T-cell Expansion Research Articles

Abstract CT129: Trial in progress: ATHENA-1 - a phase 1, open-label, first-in-human study to assess safety and tolerability of REGN5837 in combination with odronextamab in patients with relapsed/refractory aggressive B-cell non-Hodgkin lymphomas

Abstract Background: Many patients with relapsed/refractory (R/R) aggressive B-cell non-Hodgkin lymphoma (B-NHL) are unable to tolerate, access, or benefit from intensive chemo-therapeutic approaches or cellular therapies and will invariably relapse; therefore, novel approaches are urgently required. Odronextamab (REGN1979) is a hinge-stabilized, human CD20 × CD3 IgG4-based bispecific antibody that elicits T-cell-mediated cytotoxicity of malignant B cells. In a Phase 1 study, odronextamab monotherapy showed a manageable safety profile with encouraging preliminary activity in heavily pre-treated patients with R/R B-NHL (Bannerji R, et al. Lancet Haematol. 2022;9(5):e327-39). REGN5837 is a hinge-stabilized, human CD28 × CD22 IgG4-based bispecific antibody that provides a co-stimulatory signal (signal 2). When combined with odronextamab (signal 1), REGN5837 improved anti-tumor efficacy and survival in in vivo diffuse large B-cell lymphoma tumor models via enhanced T-cell expansion. We hypothesize that combining REGN5837 with odronextamab may deepen and extend anti-tumor activity in patients with aggressive lymphoma. Methods: ATHENA-1 (NCT05685173) is a Phase 1, open-label, first-in-human study of REGN5837 in combination with odronextamab in patients with R/R aggressive B-NHL. During induction, odronextamab and REGN5837 will be administered weekly over 21-day cycles. To mitigate potential CRS events, odronextamab will be introduced with step-up dosing as a monotherapy, followed by introduction of REGN5837 on C2 D15 with step-up dosing. Maintenance will consist of 28-day cycles (odronextamab and REGN5837 administration on D1, 15). Patients who achieve a sustained complete response (≥9 months) will have study drug(s) administration changed to once every 4 weeks. Patients must be aged ≥18 years, have Eastern Cooperative Oncology Group performance status ≤1, with adequate organ function, and have CD20+ aggressive B-NHL that progressed after ≥2 lines of systemic therapy containing at least an anti-CD20 antibody and an alkylating agent, with or without prior chimeric antigen receptor T-cell therapy. Exclusion criteria include prior allogeneic stem cell transplant, organ transplant, or CD20xCD3 bispecific antibodies, or mantle cell lymphoma or central nervous system lymphoma. Primary endpoints are incidence of dose-limiting toxicities and the incidence and severity of treatment-emergent adverse events. Secondary endpoints include pharmacokinetics of odronextamab and REGN5837, anti-drug antibody incidence, objective response rate, complete response rate, duration of response, progression-free survival, and overall survival. Enrolment is planned to open in early 2023. Citation Format: John Baird, Pim G. Mutsaers, Jeremy S. Abramson, Manjusha Namuduri, Jingjin Li, Nickolas A. Sophos, Min Zhu, Jurriaan Brouwer-Visser, Hesham Mohamed, Aafia Chaudhry, Andrew J. Davies. Trial in progress: ATHENA-1 - a phase 1, open-label, first-in-human study to assess safety and tolerability of REGN5837 in combination with odronextamab in patients with relapsed/refractory aggressive B-cell non-Hodgkin lymphomas [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 2 (Clinical Trials and Late-Breaking Research); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(8_Suppl):Abstract nr CT129.

Uncoupled pyroptosis and IL-1β secretion downstream of inflammasome signaling.

Inflammasomes are supramolecular platforms that organize in response to various damage-associated molecular patterns and pathogen-associated molecular patterns. Upon activation, inflammasome sensors (with or without the help of ASC) activate caspase-1 and other inflammatory caspases that cleave gasdermin D and pro-IL-1β/pro-IL-18, leading to pyroptosis and mature cytokine secretion. Pyroptosis enables intracellular pathogen niche disruption and intracellular content release at the cost of cell death, inducing pro-inflammatory responses in the neighboring cells. IL-1β is a potent pro-inflammatory regulator for neutrophil recruitment, macrophage activation, and T-cell expansion. Thus, pyroptosis and cytokine secretion are the two main mechanisms that occur downstream of inflammasome signaling; they maintain homeostasis, drive the innate immune response, and shape adaptive immunity. This review aims to discuss the possible mechanisms, timing, consequences, and significance of the two uncoupling preferences downstream of inflammasome signaling. While pyroptosis and cytokine secretion may be usually coupled, pyroptosis-predominant and cytokine-predominant uncoupling are also observed in a stimulus-, cell type-, or context-dependent manner, contributing to the pathogenesis and development of numerous pathological conditions such as cryopyrin-associated periodic syndromes, LPS-induced sepsis, and Salmonella enterica serovar Typhimurium infection. Hyperactive cells consistently release IL-1β without LDH leakage and pyroptotic death, thereby leading to prolonged inflammation, expanding the lifespans of pyroptosis-resistant neutrophils, and hyperactivating stimuli-challenged macrophages, dendritic cells, monocytes, and specific nonimmune cells. Death inflammasome activation also induces GSDMD-mediated pyroptosis with no IL-1β secretion, which may increase lethality in vivo. The sublytic GSDMD pore formation associated with lower expressions of pyroptotic components, GSDMD-mediated extracellular vesicles, or other GSDMD-independent pathways that involve unconventional secretion could contribute to the cytokine-predominant uncoupling; the regulation of caspase-1 dynamics, which may generate various active species with different activities in terms of GSDMD or pro-IL-1β, could lead to pyroptosis-predominant uncoupling. These uncoupling preferences enable precise reactions to different stimuli of different intensities under specific conditions at the single-cell level, promoting cooperative cell and host fate decisions and participating in the pathogen "game". Appropriate decisions in terms of coupling and uncoupling are required to heal tissues and eliminate threats, and further studies exploring the inflammasome tilt toward pyroptosis or cytokine secretion may be helpful.

