opinions from other field experts.

RESULTS

Response rates were 62%, 77%, and 69% for each of the three survey rounds, respectively. The panel identified that the most important perforator characteristics in selecting the optimal perforator are diameter of the vein, perforator location within the flap, and diameter of the artery, respectively. The stated preference was for perforators located below the umbilicus. If no suitable perforator was located below the umbilicus, the panel would consider perforators up to 2 cm above the umbilicus. The most important considerations for the preoperative radiology planning report are: the size of the perforator vein, perforator location relative to landmarks, and the size of the perforator artery.

DISCUSSION

Based on the panel of expert reconstructive microsurgeons, the most surgically important anatomical considerations to be assessed and included in preoperative CTA reports for DIEP flap breast reconstruction were determined. The recommendations for reporting of preoperative DIEP breast reconstructions are presented, which, in consultation with local surgeons, can be used to form a template for reporting.

Association of anti-CLIC2 and anti-HMGB1 autoantibodies with higher disease activity in systemic lupus erythematosus patients

BACKGROUND

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by numerous autoantibodies. In this study, we investigated the presence of anti-chloride intracellular channel 2 (anti-CLIC2) and anti-high mobility group box 1 (anti-HMGB1) autoantibodies in SLE patients (n = 43) versus healthy controls ([HCs] n = 43), and their association with serological parameters (antinuclear antibody [ANA], anti-double-stranded DNA [anti-dsDNA], and C-reactive protein [CRP]) and disease activity using Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score (active or inactive).

SETTINGS AND DESIGN

Case-control study at Rheumatology Clinic of Universiti Sains Malaysia Hospital.

SUBJECTS AND METHODS

The sera of SLE patients and HCs were tested for the presence of anti-CLIC2 and anti-HMGB1 autoantibodies using human recombinant proteins and ELISA methodologies. Other serological parameters were evaluated according to routine procedures, and patients' demographic and clinical data were obtained.

STATISTICAL ANALYSIS

Mann-Whitney U-test, Chi-square test, Fisher's exact test, and receiver operating characteristic analysis.

RESULTS

Anti-CLIC2 autoantibody levels were significantly higher in SLE patients compared to HCs (P = 0.0035), whereas anti-HMGB1 autoantibody levels were not significantly elevated (P = 0.7702). Anti-CLIC2 and anti-HMGB1 autoantibody levels were not associated with ANA pattern, anti-dsDNA, and CRP. Interestingly, SLEDAI score (≥6) was associated with anti-CLIC2 (P = 0.0046) and with anti-HMGB1 (P = 0.0091) autoantibody levels.

CONCLUSION

Our findings support the potential of using anti-CLIC2 autoantibodies as a novel biomarker for SLE patients. Both anti-CLIC2 and anti-HMGB1 autoantibody levels demonstrated potential in monitoring SLE disease activity.

Major depressive disorder patients on antidepressant treatments display higher number of regulatory T cells

INTRODUCTION

Regulatory T cell (Treg) is a subtype of T lymphocyte that plays a crucial role in establishing immunologic self-tolerance and maintaining immune homeostasis. In this study, we set out to investigate the percentage and absolute count of Tregs in major depressive disorder (MDD) patients and their correlation with disease severity.

MATERIALS & METHODS

This is a case-control study consisting of 47 MDD patients and 47 healthy controls. MDD patients were treated with antidepressant drugs according to their physician's choice. The severity of MDD was assessed using Beck Depression Inventory (BDI) and Montgomery-Asberg Depression Rating Scale (MADRS) at the time of recruitment. Healthy controls completed the Depression Anxiety Scoring System (DASS21) questionnaire to ensure they were in good mental health without history of MDD. The percentage and absolute count of CD4⁺ CD25⁺ Tregs and CD4⁺ CD25⁺ FOXP3⁺ Tregs were identified by multiparameter flow cytometry.

RESULTS

The percentage and absolute count of CD4⁺ CD25⁺ Treg cells were significantly higher in MDD patients than in healthy controls (P<0.001, in both cases). Likewise, the percentage and absolute count of CD4⁺ CD25⁺ FOXP3⁺ Treg cells were also significantly higher in MDD patients compared to healthy controls (P=0.003 and P=0.002, respectively). However, there was no significant correlation between the percentage and absolute count of CD4⁺ CD25⁺ Treg and CD4⁺ CD25⁺ FOXP3⁺ Treg cells with BDI or MADRS score.

CONCLUSIONS

Our results suggest that antidepressant treatments contributed to an upregulation of Tregs in MDD patients.

Molecular detection of Enterobacteriaceae isolates producing blaOXA-48 and blaOXA-181 genes: A single centre study

INTRODUCTION

OXA-48, a carbapenem-hydrolysing class D β-lactamase, and its variant, OXA-181, are increasingly reported worldwide. This study aimed to describe the prevalence and distribution of OXA-48 and OXA-181 carbapenem-resistant Enterobacteriaceae (CRE) in a tertiary medical centre in Malaysia.

MATERIALS & METHODS

A total of 13,098 Enterobacteriaceae isolates from various clinical samples were sent to our laboratory between January 2011 and December 2012. Of these, 90 demonstrated reduced susceptibility to at least one carbapenem and were included in this study. Only 88 isolates were successfully subcultured on blood agar (BA). Another 2 isolates failed to grow and were excluded. Of the 88, 2 isolates had the same identification number (repetitive isolates); therefore, 1 isolate was excluded from further analyses. Only 87 isolates were subjected to molecular detection of the bla_OXA-48 and bla_OXA-181 genes by polymerase chain reaction.

RESULTS

Eighty-seven non-repetitive isolates grew following subculture on BA. Of these, 9 (10.34%) were positive for OXA-48 (7 Klebsiella pneumoniae, 2 Escherichia coli). Each isolate originated from different patients. All patients had a history of treatment with at least one cephalosporin and/or carbapenem prior to the isolation of OXA-48 CRE. OXA-181 was detected in one (1.15%) out of the 87 isolates; CONCLUSIONS: The prevalence of OXA-48 and OXA-181 CRE among all Enterobacteriaceae isolates in our institution is 0.069% and 0.008%, respectively. Nevertheless, our findings suggest that OXA-48 and OXA-181 carbapenemases appear to be important and possibly under-recognised causes of carbapenem resistance in Malaysia.

Author Correction: A systems biology pipeline identifies regulatory networks for stem cell engineering

In the version of this article initially published, the second NIH grant "R24-DK49216" to author George Q. Daley contained an error. The grant number should have read U54DK110805. The error has been corrected in the HTML and PDF versions of the article.

CXCR7 Reactivates ERK Signaling to Promote Resistance to EGFR Kinase Inhibitors in NSCLC

Although EGFR mutant-selective tyrosine kinase inhibitors (TKI) are clinically effective, acquired resistance can occur by reactivating ERK. We show using in vitro models of acquired EGFR TKI resistance with a mesenchymal phenotype that CXCR7, an atypical G protein-coupled receptor, activates the MAPK-ERK pathway via β-arrestin. Depletion of CXCR7 inhibited the MAPK pathway, significantly attenuated EGFR TKI resistance, and resulted in mesenchymal-to-epithelial transition. CXCR7 overexpression was essential in reactivation of ERK1/2 for the generation of EGFR TKI-resistant persister cells. Many patients with non-small cell lung cancer (NSCLC) harboring an EGFR kinase domain mutation, who progressed on EGFR inhibitors, demonstrated increased CXCR7 expression. These data suggest that CXCR7 inhibition could considerably delay and prevent the emergence of acquired EGFR TKI resistance in EGFR-mutant NSCLC. SIGNIFICANCE: Increased expression of the chemokine receptor CXCR7 constitutes a mechanism of resistance to EGFR TKI in patients with non-small cell lung cancer through reactivation of ERK signaling.

EZH2 Inhibitors: Take It EZy, It Is All About Context

Even in diffuse large B-cell lymphoma (DLBCL), a cancer of professional antigen-presenting cells, response rates to immune checkpoint blockade therapy have been limited. One reason for DLBCL immune evasion is epigenetic repression instead of activation of the antigen-presenting MHC-a dissection of mechanisms underlying this repression suggests an opening for restoring B-cell maturation and, along the way, MHC expression as a novel modality of cytoreducing DLBCL and simultaneously augmenting possibilities for immunotherapy.See related article by Ennishi et al., p. 546.

