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Identifying factors that ameliorates clinical outcomes following CART therapy represents an unmet need. We hypothesized that CAR expression level would have a significant impact on CART efficacy and tested this with CAR30(+) T-SCM(-)LIKE enriched cells. By sorting T-cells according to CAR mean fluorescence intensity in two markedly different populations (CAR(HI) and CAR(LO)), we showed that a high CAR expression enhances antitumor efficacy in vitro, that is sustained after sequential re-exposures to tumor cells and is not associated with T-cell exhaustion or differentiation. Furthermore, we found a correlation between high surface CAR expression and antitumor effect with CAR19(+) T-cells, thus validating our findings with CAR30. Definitive proof of CAR(HI) T-cells improved antitumor efficacy was demonstrated in a human Hodgkin's lymphoma xenograft mouse model, where CAR30-T-SCM(-)LIKE enriched products with high intensity of CAR expression achieved superior tumor control in vivo and longer survival than those with a low intensity of CAR expression. Our data suggest that modulation of CAR intensity of expression represents an additional strategy to increase CART therapy clinical efficacy.

Background While immunotherapy with anti-CD19 chimeric antigen receptor (CAR) T cells has shown significant efficacy in B-cell malignancies, CAR T cells directed against CD30 (CAR30) for the treatment of Hodgkin lymphoma (HL) showed modest antitumor effect, with more than 50% of patients being unresponsive. Several factors related to the infused product and persistence may be relevant to increase clinical efficacy, but further investigation is needed. In this way, CAR expression intensity may play an important role on CAR T cell function, but this has not been systematically explored. Aim We have evaluated the impact of CAR expression intensity on T cell function, cell exhaustion and antitumor efficacy against HL and B cell lymphoma. Methods T cells were generated as previously described (Alvarez-Fernández C et al. 2016) and transduced with third generation lentivirus encoding a 4-1BBz CAR (either CAR30 or CAR19). Two populations of CAR+ T cells were sorted according to mean fluorescence intensity (MFI) of CAR: CARHI (MFI> 5x103) and CARLO (MFI Results CAR30+ T cells were sorted into CARLO (MFI: 1064±124.7) and CARHI (MFI: 7068±1377) (p=0.01). TSCM were highly represented in CARLO compared to CARHI (CD4+: 70.14±1.78% vs. 55.61±5.5%, CD8+: 83.78±3.8% vs 72.2±5.47%, respectively) (p CARHI showed a significantly higher in vitro antitumor effect compared to CARLO (tumor death at 5:1 E:T ratio: 96.6±1.86% vs. 89.1±3.83%; 1.25:1 E:T ratio: 84.61±4.7% vs. 31.15±19.79%; CARHI vs. CARLO, respectively) (p At 24h and 72h of antigen encounter, expression of inhibitory markers was determined in both CAR30+ populations. While CD4+ T cells showed significantly higher PD1 and TIM3 co-expression in CARHI compared to CARLO (p A similar kinetics was observed in CAR19+ T cells, suggesting that it could be related to an inhibitory control of activation, but not cellular exhaustion. To confirm this, functional performance of CAR30HI and CAR30LO T cells was evaluated by continuous tumor exposure. CAR30HI function persisted after sequential re-exposition (n=5) to tumor cells; in contrast, the CAR30LO subpopulation showed progressive loss of cytotoxic activity (i.e., tumor death at ratio E:T 5:1 after 4 expositions: 0% vs. 91.96%, CAR30LO and CAR30HI respectively; representative of 2 independent studies with different donors). To assess if these results were consistent in vivo, the antitumor effect of CAR30HI and CAR30LO were evaluated in a xenograft model of HL. Mice treated with CAR30HI T cells showed reduced tumor growth compared to those treated with CAR30LO T cells, which translated into an improved survival. Conclusion We have shown that high expression of a CAR (either CAR30 or CAR19) confers an enhanced in vitro antitumor effect against HL and B cell lymphoma. This effect is maintained after repetitive exposures to tumor cells and is not associated with T cell exhaustion or differentiation. Notably, this enhanced antitumor effect was also found in vivo. Our data shows that CAR expression intensity should be considered as an additional important factor to improve the efficacy of CAR T cells. Disclosures Sierra: Jazz Pharmaceuticals: Research Funding; Pfizer: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Daiichi Sankyo: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Astellas: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Gilead-Kite: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees.