Abstract 3245: AXL as a therapeutic target in STK11 mutant NSCLC

Abstract STK11 (LKB1) is a tumor suppressor, and loss-of-function mutations contribute to tumorigenesis. Mutations in the STK11 gene (STK11m) are present in ~ 20% of NSCLCs and are associated with poor response to chemotherapy and immune checkpoint inhibition (ICI) resulting in inferior survival outcomes. STK11m tumors are characterized by high oxidative stress/ROS, EMT, enhanced replication stress tolerance, resistance to DNA damage and a highly immunosuppressive tumor microenvironment with limited activation and expansion of anti-tumor CD8 T-cells. AXL, a member of the TAM family of receptor tyrosine kinases, is activated in response to cellular stress such as ROS and hypoxia. AXL expression and activation is associated with EMT and drug resistance, tumor tolerance towards oxidative stress and apoptosis, as well as an immunosuppressed tumor microenvironment. We have previously shown that selective AXL inhibition by bemcentinib potentiated ICI in STK11m NSCLC preclinical models and led to objective clinical response in individuals with STK11m NSCLC receiving bemcentinib and pembrolizumab (NCT03184571). Data from this clinical study, an independent real-world cohort of patients studied at the Haukeland Hospital in Bergen, Norway (REC 45562) and published results1, suggest AXL is expressed in ~ 80% of NSCLCs harboring a STK11m, indicating AXL expression is a characteristic of STK11m NSCLC and confirming that AXL is an attractive target in STK11m NSCLC. Inhibition of AXL in dendritic cells has been shown to increase ICI responses in preclinical models of STK11m NSCLC1. The relative contribution of targeting AXL in STK11m tumor cells vs the tumor microenvironment, and the impact on tumor cells after tumor cell targeting needs further exploration. Transcriptional analysis of STK11m and STK11wt sequences from public datasets, NCT03184571 patients and NSCLC cell lines identified transcriptional signatures consistent with the known roles of STK11 in DNA damage response and immunosuppression. Treatment of STK11m NSCLC cell lines with the AXL inhibitor bemcentinib led to a reduction in the STK11-associated DDR signature and increase in inflammatory signatures demonstrating the impact of AXL targeting on tumor cells. Due to the high unmet medical need in individuals harboring a STK11 mutation, the encouraging efficacy in the NCT03184571 clinical trial and the high incidence of AXL protein expression in STK11m tumors, a global, open-label Phase 1b/2a trial to determine the safety, tolerability and anti-tumor activity of bemcentinib with SOC (pembrolizumab, pemetrexed and carboplatin) in 1L advanced/metastatic non-squamous NSCLC patients with STK11 mutations and no actionable mutations is currently enrolling. The Phase 1b part of the study will evaluate the safety and tolerability of bemcentinib regardless of STK11 status, whereas the Phase 2a part will assess the efficacy in NSCLC patients with STK11 mutations. 1 Li et al., 2022; Cell Rep Med., PMID: 35492873 Citation Format: Magnus Blø, Austin Rayford, Noëlly Madeleine, Fabian Gärtner, Dana Bohan, Natalie Ruggio, Huiyu Li, Luc Girard, Rolf Brekken, John Minna, Marianne Ånerud, Wendy Maury, Claudia Gorcea-Carson, Gro Gausdal, David R. Micklem, Nigel McCracken. AXL as a therapeutic target in STK11 mutant NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3245.

Abstract 610: Modeling tumor immunoediting coupled with T-cell repertoire dynamic

Abstract As tumors evolve, cancer cells acquire somatic mutations and these mutations generate tumor specific neoantigens that are different from self and can be recognized by T-cells, inducing anti-tumor immune responses. Such immunogenic antigens can be effective targets for neoantigen-based cancer vaccines. However, the identification of immunogenic neoantigens remains limited with the current prediction models. Here we designed mouse experiments to model tumor evolution under immune pressure and its association with T-cell clones to identify these antigens agnostically and improve current prediction models. We injected three lung cancer cell lines (KPA, KPC, and HKP1) in wildtype immune-competent C57BL/6 mice and immune-deficient Rag1 defective (Rag1 KO) mice, respectively. The three tumor cell lines have common driver mutations, Kras G12D/+ and p53 flox/flox. Two weeks post tumor implantation, whole exome sequencing and RNA-seq was performed on tumor samples. We also performed T cell receptor (TCR) sequencing to profile tumor infiltrated TCR clones. Despite the shared driver mutations, tumor growth patterns in vivo over time are very distinct for each cell line. Interestingly, KPA tumors show differential evolutionary patterns in wild type mice versus Rag1 KO mice, regressing in the former but rapidly progressing in the latter, suggesting that the difference can be attributed to immunoediting of KPA specific neoantigens. HKP1 tumors do not show substantial differences in that aggressive tumor progression is observed in both types of mice. Using WES data, we estimated the cancer cell fraction of each mutation based on phylogeny re-construction. We found that evolved KPA tumors (immunogenic) had significantly lower mutation burden in wild type mice compared to Rag1 KO mice (3410 vs 4199 on average), and the fraction of cell line mutations edited in vivo is significantly higher in wild type than in Rag1 KO (26% vs 14% on average), suggesting again the active on-going immunosurveillance in immune competent mice. In contrast, HKP1 tumors (non-immunogenic) do not show significant differences in mutation burden nor fraction of mutations edited between wild type and Rag1 KO mice. Furthermore, TCR-seq data show that the clonal expansion of T-cells is strongly associated with tumor immunogenicity. KPA tumor samples show significantly higher TCR clustering but with less diversity, quantified by modified Simpson’s Index, that is strongly correlated with the suppression of mutational burden (r=0.74). In summary, we found that tumor evolution in immune competent mice is dependent on mutational context of the tumor. By analyzing longitudinal tumor and TCR sequencing data, we showed that the immunogenicity of tumors is associated with significant decrease in mutational burden and higher T-cell clustering that is indicative of tumor mutation and TCR clone expansion co-evolution in immune competent mice. Citation Format: Jayon Lihm, Hyejin Choi, Mariam M. George, Yuval Elhanati, David Hoyos, Marta Luksza, Taha Merghoub, Benjamin D. Greenbaum. Modeling tumor immunoediting coupled with T-cell repertoire dynamic [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 610.

