Sarcoma in patients with Lynch syndrome and response to immunotherapy.

BACKGROUND: Lynch syndrome (LS) is an autosomal dominant genetic predisposition to multiple malignancies and is characterized by deficient DNA mismatch repair. Increased incidence of sarcomas is not formally ascribed to LS; however, increasing evidence suggests a preponderance of these malignancies in affected families. Sarcomas typically possess a low tumor mutational burden and incite a poor immune infiltrate, thereby rendering them poorly responsive to immunotherapy. METHODS: We searched the University of California, Los Angeles (UCLA) sarcoma program database for patients with a diagnosis of sarcoma and LS from 2016 to 2023. Three such patients were identified and all three were treated with PD1 blockade. RESULTS: We present three cases of LS-associated sarcomas (two soft tissue sarcoma and one osteosarcoma) with increased tumor mutational burdens. These patients were each treated with an anti-PD1 antibody and experienced a response far superior to that reported for non-LS-associated sarcomas. CONCLUSIONS: Increased mutational burden and immune infiltrate are observed for sarcomas associated with LS. Although unselected patients with sarcoma have demonstrated poor response rates to immunotherapy, our findings suggest that patients with Lynch-associated sarcomas are more likely to respond to treatment with anti-PD1. These patients should be given consideration for immunotherapy.

Lifelong Imaging Surveillance is Indicated for Patients with Primary Retroperitoneal Liposarcoma.

BACKGROUND: Surveillance imaging of patients with retroperitoneal liposarcoma (RP-LPS) after surgical resection is based on a projected risk of locoregional and distant recurrence. The duration of surveillance is not well defined because the natural history of RP-LPS after treatment is poorly understood. This study evaluated the long-term risk of recurrence and disease-specific survival (DSS) for a cohort of patients with at least 10 years of progression-free survival (10yr-PFS) from their primary resection. METHODS: The prospective University of California, Los Angeles (UCLA) Sarcoma Database identified RP-LPS patients with 10yr-PFS after initial resection. The patients in the 10yr-PFS cohort were subsequently evaluated for recurrence and DSS. The time intervals start at date of initial surgical resection. Cox proportional hazards models were used to determine factors associated with recurrence and DSS. RESULTS: From 1972 to 2010, 76 patients with RP-LPS had at least 10 years of follow-up evaluation. Of these 76 patients, 39 (51%) demonstrated 10yr-PFS. The median follow-up period was 15 years (range 10-33 years). Among the 10yr-PFS patients, 49% (19/39) experienced a recurrence at least 10 years after surgery. Of those who experienced recurrence, 42% (8/19) died of disease. Neither long-term recurrence nor DSS were significantly associated with age, sex, tumor size, LPS subtype, surgical margin, or perioperative treatment with radiation or chemotherapy. CONCLUSION: Patients who have primary RP-LPS treated with surgical resection ± multimodality therapy face a long-term risk of recurrence and disease-specific death unacknowledged by current surveillance imaging guidelines. Among the patients with 10yr-PFS, 49% experienced a recurrence, and 42% of those died of disease. These findings suggest a need for lifelong surveillance imaging for patients with RP-LPS.

Gamma Secretase Inhibitors in Cancer: A Current Perspective on Clinical Performance.

Gamma secretase inhibitors (GSIs), initially developed as Alzheimer's therapies, have been repurposed as anticancer agents given their inhibition of Notch receptor cleavage. The success of GSIs in preclinical models has been ascribed to induction of cancer stem-like cell differentiation and apoptosis, while also impairing epithelial-to-mesenchymal transition and sensitizing cells to traditional chemoradiotherapies. The promise of these agents has yet to be realized in the clinic, however, as GSIs have failed to demonstrate clinical benefit in most solid tumors with the notable exceptions of CNS malignancies and desmoid tumors. Disappointing clinical performance to date reflects important questions that remain to be answered. For example, what is the net impact of these agents on antitumor immune responses, and will they require concurrent targeting of tumor-intrinsic compensatory pathways? Addressing these limitations in our current understanding of GSI mechanisms will undoubtedly facilitate their rational incorporation into combinatorial strategies and provide a valuable tool with which to combat Notch-dependent cancers. In the present review, we provide a current understanding of GSI mechanisms, discuss clinical performance to date, and suggest areas for future investigation that might maximize the utility of these agents. IMPLICATIONS FOR PRACTICE: The performance of gamma secretase inhibitors (GSIs) in clinical trials generally has not reflected their encouraging performance in preclinical studies. This review provides a current perspective on the clinical performance of GSIs across various solid tumor types alongside putative mechanisms of antitumor activity. Through exploration of outstanding gaps in knowledge as well as reasons for success in certain cancer types, the authors identify areas for future investigation that will likely enable incorporation of GSIs into rational combinatorial strategies for superior tumor control and patient outcomes.

Histone deacetylase inhibition promotes intratumoral CD8+ T-cell responses, sensitizing murine breast tumors to anti-PD1.

Histone deacetylase (HDAC) inhibitors impair tumor cell proliferation and alter gene expression. However, the impact of these changes on anti-tumor immunity is poorly understood. Here, we showed that the class I HDAC inhibitor, entinostat (ENT), promoted the expression of immune-modulatory molecules, including MHCII, costimulatory ligands, and chemokines on murine breast tumor cells in vitro and in vivo. ENT also impaired tumor growth in vivo-an effect that was dependent on both CD8+ T cells and IFNγ. Moreover, ENT promoted intratumoral T-cell clonal expansion and enhanced their functional activity. Importantly, ENT sensitized normally unresponsive tumors to the effects of PD1 blockade, predominantly through increases in T-cell proliferation. Our findings suggest that class I HDAC inhibitors impair tumor growth by enhancing the proliferative and functional capacity of CD8+ T cells and by sensitizing tumor cells to T-cell recognition.

The expression of MHC class II molecules on murine breast tumors delays T-cell exhaustion, expands the T-cell repertoire, and slows tumor growth.

The expression of MHC class II molecules (MHCII) on tumor cells correlates with survival and responsiveness to immunotherapy. However, the mechanisms underlying these observations are poorly defined. Using a murine breast tumor line, we showed that MHCII-expressing tumors grew more slowly than controls and recruited more functional CD4+ and CD8+ T cells. In addition, MHCII-expressing tumors contained more TCR clonotypes expanded to a larger degree than control tumors. Functional CD8+ T cells in tumors depended on CD4+ T cells. However, both CD4+ and CD8+ T cells eventually became exhausted, even in MHCII-expressing tumors. Treatment with anti-CTLA4, but not anti-PD-1 or anti-TIM-3, promoted complete eradication of MHCII-expressing tumors. These results suggest tumor cell expression of MHCII facilitates the local activation of CD4+ T cells, indirectly helps the activation and expansion of CD8+ T cells, and, in combination with the appropriate checkpoint inhibitor, promotes tumor regression.

The antitumor effects of entinostat in ovarian cancer require adaptive immunity.

BACKGROUND: Ovarian cancer is poorly immunogenic; however, increased major histocompatibility complex class II (MHCII) expression correlates with improved immune response and prolonged survival in patients with ovarian cancer. The authors previously demonstrated that the histone deacetylase inhibitor entinostat increases MHCII expression on ovarian cancer cells. In the current study, they evaluated whether entinostat treatment and resultant MHCII expression would enhance beneficial immune responses and impair tumor growth in mice with ovarian cancer. METHODS: C57BL/6 mice bearing intraperitoneal ID8 tumors were randomized to receive entinostat 20 mg/kg daily versus control. Changes in messenger RNA (mRNA) expression of 46 genes important for antitumor immunity were evaluated using NanoString analysis, and multicolor flow cytometry was used to measure changes in protein expression and tumor-infiltrating immune cells. RESULTS: Entinostat treatment decreased the growth of both subcutaneously and omental ID8 tumors and prolonged survival in immunocompetent C57BL/6 mice. NanoString analysis revealed significant changes in mRNA expression in 21 of 46 genes, including increased expression of the MHCI pathway, the MHCII transactivator (CIITA), interferon γ, and granzyme B. C57BL/6 mice that received entinostat had increased MHCII expression on omental tumor cells and a higher frequency of tumor-infiltrating, CD8-positive T cells by flow cytometry. In immunocompromised mice, treatment with entinostat had no effect on tumor size and did not increase MHCII expression. CONCLUSIONS: In the current murine ovarian cancer model, entinostat treatment enhances beneficial immune responses. Moreover, these antitumor effects of entinostat are dependent on an intact immune system. Future studies combining entinostat with checkpoint inhibitors or other immunomodulatory agents may achieve more durable antitumor responses in patients with ovarian cancer.

