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Treatment with T cells expressing chimeric antigen receptors (CAR) is a promising anticancer therapy. However, this approach has several limitations and has not yet been effectively applied to treat solid tumors. The study by Panowski and colleagues represents the first comparative analysis of multiple single chain fragment variable (scFv)-based anti-CD70 CAR T-cell clones for the development of a clinical product to treat renal cell carcinoma (RCC). Despite the risk of T-cell fratricide due to CD70 expression on T cells, CD70 CAR T cells were produced successfully thanks to the protective CD70 masking phenomenon. Two distinct classes of CAR T cells were identified with different memory phenotypes, activation statuses, and cytotoxic activity. CD70 CAR T cells presented high cytotoxic activity against RCC both in vitro in RCC cell lines and in vivo in patient-derived xenograft mouse models. The off-target effects expected on the lymphoid compartment were confirmed by tissue cross-reactivity staining and in a cynomolgus monkey preclinical model with CD3-CD70 bispecific antibody treatment. The efficacy and the toxicity profile of the lead CD70 CAR T-cell candidate instigated the researchers to proceed with upscaled clinical production. This article emphasizes the influence of the scFv of the CARs on their efficacy:toxicity balance. Ultimately, they successfully managed to develop a highly effective CAR T-cell candidate to treat a solid tumor by an allogeneic approach, thereby overcoming two major hurdles to broaden application of CAR T-cell therapy. See related article by Panowski et al., p. 2610

Chronic myeloid leukemia (CML) is a chronic disease resulting in myeloid cell expansion through expression of the BCR-ABL1 fusion transcript. Tyrosine kinase inhibitors (TKI) have significantly increased survival of patients with CML, and deep responders may consider stopping the treatment. However, more than 50% of patients relapse and restart TKI, subsequently suffering unknown toxicity. Because CML is a model immune system–sensitive disease, we hypothesize that chimeric antigen receptor (CAR) T cells targeting IL1 receptor-associated protein (IL1RAP) in quiescent CML stem cells may offer an opportunity for a permanent cure. In this study, we produced and molecularly characterized a specific monoclonal anti-IL1RAP antibody from which fragment antigen-binding nucleotide coding sequences were cloned as a single chain into a lentiviral backbone and secured with the suicide gene iCASP9/rimiducid system. Our CAR T-cell therapy exhibited cytotoxicity against both leukemic stem cells and, to a lesser extent, monocytes expressing IL1RAP, with no apparent effect on the hematopoietic system, including CD34+ stem cells. This suggests IL1RAP as a tumor-associated antigen for immunotherapy cell targeting. IL1RAP CAR T cells were activated in the presence of IL1RAP+ cell lines or primary CML cells, resulting in secretion of proinflammatory cytokines and specifically killing in vitro and in a xenograft murine model. Overall, we demonstrate the proof of concept of a CAR T-cell immunotherapy approach in the context of CML that is applicable for young patients and primary TKI-resistant, intolerant, or allograft candidate patients. Significance: These findings present the first characterization and proof of concept of a chimeric antigen receptor directed against IL1RAP expressed by leukemic stem cells in the context of CML.