Abstract 4539: Tumor evolution and immune microenvironment dynamics define response to neoadjuvant treatment of esophageal adenocarcinoma

Abstract Introduction: Locally advanced esophageal adenocarcinoma (EAC) remains difficult to treat, and resistance is common. The ecological and evolutionary dynamics responsible for treatment failure are incompletely understood. Aim & Methods: We performed a multi-omic study with a multi-timepoint strategy to examine neoadjuvant treatment response at clonal resolution and in the surrounding tumor microenvironment. EAC samples from chemotherapy responding (REs) and chemotherapy non-responding (NRs) patients with locally advanced EAC were collected at three time points (prior, during, and after neoadjuvant therapy) within the multicenter MEMORI trial. Whole exome sequencing (mean depth 300x) was performed on 47 samples from 17 REs and on 24 samples from 10 NRs. Matched RNA sequencing was performed on 53 samples from 17 REs and on 26 samples from 10 NRs. To characterize immune response we performed imaging mass cytometry (IMC) with a 18-marker panel on 26 samples from 9 REs and 16 samples from 6 NRs and T-cell receptor sequencing in 18 RE-samples and 9 NR-samples. Results: We observed profound changes in mutation signatures over time, characterized by C>A transitions after exposure to neoadjuvant chemotherapy (FOLFOX), which is consistent with earlier observed oxaliplatin induced mutational signatures. Phylogenetic analysis showed no major changes in the clonal make-up during treatment, suggesting phenotypic plasticity rather than clonal evolution caused treatment resistance. EAC samples displayed widespread copy number alterations (CNAs), as previously described. CNAs arising during treatment were significantly more likely to be small, focal alterations rather than large alterations. At the transcriptome level neoadjuvant treatment led to significant changes with significant upregulation of immune and stromal pathways and oncogenic pathways such as KRAS, Hedgehog and WNT. The presence of immune escape mechanisms (defined as LOH or mutations in HLA, B2M mutations or PDL-1 overexpression) and a lack of clonal T-cell expansions were linked to poor clinical treatment response. Moreover, IMC analyses showed a less activated T-cell phenotype in NRs than in REs throughout treatment. Conclusion: Using a multi-timepoint approach, we integrated genetic analyses with transcriptomic analyses and analyses of the tumor immune microenvironment for a holistic understanding of treatment resistance. This study identifies profound transcriptional changes during treatment with limited evidence that clonal replacement is the cause, suggesting phenotypic plasticity as a mechanism for therapy resistance. The presence of immune escape, a less activated T-cell phenotype and a lack of clonal T-cell expansions in patients with poor clinical treatment response has high pharmacological relevance and could be exploited via combined immune-chemotherapy treatments. Citation Format: Melissa Barroux, Jacob Househam, Eszter Lakatos, Tahel Ronel, Ann-Marie Baker, Henrike Salié, Max Mossner, Kane Smith, Chris Kimberley, Salpie Nowinski, Alison Berner, Vinaya Gunasri, Marnix Jansen, Giulio Caravagna, Julia Slotta-Huspenina, Wilko Weichert, Markus Alberstmeier, Benny Chain, Helmut Friess, Bertram Bengsch, Roland M. Schmid, Jens T. Siveke, Michael Quante, Trevor A. Graham. Tumor evolution and immune microenvironment dynamics define response to neoadjuvant treatment of esophageal adenocarcinoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4539.