Paradigm Shift: Outcomes from a Physician-Scientist Undergraduate Pipeline Program.

Diverse medical and research teams are essential to culturally-responsive care and robust progress of biomedical research. However, structural inequities stymie the entry of trainees from underrepresented in medicine (URiM) backgrounds into the physician-scientist pipeline. The Preparation for Graduate and Medical Education (PARAdiGM) program was designed to provide students from underrepresented backgrounds early exposure to physician-scientist training in the context of ample mentorship and programmatic support. By emphasizing research experience, career exposure, presentation skills, mentorship, and application assistance, PARAdiGM is an incipient experience priming this student group to pursue careers in academic medicine. Since its establishment in 2014, PARAdiGM is already increasing entry of URiM students into the physician-scientist pipeline. Encouragingly, the majority of PARAdiGM alumni have matriculated into US medical schools, of which 16% are currently enrolled in MD-PhD programs. Early outcomes from PARAdiGM suggest that an immersive framework, longitudinal mentoring, and opportunity for self-growth should be incorporated into URiM pipeline programs on a larger scale. In these ways, helping students to envision themselves as members of the physician-scientist community is a step toward breaking down the barriers currently limiting URiM entry into academic medicine.

Clonal redemption of B cells in cancer.

Potentially self-reactive B cells constitute a large portion of the peripheral B cell repertoire in both mice and humans. Maintenance of autoreactive B cell populations could conceivably be detrimental to the host but their conservation throughout evolution suggests performance of a critical and beneficial immune function. We discuss herein how the process of clonal redemption may provide insight to preservation of an autoreactive B cell pool in the context of infection and autoimmunity. Clonal redemption refers to additional recombination or hypermutation events decreasing affinity for self-antigen, while increasing affinity for foreign antigens. We then review findings in murine models and human patients to consider whether clonal redemption may be able to provide tumor antigen-specific B cells and how this may or may not predispose patients to autoimmunity.

Class I histone deacetylase inhibition promotes CD8 T cell activation in ovarian cancer.

OBJECTIVE: Patients with epithelial ovarian cancer (EOC) typically present with late-stage disease, posing a significant challenge to treatment. Although taxane and platinum-based chemotherapy plus surgical debulking are initially effective, EOC is marked by frequent recurrence with resistant disease. Immunotherapy represents an appealing treatment paradigm given the ability of immune cells to engage metastatic sites and impede recurrence; however, response rates to checkpoint blockade in ovarian cancer have been disappointing. Here, we tested whether class I HDAC inhibition can promote anti-tumor T cell responses in a spontaneous and nonspontaneous murine model of EOC. METHODS: We used the spontaneous Tg-MISIIR-Tag and nonspontaneous ID8 models of murine ovarian cancer to test this hypothesis. Whole tumor transcriptional changes were assessed using the nCounter PanCancer Mouse Immune Profiling Panel. Changes in select protein expression of regulatory and effector T cells were measured by flow cytometry. RESULTS: We found that treatment with the class I HDAC inhibitor entinostat upregulated pathways and genes associated with CD8 T cell cytotoxic function, while downregulating myeloid derived suppressor cell chemoattractants. Suppressive capacity of regulatory T cells within tumors and associated ascites was significantly reduced, reversing the CD8-Treg ratio. CONCLUSIONS: Our findings suggest class I HDAC inhibition can promote activation of intratumoral CD8 T cells, potentially by compromising suppressive networks within the EOC tumor microenvironment. In this manner, class I HDAC inhibition might render advanced-stage EOC susceptible to immunotherapeutic treatment modalities.

Cdk5 drives formation of heterogeneous pancreatic neuroendocrine tumors.

