Abstract A028: Memory stem T-cells expressing an optimized CD30-specific chimeric antigen receptor (CAR) efficiently eradicate peripheral T-cell lymphoma in vivo

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; p 80% 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 Escriba-Garcia, Carmen Alvarez-Fernandez, 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.