Abstract 3283: GEN1046 (DuoBody®-PD-L1x4-1BB) in combination with PD-1 blockade potentiates anti-tumor immunity

Abstract GEN1046 (DuoBody®-PD-L1x4-1BB) is an investigational, potential first-in-class bispecific immunomodulatory antibody designed to elicit an anti-tumor immune response by simultaneous and complementary blockade of PD-L1 on tumor or immune cells and conditional 4-1BB stimulation on T cells and NK cells. Previously, we described encouraging preclinical and early clinical activity of GEN1046 (Muik, et al., 2022, Cancer Discovery). We hypothesized that combining GEN1046 with PD-1 blockade would further potentiate anti-tumor activity through distinct and complementary immune modulatory effects. Addition of an anti-PD-1 agent would free up PD-L1 for binding to GEN1046, thus promoting PD-L1-dependent 4-1BB conditional agonism, while maintaining complete blockade of the PD-1 pathway by inhibiting interactions with both PD-L1 and PD-L2. ​Here we provide preclinical evidence supportive of therapeutic synergy by the combination of GEN1046 and anti-PD-1 and describe the mechanisms of enhanced anti-tumor immunity elicited by the combination. In in vitro studies, combining GEN1046 with an anti-PD-1 agent potentiated cytokine release in mixed lymphocyte reaction assays (using either unstimulated T cells or T cells exhausted by repeated CD3/CD28 co-stimulation) and enhanced T-cell expansion and cytokine secretion in antigen-specific proliferation assays compared to each single agent. In in vivo studies in mice bearing syngeneic subcutaneous MC38 tumors, the combination of an anti-mouse PD-L1x4-1BB bispecific antibody with anti-mouse PD-1 potentiated anti-tumor activity with significant enhancement of survival (P≤0.001) and durable, complete tumor regressions (CR) in 7/10 mice compared to no CR observed with either single agent, suggesting therapeutic synergy with the combination. The combination treatment elicited long-lasting immune memory response, as animals with CR were protected from tumor outgrowth upon rechallenge with MC38 cells. Mechanistically, animals treated with the combination showed a trend for ≥1.5-fold increase in the average density of CD3+ and CD4+ tumor-infiltrating lymphocytes (TILs), as well as proliferating (Ki67+) and cytotoxic (GZMB+) CD8+ TILs relative to each single agent, consistent with an amplified anti-tumor immune response. Together, these preclinical results suggest that combining GEN1046-induced conditional 4-1BB stimulation with complete PD-1 blockade can improve the anti-tumor immune response via distinct and complementary immune modulatory effects. The combination of GEN1046 with pembrolizumab is currently being investigated in ongoing clinical studies in patients with advanced NSCLC, who are treatment-naïve (NCT03917381) or have progressed on prior CPI-containing therapy (NCT05117242). Citation Format: Michela Capello, Angelica Sette, Theo Plantinga, Vanessa Spires, Kristina Nuermberger, Jordan Blum, Alexander Muik, Carol Costa Sa, Omar Jabado, Saskia Burm, Aras Toker, Sina Fellermeier-Kopf, Tahi Ahmadi, Brandon Higgs, Suzana Couto, Özlem Türeci, Mark Fereshteh, Ugur Sahin, Maria Jure-Kunkel, Nora Pencheva. GEN1046 (DuoBody®-PD-L1x4-1BB) in combination with PD-1 blockade potentiates anti-tumor immunity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3283.

Abstract 1778: B7-H3-CAR T-cell therapy in immune-competent osteosarcoma models: Regnase-1 KO overcomes limited CAR T-cell expansion

Abstract Chimeric antigen receptor (CAR) T-cell therapy offers promise to improve outcomes for pediatric patients with recurrent/refractory osteosarcoma (OS), a ‘poor-prognosis’ cancer. However, early-phase clinical studies have shown limited activity despite potent antitumor activity in preclinical xenograft models, highlighting the need to develop better preclinical models. B7-H3 has emerged as a promising immunotherapeutic target for pediatric solid tumors including OS, and we and other investigators are actively exploring B7-H3-CAR T cell therapies in early-phase clinical studies. Our goal was to develop a murine immunocompetent OS model (F331) for the realistic pre-clinical evaluation of B7-H3-CAR T cells and to explore additional genetic modifications to improve their effector function. We generated murine B7-H3-CAR T cells expressing a 2nd generation B7-H3-CD28.ζ CAR by retroviral transduction. In vitro, B7-H3-CAR T cells recognized B7-H3-positive F331 cells as judged by IFNγ production and cytolytic activity in contrast to B7-H3-negative tumor cells; Control (ctrl) CAR T-cells recognizing an irrelevant antigen (SP6) did not recognize or kill B7-H3-positive tumor cells confirming specificity. Since lung is the primary OS metastasis site, we focused on the intravenous (i.v.) disseminated lung F331 OS metastasis model. In this model, a single i.v. infusion of 5x106 CD8+ B7-H3-CAR T cells demonstrated significant antitumor activity compared to CD8+ ctrl CAR T cells, resulting in a significant survival advantage (median: 70 vs 38 days respectively). Unfortunately, tumors invariably recurred. We found limited B7-H3-CAR T cell expansion and persistence, even though recurring tumors still expressed B7-H3, excluding tumor antigen escape mechanism. We therefore embarked on a comprehensive screen to knock out (KO) known negative regulators of T-cell function, starting with Regnase-1 (Reg-1). Reg-1 is known to have RNase activity and to regulate activation of immune cells. KO of Reg-1 in CD8+ B7-H3-CAR T cells improved their expansion post-infusion in spleen and lungs as judged by flow cytometric analysis without systemic toxicities based on mice body weight assessment. This resulted in a significant improvement in overall survival in comparison to control KO B7-H3-CAR T cells at a cell dose (1x106) at which ctrl-KO CD8+ B7-H3-CAR T cells were ineffective. Reg1-KO ctrl CAR T cells had no therapeutic benefit, excluding nonspecific effects. In summary, we have established an immune-competent OS model to evaluate the effector function of B7-H3-CAR T cells and have demonstrated the advantage given by 2nd genetic modifications to enhance their antitumor activity. We are currently using this model to define mechanisms of immune resistance with the goal of further enhancing OS-redirected CAR T-cell therapy. Citation Format: Adeleye O. Adeshakin, Peipei Zhou, Jean-Yves Métais, Phuong Nguyen, Scott Perry, Heather Sheppard, Xiang Sun, Trevor Cunningham, Hao Shi, Jessica Wagner, Jason T. Yustein, Christopher DeRenzo, Giedre Krenciute, Hongbo Chi, Stephen Gottschalk. B7-H3-CAR T-cell therapy in immune-competent osteosarcoma models: Regnase-1 KO overcomes limited CAR T-cell expansion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1778.

