Efficacy and safety of tabelecleucel in patients with EpsteinBarr Virus-associated leiomyosarcomas (EBV+ LMS)
Authors: L.S. Kurlander, A. Srinivasan, A. Ghobadi, S. Suser, E. Doubrovina, F. Boulad, L. Mascarenhas, M. Laquaglia, A. Price, G. Behr, B. Shulkin, A. Sudhindra, Y. Wei, M. Hiremath, W. Navarro, R. O'Reilly, S. