Cancer chemoprevention with PV-1, a novel Prunella vulgaris-containing herbal mixture that remodels the tumor immune microenvironment in mice.

The herb Prunella vulgaris has shown significant immune-stimulatory and anti-inflammatory effects in mouse models. Here, the effects of a novel Prunella vulgaris-containing herbal mixture, PV-1, were examined in several mouse models for cancer, including chemically induced models of lung and oral cancers as well as syngraft models for lung cancer and melanoma. PV-1, consisting of extracts from Prunella vulgaris, Polygonum bistorta, Sonchus brachyotus and Dictamnus dasycarpus, exhibited no toxicity in a dose escalation study in A/J mice. PV-1 significantly inhibited mouse lung tumor development induced by the lung carcinogens vinyl carbamate and benzo[a]pyrene. PV-1 also hindered the induction of oral squamous cell carcinomas in C57BL/6 mice caused by 4-nitroquinoline-1-oxide. Flow cytometry analysis showed that PV-1 increased the numbers of CD8+ tumor-infiltrating lymphocytes (TILs) and increased the production of granzyme B, TNF-α, and IFN-γ by CD8+ TILs. PV-1 also suppressed granulocytic myeloid-derived suppressor cell numbers (g-MDSCs) and improved the anti-cancer activity of anti-PD-1 immunotherapy. These results indicate that PV-1 remodels the tumor immune microenvironment by selectively inhibiting g-MDSCs and increasing CD8+ TILs within tumors, resulting in decreased immune suppression and enhanced cancer chemopreventive efficacy.

Striking efficacy of a vaccine targeting TOP2A for triple-negative breast cancer immunoprevention.

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer that has a poor prognosis. TOP2A is a key enzyme in DNA replication and is a therapeutic target for breast and other cancers. TOP2A-specific Th1-promoting epitopes with optimal binding affinity to MHC II were identified using a combined scoring system. The multi-peptide TOP2A vaccine elicited a robust immunologic response in immunized mice, as demonstrated by the significant production of Th1 cytokines from immunized animals' splenocytes stimulated in vitro with TOP2A peptides. Anti-tumor efficacy of the TOP2A vaccine was demonstrated in a syngeneic TNBC mouse model, in which pre-graft preventive vaccination was associated with significantly decreased tumor growth as compared to adjuvant control. In a genetically engineered mouse (GEM) model of TNBC, vaccinated animals demonstrated a significant reduction in tumor incidence and average tumor volume compared to adjuvant control. Finally, we examined TCR sequences in CD4 tumor Infiltrating lymphocytes (TIL) from vaccinated mice and found that the TIL contained TCR sequences specific to the three vaccine peptides. These data indicate that our newly developed multi-peptide TOP2A vaccine is highly immunogenic, elicits TILs with vaccine specific TCRs, and is highly effective in preventing and intercepting TNBC development and progression in vivo.

Randomized Phase II Trial of Dendritic Cell/Myeloma Fusion Vaccine with Lenalidomide Maintenance after Upfront Autologous Hematopoietic Cell Transplantation for Multiple Myeloma: BMT CTN 1401.

PURPOSE: Vaccination with dendritic cell (DC)/multiple myeloma (MM) fusions has been shown to induce the expansion of circulating multiple myeloma-reactive lymphocytes and consolidation of clinical response following autologous hematopoietic cell transplant (auto-HCT). PATIENTS AND METHODS: In this randomized phase II trial (NCT02728102), we assessed the effect of DC/MM fusion vaccination, GM-CSF, and lenalidomide maintenance as compared with control arms of GM-CSF and lenalidomide or lenalidomide maintenance alone on clinical response rates and induction of multiple myeloma-specific immunity at 1-year posttransplant. RESULTS: The study enrolled 203 patients, with 140 randomized posttransplantation. Vaccine production was successful in 63 of 68 patients. At 1 year, rates of CR were 52.9% (vaccine) and 50% (control; P = 0.37, 80% CI 44.5%, 61.3%, and 41.6%, 58.4%, respectively), and rates of VGPR or better were 85.3% (vaccine) and 77.8% (control; P = 0.2). Conversion to CR at 1 year was 34.8% (vaccine) and 27.3% (control; P = 0.4). Vaccination induced a statistically significant expansion of multiple myeloma-reactive T cells at 1 year compared with before vaccination (P = 0.024) and in contrast to the nonvaccine arm (P = 0.026). Single-cell transcriptomics revealed clonotypic expansion of activated CD8 cells and shared dominant clonotypes between patients at 1-year posttransplant. CONCLUSIONS: DC/MM fusion vaccination with lenalidomide did not result in a statistically significant increase in CR rates at 1 year posttransplant but was associated with a significant increase in circulating multiple myeloma-reactive lymphocytes indicative of tumor-specific immunity. Site-specific production of a personalized cell therapy with centralized product characterization was effectively accomplished in the context of a multicenter cooperative group study. See related commentary by Qazilbash and Kwak, p. 4703.