Deficiency of the CD155-CD96 immune checkpoint controls IL-9 production in giant cell arteritis

Loss of function of inhibitory immune checkpoints, unleashing pathogenic immune responses, is a potential risk factor for autoimmune disease. Here, we report that patients with the autoimmune vasculitis giant cell arteritis (GCA) have a defective CD155-CD96 immune checkpoint. Macrophages from patients with GCA retain the checkpoint ligand CD155 in the endoplasmic reticulum (ER) and fail to bring it to the cell surface. CD155low antigen-presenting cells induce expansion of CD4+CD96+ Tcells, which become tissue invasive, accumulate in the blood vessel wall, and release the effector cytokine interleukin-9 (IL-9). In a humanized mouse model of GCA, recombinant human IL-9 causes vessel wall destruction, whereas anti-IL-9 antibodies efficiently suppress innate and adaptive immunity in the vasculitic lesions. Thus, defective surface translocation of CD155 creates antigen-presenting cells that deviate Tcell differentiation toward Th9 lineage commitment and results in the expansion of vasculitogenic effector Tcells.

MP20-06 ATORVASTATIN WITH DEGARELIX MODULATES TUMOR PROLIFERATION AND THE PROSTATE TUMOR IMMUNE ENVIRONMENT IN A Myc-CaP/AS MURINE MODEL

You have accessJournal of UrologyCME1 Apr 2023MP20-06 ATORVASTATIN WITH DEGARELIX MODULATES TUMOR PROLIFERATION AND THE PROSTATE TUMOR IMMUNE ENVIRONMENT IN A Myc-CaP/AS MURINE MODEL Ashanda Esdaille, Bing Yang, Tanaya Purohit, Kayla Bahr, Ali Ghasemzadeh, Dagna Sheerar, Douglas McNeel, and David Jarrard Ashanda EsdailleAshanda Esdaille More articles by this author , Bing YangBing Yang More articles by this author , Tanaya PurohitTanaya Purohit More articles by this author , Kayla BahrKayla Bahr More articles by this author , Ali GhasemzadehAli Ghasemzadeh More articles by this author , Dagna SheerarDagna Sheerar More articles by this author , Douglas McNeelDouglas McNeel More articles by this author , and David JarrardDavid Jarrard More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003245.06AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Androgen deprivation therapy (ADT) exerts immunomodulatory effects and induces a unique phenotypic response that accumulating data suggests may be improved with the addition of standard medications. Prior studies have shown that ADT and metformin or statins improves oncologic outcomes versus ADT alone. We hypothesize that these outcomes may be due to the effects of statins and ADT in immune and prostate tumor modulation. We aim to investigate whether Atorvastatin±ADT alters tumor growth, proliferation, apoptosis and the immune infiltrate within myc-CaP/AS murine models. METHODS: FVB/NJ, immunocompetent mice were injected subcutaneously with 1x106 Myc-CaP/AS cells. Treatment was initiated at an average tumor volume of 400mm3. Groups were randomized into short term (5 days post ADT) and long term (10 days post) for a total of 8 mice per group per time period. Mice were injected i.p. with: 1) 5µg/g Atorvastatin, q2 days x 3 doses OR q2 days x 5 doses AND/OR 2) Degarelix 25µg/g x 1 dose OR 3) PBS i.p. for controls. Immunohistochemical staining, followed by flow cytometry, was performed using single cell suspensions of harvested tumors. Western blots were performed to assess expression of PCNA and CC3. RESULTS: ADT + Atorvastatin treated tumors had the greatest decrease in volume (Figure 1). Tumor volume differences were present between post-treatment Atorvastatin vs control (p=0.029) and post-treatment Degarelix +Atorvastatin vs control (p=0.018). On flow cytometric analysis, Atorvastatin-treated tumors had the greatest CD8 T-cell expansion over time. MDSC expression decreased significantly over time for ADT and ADT + Atorvastatin-treated tumors. Early ADT and ADT + Atorvastatin decreased tumor proliferation and late Atorvastatin increased apoptosis in myc-CaP/AS tumors. CONCLUSIONS: Atorvastatin+ADT combination therapy decreased tumor volume and tumor proliferation when compared to ADT or statin drug alone. Atorvastatin alone increased CD8 T-cell presence, important for cell death, and in combination with ADT, decreased MDSC expression, which impedes cancer cell death. Demonstrating synergy between androgen deprivation and immunomodulatory agents has to potential to shift the treatment paradigm in patients with high-risk prostate cancer. Source of Funding: AUA/UCF Grant# 017-822959 © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e277 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Ashanda Esdaille More articles by this author Bing Yang More articles by this author Tanaya Purohit More articles by this author Kayla Bahr More articles by this author Ali Ghasemzadeh More articles by this author Dagna Sheerar More articles by this author Douglas McNeel More articles by this author David Jarrard More articles by this author Expand All Advertisement PDF downloadLoading ...