Background INVAC-1 is an optimized DNA plasmid encoding an inactive form of human Telomerase Reverse Transcriptase (hTERT), a universal tumor antigen expressed in most of human tumors with little or no expression in normal somatic cells. Primary pharmacodynamics, safety and toxicology studies showed that INVAC-1 was enzymatically inactive, immunogenically safe and well tolerated. In murine models, we demonstrated that INVAC-1 was able to induce hTERT specific cellular immune responses with CD4+ Th1 effector and memory CD8+ T-cells as well as slow tumor growth and increase survival rate by 50% in tumor-bearing mice. Methods We conducted a First-In-Human (FIH) study, 2-centre, Phase I, open label, 3+3 escalation design and multiple dose study examining the safety and tolerability of INVAC-1 administered at three dose levels (100, 400 and 800 µg) in 26 patients with relapsed or solid refractory tumors. INVAC-1 was administered either by intradermal (ID) injection followed by electroporation (EP) (n=20) or by Tropis® Needle Free Injection System (n=6). Results INVAC-1 vaccination was safe and well tolerated when administered ID (either with EP or by Tropis®) at the three tested doses. Only one treatment-related grade 3 SAE was reported. 58% of patients experienced disease stabilization up to 9.9 months. One-year survival was reached for 65% of patients. INVAC-1 elicited both hTERT specific Th1-dominant CD4 and cytotoxic CD8 T cell responses with no vaccine-induced peripheral immunosuppression. Anti-hTERT immune responses were enhanced by adding anti-PD-1 immune checkpoint inhibitor ex vivo. In addition, INVAC-1 vaccination was able to promote epitope spreading. Finally, correlation analysis between clinical and immunological data showed that patients with OS >1 year presented a significantly higher hTERT immune response after INVAC-1 vaccination compared to patients with OS Citation Format: Julie Garibal, Jacques Medioni, Luis Teixeira, Olivier Adotevi, Marie-Agnès Dragon-Durey, Caroline Laheurte, Claire Germain, Marie Escande, Maria Wehbe, Valérie Doppler, Thierry Huet, Pierre Langlade Demoyen. INVAC-1, an optimized telomerase DNA vaccine in patients with advanced solid tumors: Final results of first-in-human phase I study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT021.

Immunotherapies targeting the PD-1 pathway have profoundly transformed the clinical care of cancer patients for a growing variety of cancer types. However, most patients do not experience durable clinical benefit. The definition of robust and convenient biomarkers of PD-1 therapy efficacy to stratify patients beforehand or early after initiation of the therapy that could guide therapeutic management is still lacking while being a very active research field. Biomarkers described to date include tumor burden, neoantigen load, presence and number of PD-1+ CD8+ at the tumor margin, T-cell inflamed tumor microenvironment and PD-L1 expression by the tumor cells or other immune cells and composition of the gut microbiota. Most of these parameters are closely related/influenced by the presence, activation status and functional capacities of CD8+ T cells infiltrating the tumor site demonstrating their pivotal role for anti-PD-1 mediated anti-tumor efficacy. A population of PD-1high CD8 TILs was consequently described as predictive of PD-1 blockade in NSCLC. The exact contribution for clinical efficacy of TILs versus distinct CD8+ T cells from peripheral origins recirculating to the tumor site remains to be elucidated. Notably, immunological responses to PD-1 blockade at the periphery were described within the very first days following the first therapy dose. Therefore, describing circulating cellular population predictive of PD-1 inhibitor efficacy could represent a convenient, non-invasive and rapid method to assess anti-tumor benefits. Original findings reported in this study identified a circulating CD8 T cell population delineated by the co-expression of TIGIT and PD-1 inhibitory receptors as an early immune marker of anti-PD-1 efficacy in three independent cohorts of cancer patients (two melanoma patient's cohorts and one Merkel-cell carcinoma patient's cohort). The frequency of this double positive (DPOS) population even appeared predictive of PD-1 inhibitor therapy efficacy at baseline in the MCC cohort. Furthermore, to understand the mechanistical relevance of this subset for PD-1 blockade efficacy, we thoroughly described this DPOS T cell subset by flow cytometry, gene expression analysis, anti-tumor reactivity assay and TCR repertoire analysis, and compared it to its double negative (DNEG), PD-1 and TIGIT single positive counterparts. This DPOS subset was enriched in activated and proliferative T cells, retained expression of co-stimulatory molecules and was enriched for common features with Tfc. Moreover, this subpopulation exhibited a specific gene signature, strongly predictive of long-term survival in melanoma patients (TCGA analyses). We demonstrated that this subpopulation was enriched in tumor-specific T-cells (ELISPOT analysis against 11 antigen-derived peptides). Finally, clustering of TCR clonotypes revealed that the DPOS T cell population was significantly enriched in emerging clonotypes in responding patients, after 1 month of anti-PD-1 therapy echoing recent work from others. Our findings provide a compelling rationale to measure PD-1+TIGIT+ CD8 T-cell subset in the blood of cancer patients to monitor early anti-PD1 mediated clinical efficacy, and to use DPOS T cells as a window to study the dynamic changes that underly successful antitumor immunity. Citation Format: Sylvain Simon, Valentin Voillet, Virginie Vignard, Zhong Wu, Camille Dabrowski, Nicolas Jouand, Tiffany Beauvais, Amir Khammari, Cecile Braudeau, Regis Josien, Olivier Adotevi, Caroline Laheurte, Francçois Aubin, Charles Nardin, Samuel Rulli, Raphaël Gottardo, Nirasha Ramchurren, Cheever Martin, Steven P. Fling, Candice D. Church, Paul Nghiem, Brigitte Dreno, Stanley R. Riddell, Nathalie Labarriere. PD-1 and TIGIT co-expression identifies a circulating CD8 T cell population predictive of response to anti-PD-1 therapy in melanoma and Merkel-cell carcinoma patients [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4476.