Pancreatic neuroendocrine tumors (PanNETs) are a heterogeneous population of neoplasms that arise from hormone-secreting islet cells of the pancreas and have increased markedly in incidence over the past four decades. Non-functional PanNETs, which occur more frequently than hormone-secreting tumors, are often not diagnosed until later stages of tumor development and have poorer prognoses. Development of successful therapeutics for PanNETs has been slow, partially due to a lack of diverse animal models for pre-clinical testing. Here, we report development of an inducible, conditional mouse model of PanNETs by using a bi-transgenic system for regulated expression of the aberrant activator of Cdk5, p25, specifically in ß-islet cells. This model produces a heterogeneous population of PanNETs that includes a subgroup of well-differentiated, non-functional tumors. Production of these tumors demonstrates the causative potential of aberrantly active Cdk5 for generation of PanNETs. Further, we show that human PanNETs express Cdk5 pathway components, are dependent on Cdk5 for growth, and share genetic and transcriptional overlap with the INS-p25OE model. The utility of this model is enhanced by the ability to form tumor-derived allografts. This new model of PanNETs will facilitate molecular delineation of Cdk5-dependent PanNETs and the development of new targeted therapeutics.

Mechanistic inferences from clinical reports of SARS-CoV-2.

SARS-CoV-2 was identified as the causative pathogen in an outbreak of viral pneumonia cases originating in Wuhan, China, with an ensuing rapid global spread that led it to be declared a pandemic by the WHO on March 11, 2020. Given the threat to public health posed by sequelae of SARS-CoV-2 infection, the literature surrounding patient presentation in severe and non-severe cases, transmission rates and routes, management strategies, and initial clinical trial results have become available at an unprecedented pace. In this review we collate current clinical and immunologic reports, comparing these to reports of previous coronaviruses to identify mechanisms driving progression to severe disease in some patients. In brief, we propose a model wherein dysregulated type I interferon signalling leads to aberrant recruitment and accumulation of innate immune lineages in the lung, impairing establishment of productive adaptive responses, and permitting a pathologic pro-inflammatory state. Finally, we extend these findings to suggest possible treatment options that may merit investigation in randomized clinical trials.

Inhibition of the Wnt/ß-catenin pathway enhances antitumor immunity in ovarian cancer.

BACKGROUND: The Wnt/ß-catenin pathway is linked to tumorigenesis in a variety of tumors and promotes T cell exclusion and resistance to checkpoint inhibitors. We sought to determine whether a small molecule inhibitor of this pathway, WNT974, would impair tumor growth, affect gene expression patterns, and improve the immune response in human and murine ovarian cancer models. METHODS: Human ovarian cancer cells were treated with WNT974 in vitro. RNAseq libraries were constructed and differences in gene expression patterns between responders and nonresponders were compared to The Cancer Genome Atlas (TCGA). Mice with subcutaneous or intraperitoneal ID8 ovarian cancer tumors were treated with WNT974, paclitaxel, combination, or control. Tumor growth and survival were measured. Flow cytometry and ß-TCR repertoire analysis were used to determine the immune response. RESULTS: Gene expression profiling revealed distinct signatures in responders and nonresponders, which strongly correlated with T cell infiltration patterns in the TCGA analysis of ovarian cancer. WNT974 inhibited tumor growth, prevented ascites formation, and prolonged survival in mouse models. WNT974 increased the ratio of CD8+ T cells to T regulatory cells (Tregs) in tumors and enhanced the effector functions of infiltrating CD4+ and CD8+ T cells. Treatment also decreased the expression of inhibitory receptors on CD8+ T cells. Combining WNT974 with paclitaxel further reduced tumor growth, prolonged survival, and expanded the T cell repertoire. CONCLUSIONS: These findings suggest that inhibiting the Wnt/ß-catenin pathway may have a potent immunomodulatory effect in the treatment of ovarian cancer, particularly when combined with paclitaxel.

Overcoming immune suppression with epigenetic modification in ovarian cancer.

