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Tumor-associated macrophages (TAM) constitute a prominent immune cell population within various solid cancers, playing a pivotal role in disease progression. Their increased numbers and frequencies often strongly correlate with resistance to therapy and reduced overall survival rates. Within the complex ecosystem of the tumor microenvironment (TME), activated cancer-associated fibroblasts (CAF) are expanded and contribute significantly to tumor growth and metastasis and chemotherapy or immunotherapy resistance. CAFs exert a critical influence on TAM phenotypes and functions by orchestrating the reprogramming of tissue-infiltrating monocytes, thereby modulating their survival and differentiation. This reciprocal interaction between TAMs and CAFs forms a crucial axis in fostering a suppressive crosstalk within the TME, mediated by a diverse array of signals exchanged between these cell types. Recent advancements in single-cell RNA sequencing technologies and spatial transcriptomics have enhanced our comprehension of the signaling dynamics at the interface between TAMs and CAFs, including their spatial distribution within the tissue. In this review, we delve into the latest discoveries elucidating the biology of TAM and CAF crosstalk. We examine the complexity of TAM-CAF and CAF-TAM interactions within the TME of solid cancers, with particular focus on ligand-receptor interactions and clinically significant targets for novel therapeutic strategies., (©2024 American Association for Cancer Research.)

Tumors are complex assemblies of cellular and acellular structures patterned on spatial scales from microns to centimeters. Study of these assemblies has advanced dramatically with the introduction of high-plex spatial profiling. Image-based profiling methods reveal the intensities and spatial distributions of 20-100 proteins at subcellular resolution in 10 3 -10 7 cells per specimen. Despite extensive work on methods for extracting single-cell data from these images, all tissue images contain artifacts such as folds, debris, antibody aggregates, optical aberrations and image processing errors that arise from imperfections in specimen preparation, data acquisition, image assembly and feature extraction. Here we show that these artifacts dramatically impact single-cell data analysis, obscuring meaningful biological interpretation. We describe an interactive quality control software tool, CyLinter, that identifies and removes data associated with imaging artifacts. CyLinter greatly improves single-cell analysis, especially for archival specimens sectioned many years before data collection, such as those from clinical trials., Competing Interests: Competing interests: P.K.S. is a cofounder and member of the Board of Directors of Glencoe Software, a member of the Board of Directors for Applied Biomath and a member of the Scientific Advisory Board for RareCyte, NanoString and Montai Health; he holds equity in Glencoe and RareCyte. P.K.S. is a consultant for Merck and declares that none of these relationships has influenced the content of this manuscript. E.A.M. reports compensated service on Scientific Advisory Boards for AstraZeneca, BioNTech and Merck; uncompensated service on Steering Committees for Bristol Myers Squibb and Roche/Genentech; speakers’ honoraria and travel support from Merck Sharp & Dohme; and institutional research support from Roche/Genentech (via an SU2C grant) and Gilead. She also reports research funding from Susan Komen for the Cure for which she serves as a Scientific Advisor, and uncompensated participation as a member of the American Society of Clinical Oncology Board of Directors. J.L.G. serves or has previously served on advisory boards and/or as a scientific advisory board member for Array BioPharma/Pfizer, AstraZeneca, BD Biosciences, Carisma, Codagenix, Duke Street Bio, GlaxoSmithKline, Kowa, Kymera, OncoOne and Verseau Therapeutics and has research grants from Array BioPharma/Pfizer, Duke Street Bio, Eli Lilly, GlaxoSmithKline and Merck. The other authors declare no competing interests., (© 2024. The Author(s).)

T cells are generally sparse in hormone receptor-positive (HR+) breast cancer, potentially due to limited antigen presentation, but the driving mechanisms of low T cell abundance remains unclear. Therefore, we defined and investigated programs ('gene modules'), related to estrogen receptor signaling (ERS) and immune signaling using bulk and single-cell transcriptome and multiplexed immunofluorescence of breast cancer tissues from multiple clinical sources and human cell lines. The ERS gene module, dominantly expressed in cancer cells, was negatively associated with immune-related gene modules TNFα/NF-κB signaling and type-I interferon (IFN-I) response, which were expressed in distinct stromal and immune cell types, but also, in part, expressed and preserved as a cancer cell-intrinsic mechanisms. Spatial analysis revealed that ERS strongly correlated with reduced T cell infiltration, potentially due to its association with suppression of TNFα/NF-κB-induced angiogenesis and IFN-I-induced HLA expression in macrophages. Preoperative endocrine therapy in ER+/HER2-breast cancer patients produced better responses in ERS-high patients, with TNFα/NF-κB expression associated with reduced ERS. Targeting these pathways may enhance T cell infiltration in HR+ breast cancer patients., Statement of Significance: This study elucidates the immunosuppressive role of ER signaling in breast cancer, highlighting a complex interplay between cancer, stromal, and immune cells and reveals potential approaches to enhance immunogenicity in HR+ breast cancer. These findings offer crucial insights into immune evasion in breast cancer and identify strategies to enhance T cell abundance.

Adoptive cell therapies are dramatically altering the treatment landscape of cancer. However, treatment of solid tumors remains a major unmet need, in part due to limited adoptive cell infiltration into the tumor and in part due to the immunosuppressive tumor microenvironment. The heterogeneity of tumors and presence of nonresponders also call for development of antigen-independent therapeutic approaches. Myeloid cells offer such an opportunity, given their large presence in the immunosuppressive tumor microenvironment, such as in triple negative breast cancer. However, their therapeutic utility is hindered by their phenotypic plasticity. Here, the impressive trafficking ability of adoptively transferred monocytes is leveraged into the immunosuppressive 4T1 tumor to develop an antitumor therapy. To control monocyte differentiation in the tumor microenvironment, surface-adherent "backpacks" stably modified with interferon gamma (IFNγ) are developed to stimulate macrophage plasticity into a pro-inflammatory, antitumor phenotype, a strategy as referred to as Ornate Polymer backpacks on Tissue Infiltrating Monocytes (OPTIMs). Treatment with OPTIMs substantially reduces tumor burden in a mouse 4T1 model and significantly increases survival. Cytokine and immune cell profiling reveal that OPTIMs remodeled the tumor microenvironment into a pro-inflammatory state., (© 2024 Wiley‐VCH GmbH.)

Estrogen receptor-positive (ER+) breast cancer is not considered immunogenic and, to date, has been proven resistant to immunotherapy. Endocrine therapy remains the cornerstone of treatment for ER+ breast cancers. However, constitutively activating mutations in the estrogen receptor alpha (ESR1) gene can emerge during treatment, rendering tumors resistant to endocrine therapy. Although these mutations represent a pathway of resistance, they also represent a potential source of neoepitopes that can be targeted by immunotherapy. In this study, we investigated ESR1 mutations as novel targets for breast cancer immunotherapy. Using machine learning algorithms, we identified ESR1-derived peptides predicted to form stable complexes with HLA-A*0201. We then validated the binding affinity and stability of the top predicted peptides through in vitro binding and dissociation assays and showed that these peptides bind HLA-A*0201 with high affinity and stability. Using tetramer assays, we confirmed the presence and expansion potential of antigen-specific CTLs from healthy female donors. Finally, using in vitro cytotoxicity assays, we showed the lysis of peptide-pulsed targets and breast cancer cells expressing common ESR1 mutations by expanded antigen-specific CTLs. Ultimately, we identified five peptides derived from the three most common ESR1 mutations (D538G, Y537S, and E380Q) and their associated wild-type peptides, which were the most immunogenic. Overall, these data confirm the immunogenicity of epitopes derived from ESR1 and highlight the potential of these peptides to be targeted by novel immunotherapy strategies., Significance: Estrogen receptor (ESR1) mutations have emerged as a key factor in endocrine therapy resistance. We identified and validated five novel, immunogenic ESR1-derived peptides that could be targeted through vaccine-based immunotherapy., (© 2024 The Authors; Published by the American Association for Cancer Research.)