Current Update on Prostate Cancer Immunotherapy

Immunotherapy encompasses a wide array of treatment modalities that utilize our natural defense system to fight against cancer and in recent years has contributed to significant improvement in survival and quality of life in patients. However, its use in prostate cancer has been limited due to low efficacy and lack of effective biomarkers. Prostate cancer’s unfavorable tumor microenvironment characterized by T-cell exclusion and expansion of T-reg cells, along with the possible inhibitory effect of androgen deprivation therapy (ADT) on the immune system further explains this poor response to immunotherapy. Here, we review current immunotherapies and ongoing clinical trials as well as potential biomarkers being investigated to predict treatment responses to immunotherapy. Finally, we discuss the conflicting results on the best approach to sequencing immunotherapy in relation to ADT.

Maternal diet modulates the infant microbiome and intestinal Flt3L necessary for dendritic cell development and immunity to respiratory infection

Poor maternal diet during pregnancy is a risk factor for severe lower respiratory infections (sLRIs) in the offspring, but the underlying mechanisms remain elusive. Here, we demonstrate that in mice a maternal low-fiber diet (LFD) led to enhanced LRI severity in infants because of delayed plasmacytoid dendritic cell (pDC) recruitment and perturbation of regulatory Tcell expansion in the lungs. LFD altered the composition of the maternal milk microbiome and assembling infant gut microbiome. These microbial changes reduced the secretion of the DC growth factor Flt3L by neonatal intestinal epithelial cells and impaired downstream pDC hematopoiesis. Therapy with a propionate-producing bacteria isolated from the milk of high-fiber diet-fed mothers, or supplementation with propionate, conferred protection against sLRI by restoring gut Flt3L expression and pDC hematopoiesis. Our findings identify a microbiome-dependent Flt3L axis in the gut that promotes pDC hematopoiesis in early life and confers disease resistance against sLRIs.

Evaluation of Mycobacterium avium subsp. paratuberculosis isocitrate lyase (IcL) and ABC transporter (BacA) knockout mutants as vaccine candidates.

There has been little success in controlling Johne's disease, caused by Mycobacterium avium subsp. paratuberculosis, due to suboptimal diagnostics and the ineffectiveness of available vaccines. By knocking out BacA and IcL, genes required for MAP survival in dairy calves, two live-attenuated vaccine candidates were created. This study evaluated the host-specific attenuation of MAP IcL and BacA mutants in mouse and calf models, as well as the elicited immune responses. Deletion mutants were generated in MAP strain A1-157 through specialized transduction and found viable in vitro. First, the mutants' attenuation and elicited cytokine secretion were assessed in a mouse model, 3 weeks after intraperitoneal inoculation with MAP strains. Later, vaccine strains were assessed in a natural host infection model where calves received 109CFU oral dose of MAP wild-type or mutant strains at 2 weeks old. Transcription levels of cytokines in PBMCs were evaluated at 12-, 14-, and 16-weeks post-inoculation (WPI) and MAP colonization in tissue was assessed at 4.5 months after inoculation. Whereas both vaccine candidates colonized mouse tissues similarly to wild-type strain, both failed to persist in calf tissues. In either mouse or calf models, gene deletion did not reduce immunogenicity. Instead, inoculation with ΔBacA induced a greater upregulation of proinflammatory cytokines than ΔIcL and wild-type in both models and a greater expansion of cytotoxic and memory T-cells than uninfected control in calves. ΔBacA and wild-type strains significantly increased secretion of IP-10, MIG, TNFα, and RANTES in mice serum compared to uninfected control. This agreed with upregulation of IL-12, IL-17, and TNFα in calves inoculated with ΔBacA at all time points. The ΔBacA also gave rise to greater populations of CD4+CD45RO+, and CD8+ cells than uninfected control calves at 16 WPI. Low survival rate of MAP in macrophages co-incubated with PBMCs isolated from the ΔBacA group indicated that these cell populations are capable of killing MAP. Overall, the immune response elicited by ΔBacA is stronger compared to ΔIcL and it is maintained over two different models and over time in calves. Further investigation is warranted to evaluate the BacA mutant's protection against MAP infection as a live attenuated vaccine candidate.

Systems-based digital twins to help characterize clinical dose-response and propose predictive biomarkers in a Phase I study of bispecific antibody, mosunetuzumab, in NHL.

Phase I oncology clinical trials often comprise a limited number of patients representing different disease subtypes who are divided into cohorts receiving treatment(s) at different dosing levels and schedules. Here, we leverage a previously developed quantitative systems pharmacology model of the anti-CD20/CD3 T-cell engaging bispecific antibody, mosunetuzumab, to account for different dosing regimens and patient heterogeneity in the phase I study to inform clinical dose/exposure-response relationships and to identify biological determinants of clinical response. We developed a novel workflow to generate digital twins for each patient, which together form a virtual population (VPOP) that represented variability in biological, pharmacological, and tumor-related parameters from the phase I trial. Simulations based on the VPOP predict that an increase in mosunetuzumab exposure increases the proportion of digital twins with at least a 50% reduction in tumor size by day 42. Simulations also predict a left-shift of the exposure-response in patients diagnosed with indolent compared to aggressive non-Hodgkin's lymphoma (NHL) subtype; this increased sensitivity in indolent NHL was attributed to the lower inferred values of tumor proliferation rate and baseline T-cell infiltration in the corresponding digital twins. Notably, the inferred digital twin parameters from clinical responders and nonresponders show that the potential biological difference that can influence response include tumor parameters (tumor size, proliferation rate, and baseline T-cell infiltration) and parameters defining the effect of mosunetuzumab on T-cell activation and B-cell killing. Finally, the model simulations suggest intratumor expansion of pre-existing T-cells, rather than an influx of systemically expanded T-cells, underlies the antitumor activity of mosunetuzumab.