Despite the critical roles played by IFN-γ+ CD4 Th1 response in tumor immunity, the translation of their potential in clinic remains challenging. Here, we evaluate the clinical significance of circulating anti-tumor CD4 Th1 response in non-small cell lung cancer (NSCLC) patients. 170 naïve-treatment patients were enrolled in this immune monitoring study. The antitumor adaptive Th1 response was assessed by IFN-γ ELISPOT assay in blood lymphocytes using a mixture of eight highly promiscuous and Th1-polarized HLA class II-restricted epitopes from telomerase (TERT). The presence of anti-TERT Th1 response was detected in 59/170 patients (35%). We found an opposite link between anti-TERT Th1 and hyper exhausted T cells co-expressing PD-1+ and TIM-3+ in NSCLC patients. In contrast to hyper exhausted CD8 T cells, the presence of anti-TERT Th1 response was associated with a low rate of hyper exhausted CD4 T cells. We showed that NSCLC stage dissemination is associated with a decrease of anti-TERT Th1 response but an increase of circulating hyper exhausted PD-1+/TIM-3+ CD4 T cells. Notably, anti-telomerase Th1 response and hyper exhausted CD4 T-cells displayed opposite prognosis value in NSCLC. While high level of anti-TERT Th1 cells play a protective role, hyper-exhausted PD-1+TIM-3+ CD4 T cells negatively affect patients’ survival. By using these two circulating immune factors, we stratified patients in distinct prognostic group. Patients with anti-TERT Th1high/CD4 PD-1 TIM-3low immune profile had better overall survival than anti-TERT Th1low/CD4 PD-1 TIM-3high group (median OS : not reached versus 4 months respectively p Citation Format: Caroline Laheurte, Magalie Dosset, Dewi Vernerey, Elodie Lauret Marie Joseph, Laura Boullerot, Vincent Kaulec, Marion Jacquin, Laurie Cuche, Guillaume Eberst, Pascale Jacoulet, Virginie Westeel, Olivier Adotevi. Adaptive CD4 Th1 response against telomerase in blood counteracts T-cell exhaustion in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 575.