Current immunotherapeutic approaches are tailored towards biomarkers and mechanisms presented in the primary tumor microenvironment, yet few are designed against targets that arise in the metastatic site. In a recent Cancer Discovery article, Yofe and colleagues spatially and temporally mapped the evolving breast tumor metastatic environment within the lung at single-cell resolution to identify immunologic cell types and mechanisms underlying the formation of metastatic nodules. The authors identified myeloid cell, monocyte, and neutrophil phenotypes as the most significant differences between the primary tumor and metastatic site. The authors also revealed the existence of a metastasis-specific population of macrophages expressing Trem2 in both human and murine models that exhibit immunosuppressive features. Interestingly, Trem2+ macrophages are enriched at the invasive border of metastatic nodules compared with the metastatic core, suggesting they play an exclusionary role within the site. Characterization of the premetastatic lung in conjunction with pseudotime lineage analysis revealed that Fn1+ monocytes precede metastasis formation and are the likely source of Trem2+ macrophages in developed nodules. This study supports the characterization of metastatic immune microenvironments to identify novel immunotherapeutic targets that may not exist within the primary site but play a significant role in patient outcome., (©2023 American Association for Cancer Research.)

Emerging data suggests that HER2 intratumoral heterogeneity (ITH) is associated with therapy resistance, highlighting the need for new strategies to assess HER2 ITH. A promising approach is leveraging multiplexed tissue analysis techniques such as cyclic immunofluorescence (CyCIF), which enable visualization and quantification of 10-60 antigens at single-cell resolution from individual tissue sections. In this study, we qualified a breast cancer-specific antibody panel, including HER2, ER, and PR, for multiplexed tissue imaging. We then compared the performance of these antibodies against established clinical standards using pixel-, cell- and tissue-level analyses, utilizing 866 tissue cores (representing 294 patients). To ensure reliability, the CyCIF antibodies were qualified against HER2 immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) data from the same samples. Our findings demonstrate the successful qualification of a breast cancer antibody panel for CyCIF, showing high concordance with established clinical antibodies. Subsequently, we employed the qualified antibodies, along with antibodies for CD45, CD68, PD-L1, p53, Ki67, pRB, and AR, to characterize 567 HER2+ invasive breast cancer samples from 189 patients. Through single-cell analysis, we identified four distinct cell clusters within HER2+ breast cancer exhibiting heterogeneous HER2 expression. Furthermore, these clusters displayed variations in ER, PR, p53, AR, and PD-L1 expression. To quantify the extent of heterogeneity, we calculated heterogeneity scores based on the diversity among these clusters. Our analysis revealed expression patterns that are relevant to breast cancer biology, with correlations to HER2 ITH and potential relevance to clinical outcomes., (© 2024. The Author(s).)

Immune checkpoint inhibition combined with chemotherapy is currently approved as first-line treatment for patients with advanced PD-L1-positive triple-negative breast cancer (TNBC). However, a significant proportion of metastatic TNBC is PD-L1-negative and, in this population, chemotherapy alone largely remains the standard-of-care and novel therapeutic strategies are needed to improve clinical outcomes. Here, we describe a triple combination of anti-PD-L1 immune checkpoint blockade, epigenetic modulation thorough bromodomain and extra-terminal (BET) bromodomain inhibition (BBDI), and chemotherapy with paclitaxel that effectively inhibits both primary and metastatic tumor growth in two different syngeneic murine models of TNBC. Detailed cellular and molecular profiling of tumors from single and combination treatment arms revealed increased T- and B-cell infiltration and macrophage reprogramming from MHCIIlow to a MHCIIhigh phenotype in mice treated with triple combination. Triple combination also had a major impact on gene expression and chromatin profiles shifting cells to a more immunogenic and senescent state. Our results provide strong preclinical evidence to justify clinical testing of BBDI, paclitaxel, and immune checkpoint blockade combination., (©2023 The Authors; Published by the American Association for Cancer Research.)

Anticancer immunotherapies, such as immune checkpoint inhibitors, bispecific antibodies, and chimeric antigen receptor T cells, have improved outcomes for patients with a variety of malignancies. However, most patients either do not initially respond or do not exhibit durable responses due to primary or adaptive/acquired immune resistance mechanisms of the tumor microenvironment. These suppressive programs are myriad, different between patients with ostensibly the same cancer type, and can harness multiple cell types to reinforce their stability. Consequently, the overall benefit of monotherapies remains limited. Cutting-edge technologies now allow for extensive tumor profiling, which can be used to define tumor cell intrinsic and extrinsic pathways of primary and/or acquired immune resistance, herein referred to as features or feature sets of immune resistance to current therapies. We propose that cancers can be characterized by immune resistance archetypes, comprised of five feature sets encompassing known immune resistance mechanisms. Archetypes of resistance may inform new therapeutic strategies that concurrently address multiple cell axes and/or suppressive mechanisms, and clinicians may consequently be able to prioritize targeted therapy combinations for individual patients to improve overall efficacy and outcomes., Competing Interests: Competing interests: DB reports nonfinancial support from Bristol Myers Squibb, honoraria from LM Education/Exchange Services, advisory board fees from Exelixis and AVEO, personal fees from Charles River Associates, Schlesinger Associates, Imprint Science, Insight Strategy, Trinity Group, Cancer Expert Now, Adnovate Strategies, MDedge, CancerNetwork, Catenion, OncLive, Cello Health BioConsulting, PWW Consulting, Haymarket Medical Network, Aptitude Health, ASCO Post/Harborside, Targeted Oncology, AbbVie, and research support from Exelixis and AstraZeneca, outside of the submitted work. BPK reports advisory board fees from Regeneron Pharmaceuticals, travel support from Roche/Genentech, and research funding (to institution) from Partner Therapeutics, outside of this submitted work., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Recently developed inhibitors of polymerase theta (POLθ) have demonstrated synthetic lethality in BRCA-deficient tumor models. To examine the contribution of the immune microenvironment to antitumor efficacy, we characterized the effects of POLθ inhibition in immunocompetent models of BRCA1-deficient triple-negative breast cancer (TNBC) or BRCA2-deficient pancreatic ductal adenocarcinoma (PDAC). We demonstrate that genetic POLQ depletion or pharmacological POLθ inhibition induces both innate and adaptive immune responses in these models. POLθ inhibition resulted in increased micronuclei, cGAS/STING pathway activation, type I interferon gene expression, CD8 + T cell infiltration and activation, local paracrine activation of dendritic cells and upregulation of PD-L1 expression. Depletion of CD8 + T cells compromised the efficacy of POLθ inhibition, whereas antitumor effects were augmented in combination with anti-PD-1 immunotherapy. Collectively, our findings demonstrate that POLθ inhibition induces immune responses in a cGAS/STING-dependent manner and provide a rationale for combining POLθ inhibition with immune checkpoint blockade for the treatment of HR-deficient cancers., (© 2023. The Author(s).)

Poly (ADP-ribose) polymerase (PARP) inhibitors exert their efficacy via synthetic lethal effects and by inducing cGAS/STING-mediated immune responses. We demonstrate that compared to monotherapies, combined PARP inhibition and STING agonism results in increased STING pathway activation, greater cytotoxic T-cell recruitment and enhanced dendritic cell activation in BRCA1-deficient breast cancer models. The combination markedly improved anti-tumor efficacy in vivo, with evidence of complete tumor clearance, prolongation of survival and induction of immunologic memory., (© 2022. The Author(s).)