Spheromers reveal robust T cell responses to the Pfizer/BioNTech vaccine and attenuated peripheral CD8+ T cell responses post SARS-CoV-2 infection

T cells are a critical component of the response to SARS-CoV-2, but their kinetics after infection and vaccination are insufficiently understood. Using "spheromer" peptide-MHC multimer reagents, we analyzed healthy subjects receiving two doses of the Pfizer/BioNTech BNT162b2 vaccine. Vaccination resulted in robust spike-specific Tcell responses for the dominant CD4+ (HLA-DRB1∗15:01/S191) and CD8+ (HLA-A∗02/S691) Tcell epitopes. Antigen-specific CD4+ and CD8+ Tcell responses were asynchronous, with the peak CD4+ Tcell responses occurring 1week post the second vaccination (boost), whereas CD8+ Tcells peaked 2weeks later. These peripheral Tcell responses were elevated compared with COVID-19 patients. We also found that previous SARS-CoV-2 infection resulted in decreased CD8+ Tcell activation and expansion, suggesting that previous infection can influence the Tcell response to vaccination.

Predictive Biomarkers for Checkpoint Inhibitor Immune-Related Adverse Events.

Immune-checkpoint inhibitors (ICIs) are antagonists of inhibitory receptors in the immune system, such as the cytotoxic T-lymphocyte-associated antigen-4, the programmed cell death protein-1 and its ligand PD-L1, and they are increasingly used in cancer treatment. By blocking certain suppressive pathways, ICIs promote T-cell activation and antitumor activity but may induce so-called immune-related adverse events (irAEs), which mimic traditional autoimmune disorders. With the approval of more ICIs, irAE prediction has become a key factor in improving patient survival and quality of life. Several biomarkers have been described as potential irAE predictors, some of them are already available for clinical use and others are under development; examples include circulating blood cell counts and ratios, T-cell expansion and diversification, cytokines, autoantibodies and autoantigens, serum and other biological fluid proteins, human leucocyte antigen genotypes, genetic variations and gene profiles, microRNAs, and the gastrointestinal microbiome. Nevertheless, it is difficult to generalize the application of irAE biomarkers based on the current evidence because most studies have been retrospective, time-limited and restricted to a specific type of cancer, irAE or ICI. Long-term prospective cohorts and real-life studies are needed to assess the predictive capacity of different potential irAE biomarkers, regardless of the ICI type, organ involved or cancer site.

Immortalized B Cells Transfected with mRNA of Antigen Fused to MITD (IBMAM): An Effective Tool for Antigen-Specific T-Cell Expansion and TCR Validation

Peripheral mononuclear blood cells (PBMCs) are the most widely used study materials for immunomonitoring and antigen-specific T-cell identification. However, limited patient PBMCs and low-frequency antigen-specific T cells remain as significant technical challenges. To address these limitations, we established a novel platform comprised of optimized HLA-matched immortalized B cells transfected with mRNA of a prototype viral or tumor antigen conjugated to MHC class-I trafficking domain protein (MITD) to increase the efficiency of epitope expression in antigen-presenting cells (APCs) essential to expanding antigen-specific T cells. When applied to CMV as a model, the IBMAM platform could successfully expand CMV-specific T cells from low-frequency CMV PBMCs from seropositive donors. Additionally, this platform can be applied to the validation of antigen specific TCRs. Together, compared to using APCs with synthesized peptides, this platform is an unlimited, highly efficient, and cost-effective resource in detecting and expanding antigen-specific T cells and validating antigen-specific TCRs.

Modulating the proliferative and cytotoxic properties of patient-derived TIL by a synthetic immune niche of immobilized CCL21 and ICAM1.

A major challenge in developing an effective adoptive cancer immunotherapy is the ex-vivo generation of tumor-reactive cells in sufficient numbers and with enhanced cytotoxic potential. It was recently demonstrated that culturing of activated murine CD8+ T-cells on a "Synthetic Immune Niche" (SIN), consisting of immobilized CCL21 and ICAM-1, enhances T-cell expansion, increases their cytotoxicity against cultured cancer cells and suppresses tumor growth in vivo. In the study reported here, we have tested the effect of the CCL21+ICAM1 SIN, on the expansion and cytotoxic phenotype of Tumor Infiltrating Lymphocytes (TIL) from melanoma patients, following activation with immobilized anti-CD3/CD28 stimulation, or commercial activation beads. The majority of TIL tested, displayed higher expansion when cultured on the coated SIN compared to cells incubated on uncoated substrate and a lower frequency of TIM-3+CD8+ cells after stimulation with anti-CD3/CD28 beads. Comparable enhancement of TIL proliferation was obtained by the CCL21+ICAM1 SIN, in a clinical setting that included a 14-day rapid expansion procedure (REP). Co-incubation of post-REP TIL with matching target cancerous cells demonstrated increased IFNγ secretion beyond baseline in most of the TIL cultures, as well as a significant increase in granzyme B levels following activation on SIN. The SIN did not significantly alter the relative frequency of CD8/CD4 populations, as well as the expression of CD28, CD25, several exhaustion markers and the differentiation status of the expanded cells. These results demonstrate the potential capacity of the CCL21+ICAM1 SIN to reinforce TIL-based immunotherapy for cancer patients.