Precision immunointerception of EGFR-driven tumorigenesis for lung cancer prevention.

Epidermal growth factor receptor (EGFR) mutations occur in about 50% of lung adenocarcinomas in Asia and about 15% in the US. EGFR mutation-specific inhibitors have been developed and made significant contributions to controlling EGFR mutated non-small cell lung cancer. However, resistance frequently develops within 1 to 2 years due to acquired mutations. No effective approaches that target mutant EGFR have been developed to treat relapse following tyrosine kinase inhibitor (TKI) treatment. Vaccination against mutant EGFR is one area of active exploration. In this study, we identified immunogenic epitopes for the common EGFR mutations in humans and formulated a multi-peptide vaccine (Emut Vax) targeting the EGFR L858R, T790M, and Del19 mutations. The efficacy of the Emut Vax was evaluated in both syngeneic and genetic engineered EGFR mutation-driven murine lung tumor models with prophylactic settings, where the vaccinations were given before the onset of the tumor induction. The multi-peptide Emut Vax effectively prevented the onset of EGFR mutation-driven lung tumorigenesis in both syngeneic and genetically engineered mouse models (GEMMs). Flow cytometry and single-cell RNA sequencing were conducted to investigate the impact of Emut Vax on immune modulation. Emut Vax significantly enhanced Th1 responses in the tumor microenvironment and decreased suppressive Tregs to enhance anti-tumor efficacy. Our results show that multi-peptide Emut Vax is effective in preventing common EGFR mutation-driven lung tumorigenesis, and the vaccine elicits broad immune responses that are not limited to anti-tumor Th1 response.

Manufacture and Characterization of Good Manufacturing Practice-Compliant SARS-COV-2 Cytotoxic T Lymphocytes.

BACKGROUND: Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). SARS-CoV-2 virus-specific cytotoxic T-cell lymphocytes (vCTLs) could provide a promising modality in COVID-19 treatment. We aimed to screen, manufacture, and characterize SARS-CoV-2-vCTLs generated from convalescent COVID-19 donors using the CliniMACS Cytokine Capture System (CCS). METHODS: Donor screening was done by stimulation of convalescent COVID-19 donor peripheral blood mononuclear cells with viral peptides and identification of interferonγ (IFN-γ)+ CD4 and CD8 T cells using flow cytometry. Clinical-grade SARS-CoV-2-vCTLs were manufactured using the CliniMACS CCS. The enriched SARS-CoV-2-vCTLs were characterized by T-cell receptor sequencing, mass cytometry, and transcriptome analysis. RESULTS: Of the convalescent donor blood samples, 93% passed the screening criteria for clinical manufacture. Three validation runs resulted in enriched T cells that were 79% (standard error of the mean 21%) IFN-γ+ T cells. SARS-CoV-2-vCTLs displayed a highly diverse T-cell receptor repertoire with enhancement of both memory CD8 and CD4 T cells, especially in CD8 TEM, CD4 TCM, and CD4 TEMRA cell subsets. SARS-CoV-2-vCTLs were polyfunctional with increased gene expression in T-cell function, interleukin, pathogen defense, and tumor necrosis factor superfamily pathways. CONCLUSIONS: Highly functional SARS-CoV-2-vCTLs can be rapidly generated by direct cytokine enrichment (12 hours) from convalescent donors. CLINICAL TRIALS REGISTRATION: NCT04896606.

Donor chimerism and immune reconstitution following haploidentical transplantation in sickle cell disease.