Background: Inflammatory breast cancer (IBC) is a rare and understudied disease, with 40% of cases presenting with human epidermal growth factor receptor 2 (HER2)-positive subtype. The goals of this study were to (i) assess the pathologic complete response (pCR) rate of short-term neoadjuvant dual-HER2-blockade and paclitaxel, (ii) contrast baseline and on-treatment transcriptional profiles of IBC tumor biopsies associated with pCR, and (iii) identify biological pathways that may explain the effect of neoadjuvant therapy on tumor response., Patients and Methods: A single-arm phase II trial of neoadjuvant trastuzumab (H), pertuzumab (P), and paclitaxel for 16 weeks was completed among patients with newly diagnosed HER2-positive IBC. Fresh-frozen tumor biopsies were obtained pretreatment (D1) and 8 days later (D8), following a single dose of HP, prior to adding paclitaxel. We performed RNA-sequencing on D1 and D8 tumor biopsies, identified genes associated with pCR using differential gene expression analysis, identified pathways associated with pCR using gene set enrichment and gene expression deconvolution methods, and compared the pCR predictive value of principal components derived from gene expression profiles by calculating and area under the curve for D1 and D8 subsets., Results: Twenty-three participants were enrolled, of whom 21 completed surgery following neoadjuvant therapy. Paired longitudinal fresh-frozen tumor samples (D1 and D8) were obtained from all patients. Among the 21 patients who underwent surgery, the pCR and the 4-year disease-free survival were 48% (90% CI 0.29-0.67) and 90% (95% CI 66-97%), respectively. The transcriptional profile of D8 biopsies was found to be more predictive of pCR (AUC = 0.91, 95% CI: 0.7993-1) than the D1 biopsies (AUC = 0.79, 95% CI: 0.5905-0.9822)., Conclusions: In patients with HER2-positive IBC treated with neoadjuvant HP and paclitaxel for 16 weeks, gene expression patterns of tumor biopsies measured 1 week after treatment initiation not only offered different biological information but importantly served as a better predictor of pCR than baseline transcriptional analysis., Trial Registration: ClinicalTrials.gov identifier: NCT01796197 (https://clinicaltrials.gov/ct2/show/NCT01796197); registered on February 21, 2013., Competing Interests: Competing Interests: SP has served as an advisor/consultant for AstraZeneca, Daiichi Sankyo Eisai, Novartis, Polyphor, Roche, Pierre-Fabre, and SeattleGenetics. SG has received laboratory research funding from Eli Lilly and performs clinical research sponsored by Novartis and Eli Lilly. SG has served as a paid advisor to Eli Lilly, G1 therapeutics, and Novartis. JLG is a consultant for Glaxo-Smith Kline (GSK), Array BioPharma, Codagenix, Verseau Therapeutics, Kymera, Carisma, Kowa, Duke Street Bio and MPM Capital, and receives sponsored research support from GSK, Eli Lilly and Array BioPharma. NUL reports institutional research funding from Genentech, Merck, Pfizer, Seattle Genetics, AstraZeneca, Zion Pharmaceuticals, and Olema Pharmaceuticals; consultant/advisory board work for Pfizer, Puma, Seattle Genetics, Daiichi Sankyo, AstraZeneca, Prelude Therapeutics, Denali Therapeutics, Olema Pharmaceuticals, Aleta BioPharma, Affinia Therapeutics, Voyager Therapeutics, and Artera, Inc.; royalties from UpToDate; and stock or other ownership interests in Artera Inc. (a startup with no current value, but options only valued at <5% and <$50,000 will be provided at a later date). MR reports research funding (and/or provision of drug supply for clinical trials) from Novartis, Pfizer, Ipsen, TerSera, Merck, Ferring, Pierre Fabre, Roche, AstraZeneca, Bayer, Bristol-Myers Squibb; consulting or advisory role for Ipsen, Bristol-Myers Squibb, Tolmar Pharmaceuticals. BO has received clinical trial support from Genentech, Incyte, and Eisai. AM reports a consulting or advisory role for Lilly and Seagen, in-kind research support from Tempus, and institutional research funding from Eisai, Seagen, MTEM, Lilly, Seagen, Takeda Millennium, and Pfizer. EAM reports compensated service on scientific advisory boards for AstraZeneca, Exact Sciences, Merck, and Roche/Genentech; uncompensated service on steering committees for Bristol Myers Squibb, Lilly, and Roche/Genentech; honoraria from Physicians’ Education Resource; and institutional research support from Roche/Genentech (via SU2C grant) and Gilead. EAM reports the following nonfinancial interests, nonremunerated activities: Board of Directors for the American Society of Clinical Oncology and Scientific Advisor for Susan G. Komen for the Cure Foundation., (© The Author(s), 2022.)

Introduction: The addition of immune checkpoint inhibitors (ICIs) to frontline chemotherapy has improved survival for patients with advanced triple-negative breast cancer (TNBC) expressing programmed death-ligand 1 (PD-L1). Nonetheless, most patients develop resistance, with outcomes remaining poor for this population. Moreover, unsatisfactory activity has been observed with ICIs in PD-L1-negative TNBC and in other breast cancer (BC) subtypes, warranting a deeper understanding of resistance to ICIs in BC., Areas Covered: We discuss the immune landscape of distinct BC subtypes, review the clinical activity of immunotherapy in BC, and highlight strategies under development to overcome resistance to ICIs., Expert Opinion: Activity and resistance to ICIs in BC are strongly related to the intrinsic immunophenotype of the tumor tissue. Several promising biomarkers reflecting the immunological state of BC are emerging, with only PD-L1 expression currently adopted into clinical practice. However, limitations make of PD-L1 a sub-optimal biomarker for patient selection, which require efforts to integrate this marker with other immunological features. Concomitantly, a wide variety of drug combinations designed to overcome immune-resistance are being evaluated, with some encouraging signals observed in early-phase trials. Combination strategies tailored to patient and tumor immunophenotype may allow to overcome resistance and fully exploit the potential of ICIs.

Background: Biological evidence indicates that smoking can influence macrophage functions and polarization, thereby promoting tumor evolution. We hypothesized that the association of smoking with colorectal cancer incidence might differ by macrophage infiltrates., Methods: Using the Nurses' Health Study and the Health Professionals Follow-up Study, we examined the association of smoking with incidence of colorectal cancer subclassified by macrophage counts. Multiplexed immunofluorescence (for CD68, CD86, IRF5, MAF, and MRC1 [CD206]) combined with digital image analysis and machine learning was used to identify overall, M1-polarized, and M2-polarized macrophages in tumor. We used inverse-probability-weighted multivariable Cox proportional hazards regression models to control for potential confounders and selection bias because of tissue data availability. All statistical tests were 2-sided., Results: During follow-up of 131 144 participants (3 648 370 person-years), we documented 3092 incident colorectal cancer cases, including 871 cases with available macrophage data. The association of pack-years smoked with colorectal cancer incidence differed by stromal macrophage densities (Pheterogeneity = .003). Compared with never smoking, multivariable-adjusted hazard ratios (95% confidence interval) for tumors with low macrophage densities were 1.32 (0.97 to 1.79) for 1-19 pack-years, 1.31 (0.92 to 1.85) for 20-39 pack-years, and 1.74 (1.26 to 2.41) for 40 or more pack-years (Ptrend = .004). In contrast, pack-years smoked was not statistically significantly associated with the incidence of tumors having intermediate or high macrophage densities (Ptrend > .009, with an α level of .005). No statistically significant differential association was found for colorectal cancer subclassified by M1-like or M2-like macrophages., Conclusions: The association of smoking with colorectal cancer incidence is stronger for tumors with lower stromal macrophage counts. Our findings suggest an interplay of smoking and macrophages in colorectal carcinogenesis., (© The Author(s) 2021. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Background: Parents of neonates with seizures are at risk of mental health symptoms due to the impact of illness on family life, prognostic uncertainty, and the emotional toll of hospitalization. A family-centered approach is the preferred model to mitigate these challenges. We aimed to identify strategies to promote family-centered care through an analysis of parent-offered advice to clinicians caring for neonates with seizures., Methods: This prospective, observational, and multicenter (Neonatal Seizure Registry) study enrolled parents of neonates with acute symptomatic seizures. Parents completed surveys about family well-being at 12, 18, and 24 months corrected gestational age. Parents were asked open-ended questions eliciting their advice to clinicians caring for neonates with seizures. Responses were analyzed using a conventional content analysis approach., Results: Among the 310 parents who completed surveys, 118 (38%) shared advice for clinicians. These parents were predominantly mothers (n = 103, 87%). Three overarching themes were identified. (1) Communicate information effectively: parents appreciate when clinicians offer transparent and balanced information in an accessible way. (2) Understand and validate parent experience: parents value clinicians who display empathy, compassion, and a commitment to parent-partnered clinical care. (3) Providesupportand resources: parents benefit from emotional support, education, connection with peers, and help navigating the health care system., Conclusions: Parents caring for neonates with seizures appreciate a family-centered approach in health care encounters, including skilled communication, understanding and validation of the parent experience, and provision of support and resources. Future interventions should focus on building structures to reinforce these priorities., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Recent success in the use of immunotherapy for a broad range of cancers has propelled the field of cancer immunology to the forefront of cancer research. As more and more young investigators join the community of cancer immunologists, the Arthur L. Irving Family Foundation Cancer Immunology Symposium provided a platform to bring this expanding and vibrant community together and support the development of the future leaders in the field. This commentary outlines the lessons that emerged from the inaugural symposium highlighting the areas of scientific and career development that are essential for professional growth in the field of cancer immunology and beyond. Leading scientists and clinicians in the field provided their experience on the topics of scientific trajectory, career trajectory, publishing, fundraising, leadership, mentoring, and collaboration. Herein, we provide a conceptual and practical framework for career development to the broader scientific community., (©2021 The Authors; Published by the American Association for Cancer Research.)