Innate αβ T Cells Mediate Antitumor Immunity by Orchestrating Immunogenic Macrophage Programming

Unconventional T-lymphocyte populations are emerging as important regulators of tumor immunity. Despite this, the role of TCRαβ⁺CD4^-CD8^-NK1.1^- innate αβ T cells (iαβT) in pancreatic ductal adenocarcinoma (PDA) has not been explored. We found that iαβTs represent ∼10% of T lymphocytes infiltrating PDA in mice and humans. Intratumoral iαβTs express a distinct T-cell receptor repertoire and profoundly immunogenic phenotype compared with their peripheral counterparts and conventional lymphocytes. iαβTs comprised ∼75% of the total intratumoral IL17⁺ cells. Moreover, iαβT-cell adoptive transfer is protective in both murine models of PDA and human organotypic systems. We show that iαβT cells induce a CCR5-dependent immunogenic macrophage reprogramming, thereby enabling marked CD4⁺ and CD8⁺ T-cell expansion/activation and tumor protection. Collectively, iαβTs govern fundamental intratumoral cross-talk between innate and adaptive immune populations and are attractive therapeutic targets. SIGNIFICANCE: We found that iαβTs are a profoundly activated T-cell subset in PDA that slow tumor growth in murine and human models of disease. iαβTs induce a CCR5-dependent immunogenic tumor-associated macrophage program, T-cell activation and expansion, and should be considered as novel targets for immunotherapy.See related commentary by Banerjee et al., p. 1164.This article is highlighted in the In This Issue feature, p. 1143.

Abstract 4044: The immune phenotype in serial biopsies from metastatic TNBC undergoing chemo-immunotherapy

Triple negative breast cancer (TNBC) is an aggressive subtype of breast cancer with poor prognosis when metastatic. Immunotherapy, especially in combination with taxane chemotherapy has recently been shown to improve outcomes with PD-L1 as predictive biomarker for survival. To understand the mechanisms of response/resistance to chemo-immunotherapy for TNBC, we obtained serial core biopsies of TNBC patients (n=30) undergoing nab-paclitaxel and pembrolizumab treatment in a prospective trial at three time points, including baseline (before treatment), after 1 cycle (nab-paclitaxel treatment without immunotherapy), and after 2 cycles (nab-paclitaxel plus pembrolizumab treatment). fluorescence-activated cell sorter (FACS). We performed 10x genomics single-cell RNA sequencing (scRNA-seq) of immune cells isolated from these fresh, serial tumor specimens from two patients, a patient with subsequent RECIST response and a patient with rapid disease progression. Results were further validated by FACS and immunohistochemistry analyses. ScRNA-seq showed significant baseline heterogeneity as well as perturbations of the immune cell infiltrates with chemotherapy and chemo-immunotherapy. In the responder patient there was a significant expansion of T cells, including both CD4+ and CD8+ T cells. Before the pembrolizumab treatment, there are 1.84% of CD4+ T cells and 6.45% of CD8+ cells among total tumor infiltrating leukocytes (TILs). After the treatment, the percentage of CD4+ and CD8+ cells increased to 33.32% and 23.42% among TILs, respectively, as determined by FACS analysis. Cytotoxic T lymphocytes (CTLs) showed enrichments for transcripts of tissue-resident memory T cells (Trm). In contrast, tumors from a patient with rapid disease progression showed persistence of a myeloid compartment that suppress anti-tumor immunity. Although T cells were initially present, they mainly consisted of a naïve T cell phenotype and did not expand even after treatment. No Trm cells were detected within TILs by scRNAseq from this patient after pembrolizumab treatment. When comparing baseline samples from these two patients, we found there is a distinct tumor cell population in the non-responder with differentially expressed genes related to oxygen transport and proliferation. The association between this population and the response to chemo-immunotherapy remains to be explored. Our study provides proof of concept that single cell analyses of serial biopsies are a feasible tool to understand or even predict responses to chemo-immunotherapy for TNBC patients.

Citation Format: Jiehui Deng, Suhagi Shah, Aatish Thennavan, Michelle Krogsgaard, Charles M. Perou, Kwok-Kin Wong, Sylvia Adams. The immune phenotype in serial biopsies from metastatic TNBC undergoing chemo-immunotherapy [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 4044.