Introduction: We previously reported the initial results of a phase II multicenter transplant trial using haploidentical parental donors for children and aolescents with high-risk sickle cell disease achieving excellent survival with exceptionally low rates of graft-versus-host disease and resolution of sickle cell disease symptoms. To investigate human leukocyte antigen (HLA) sensitization, graft characteristics, donor chimerism, and immune reconstitution in these recipients. Methods: CD34 cells were enriched using the CliniMACS® system with a target dose of 10 x 106 CD34+ cells/kg with a peripheral blood mononuclear cell (PBMNC) addback dose of 2x105 CD3/kg in the final product. Pre-transplant HLA antibodies were characterized. Donor chimerism was monitored 1-24 months post-transplant. Comprehensive assessment of immune reconstitution included lymphocyte subsets, plasma cytokines, complement levels, anti-viral T-cell responses, activation markers, and cytokine production. Infections were monitored. Results: HLA antibodies were detected in 7 of 11 (64%) evaluable patients but rarely were against donor antigens. Myeloid engraftment was rapid (100%) at a median of 9 days. At 30 days, donor chimerism was 93-99% and natural killer cell levels were restored. By 60 days, CD19 B cells were normal. CD8 and CD4 T-cells levels were normal by 279 and 365 days, respectively. Activated CD4 and CD8 T-cells were elevated at 100-365 days post-transplant while naïve cells remained below baseline. Tregs were elevated at 100-270 days post-transplant, returning to baseline levels at one year. At one year, C3 and C4 levels were above baseline and CH50 levels were near baseline. At one year, cytokine levels were not significantly different from baseline. Discussion: These results suggest that haploidentical transplantation with CD34-enriched cells and peripheral blood mononuclear cell addback results in rapid engraftment, sustained donor chimerism and broad-based immune reconstitution.

Long-term outcomes and predictors of early response, late relapse, and survival for patients treated with bispecific LV20.19 CAR T-cells.

We previously reported results of a first-in-human trial of bispecific LV20.19 chimeric antigen receptor T-cell (CAR-T) therapy, demonstrating high response rates in patients with relapsed, refractory (R/R) B-cell malignancies. We now report two-year survival outcomes and predictors of early response, late relapse, and survival. Patients from the previously reported phase 1 dose escalation and expansion trial of LV20.19 CAR-T therapy (NCT03019055) treated at target dose of 2.5 × 106 cells/kg (n = 16) were included in this updated analysis. Two-year progression-free survival (PFS) and overall survival (OS) were estimated using Kaplan-Meier method. The relationship of in-vivo CAR-T expansion, tumor burden, and effector: target ratio on early response (day 28) and late relapse (>180 days post-CAR-T) were assessed. Exact log-rank testing was performed to evaluate the impacts of clinical variables on survival outcomes. With a median of 31 months (range 27-40) of follow-up, two-year PFS and OS were 44% and 69%. Median PFS and OS were 15.6 months and not reached, respectively. For CAR-naïve large B-cell lymphoma patients (n = 8), two-year PFS and OS were 50% and 75%. No patient with progression experienced dual target antigen (CD19 or CD20) loss on post-relapse biopsy. Lower in vivo expansion was strongly associated with late relapse. Early treatment response was impeded by high metabolic tumor volume and low effector: target ratio. Bridging therapy and higher absolute lymphocyte count on day of CAR-T infusion were associated with inferior survival outcomes. In conclusion, this initial trial of LV20.19 CAR-T demonstrates a signal for favorable long-term outcomes for patients with R/R B-cell malignancies.

The effect of tocilizumab on patient reported outcomes and inflammatory biomarkers in hematopoietic cell transplantation.