Invariant natural killer T (iNKT) cells are a small population of T lymphocytes that expresses an invariant T cell receptor with a unique specificity for glycolipid antigens. Their activation using the glycolipid alpha-galactosylceramide (alpha-GalCer) triggers innate and adaptive immune responses. The use of alpha-GalCer in preclinical models as a single antitumor treatment showed moderate effect, but its efficacy in cancer patients was less effective. In addition, this glycolipid induces long-term iNKT-cell anergy precluding the possibility of retreatment. Recently, the first murine iNKT-cell agonistic antibody, NKT14m, has been developed. Here, we analyzed, for the first time, the antitumor efficacy of NKT14m in a B-cell lymphoma model. In a therapeutic setting, a single dose of NKT14m had a moderate antitumor efficacy that was associated with an increase of IFN-gamma producing iNKT cells even after a second dose of the NKT14m antibody. Importantly, the combination of a single dose of NKT14m with cyclophosphamide had a potent antitumor efficacy and long-lasting immunity in vivo. Our findings provide the first evidence of the in vivo antitumor efficacy of NKT14m antibody, showing that, either alone or in combination with chemotherapy, induces an effective antitumor response. These results open new opportunities for iNKT-cell mediated immunotherapy to treat B-cell lymphoma.

Background: Up to 20% of patients with advanced Hodgkin lymphoma (HL) are not cured with current chemo-immunotherapy treatments. Adoptive immunotherapy (AIT) with mature T-cells modified with a chimeric antigen receptor (CAR) holds promise for the treatment of various types of B cell lymphoma. The CD30 antigen, expressed in virtually all HL tumor cells, is absent in most healthy tissues, thus representing an ideal target for AIT of HL. In contrast to CAR19 for B cell malignancies, efficacy of CAR30 T-cells for Hodgkin and other CD30 lymphomas remains modest. Thus, novel approaches are needed to significantly improve the clinical efficacy of this approach. To this end, we used a novel antigen binding domain of a CD30 mAb, unaffected by soluble CD30 protein, as part of a chimeric antigen receptor (CAR) coupled to the 4.1BB and ζ chain endodomains, and transduced memory stem T-cells (TSCM) in an effort to ensure efficient engraftment, prolonged persistence, and enhancement of in vivo antitumor activity. To evaluate the feasibility of ex vivo expansion and antitumor efficacy of genetically-modified TSCM with a novel CD30-specific CAR that recognizes a membrane-proximal epitope of the CD30 molecule for the treatment of HL. Methods: A second-generation CD30-41BBz-EGFRt CAR was developed using a scFv that recognizes a membrane-proximal epitope of the CD30 protein. TSCM cells were generated with IL-7, IL-15 and IL-21, and transduced on day 2 of culture with a third-generation lentiviral vector encoding the CD30-CAR. The HL derived cell line L540 was used as tumor model. Tumor-specific cytotoxicity and cytokines were analysed at 24 hours. The in vivo antitumor efficacy was tested in a NSG (NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ) mouse model of HL xenografted with 2,5x10^6 L450 cells. Results: After 10 days, TSCM represented the majority of T-cells in culture (50.38±5.47 % for CD4+ and 70.84 ± 3.36 % for CD8+ TSCM, respectively) with a very high expression of CD30-CAR (77 ± 3.64 % in CD4+ and 83.12 ± 4.25 % in CD8+ TSCM, respectively). Expression of CD30 protein in TSCM increased over the culture period, peaking at day 8 in both CD4+ (17.5 ± 4.17 %) and CD8+ TSCM (42.37 ± 5.75 %), respectively. Despite these high levels of CD30 expression, TSCM expanded ex vivo very efficiently (CD4+ CD30-CAR: 97.24 ± 26.2 fold expansion, and CD8+ CD30-CAR: 96.79 ± 22.84 fold expansion, respectively), although lower than TSCM transduced with a CD19-CAR (CD4+ CD19-CAR: 161.96±35.9 fold expansion, and CD8+ CD19-CAR: 163.25 ± 26.51, fold expansion, respectively). Bulky CD30-CAR TSCM mediated very efficient in vitro tumor cytotoxicity (tumor cell death at 5:1 ratio: 85.25% vs. 0% with untransduced TSCM), while control CD30- targeT-cells were not killed. In addition, we evaluated the antitumor efficacy of CD30-CAR TSCM in vivo. Upon adoptive transfer of 10x10^6 bulk (CD4+ and CD8+) TSCM into NSG mice engrafted with L540 (2,5x10^6 subcutaneously), complete eradication of HL was observed. In addition, in a stress L540 model where equal numbers of CAR30 T-cells were infused at a low, suboptimal dose (i.e, 50% of effective T-cell dose to induce complete remission), highly enriched CAR30 TSCM (>70% of TSCM) had significantly antitumor effect compared to the infusion of CAR30 T-cells predominantly represented by effector cells ( Citation Format: Carmen Alvarez-Fernández, Laura Escribà-Garcia, Ana Carolina Caballero, Jorge Sierra, Javier Briones. Highly enriched memory stem T-cell subsets (TSCM) expressing a novel CAR30 have enhanced antitumor effect in Hodgkin lymphoma [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A023.