Purpose: Increasing tumor-infiltrating lymphocytes (TIL) is associated with higher rates of pathologic complete response (pCR) to neoadjuvant therapy (NAT) in patients with triple-negative breast cancer (TNBC). However, the presence of TILs does not consistently predict pCR, therefore, the current study was undertaken to more fully characterize the immune cell response and its association with pCR., Experimental Design: We obtained pretreatment core-needle biopsies from 105 patients with stage I-III TNBC enrolled in ARTEMIS (NCT02276443) who received NAT from Oct 22, 2015 through July 24, 2018. The tumor-immune microenvironment was comprehensively profiled by performing T-cell receptor (TCR) sequencing, programmed death-ligand 1 (PD-L1) IHC, multiplex immunofluorescence, and RNA sequencing on pretreatment tumor samples. The primary endpoint was pathologic response to NAT., Results: The pCR rate was 40% (42/105). Higher TCR clonality (median = 0.2 vs. 0.1, P = 0.03), PD-L1 positivity (OR: 2.91, P = 0.020), higher CD3+:CD68+ ratio (median = 14.70 vs. 8.20, P = 0.0128), and closer spatial proximity of T cells to tumor cells (median = 19.26 vs. 21.94 μm, P = 0.0169) were associated with pCR. In a multivariable model, closer spatial proximity of T cells to tumor cells and PD-L1 expression enhanced prediction of pCR when considered in conjunction with clinical stage., Conclusions: In patients receiving NAT for TNBC, deep immune profiling through detailed phenotypic characterization and spatial analysis can improve prediction of pCR in patients receiving NAT for TNBC when considered with traditional clinical parameters., (©2021 American Association for Cancer Research.)

Immune checkpoint inhibitors (ICIs) have minimal therapeutic effect in hormone receptor-positive (HR+ ) breast cancer. We present final overall survival (OS) results (n = 88) from a randomized phase 2 trial of eribulin ± pembrolizumab for patients with metastatic HR+ breast cancer, computationally dissect genomic and/or transcriptomic data from pre-treatment tumors (n = 52) for molecular associations with efficacy, and identify cytokine changes differentiating response and ICI-related toxicity (n = 58). Despite no improvement in OS with combination therapy (hazard ratio 0.95, 95% CI 0.59-1.55, p = 0.84), immune infiltration and antigen presentation distinguished responding tumors, while tumor heterogeneity and estrogen signaling independently associated with resistance. Moreover, patients with ICI-related toxicity had lower levels of immunoregulatory cytokines. Broadly, we establish a framework for ICI response in HR+ breast cancer that warrants diagnostic and therapeutic validation. ClinicalTrials.gov Registration: NCT03051659., (© 2021. The Author(s).)

Background: The heterogeneity of the breast tumor microenvironment (TME) may contribute to the lack of durable responses to immune checkpoint blockade (ICB); however, mouse models to test this are currently lacking. Proper selection and use of preclinical models are necessary for rigorous, preclinical studies to rapidly move laboratory findings into the clinic., Methods: Three versions of a common syngeneic model derived from the MMTV-PyMT autochthonous model were generated by inoculating 1E6, 1E5, or 1E4 cells derived from the MMTV-PyMT mouse into wildtype recipient mice. To elucidate how tumor latency and TME heterogeneity contribute to ICB resistance, comprehensive characterization of the TME using quantitative flow-cytometry and RNA expression analysis (NanoString) was performed. Subsequently, response to ICB was tested. These procedures were repeated using the EMT6 breast cancer model., Results: The 3 syngeneic versions of the MMTV-PyMT model had vastly different TMEs that correlated to ICB response. The number of cells used to generate syngeneic tumors significantly influenced tumor latency, infiltrating leukocyte populations, and response to ICB. These results were confirmed using the EMT6 breast cancer model. Compared to the MMTV-PyMT autochthonous model, all 3 MMTV-PyMT syngeneic models had significantly more tumor-infiltrating lymphocytes (TILs; CD3 + , CD4 + , and CD8 + ) and higher proportions of PD-L1-positive myeloid cells, whereas the MMTV-PyMT autochthonous model had the highest frequency of myeloid cells out of total leukocytes. Increased TILs correlated with response to anti-PD-L1 and anti-CTLA-4 therapy, but PD-L1expression on tumor cells or PD-1 expression of T cells did not., Conclusions: These studies reveal that tumor cell number correlates with tumor latency, TME, and response to ICB. ICB-sensitive and resistant syngeneic breast cancer models were identified, in which the 1E4 syngeneic model was most resistant to ICB. Given the lack of benefit from ICB in breast cancer, identifying robust murine models presented here provides the opportunity to further interrogate the TME for breast cancer treatment and provide novel insights into therapeutic combinations to overcome ICB resistance., (© 2021. The Author(s).)

Immune checkpoint blockade (ICB) has revolutionized the treatment of cancer patients. The main focus of ICB has been on reinvigorating the adaptive immune response, namely, activating cytotoxic T cells. ICB has demonstrated only modest benefit against advanced breast cancer, as breast tumors typically establish an immune suppressive tumor microenvironment (TME). Triple-negative breast cancer (TNBC) is associated with infiltration of tumor infiltrating lymphocytes (TILs) and patients with TNBC have shown clinical responses to ICB. In contrast, hormone receptor positive (HR+) breast cancer is characterized by low TIL infiltration and minimal response to ICB. Here we review how HR+ breast tumors establish a TME devoid of TILs, have low HLA class I expression, and recruit immune cells, other than T cells, which impact response to therapy. In addition, we review emerging technologies that have been employed to characterize components of the TME to reveal that tumor associated macrophages (TAMs) are abundant in HR+ cancer, are highly immune-suppressive, associated with tumor progression, chemotherapy and ICB-resistance, metastasis and poor survival. We reveal novel therapeutic targets and possible combinations with ICB to enhance anti-tumor immune responses, which may have great potential in HR+ breast cancer., Competing Interests: EM has been compensated for participation on Scientific Advisory Boards for Astra-Zeneca/Medimmune, Celgene, Genentech, Exact Sciences (formerly Genomic Health), Merck, Peregrine Pharmaceuticals, SELLAS Lifescience, and Tapimmune and has had clinical trial support to her former institution (M.D. Anderson Cancer Center) from Astra-Zeneca/Medimmune, EMD-Serono, Galena Biopharma and Genentech, and current institution from Genentech via a SU2C grant. EM has also had sponsored Research Support to the laboratory from GSK and Eli Lilly. JG is a consultant for Glaxo-Smith Kline (GSK), Codagenix, Verseau, Kymera and Array BioPharma and receives sponsored research support from GSK, Array BioPharma and Eli Lilly. ST receives institutional research funding from AstraZeneca, Lilly, Merck, Nektar, Novartis, Pfizer, Genentech/Roche, Immunomedics, Gilead Exelixis, Bristol-Myers Squibb, Eisai, Nanostring, Cyclacel, Odonate, and Seagen; has served as an advisor/consultant to AstraZeneca, Lilly, Merck, Nektar, Novartis, Pfizer, Genentech/Roche, Immunomedics, Bristol-Myers Squibb, Eisai, Nanostring, Seagen, Puma, Sanofi, Celldex, Paxman, Puma, Silverback Therapeutics, G1 Therapeutics, AbbVie, Anthenex, OncoPep, Outcomes4Me, Kyowa Kirin Pharmaceuticals, Daiichi-Sankyo, Gilead and Samsung Bioepsis Inc. AW receives institutional research funding from Genentech/Roche. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Goldberg, Pastorello, Vallius, Davis, Cui, Agudo, Waks, Keenan, McAllister, Tolaney, Mittendorf and Guerriero.)