Inflammatory physiology has been linked to behavioral and emotional symptoms in a variety of contexts and experimental paradigms. Hematopoietic cell transplantation (HCT) represents an intersection of significant immune dysregulation and psychosocial stress, and this biobehavioral relationship can influence important clinical outcomes. For those undergoing HCT with inflammation-related neuropsychiatric symptoms, using targeted agents such as the IL-6 receptor antagonist tocilizumab may be an effective therapeutic approach. We conducted an observational cohort study to explore patient reported outcomes (PROs) and inflammatory biomarkers among allogeneic HCT recipients who received tocilizumab compared to those who did not. Individuals on a larger trial of tocilizumab for prevention of graft-versus-host disease received a single dose of tocilizumab 24 h prior to stem cell infusion. Measures of anxiety, depression, pain, fatigue, and sleep quality and parallel blood samples for inflammatory cytokines were collected from participants and an analogous comparison cohort at baseline and Day 28 after stem cell infusion. Demographic and medical characteristics were reported; an analysis of covariance regression model was fitted to evaluate differences in PROs and distance correlation t-tests assessed for associations between biomarkers and PRO measures. For n = 18 tocilizumab-treated and n = 22 comparison patients, there were no significant differences between patient demographics, but the tocilizumab cohort had a different distribution of primary diagnoses (p = 0.009) with more patients with leukemias and a higher proportion of patients in their first remission (64% vs 28%, p = 0.024). Depression was higher at Day 28 compared to baseline in both groups (comparison group: +5.1 [95% CI 0.14-10, p = 0.045], tocilizumab: +8.6 [95% CI 2.3-15, p = 0.011]), though the difference between groups did not reach statistical significance. The tocilizumab group had significantly increased circulating IL-6 and decreased CRP at Day 28 (all p < 0.05). There was an association between collective baseline biomarkers and PROs (distance correlation dCor = 0.110, p = 0.005), but this same association was not present at Day 28 (dCor = -0.001, p = 0.5). In univariate analyses, a 10-fold increase in plasma IL-6 was associated with a 3.6-point higher depression score (95% CI 1.0-6.2, p = 0.008). In this exploratory analysis of PROs and inflammatory biomarkers in patients undergoing HCT, tocilizumab was not associated with favorable patient-reported symptom profiles. This finding is aligned with our prior work in the HCT population but diverges from hypothesized therapeutic effects of tocilizumab on depressive symptoms, thus highlighting the need for larger prospective translational studies in biobehavioral HCT research.

Patient-reported outcomes and neurotoxicity markers in patients treated with bispecific LV20.19 CAR T cell therapy.

Background: With the rising number of chimeric antigen receptor (CAR) T cell treated patients, it is increasingly important to understand the treatment's impact on patient-reported outcomes (PROs) and, ideally, identify biomarkers of central nervous system (CNS) adverse effects. Methods: The purpose of this exploratory study was to assess short-term PROs and serum kynurenine metabolites for associated neurotoxicity among patients treated in an anti-CD20, anti-CD19 (LV20.19) CAR T cell phase I clinical trial (NCT03019055). Fifteen CAR T treated patients from the parent trial provided serum samples and self-report surveys 15 days before and 14, 28, and 90 days after treatment. Results: Blood kynurenine concentrations increased over time in patients with evidence of neurotoxicity (p = 0.004) and were increased in self-reported depression (r = 0.52, p = 0.002). Depression improved after CAR T infusion (p = 0.035). Elevated 3-hydroxyanthranilic acid (3HAA) concentrations prior to cell infusion were also predictive of neurotoxicity onset (p = 0.031), suggesting it is a biomarker of neurotoxicity following CAR T cell therapy. Conclusions: Elevated levels of kynurenine pathway metabolites among CAR T cell recipients are associated with depressed mood and neurotoxicity. Findings from this exploratory study are preliminary and warrant validation in a larger cohort.

This study examined the impact of chimeric antigen receptor (CAR) T cell therapy­a therapy that gets immune cells to fight cancer by changing them in the lab to find and destroy cancer cells­on blood markers associated with depression, anxiety, pain, fatigue, and poor sleep. Fifteen CAR T cell patients provided blood samples and completed surveys before and three timepoints after treatment. We found that the amount of kynurenine, a normal blood constituent, and related molecules was higher in patients who experienced significant CAR T cell side effects on the brain and in patients reporting more depression. These results identify the excessive elevation of blood constituents related to the mood that may also be associated with depression and brain dysfunction following CAR T. These blood constituents could potentially be used as markers and targeted with interventions to prevent brain dysfunction.

Bispecific targeting of CD20 and CD19 increases polyfunctionality of chimeric antigen receptor T-cell products in B-cell malignancies.