Peripheral T-cell lymphomas (PTCL) represent the most aggressive form among non-Hodgkin lymphomas with a very poor prognosis (5-year survival of 30%), demanding innovative novel treatment strategies. Adoptive immunotherapy with chimeric antigen receptor (CAR) T-cells has demonstrated its therapeutic potential in advanced B-cell hematologic malignancies. However, its application to PTCL remains a formidable challenge mainly due to a lack of truly tumor-specific antigens that are not expressed on normal T-cells. Anaplastic large T-cell lymphomas (ALCL) and several other subtypes of PTCL express CD30, which is also expressed by activated normal T-cells but no other healthy tissues. Indeed, brentuximab-vedotin, an anti-CD30 antibody-drug conjugate, has shown some clinical efficacy in PTCL and ALCL patients although duration of responses is short in the majority of cases. Here, we developed a refined CD30-CAR T-cell approach to target CD30+ PTCL as a potential novel therapeutic strategy. We selected a novel targeting domain that is unaffected by soluble CD30 protein (Nagata S et al., Clin Cancer Res 2002) to prevent blockade of the CD30-CAR. Moreover, we optimized the therapy by using memory stem T-cells (TSCM) to promote engraftment and persistence of CD30-CAR T-cells after transfer.TSCM were generated with CD3/CD28 costimulation in presence of IL-7, IL-15 and IL-21 (Alvarez C et al., J Transl Med 2016). On day 2 of culture, cells were transduced with a third-generation lentiviral vector encoding the CD30-41BBz-EGFRt CAR. The cell line Karpas 299 (ALCL) was used as tumor model. Cytotoxicity assay was performed at 24 hours and the tumor cell death was detected by luminiscence. Mice were injected with Karpas 299 tumor cells (2x10^6 cells/mice; iv) and were treated with CD30-CAR TSCM (1x10^7 cells/mice; iv) when the tumor was established (day 10). Mice were followed daily for survival. The presence of CD30-CAR TSCM in lymphoid organs and their expression of immune checkpoint molecules (i.e., TIM-3, LAG-3) were analyzed at the end of the in vivo study by flow cytometry. TSCM were the most prevalent T-cell subset at day 10 of culture (84±3.1% of total cells), and the CD30-CAR expression was 82.8±1.0% in CD4+ TSCM and 85.2±2.0% in CD8+ TSCM. Although CD30 protein was detected in a fraction of activated T-cells in culture, CD30-CAR TSCM could be expanded ex vivo (CD4+ CD30-CAR TSCM: 96.0±3.2 fold expansion; CD8+ CD30-CAR TSCM: 109.0±4.2 fold expansion). CD30-CAR TSCM conferred specific cytolytic activity against Karpas 299 cells in vitro (tumor cell death 5:1 (effector:target) ratio: 70.2±5.1% vs. 0% with untransduced TSCM; p80% of detected CD4+ and CD8+ T-cells) were still present in lymphoid organs (bone marrow, spleen and lymph nodes) of surviving mice at 50 days after infusion. Tumor-bearing mice also showed CD30-CAR T-cells in their lymphoid organs (80% of total CD4+ and CD8+ T-cells) and in the tumor (67.5% of detected T-cells). Interestingly, a high expression of exhaustion markers TIM-3 (74%±6.8%) and LAG-3 (34%±9.7%) were found on those tumor-infiltrating lymphocytes (TILs). Collectively, our data demonstrate that TSCM cells can be efficiently transduced and ex vivo expanded with a novel CD30-CAR and confer potent antitumor efficacy against CD30+ PTCL in vitro and in vivo, with a potential improvement of the therapy using an immune checkpoint blockade for either TIM-3 or LAG-3. Our findings suggest the potential to improve outcome of patients with CD30+ PTCL through adoptive therapy with CD30-CAR modified T-cells. Citation Format: Laura Escribà-Garcia, Carmen Alvarez-Fernández, Ana Carolina Caballero, Rydzek Julian, Einsele Hermann, Jorge Sierra, Michael Hudecek, Javier Briones. Memory stem T-cells expressing an optimized CD30-specific chimeric antigen receptor (CAR) efficiently eradicate peripheral T-cell lymphoma in vivo [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A028.