The impressive successes of immunotherapy have yet to be reliably translated to treatment of ovarian cancer, which may be a consequence of the unique barriers to T cell migration and tumor engagement in the peritoneal cavity and omentum. Epigenetic alterations contribute to establishment of these barriers and other mechanisms of immune subversion; therefore, epigenetic modifying agents represent an opportunity to mount effective antitumor immune responses by disrupting this finely tuned tumor epigenetic framework. Here, we discuss how epigenetic modifiers might permit and stimulate de novo antitumor immune responses in ovarian cancer, focusing largely on 2 common classes, DNA methyltransferase and histone deacetylase inhibitors. Specifically, increasing T and NK cell trafficking to the tumor microenvironment as well as induction of altered tumor cell phenotypes that promote immune engagement and cytotoxicity may provide a platform upon which to elaborate existing immunotherapeutic strategies. Indeed, promising combination of epigenetic modifying agents with checkpoint blockade antibodies or cellular therapies in preclinical models has led to a burgeoning number of clinical trials. Therefore, rather than implementation as a monotherapy, epigenetic modifiers may well be best suited as adjuvants in combinatorial strategies, potentiating antitumor immune responses and unleashing the promise of immunotherapy in ovarian cancer.

Modulation of antitumor immunity with histone deacetylase inhibitors.

Histone deacetylase inhibitors possess a broad array of antitumor activities; however, their net impact on the evolving antitumor immune response is highly dependent on the inhibitors used and the histone deacetylases they target. Herein, we sequentially focus on each stage of the antitumor immune response - from dendritic cell activation and migration, antigen uptake and presentation, T-cell activation and differentiation and the enactment of antitumor effector functions within the tumor microenvironment. In particular, we will discuss how various inhibitors have different effects depending on cellular activation, experimental design and specific histone deacetylases being targeted - and how these changes impact the outcome of an antitumor immune response. At last, we consider the impact these inhibitors may have on T-cell exhaustion and implications for combination with other immunomodulating therapies.

Impact of elective versus required medical school research experiences on career outcomes.

Many US medical schools have added a scholarly or research requirement as a potential intervention to increase the number of medical students choosing to become academic physicians and physician scientists. We designed a retrospective qualitative survey study to evaluate the impact of medical school research at the University of Alabama at Birmingham (UAB) on career choices. A survey tool was developed consisting of 74 possible questions with built-in skip patterns to customize the survey to each participant. The survey was administered using the web-based program Qualtrics to UAB School of Medicine alumni graduating between 2000 and 2014. Alumni were contacted 3 times at 2-week intervals during the year 2015, resulting in 168 completed surveys (11.5% response rate). MD/PhD graduates were excluded from the study. Most respondents completed elective research, typically for reasons relating to career advancement. 24 per cent said medical school research increased their desire for research involvement in the future, a response that positively correlated with mentorship level and publication success. Although completion of medical school research was positively correlated with current research involvement, the strongest predictor for a physician scientist career was pre-existing passion for research (p=0.008). In contrast, students motivated primarily by curricular requirement were less likely to pursue additional research opportunities. Positive medical school research experiences were associated with increased postgraduate research in our study. However, we also identified a strong relationship between current research activity and passion for research, which may predate medical school.

Evaluation of a novel methacrylate-based Protein A resin for the purification of immunoglobulins and Fc-fusion proteins.

Protein A affinity chromatography is a central part of most commercial monoclonal antibody and Fc-fusion protein purification processes. In the last couple years an increasing number of new Protein A technologies have emerged. One of these new Protein A technologies consists of a novel, alkaline-tolerant, Protein A ligand coupled to a macroporous polymethacrylate base matrix that has been optimized for immunoglobulin (Ig) G capture. The resin is interesting from a technology perspective because the particle size and pore distribution of the base beads are reported to have been optimized for high IgG binding and fast mass transfer, while the Protein A ligand has been engineered for enhanced alkaline tolerance. This resin was subjected to a number of technical studies including evaluating dynamic and static binding capacities, alkaline stability, Protein A leachate propensity, impurity clearance, and pressure-flow behavior. The results demonstrated similar static binding capacities as those achieved with industry standard agarose Protein A resins, but marginally lower dynamic binding capacities. Removal of impurities from the process stream, particularly host cell proteins, was molecule dependent, but in most instances matched the performance of the agarose resins. This resin was stable in 0.1 M NaOH for at least 100 h with little loss in binding capacity, with Protein A ligand leakage levels comparable to values for the agarose resins. Pressure-flow experiments in lab-scale chromatography columns demonstrated minimal resin compression at typical manufacturing flow rates. Prediction of resin compression in manufacturing scale columns did not suggest any pressure limitations upon scale up.