Immune checkpoint blockade (ICB) results in durable disease control in a subset of patients with advanced renal cell carcinoma (RCC), but mechanisms driving resistance are poorly understood. We characterize the single-cell transcriptomes of cancer and immune cells from metastatic RCC patients before or after ICB exposure. In responders, subsets of cytotoxic T cells express higher levels of co-inhibitory receptors and effector molecules. Macrophages from treated biopsies shift toward pro-inflammatory states in response to an interferon-rich microenvironment but also upregulate immunosuppressive markers. In cancer cells, we identify bifurcation into two subpopulations differing in angiogenic signaling and upregulation of immunosuppressive programs after ICB. Expression signatures for cancer cell subpopulations and immune evasion are associated with PBRM1 mutation and survival in primary and ICB-treated advanced RCC. Our findings demonstrate that ICB remodels the RCC microenvironment and modifies the interplay between cancer and immune cell populations critical for understanding response and resistance to ICB., Competing Interests: Declaration of interests M.X.H. has consulted for Amplify Medicines and Ikena Oncology. Z.B. reports research support from Bristol-Meyers Squibb (BMS) and Genentech/imCORE unrelated to this study. D.A.B. reports non-financial support from BMS, honoraria from LM Education/Exchange Services, and personal fees from Octane Global, Defined Health, Dedham Group, Adept Field Solutions, Slingshot Insights, Blueprint Partnerships, Charles River Associates, Trinity Group, and Insight Strategy, outside of this work. B.A.M. has consulted for Bayer, Astellas, AstraZeneca, Seattle Genetics, Exelixis, Nektar, Pfizer, Janssen, Genentech, Eisai, and EMD Serono. He received research support to Dana-Farber Cancer Institute from BMS, Calithera, Exelixis, and Seattle Genetics. J.L.G. is a consultant for and/or receives sponsored research support from GlaxoSmithKline (GSK), Array BioPharma, Codagenix, Verseau, Kymera, and Eli Lilly. A. Rotem is an employee of AstraZeneca and an equity holder in NucleAI and Celsius Therapeutics. A. Regev is a founder and equity holder of Celsius Therapeutics, holds equity in Immunitas Therapeutics, and, until August 31, 2020, was an SAB member of Syros Pharmaceuticals, Neogene Therapeutics, Asimov, and Thermo Fisher Scientific; since August 1, 2020, she has been an employee of Genentech. E.M.V.A. reports advisory/consulting with Tango Therapeutics, Genome Medical, Invitae, Monte Rosa, Enara Bio, Manifold Bio, and Janssen; research support from Novartis and BMS; equity in Tango Therapeutics, Genome Medical, Syapse, Manifold Bio, Monte Rosa, and Enara Bio. T.K.C. reports research support/honoraria from, consulting/advisory relationships with, and/or equity stakes in Alexion, Analysis Group, AstraZeneca, Aveo, Bayer, BMS, Calithera, Cerulean, Corvus, Eisai, EMD Serono, Exelixis, F. Hoffmann-La Roche, Foundation Management, Genentech, GSK, Heron Therapeutics, Infinity Pharma, Janssen Oncology, IQVIA, Ipsen, Lilly, Merck, NCCN, Novartis, Peloton, Pfizer, Pionyr, Prometheus Labs, Roche, Roche Products Limited, Sanofi/Aventis, Takeda, Tracon, Surface Oncology, Tempest, Up-to-Date, OncLIve, PVI, and MJH Life Sciences; patents filed, royalties, or other intellectual properties related to biomarkers of immune checkpoint blockers; and support from the Dana-Farber/Harvard Cancer Center Kidney SPORE and Program, the Kohlberg Chair at Harvard Medical School and the Trust Family, Michael Brigham, and Loker Pinard Funds for Kidney Cancer Research at DFCI., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Macrophages are crucial innate immune cells that maintain tissue homeostasis and defend against pathogens; however, their infiltration into tumors has been associated with adverse outcomes. Tumor-associated macrophages (TAMs) represent a significant component of the inflammatory infiltrate in breast tumors, and extensive infiltration of TAMs has been linked to poor prognosis in breast cancer. Here, we detail how TAMs impede a productive tumor immunity cycle by limiting antigen presentation and reducing activation of cytotoxic T lymphocytes (CTLs) while simultaneously supporting tumor cell survival, angiogenesis, and metastasis. There is an urgent need to overcome TAM-mediated immune suppression for durable anti-tumor immunity in breast cancer. To date, failure to fully characterize TAM biology and classify multiple subsets has hindered advancement in therapeutic targeting. In this regard, the complexity of TAMs has recently taken center stage owing to their subset diversity and tightly regulated molecular and metabolic phenotypes. In this review, we reveal major gaps in our knowledge of the functional and phenotypic characterization of TAM subsets associated with breast cancer, before and after treatment. Future work to characterize TAM subsets, location, and crosstalk with neighboring cells will be critical to counteract TAM pro-tumor functions and to identify novel TAM-modulating strategies and combinations that are likely to enhance current therapies and overcome chemo- and immuno-therapy resistance., Competing Interests: JG is a consultant for Glaxo-Smith Kline (GSK), Codagenix, Verseau, Kymera, and Array BioPharma and receives sponsored research support from GSK, Array BioPharma, and Eli Lilly. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Mehta, Kadel, Townsend, Oliwa and Guerriero.)

Immune checkpoint inhibitors (ICIs) have improved overall survival for cancer patients, however, optimal duration of ICI therapy has yet to be defined. Given ICIs were first used to treat patients with metastatic melanoma, a condition that at the time was incurable, little attention was initially paid to how much therapy would be needed for a durable response. As the early immunotherapy trials have matured past 10 years, a significant per cent of patients have demonstrated durable responses; it is now time to determine whether patients have been overtreated, and if durable remissions can still be achieved with less therapy, limiting the physical and financial toxicity associated with years of treatment. Well-designed trials are needed to identify optimal duration of therapy, and to define biomarkers to predict who would benefit from shorter courses of immunotherapy. Here, we outline key questions related to health, financial and societal toxicities of over treating with ICI and present four unique clinical trials aimed at exposing criteria for early cessation of ICI. Taken together, there is a serious liability to overtreating patients with ICI and future work is warranted to determine when it is safe to stop ICI., Competing Interests: Competing interests: TM is a consultant for AstraZeneca, Genentech, Boehringe Ingelheim, Atara, and Regeneron. And receives research grant support from Bristol Myers Squibb, Regeneron, Merck, and Boehringer Ingelheim. AER receives sponsored research support from Janssen, AbbVie, Bristol Myers Squibb, Celgene SMR receives consulting fees from Eli Lilly, Daiichi Sankyo and Silverback Therapeutics and research support from Cancer Prevention and Research Institute of Texas RR190020. MER-R receives research grant support from ROCHE and Highlight Therapeutics. SC and CF are employees and shareholder at NanoString Technologies. DHA has received royalties from the University of Illinois and has received consulting fees from Boehringer Ingelheim. JG is a consultant for Glaxo-Smith Kline (GSK), Array BioPharma, Codagenix, Verseau Therapeutics and Kymera and receives sponsored research support from GSK, Eli Lilly and Array BioPharma., (© Author(s) (or their employer(s)) 2021. Re-use permitted under CC BY. Published by BMJ.)