Abstract 4563: Profiling the tumor immune microenvironment of adenocarcinoma and squamous cell NSCLC

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 3223: Overcome LKB1 mutated cancer resistance to anti-PD1 treatment

KRAS/STK11 (LKB1) mutant lung cancers are a subtype of cancer that respond poorly in the clinic to immunotherapies with shorter progression-free survival and overall survival comparing with other KRAS mutant lung cancer patients. Interestingly, this group of patients have high tumor mutational burden (TMB) comparable with other KRAS mutant lung cancers, which usually is an indicator for better response to anti-PD1 treatment. By using genetically engineered mouse model (GEMMs), we found that LKB1 loss of function can cause high level of nonsynonymous mutations, as a consequence of both replication dependent and independent DNA repair machinery dysfunctions. This LKB1 mutant dependent increased mutational load might further synergize with smoking mutagen exposures. When LKB1 function is defective, the neoantigens are not properly presented to T cells, which is required for proper T cell activation and effector T cells expansion. This will lead to insensitivity to anti-PD1 antibodies in high TMB tumors and tolerance to neoantigens produced by cancer cells. We further demonstrated that using a small molecule drug that impacts on the LKB1 downstream effector pathway, we can reverse this process through activating innate immunity in tumors, which will restore the antigen presentation functions. Combinational treatment of this small molecule with anti-PD1 can reverse the tumor progression in vivo, through releasing the suppressive tumor infiltrating lymphocytes (TILs) in LKB1 mutant lung cancers. Our study not only helps to further our understanding of the mechanism that contributes to immune evasion in high TMB tumors, but also provides a potential solution for LKB1 mutant cancers to overcome resistance to anti-PD1 treatment in the clinic.

Citation Format: Jiehui Deng, Aatish Thennavan, Yuanwang Pan, Igor Dolgalev, Ting Chen, Heather Silver, Matthew Harris, Val Pyon, Fei Li, Chelsea Lee, Aristotelis Tsirigos, Eli Rothenberg, Charles M. Perou, Kwok-Kin Wong. Overcome LKB1 mutated cancer resistance to anti-PD1 treatment [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 3223.

Toward a comprehensive view of cancer immune responsiveness: a synopsis from the SITC workshop

Tumor immunology has changed the landscape of cancer treatment. Yet, not all patients benefit as cancer immune responsiveness (CIR) remains a limitation in a considerable proportion of cases. The multifactorial determinants of CIR include the genetic makeup of the patient, the genomic instability central to cancer development, the evolutionary emergence of cancer phenotypes under the influence of immune editing, and external modifiers such as demographics, environment, treatment potency, co-morbidities and cancer-independent alterations including immune homeostasis and polymorphisms in the major and minor histocompatibility molecules, cytokines, and chemokines. Based on the premise that cancer is fundamentally a disorder of the genes arising within a cell biologic process, whose deviations from normality determine the rules of engagement with the host's response, the Society for Immunotherapy of Cancer (SITC) convened a task force of experts from various disciplines including, immunology, oncology, biophysics, structural biology, molecular and cellular biology, genetics, and bioinformatics to address the complexity of CIR from a holistic view. The task force was launched by a workshop held in San Francisco on May 14-15, 2018 aimed at two preeminent goals: 1) to identify the fundamental questions related to CIR and 2) to create an interactive community of experts that could guide scientific and research priorities by forming a logical progression supported by multiple perspectives to uncover mechanisms of CIR. This workshop was a first step toward a second meeting where the focus would be to address the actionability of some of the questions identified by working groups. In this event, five working groups aimed at defining a path to test hypotheses according to their relevance to human cancer and identifying experimental models closest to human biology, which include: 1) Germline-Genetic, 2) Somatic-Genetic and 3) Genomic-Transcriptional contributions to CIR, 4) Determinant(s) of Immunogenic Cell Death that modulate CIR, and 5) Experimental Models that best represent CIR and its conversion to an immune responsive state. This manuscript summarizes the contributions from each group and should be considered as a first milestone in the path toward a more contemporary understanding of CIR. We appreciate that this effort is far from comprehensive and that other relevant aspects related to CIR such as the microbiome, the individual's recombined T cell and B cell receptors, and the metabolic status of cancer and immune cells were not fully included. These and other important factors will be included in future activities of the taskforce. The taskforce will focus on prioritization and specific actionable approach to answer the identified questions and implementing the collaborations in the follow-up workshop, which will be held in Houston on September 4-5, 2019.