BACKGROUND AIMS: Selective immune pressure contributes to relapse due to target antigen downregulation in patients treated with anti-CD19 chimeric antigen receptor (CAR) T cells. Bispecific lentiviral anti-CD20/anti-CD19 (LV20.19) CAR T cells may prevent progression/relapse due to antigen escape. Highly polyfunctional T cells within a CAR T-cell product have been associated with response in single-antigen-targeted anti-CD19 CAR T cells. METHODS: The authors performed a single-cell proteomic analysis to assess polyfunctional cells in our LV20.19 CAR T-cell product. Analysis was limited to those treated at a fixed dose of 2.5 × 106 cells/kg (n = 16). Unused pre-infusion CAR T cells were thawed, sorted into CD4/CD8 subsets and stimulated with K562 cells transduced to express CD19 or CD20. Single-cell production of 32 individual analytes was measured and polyfunctionality and polyfunctional strength index (PSI) were calculated. RESULTS: Fifteen patients had adequate leftover cells for analysis upon stimulation with CD19, and nine patients had adequate leftover cells for analysis upon stimulation with CD20. For LV20.19 CAR T cells, PSI was 866-1109 and polyfunctionality was 40-45%, which were higher than previously reported values for other CAR T-cell products. CONCLUSIONS: Stimulation with either CD19 or CD20 antigens resulted in similar levels of analyte activation, suggesting that this product may have efficacy in CD19- patient populations.

Prevention of Tumor Growth and Dissemination by In Situ Vaccination with Mitochondria-Targeted Atovaquone.

Atovaquone, an FDA-approved drug for malaria, is known to inhibit mitochondrial electron transport. A recently synthesized mitochondria-targeted atovaquone increased mitochondrial accumulation and antitumor activity in vitro. Using an in situ vaccination approach, local injection of mitochondria-targeted atovaquone into primary tumors triggered potent T cell immune responses locally and in distant tumor sites. Mitochondria-targeted atovaquone treatment led to significant reductions of both granulocytic myeloid-derived suppressor cells and regulatory T cells in the tumor microenvironment. Mitochondria-targeted atovaquone treatment blocks the expression of genes involved in oxidative phosphorylation and glycolysis in granulocytic-myeloid-derived suppressor cells and regulatory T cells, which may lead to death of granulocytic-myeloid-derived suppressor cells and regulatory T cells. Mitochondria-targeted atovaquone inhibits expression of genes for mitochondrial complex components, oxidative phosphorylation, and glycolysis in both granulocytic-myeloid-derived suppressor cells and regulatory T cells. The resulting decreases in intratumoral granulocytic-myeloid-derived suppressor cells and regulatory T cells could facilitate the observed increase in tumor-infiltrating CD4+ T cells. Mitochondria-targeted atovaquone also improves the anti-tumor activity of PD-1 blockade immunotherapy. The results implicate granulocytic-myeloid-derived suppressor cells and regulatory T cells as novel targets of mitochondria-targeted atovaquone that facilitate its antitumor efficacy.

Unrelated donor α/ß T cell- and B cell-depleted HSCT for the treatment of pediatric acute leukemia.

Unrelated donor (URD) hematopoietic stem cell transplant (HSCT) is associated with an increased risk of severe graft-versus-host disease (GVHD). TCRαß/CD19 depletion may reduce this risk, whereas maintaining graft-versus-leukemia. Outcome data with TCRαß/CD19 depletion generally describe haploidentical donors, with relatively few URDs. We hypothesized that TCRαß/CD19-depletion would attenuate the risks of GVHD and relapse for URD HSCT. Sixty pediatric and young adult (YA) patients with hematologic malignancies who lacked a matched-related donor were enrolled at 2 large pediatric transplantation centers between October 2014 and September 2019. All patients with acute leukemia had minimal residual disease testing, and DP typing was available for 77%. All patients received myeloablative total body irradiation- or busulfan-based conditioning with no posttransplant immune suppression. Engraftment occurred in 98%. Four-year overall survival was 69% (95% confidence interval [CI], 52%-81%), and leukemia-free survival was 64% (95% CI, 48%-76%), with no difference between lymphoid and myeloid malignancies (P = .6297 and P = .5441, respectively). One patient (1.7%) experienced primary graft failure. Relapse occurred in 11 patients (3-year cumulative incidence, 21%; 95% CI, 11-34), and 8 patients (cumulative incidence, 15%; 95% CI, 6.7-26) experienced nonrelapse mortality. Grade III to IV acute GVHD was seen in 8 patients (13%), and 14 patients (26%) developed chronic GVHD, of which 6 (11%) had extensive disease. Nonpermissive DP mismatch was associated with higher likelihood of acute GVHD (odds ratio, 16.50; 95% CI, 1.67-163.42; P = .0166) but not with the development of chronic GVHD. URD TCRαß/CD19-depleted peripheral HSCT is a safe and effective approach to transplantation for children/YAs with leukemia. This trial was registered at www.clinicaltrials.gov as #NCT02323867.

Manufacturing chimeric antigen receptor T cells from cryopreserved peripheral blood cells: time for a collect-and-freeze model?

BACKGROUND AIMS: Chimeric antigen receptor (CAR)-modified T-cell therapy has revolutionized outcomes for patients with relapsed/refractory B-cell malignancies. Despite the exciting results, several clinical and logistical challenges limit its wide applicability. First, the apheresis requirement restricts accessibility to institutions with the resources to collect and process peripheral blood mononuclear cells (PBMCs). Second, even when utilizing an apheresis product, failure to manufacture CAR T cells is a well-established problem in a significant subset. In heavily pre-treated patients, prior chemotherapy may impact T-cell quality and function, limiting the ability to manufacture a potent CAR T-cell product. Isolation and storage of T cells shortly after initial cancer diagnosis or earlier in life while an individual is still healthy are an alternative to using T cells from heavily pre-treated patients. The goal of this study was to determine if a CAR T-cell product could be manufactured from a small volume (50 mL) of healthy donor blood. METHODS: Collaborators at Cell Vault collected 50 mL of whole peripheral venous blood from three healthy donors. PBMCs were isolated, cryopreserved and shipped to the Medical College of Wisconsin. PBMCs for each individual donor were thawed, and CAR T cells were manufactured using an 8-day process on the CliniMACS Prodigy device with a CD19 lentiviral vector. RESULTS: Starting doses of enriched T-cell numbers ranged from 4.0 × 107 cells to 4.8 × 107 cells, with a CD4/CD8 purity of 74-79% and an average CD4:CD8 ratio of 1.4. On the day of harvest, total CD3 cells in the culture expanded to 3.6-4.6 × 109 cells, resulting in a 74- to 115-fold expansion, an average CD4:CD8 ratio of 2.9 and a CD3 frequency of greater than 99%. Resulting CD19 CAR expression varied from 19.2% to 48.1%, with corresponding final CD19+ CAR T-cell counts ranging from 7.82 × 108 cells to 2.21 × 109 cells. The final CAR T-cell products were phenotypically activated and non-exhausted and contained a differentiated population consisting of stem cell-like memory T cells. CONCLUSIONS: Overall, these data demonstrate the ability to successfully generate CAR T-cell products in just 8 days using cryopreserved healthy donor PBMCs isolated from only 50 mL of blood. Notably, numbers of CAR T cells were more than adequate for infusion of an 80-kg patient at dose levels used for products currently approved by the Food and Drug Administration. The authors offer proof of principle that cryopreservation of limited volumes of venous blood with an adequate starting T-cell count allows later successful manufacture of CAR T-cell therapy.

Inhibition of lung tumorigenesis by a small molecule CA170 targeting the immune checkpoint protein VISTA.

Expressed on cells of the myeloid and lymphoid lineages, V-domain Ig Suppressor of T cell Activation (VISTA) is an emerging target for cancer immunotherapy. Blocking VISTA activates both innate and adaptive immunity to eradicate tumors in mice. Using a tripeptide small molecule antagonist of VISTA CA170, we found that it exhibited potent anticancer efficacy on carcinogen-induced mouse lung tumorigenesis. Remarkably, lung tumor development was almost completely suppressed when CA170 was combined with an MHCII-directed KRAS peptide vaccine. Flow cytometry and single-cell RNA sequencing (scRNA-seq) revealed that CA170 increased CD8+ T cell infiltration and enhanced their effector functions by decreasing the tumor infiltration of myeloid-derived suppressor cells (MDSCs) and Regulatory T (Treg) cells, while the Kras vaccine primarily induced expansion of CD4+ effector T cells. VISTA antagonism by CA170 revealed strong efficacy against lung tumorigenesis with broad immunoregulatory functions that influence effector, memory and regulatory T cells, and drives an adaptive T cell tumor-specific immune response that enhances the efficacy of the KRAS vaccine.