Abstract PD2-02: Longitudinal local and peripheral immunologic changes associated with checkpoint inhibition response in murine models of breast cancer

Abstract Immune checkpoint inhibitors (ICI) have significantly enhanced patient survival in some cancer types but yield limited success in breast cancer. ICIs activate anti-tumor immunity by overriding the inhibition of tumor infiltrating lymphocytes (TILs). Clinical trials in triple negative breast cancer (TNBC) patients, who are more likely to harbor TILs within tumor stroma, have demonstrated increased progression-free survival (IMpassion130) and pathologic complete response (KEYNOTE-522) to ICI. Consequently, combinations of ICI and chemotherapy have been FDA-approved for metastatic TNBC. However, the therapeutic benefit of ICIs is highly heterogeneous among breast cancer patients; as such, we sought to model ICI response in vivo to evaluate therapeutic resistance and response heterogeneity, as well as ascertain predictive biomarkers for favorable outcomes to ICI in breast cancer. We used an immunocompetent EMT6 orthotopic mammary tumor model to investigate the efficacy of ICI (anti-PD-L1). Analysis of the primary tumor immune landscape was performed by flow cytometry and single-cell RNA sequencing. Matched longitudinal samples of the tumor microenvironment (collected by fine-needle aspiration) and peripheral blood (PBMC) from mice were profiled by bulk RNA and T-cell receptor (TCR) sequencing to identify systemic genomic alterations and T-cell expansion, respectively. Single-agent ICI robustly suppressed primary tumor growth (p =0.0046) and extended survival (p< 0.0001) beyond the control group in the EMT6 model. The addition of chemotherapy (paclitaxel and/or doxorubicin) demonstrated moderate therapeutic efficacy but failed to enhance ICI benefit. Phenotypic profiling of the tumor microenvironment (TME) revealed increased T cells, dendritic cells, and NK cells in anti-PD-L1 only and chemotherapy combination groups. Despite using a genetically identical tumor model and murine host, we found that PD-L1 blockade induced heterogeneous responses, similar to clinical outcomes in breast cancer patients, ranging from complete response to intrinsic resistance. Analysis of the primary tumor microenvironment showed upregulated signatures of cytotoxic T cell response and activation, specifically inflammatory interferon signaling (both prior to and post ICI administration) that corresponded to favorable response to anti-PD-L1 in individual mice. Longitudinal analysis of the peripheral blood identified modest changes among mice at baseline that progressively deviated by response type (non responders-vs-responder mice). Moreover, mice harbored enriched myeloid signatures and clonal T cell expansion during therapy corresponding to ICI resistance and response, respectively. Further investigations of matched peripheral blood and the primary tumor microenvironment signatures may identify systemic biomarkers and tumor antigen-specific T cell clones to accurately predict ICI response in patients and uncover mechanisms for sensitizing tumors refractory to ICI. In conclusion, we identify a heterogeneously ICI-responsive in vivo model that emulates TNBC patient response to combinatorial ICI approaches. We describe host-specific signatures, specifically myeloid cell responses, that correlate with differential responses to immunotherapy, which may serve as a basis for tracking immunotherapy response in peripheral blood from breast cancer patients. Citation Format: Ann Hanna, Xiaopeng Sun, Quanhu Sheng, Melinda Sanders, Justin Balko. Longitudinal local and peripheral immunologic changes associated with checkpoint inhibition response in murine models of breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr PD2-02.

Preclinical proof of concept for VivoVec, a lentiviral-based platform for in vivo CAR T-cell engineering

BackgroundChimeric antigen receptor (CAR) T-cell therapies have demonstrated transformational outcomes in the treatment of B-cell malignancies, but their widespread use is hindered by technical and logistical challenges associated with ex...

Five-year follow-up of ZUMA-1 supports the curative potential of axicabtagene ciloleucel in refractory large B-cell lymphoma

AbstractIn phase 2 of ZUMA-1, a single-arm, multicenter, registrational trial, axicabtagene ciloleucel (axi-cel) autologous anti-CD19 chimeric antigen receptor (CAR) T-cell therapy demonstrated durable responses at 2 years in patients with refractory large B-cell lymphoma (LBCL). Here, we assessed outcomes in ZUMA-1 after 5 years of follow-up. Eligible adults received lymphodepleting chemotherapy followed by axi-cel (2 × 106 cells per kg). Investigator-assessed response, survival, safety, and pharmacokinetics were assessed in patients who had received treatment. The objective response rate in these 101 patients was 83% (58% complete response rate); with a median follow-up of 63.1 months, responses were ongoing in 31% of patients at data cutoff. Median overall survival (OS) was 25.8 months, and the estimated 5-year OS rate was 42.6%. Disease-specific survival (excluding deaths unrelated to disease progression) estimated at 5 years was 51.0%. No new serious adverse events or deaths related to axi-cel were observed after additional follow-up. Peripheral blood B cells were detectable in all evaluable patients at 3 years with polyclonal B-cell recovery in 91% of patients. Ongoing responses at 60 months were associated with early CAR T-cell expansion. In conclusion, this 5-year follow-up analysis of ZUMA-1 demonstrates sustained overall and disease-specific survival, with no new safety signals in patients with refractory LBCL. Protracted B-cell aplasia was not required for durable responses. These findings support the curative potential of axi-cel in a subset of patients with aggressive B-cell lymphomas. This trial was registered at ClinicalTrials.gov, as #NCT02348216.