Purpose: We report results from a phase II study assessing the efficacy of the WEE1 inhibitor adavosertib with cisplatin in metastatic triple-negative breast cancer (mTNBC)., Patients and Methods: Patients with mTNBC treated with 0-1 prior lines of chemotherapy received cisplatin 75 mg/m 2 i.v. followed 21 days later by cisplatin plus adavosertib 200 mg oral twice daily for five doses every 21 days. The study had 90% power to detect the difference between null (20%) and alternative (40%) objective response rates (ORR) with a one-sided type I error of 0.1: an ORR >30% was predefined as making the regimen worthy of further study. RNA sequencing and multiplex cyclic immunofluorescence on pre- and post-adavosertib tumor biopsies, as well as targeted next-generation sequencing on archival tissue, were correlated with clinical benefit, defined as stable disease ≥6 months or complete or partial response., Results: A total of 34 patients initiated protocol therapy; median age was 56 years, 2 patients (6%) had BRCA2 mutations, and 14 (41%) had one prior chemotherapy. ORR was 26% [95% confidence interval (CI), 13-44], and median progression-free survival was 4.9 months (95% CI, 2.3-5.7). Treatment-related grade 3-5 adverse events occurred in 53% of patients, most commonly diarrhea in 21%. One death occurred because of sepsis, possibly related to study therapy. Tumors from patients with clinical benefit demonstrated enriched immune gene expression and T-cell infiltration., Conclusions: Among patients with mTNBC treated with 0-1 prior lines, adavosertib combined with cisplatin missed the prespecified ORR cutoff of >30%. The finding of immune-infiltrated tumors in patients with clinical benefit warrants validation., (©2020 American Association for Cancer Research.)

Triple-negative breast cancer (TNBC) is a subtype of breast cancer without a targeted form of therapy. Unfortunately, up to 70% of patients with TNBC develop resistance to treatment. A known contributor to chemoresistance is dysfunctional mitochondrial apoptosis signaling. We set up a phenotypic small-molecule screen to reveal vulnerabilities in TNBC cells that were independent of mitochondrial apoptosis. Using a functional genetic approach, we identified that a "hit" compound, BAS-2, had a potentially similar mechanism of action to histone deacetylase inhibitors (HDAC). An in vitro HDAC inhibitor assay confirmed that the compound selectively inhibited HDAC6. Using state-of-the-art acetylome mass spectrometry, we identified glycolytic substrates of HDAC6 in TNBC cells. We confirmed that inhibition or knockout of HDAC6 reduced glycolytic metabolism both in vitro and in vivo. Through a series of unbiased screening approaches, we have identified a previously unidentified role for HDAC6 in regulating glycolytic metabolism., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution License 4.0 (CC BY).)

Despite objective responses to PARP inhibition and improvements in progression-free survival compared to standard chemotherapy in patients with BRCA-associated triple-negative breast cancer (TNBC), benefits are transitory. Using high dimensional single-cell profiling of human TNBC, here we demonstrate that macrophages are the predominant infiltrating immune cell type in BRCA-associated TNBC. Through multi-omics profiling we show that PARP inhibitors enhance both anti- and pro-tumor features of macrophages through glucose and lipid metabolic reprogramming driven by the sterol regulatory element-binding protein 1 (SREBP-1) pathway. Combined PARP inhibitor therapy with CSF-1R blocking antibodies significantly enhanced innate and adaptive anti-tumor immunity and extends survival in BRCA-deficient tumors in vivo and is mediated by CD8 + T-cells. Collectively, our results uncover macrophage-mediated immune suppression as a liability of PARP inhibitor treatment and demonstrate combined PARP inhibition and macrophage targeting therapy induces a durable reprogramming of the tumor microenvironment, thus constituting a promising therapeutic strategy for TNBC., Competing Interests: Competing Interests Statement J.L.G. is a consultant for Glaxo-Smith Kline (GSK), Codagenix, Verseau, Kymera and Array BioPharma and receives sponsored research support from GSK, Array BioPharma and Eli Lilly. G.I.S. has served on advisory boards for Pfizer, Eli Lilly, G1 Therapeutics, Roche, Merck KGaA/EMD-Serono, Sierra Oncology, Bicycle Therapeutics, Fusion Pharmaceuticals, Cybrexa Therapeutics, Astex, Almac, Ipsen, Bayer, Angiex, Daiichi Sankyo, Seattle Genetics, Boehringer Ingelheim, ImmunoMet, Asana, Artios, Atrin, Concarlo Holdings, Syros and Zentalis, and has received sponsored research support from Merck, Eli Lilly, Merck/EMD Serono and Sierra Oncology. Clinical trial support from Pfizer and Array Biopharma has been provided to Dana-Farber Cancer Institute for the conduct of investigator-initiated studies led by G.I.S. He holds a patent entitled, “Dosage regimen for sapacitabine and seliciclib,” also issued to Cyclacel Pharmaceuticals, and a pending patent, entitled, “Compositions and Methods for Predicting Response and Resistance to CDK4/6 Inhibition,” together with Liam Cornell. E.A.M is on the SAB for Astra-Zeneca/Medimmune, Celgene, Genentech, Genomic Health, Merck, Peregrine Pharmaceuticals, SELLAS Lifescience, and Tapimmune and has clinical trial support to her former institution (MDACC) from Astra-Zeneca/Medimmune, EMD-Serono, Galena Biopharma and Genentech as well as Genentech support to a SU2C grant, as well as sponsored Research Support to the laboratory from GSK and Eli Lilly. S.R. receives research funding from Merck, Bristol-Myers Squibb, Gilead and Affimed, and on the scientific advisory board for Immunitas. S.S is a consultant for Rarecyte, Inc. N.T. receives research support from Astra-Zeneca. PKS serves on the SAB or BOD of Glencoe Software, Applied Biomath and RareCyte Inc. and has equity in these companies; he is a member of the NanoString SAB and is also co-founder of Glencoe Software, which contributes to and supports the open-source OME/OMERO image informatics software used in this paper. D.D. consults for Novartis and is on the advisory board for Oncology Analytics, Inc. S.J. receives consulting fees from Venn Therapeutics.

Macrophages are among the most common cells in the colorectal cancer microenvironment, but their prognostic significance is incompletely understood. Using multiplexed immunofluorescence for CD68, CD86, IRF5, MAF, MRC1 (CD206), and KRT (cytokeratins) combined with digital image analysis and machine learning, we assessed the polarization spectrum of tumor-associated macrophages in 931 colorectal carcinomas. We then applied Cox proportional hazards regression to assess prognostic survival associations of intraepithelial and stromal densities of M1-like and M2-like macrophages while controlling for potential confounders, including stage and microsatellite instability status. We found that high tumor stromal density of M2-like macrophages was associated with worse cancer-specific survival, whereas tumor stromal density of M1-like macrophages was not significantly associated with better cancer-specific survival. High M1:M2 density ratio in tumor stroma was associated with better cancer-specific survival. Overall macrophage densities in tumor intraepithelial or stromal regions were not prognostic. These findings suggested that macrophage polarization state, rather than their overall density, was associated with cancer-specific survival, with M1- and M2-like macrophage phenotypes exhibiting distinct prognostic roles. These results highlight the utility of a multimarker strategy to assess the macrophage polarization at single-cell resolution within the tumor microenvironment., (©2020 American Association for Cancer Research.)

Aging is closely associated with increased susceptibility to breast cancer, yet there have been limited systematic studies of aging-induced alterations in the mammary gland. Here, we leverage high-throughput single-cell RNA sequencing to generate a detailed transcriptomic atlas of young and aged murine mammary tissues. By analyzing epithelial, stromal, and immune cells, we identify age-dependent alterations in cell proportions and gene expression, providing evidence that suggests alveolar maturation and physiological decline. The analysis also uncovers potential pro-tumorigenic mechanisms coupled to the age-associated loss of tumor suppressor function and change in microenvironment. In addition, we identify a rare, age-dependent luminal population co-expressing hormone-sensing and secretory-alveolar lineage markers, as well as two macrophage populations expressing distinct gene signatures, underscoring the complex heterogeneity of the mammary epithelia and stroma. Collectively, this rich single-cell atlas reveals the effects of aging on mammary physiology and can serve as a useful resource for understanding aging-associated cancer risk., Competing Interests: Declaration of Interests J.L.G. is a consultant for Glaxo-Smith Kline (GSK), Codagenix, Verseau, Kymera, and Array BioPharma and receives sponsored research support from GSK, Array BioPharma, and Eli Lilly. A.R. is a founder and equity holder of Celsius Therapeutics, an equity holder in Immunitas Therapeutics, and until August 31, 2020, was on the science advisory boards (SABs) of Syros Pharmaceuticals, Neogene Therapeutics, Asimov, and ThermoFisher Scientific. From August 1, 2020, A.R. is an employee of Genentech, a member of the Roche Group. J.S.B. is on the SAB of Agios Pharmaceuticals, eFFECTOR Therapeutics, and Frontier Medicines., (Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.)