Synchronous effects of targeted mitochondrial complex I inhibitors on tumor and immune cells abrogate melanoma progression.

Metabolic heterogeneity within the tumor microenvironment promotes cancer cell growth and immune suppression. We determined the impact of mitochondria-targeted complex I inhibitors (Mito-CI) in melanoma. Mito-CI decreased mitochondria complex I oxygen consumption, Akt-FOXO signaling, blocked cell cycle progression, melanoma cell proliferation and tumor progression in an immune competent model system. Immune depletion revealed roles for T cells in the antitumor effects of Mito-CI. While Mito-CI preferentially accumulated within and halted tumor cell proliferation, it also elevated infiltration of activated effector T cells and decreased myeloid-derived suppressor cells (MDSC) as well as tumor-associated macrophages (TAM) in melanoma tumors in vivo. Anti-proliferative doses of Mito-CI inhibited differentiation, viability, and the suppressive function of bone marrow-derived MDSC and increased proliferation-independent activation of T cells. These data indicate that targeted inhibition of complex I has synchronous effects that cumulatively inhibits melanoma growth and promotes immune remodeling.

Meeting Report: Translational Advances in Cancer Prevention Agent Development Meeting.

The Division of Cancer Prevention of the National Cancer Institute (NCI) and the Office of Disease Prevention of the National Institutes of Health co-sponsored the Translational Advances in Cancer Prevention Agent Development Meeting on August 27 to 28, 2020. The goals of this meeting were to foster the exchange of ideas and stimulate new collaborative interactions among leading cancer prevention researchers from basic and clinical research; highlight new and emerging trends in immunoprevention and chemoprevention as well as new information from clinical trials; and provide information to the extramural research community on the significant resources available from the NCI to promote prevention agent development and rapid translation to clinical trials. The meeting included two plenary talks and five sessions covering the range from pre-clinical studies with chemo/immunopreventive agents to ongoing cancer prevention clinical trials. In addition, two NCI informational sessions describing contract resources for the preclinical agent development and cooperative grants for the Cancer Prevention Clinical Trials Network were also presented.

STING Activated Tumor-Intrinsic Type I Interferon Signaling Promotes CXCR3 Dependent Antitumor Immunity in Pancreatic Cancer.

BACKGROUND & AIMS: Pancreatic ductal adenocarcinoma (PDA) is a lethal chemoresistant cancer that exhibits early metastatic spread. The highly immunosuppressive PDA tumor microenvironment renders patients resistant to emerging immune-targeted therapies. Building from our prior work, we evaluated stimulator of interferon genes (STING) agonist activation of PDA cell interferon-α/ß-receptor (IFNAR) signaling in systemic antitumor immune responses. METHODS: PDA cells were implanted subcutaneously to wild-type, IFNAR-, or CXCR3-knockout mice. Tumor growth was monitored, and immune responses were comprehensively profiled. RESULTS: Human and mouse STING agonist ADU-S100 reduced local and distal tumor burden and activated systemic antitumor immune responses in PDA-bearing mice. Effector T-cell infiltration and inflammatory cytokine and chemokine production, including IFN-dependent CXCR3-agonist chemokines, were elevated, whereas suppressive immune populations were decreased in treated tumors. Intratumoral STING agonist treatment also generated inflammation in distal noninjected tumors and peripheral immune tissues. STING agonist treatment of type I IFN-responsive PDA tumors engrafted to IFNAR-/- recipient mice was sufficient to contract tumors and stimulate local and systemic T-cell activation. Tumor regression and CD8+ T-cell infiltration were abolished in PDA engrafted to CXCR3-/- mice treated with STING agonist. CONCLUSIONS: These data indicate that STING agonists promote T-cell infiltration and counteract immune suppression in locally treated and distant tumors. Tumor-intrinsic type I IFN signaling initiated systemic STING-mediated antitumor inflammation and required CXCR3 expression. STING-mediated induction of systemic immune responses provides an approach to harness the immune system to treat primary and disseminated pancreatic cancers.