Background: After curative local therapy, patients (pts) will experience rising PSA as an early indicator of recurrent prostate cancer and no standard of care exists. Previous studies demonstrated the clinical interest of cyclophosphamide metronomic chemotherapy (CMC) in several cancers. Multifactorial modes of action including immunological and anti-angiogenic effects have been well described by Kerbel et al and Ghiringhelli et al (Cancer Research 2006 and European Journal of immunology 2004, respectively). In the current study, we investigated the safety and immuno-modulatory effects of CMC in prostate cancer patients with PSA failure (biochemical relapse). Methods: We conducted a prospective phase II study to characterize the clinical and immunological interest of CMC in histologically proven prostate cancer patients previously treated by prostatectomy and with biochemical relapse (defined as PSA > 1 and < 20ng/mL and progressive PSA level on 3 different measures). CMC was administered per os, at daily dose of 50 mg during 6 months. PSA level, serum VEGF and immune parameters were monitored every month in blood samples. Results: Thirty-four consecutive pts were enrolled in this study and all received CMC. The median age was 68,3 (range, 56,9-82,1) and all pts had good performance status (ECOG-PS = 0). Gleason Score was 7 in 58%, ≤6 in 13%, and ≥ 8 in 13%. No serious adverse events (grade 3-5) were observed. The most common drug-related adverse event was grade 1 lymphopenia. Baseline PSA was 2,92 ng/mL (range, 1,1-9,35). Twenty-two pts presented stable PSA (64.7%), one patient had partial response defined by >50% decline in the serum PSA (3%), and 11 pts (32%) had PSA progression before 6 months. The immuno-monitoring performed in all pts who completed 6 months CMC. A decrease of immunosuppressive regulatory T cells (Treg) was observed in 56% (10/18). In addition, high rate of activated HLA-DR+ cytotoxic CD8 T cells was also detected in these pts. Furthermore, serum VEGF level decreased at month 1 but it returned to baseline level at the end of treatment in 9/17 pts evaluated (52%). In some patients the correlation was observed between the control of PSA level, the decrease of Treg and VEGF parameters. Conclusions: This study demonstrated the clinical benefit and the ability of CMC to promote the blockage of angiogenesis and immuno-modulatory effect in prostate cancer patients treated for a biochemical relapse. It will be of interest to combine CMC to vaccination in these patients. Citation Format: Olivier Adotevi, Fabien Calcagno, Tristan Maurina, Stefano Kim, Antoine Thiery-Vuillemin, Christophe Borg, Yann Godet, Caroline Laheurte. Antiangiogenic and immunomodulatory effects of metronomic cyclophosphamide (CPM) treatment in prostate cancer patients with PSA failure. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2588. doi:10.1158/1538-7445.AM2014-2588

Background: hTERT is a potential target for cancer immunotherapy because it is highly expressed in tumor cells. To assess the applicability of hTERT-based immunotherapy in NSCLC, we aimed to analyse the natural anti-hTERT CD4 T-lymphocyte responses in advanced NSCLC pts. Methods: We included in a prospective, monocentric study chemonaive NSCLC pts. Pts were required to present stage III or IV tumor, without any immune deficiency or immunosuppressive drug. Before start of chemotherapy, the anti-hTERT T-lymphocyte responses were assessed in whole blood by ELISPOT test. We evaluated the presence or absence of hTERT-specific CD4 T lymphocytes. Thereafter, we analyzed its link with age (< 70 vs. ≥ 70 yrs), ECOG performance status PS (0-1 vs. 2-3), tumoral stage (IIIA vs. IIIb + IV), histological subtype (adenocarcinoma vs. other) and smoking status (never smoker vs. smoker). Statistical analysis was performed using chi-Square or Fischer test. Results: Between February 2008 and October 2009, fifty-one NSCLC pts were included. They presented a stage IIIa (n = 5), IIIb (n = 5) or IV (n = 41) disease. Median age was 66 yrs [39-89]. Nineteen pts presented anti-telomerase CD4 T lymphocytes (37 %); among them we found 14 stage IV (73 %), 13 pts < 70 yrs (68 %), 12 pts with PS 0/1 (63 %), 18 adenocarcinoma/undifferentiated carcinoma (94 %), 13 pts with stable disease/ partial response (68%). Furthermore, all non smokers have anti-telomerase immune response. Conclusions: These preliminary results demonstrate that natural anti-hTERT immune response exists in NSCLC pts, even in case of advanced disease. However the presence of immune response is more frequently found in pts less than 70 yrs with good PS, in non squamous cell carcinoma and in pts with non progressive disease. The study is ongoing to evaluate if baseline anti-hTERT immune response could be used as selection criteria for telomerase vaccination in NSCLC. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 4780.