Despite decades of effort, the sensitivity of patient tumors to individual drugs is often not predictable on the basis of molecular markers alone. Therefore, unbiased, high-throughput approaches to match patient tumors to effective drugs, without requiring a priori molecular hypotheses, are critically needed. Here, we improved upon a method that we previously reported and developed called high-throughput dynamic BH3 profiling (HT-DBP). HT-DBP is a microscopy-based, single-cell resolution assay that enables chemical screens of hundreds to thousands of candidate drugs on freshly isolated tumor cells. The method identifies chemical inducers of mitochondrial apoptotic signaling, a mechanism of cell death. HT-DBP requires only 24 hours of ex vivo culture, which enables a more immediate study of fresh primary tumor cells and minimizes adaptive changes that occur with prolonged ex vivo culture. Effective compounds identified by HT-DBP induced tumor regression in genetically engineered and patient-derived xenograft (PDX) models of breast cancer. We additionally found that chemical vulnerabilities changed as cancer cells expanded ex vivo. Furthermore, using PDX models of colon cancer and resected tumors from colon cancer patients, our data demonstrated that HT-DBP could be used to generate personalized pharmacotypes. Thus, HT-DBP appears to be an ex vivo functional method with sufficient scale to simultaneously function as a companion diagnostic, therapeutic personalization, and discovery tool., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)

Precursor states of Multiple Myeloma (MM) and its native tumor microenvironment need in-depth molecular characterization to better stratify and treat patients at risk. Using single-cell RNA sequencing of bone marrow cells from precursor stages, MGUS and smoldering myeloma (SMM), to full-blown MM alongside healthy donors, we demonstrate early immune changes during patient progression. We find NK cell abundance is frequently increased in early stages, and associated with altered chemokine receptor expression. As early as SMM, we show loss of GrK + memory cytotoxic T-cells, and show their critical role in MM immunosurveillance in mouse models. Finally, we report MHC class II dysregulation in CD14 + monocytes, which results in T cell suppression in vitro . These results provide a comprehensive map of immune changes at play over the evolution of pre-malignant MM, which will help develop strategies for immune-based patient stratification., Competing Interests: COMPETING INTERESTS STATEMENT G.G. receives research funds from IBM and Pharmacyclics. I.M.G. has a consulting/advisory role with GSK, AbbVie, Bristol-Myers Squibb (BMS). I.M.G has a consulting role with Sanofi, Janssen, Takeda, Celgene, Karyopharm, GNS, Cellectar, Medscape, Genetech, Adaptive, Aptitude, Curio Science, Magenta, Oncopeptides. I.M.G. received research funding/ honoraria from Celgene, Takeda, BMS, Janssen Pharmaceuticals, and Amgen.

High-grade serous ovarian cancer (HGSOC) is often sensitive to initial treatment with platinum and taxane combination chemotherapy, but most patients relapse with chemotherapy-resistant disease. To systematically identify genes modulating chemotherapy response, we performed pooled functional genomic screens in HGSOC cell lines treated with cisplatin, paclitaxel, or cisplatin plus paclitaxel. Genes in the intrinsic pathway of apoptosis were among the top candidate resistance genes in both gain-of-function and loss-of-function screens. In an open reading frame overexpression screen, followed by a mini-pool secondary screen, anti-apoptotic genes including BCL2L1 (BCL-XL) and BCL2L2 (BCL-W) were associated with chemotherapy resistance. In a CRISPR-Cas9 knockout screen, loss of BCL2L1 decreased cell survival whereas loss of proapoptotic genes promoted resistance. To dissect the role of individual anti-apoptotic proteins in HGSOC chemotherapy response, we evaluated overexpression or inhibition of BCL-2, BCL-XL, BCL-W, and MCL1 in HGSOC cell lines. Overexpression of anti-apoptotic proteins decreased apoptosis and modestly increased cell viability upon cisplatin or paclitaxel treatment. Conversely, specific inhibitors of BCL-XL, MCL1, or BCL-XL/BCL-2, but not BCL-2 alone, enhanced cell death when combined with cisplatin or paclitaxel. Anti-apoptotic protein inhibitors also sensitized HGSOC cells to the poly (ADP-ribose) polymerase inhibitor olaparib. These unbiased screens highlight anti-apoptotic proteins as mediators of chemotherapy resistance in HGSOC, and support inhibition of BCL-XL and MCL1, alone or combined with chemotherapy or targeted agents, in treatment of primary and recurrent HGSOC. IMPLICATIONS: Anti-apoptotic proteins modulate drug resistance in ovarian cancer, and inhibitors of BCL-XL or MCL1 promote cell death in combination with chemotherapy., (©2019 American Association for Cancer Research.)

Purpose: Hormone receptor-positive/HER2-negative (HR + /HER2 - ) breast cancer is associated with low levels of stromal tumor-infiltrating lymphocytes (sTIL) and PD-L1, and demonstrates poor responses to checkpoint inhibitor therapy. Evaluating the effect of standard chemotherapy on the immune microenvironment may suggest new opportunities for immunotherapy-based approaches to treating HR + /HER2 - breast tumors., Experimental Design: HR + /HER2 - breast tumors were analyzed before and after neoadjuvant chemotherapy. sTIL were assessed histologically; CD8 + cells, CD68 + cells, and PD-L1 staining were assessed immunohistochemically; whole transcriptome sequencing and panel RNA expression analysis (NanoString) were performed., Results: Ninety-six patients were analyzed from two cohorts ( n = 55, Dana-Farber cohort; n = 41, MD Anderson cohort). sTIL, CD8, and PD-L1 on tumor cells were higher in tumors with basal PAM50 intrinsic subtype. Higher levels of tissue-based lymphocyte (sTIL, CD8, PD-L1) and macrophage (CD68) markers, as well as gene expression markers of lymphocyte or macrophage phenotypes (NanoString or CIBERSORT), correlated with favorable response to neoadjuvant chemotherapy, but not with improved distant metastasis-free survival in these cohorts or a large gene expression dataset ( N = 302). In paired pre-/postchemotherapy samples, sTIL and CD8 + cells were significantly decreased after treatment, whereas expression analyses (NanoString) demonstrated significant increase of multiple myeloid signatures. Single gene expression implicated increased expression of immunosuppressive (M2-like) macrophage-specific genes after chemotherapy., Conclusions: The immune microenvironment of HR + /HER2 - tumors differs according to tumor biology. This cohort of paired pre-/postchemotherapy samples suggests a critical role for immunosuppressive macrophage expansion in residual disease. The role of macrophages in chemoresistance should be explored, and further evaluation of macrophage-targeting therapy is warranted., (©2019 American Association for Cancer Research.)

Background: Despite major advancements in immunotherapy among a number of solid tumors, response rates among ovarian cancer patients remain modest. Standard treatment for ovarian cancer is still surgery followed by taxane- and platinum-based chemotherapy. Thus, there is an urgent need to develop novel treatment options for clinical translation., Methods: Our approach was to analyze the effects of standard chemotherapy in the tumor microenvironment of mice harboring orthotopic, syngeneic ID8-Vegf-Defb29 ovarian tumors in order to mechanistically determine a complementary immunotherapy combination. Specifically, we interrogated the molecular and cellular consequences of chemotherapy by analyzing gene expression and flow cytometry data., Results: These data show that there is an immunosuppressive shift in the myeloid compartment, with increased expression of IL-10 and ARG1, but no activation of CD3 + T cells shortly after chemotherapy treatment. We therefore selected immunotherapies that target both the innate and adaptive arms of the immune system. Survival studies revealed that standard chemotherapy was complemented most effectively by a combination of anti-IL-10, 2'3'-cGAMP, and anti-PD-L1. Immunotherapy dramatically decreased the immunosuppressive myeloid population while chemotherapy effectively activated dendritic cells. Together, combination treatment increased the number of activated T and dendritic cells as well as expression of cytotoxic factors. It was also determined that the immunotherapy had to be administered concurrently with the chemotherapy to reverse the acute immunosuppression caused by chemotherapy. Mechanistic studies revealed that antitumor immunity in this context was driven by CD4 + T cells, which acquired a highly activated phenotype. Our data suggest that these CD4 + T cells can kill cancer cells directly via granzyme B-mediated cytotoxicity. Finally, we showed that this combination therapy is also effective at delaying tumor growth substantially in an aggressive model of lung cancer, which is also treated clinically with taxane- and platinum-based chemotherapy., Conclusions: This work highlights the importance of CD4 + T cells in tumor immunology. Furthermore, the data support the initiation of clinical trials in ovarian cancer that target both innate and adaptive immunity, with a focus on optimizing dosing schedules.