BACKGROUND: The generation of new immunogens able to elicit strong specific immune responses remains a major challenge in the attempts to obtain a prophylactic or therapeutic vaccine against HIV/AIDS. We designed and constructed a defective recombinant virus based on the HIV-1 genome generating infective but non-replicative virions able to elicit broad and strong cellular immune responses in HIV-1 seropositive individuals. RESULTS: Viral particles were generated through transient transfection in producer cells (293-T) of a full length HIV-1 DNA carrying a deletion of 892 base pairs (bp) in the pol gene encompassing the sequence that codes for the reverse transcriptase (NL4-3/ΔRT clone). The viral particles generated were able to enter target cells, but due to the absence of reverse transcriptase no replication was detected. The immunogenic capacity of these particles was assessed by ELISPOT to determine γ-interferon production in a cohort of 69 chronic asymptomatic HIV-1 seropositive individuals. Surprisingly, defective particles produced from NL4-3/ΔRT triggered stronger cellular responses than wild-type HIV-1 viruses inactivated with Aldrithiol-2 (AT-2) and in a larger proportion of individuals (55% versus 23% seropositive individuals tested). Electron microscopy showed that NL4-3/ΔRT virions display immature morphology. Interestingly, wild-type viruses treated with Amprenavir (APV) to induce defective core maturation also induced stronger responses than the same viral particles generated in the absence of protease inhibitors. CONCLUSIONS: We propose that immature HIV-1 virions generated from NL4-3/ΔRT viral clones may represent new prototypes of immunogens with a safer profile and stronger capacity to induce cellular immune responses than wild-type inactivated viral particles. This study was supported by grants FIS PI050265, FIS PI040503, FIS PI070291, FIS Intrasalud 080752, FIS PS09/01297, FIS PI10/02984, SAF2006-26667-E, FIT 09-010-205-9, FIPSE 36780/08, Fundación Mútua Madrileña, TRA-094, EC10-153, ISCIII-RETIC RD06/0006, HIVACAT–HIV Development Program in Catalonia, FIPSE 36630/07, UE Program Health 2009 CHAARM. Spanish Health Institute Carlos III (ISCIII) and the Health Department of the Catalan Government (Generalitat de Catalunya). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Sí

Introduction: Adoptive transfer of gene modified T cells (ACT) with chimeric antigen receptors (CARs) is becoming a clinically relevant immunotherapy approach for cancer treatment. One important question involves the selection of the T cell subpopulation for gene-modified ACT. Recent preclinical studies have shown that memory stem T cells (TSCM) (with a phenotype CD45RO-, CD45RA+, CCR7+, CD62L+, CD95+) have higher in vivo persistence, self-renewal, proliferative and antitumor capacities compared to other memory and effector T cell subpopulations. For these reasons, TSCM may represent an ideal candidate for ACT with CARs. Ex vivo generation of TSCM rely on CD3/CD28 costimulation and the use of cytokines such as IL-7 and IL-15 during the entire culture period. However, a strong costimulation may induce differentiation of TSCM to effector memory T cells. In this study, we have analyzed the impact of the costimulation length and the addition of the IL-21 on the ex vivo generation of TSCM cells. Methods: Purified naïve T cells from healthy donors were cultured in the presence of anti-CD3/CD28 coated beads, IL-7, IL-15 and/or IL-21 (25ng/ml). T cells phenotype from the different memory (TCM, TSCM and TEM) and effector subpopulations were analyzed by multiparametric flow cytometry. Particularly, TSCM were identified by a specific plotting strategy. Briefly, CD4+ and CD8+ cells were gated and a CCR7 against CD45RO plot were used to select CCR7+ CD45RO- cells in each subpopulation. Within these cells, a CCR7+ CD45RO- CD45RA+ cell population was identified by plotting CCR7 against CD45RA. Then, CD27 was used to detect CCR7+ CD45RO- CD45RA+ CD27+ cells. Finally, a plot of CD95 against CCR7 was used to identify the CCR7+ CD45RO- CD45RA+ CD27+ CD95+ cell population. Cellular proliferation was analyzed by flow cytometry using CFSE. Results: A short (48 hours) anti-CD3/CD28 costimulation of naïve T cells combined with IL-7 and IL-15 significantly increased the frequencies of CD4+ and CD8+ TSCMex vivo, compared to a long (10 days) costimulation (34.6%±4.4% vs 15.6%±4.24% for CD4+; p=0.008, and 20.5%±4.00% vs 7.7%±2.53% for CD8+; p=0.02). Moreover, the addition of IL-21 to this condition further enhanced the enrichment (47.9%±4.1% vs 34.6%±4.4% for CD4+; p=0.006, and 34.1%±3.5% vs 20.5%±4% for CD8+; p Conclusion: We show that these refined in vitro conditions significantly increase the frequencies and expansion of TSCM. Since the reagents used are available in a clinical grade setting, these data may have relevant clinical implications for the generation of this memory T cell subset for adoptive cell therapy with CAR-T cells of patients with cancer. Disclosures No relevant conflicts of interest to declare.