Focal amplification of chromosome 1q23.3 in patients with advanced primary or relapsed urothelial carcinomas is associated with poor survival. We interrogated chromosome 1q23.3 and the nearby focal amplicon 1q21.3, as both are associated with increased lymph node disease in patients with urothelial carcinoma. Specifically, we assessed whether the oncogene MCL1 that resides in 1q21.3 and the genes that reside in the 1q23.3 amplicon were required for the proliferation or survival of urothelial carcinoma. We observed that suppressing MCL1 or the death effector domain-containing protein (DEDD) in the cells that harbor amplifications of 1q21.3 or 1q23.3, respectively, inhibited cell proliferation. We also found that overexpression of MCL1 or DEDD increased anchorage independence growth in vitro and increased experimental metastasis in vivo in the nonamplified urothelial carcinoma cell line, RT112. The expression of MCL1 confers resistance to a range of apoptosis inducers, while the expression of DEDD led to resistance to TNFα-induced apoptosis. These observations identify MCL1 and DEDD as genes that contribute to aggressive urothelial carcinoma. IMPLICATIONS: These studies identify MCL1 and DEDD as genes that contribute to aggressive urothelial carcinomas., (©2019 American Association for Cancer Research.)

Combinatorial clinical trials of PARP inhibitors with immunotherapies are ongoing, yet the immunomodulatory effects of PARP inhibition have been incompletely studied. Here, we sought to dissect the mechanisms underlying PARP inhibitor-induced changes in the tumor microenvironment of BRCA1-deficient triple-negative breast cancer (TNBC). We demonstrate that the PARP inhibitor olaparib induces CD8 + T-cell infiltration and activation in vivo , and that CD8 + T-cell depletion severely compromises antitumor efficacy. Olaparib-induced T-cell recruitment is mediated through activation of the cGAS/STING pathway in tumor cells with paracrine activation of dendritic cells and is more pronounced in HR-deficient compared with HR-proficient TNBC cells and in vivo models. CRISPR-mediated knockout of STING in cancer cells prevents proinflammatory signaling and is sufficient to abolish olaparib-induced T-cell infiltration in vivo . These findings elucidate an additional mechanism of action of PARP inhibitors and provide a rationale for combining PARP inhibition with immunotherapies for the treatment of TNBC. SIGNIFICANCE: This work demonstrates cross-talk between PARP inhibition and the tumor microenvironment related to STING/TBK1/IRF3 pathway activation in cancer cells that governs CD8 + T-cell recruitment and antitumor efficacy. The data provide insight into the mechanism of action of PARP inhibitors in BRCA -associated breast cancer. This article is highlighted in the In This Issue feature, p. 681 ., (©2019 American Association for Cancer Research.)

The complexity of T cell activation to maintain homeostasis and provide host defense is highlighted by the intricate step-wise process which is coordinated by multiple cell types. Crucial to T cell activation is the requirement of antigen-presenting cells (APCs) such as macrophages at each step of the activation and effector stages. Macrophages are central regulators in T cell activation and are involved in each step including initiating the series of events leading to T cell activation. Macrophages identify and present foreign antigens in classes I and II major histocompatibility complexes (MHC) to T cells, which recognize the MHC-antigen complex through their T cell receptor. This initial step is all in vain if additional costimulatory and cytokine signaling does not occur concurrently. Macrophages can mediate and provide the required costimulatory signaling and cytokine secretion required for effective T cell activation. While other cell types, especially other APCs, may be capable of playing a role during different stages of T cell activation, this review will focus on how macrophages can modulate T cell activation and effector function. This is in no way an attempt to minimize the role of other APCs but instead to bring to light to the role macrophages can play during this process. Here, the role macrophages play in cancer to either activate or inhibit T cells based on macrophage phenotype, costimulatory molecules, and cytokine secretion is highlighted as an example of how macrophages can significantly alter T cell activation and effector function in human disease., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Elotuzumab, a recently approved antibody for the treatment of multiple myeloma, has been shown to stimulate Fcγ receptor (FcγR)-mediated antibody-dependent cellular cytotoxicity by natural killer (NK) cells toward myeloma cells. The modulatory effects of elotuzumab on other effector cells in the tumor microenvironment, however, has not been fully explored. Antibody-dependent cellular phagocytosis (ADCP) is a mechanism by which macrophages contribute to antitumor potency of monoclonal antibodies. Herein, we studied the NK cell independent effect of elotuzumab on tumor-associated macrophages using a xenograft tumor model deficient in NK and adaptive immune cells. We demonstrate significant antitumor efficacy of single-agent elotuzumab in immunocompromised xenograft models of multiple myeloma, which is in part mediated by Fc-FcγR interaction of elotuzumab with macrophages. Elotuzumab is shown in this study to induce phenotypic activation of macrophages in vivo and mediates ADCP of myeloma cells though a FcγR-dependent manner in vitro Together, these findings propose a novel immune-mediated mechanism by which elotuzumab exerts anti-myeloma activity and helps to provide rationale for combination therapies that can enhance macrophage activity. Mol Cancer Ther; 17(7); 1454-63. ©2018 AACR ., (©2018 American Association for Cancer Research.)

Macrophages are present in all vertebrate tissues and have emerged as multifarious cells with complex roles in development, tissue homeostasis, and disease. Macrophages are a major constituent of the tumor microenvironment, where they either promote or inhibit tumorigenesis and metastasis depending on their state. Successful preclinical strategies to target macrophages for anticancer therapy are now being evaluated in the clinic and provide proof of concept that targeting macrophages may enhance current therapies; however, clinical success has been limited. This review discusses the promise of targeting macrophages for anticancer therapy, yet highlights how much is unknown regarding their ontogeny, regulation, and tissue-specific diversity. Further work might identify subsets of macrophages within different tissues, which could reveal novel therapeutic opportunities for anticancer therapy., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Effective therapies for non-small cell lung cancer (NSCLC) remain challenging despite an increasingly comprehensive understanding of somatically altered oncogenic pathways. It is now clear that therapeutic agents with potential to impact the tumor immune microenvironment potentiate immune-orchestrated therapeutic benefit. Herein, we evaluated the immunoregulatory properties of histone deacetylase (HDAC) and bromodomain inhibitors, two classes of drugs that modulate the epigenome, with a focus on key cell subsets that are engaged in an immune response. By evaluating human peripheral blood and NSCLC tumors, we show that the selective HDAC6 inhibitor ricolinostat promotes phenotypic changes that support enhanced T-cell activation and improved function of antigen-presenting cells. The bromodomain inhibitor JQ1 attenuated CD4 + FOXP3 + T regulatory cell suppressive function and synergized with ricolinostat to facilitate immune-mediated tumor growth arrest, leading to prolonged survival of mice with lung adenocarcinomas. Collectively, our findings highlight the immunomodulatory effects of two epigenetic modifiers that, together, promote T cell-mediated antitumor immunity and demonstrate their therapeutic potential for treatment of NSCLC. Significance: Selective inhibition of HDACs and bromodomain proteins modulates tumor-associated immune cells in a manner that favors improved T-cell function and reduced inhibitory cellular mechanisms. These effects facilitated robust antitumor responses in tumor-bearing mice, demonstrating the therapeutic potential of combining these epigenetic modulators for the treatment of NSCLC. Cancer Discov; 7(8); 852-67. ©2017 AACR. This article is highlighted in the In This Issue feature, p. 783 ., (©2017 American Association for Cancer Research.)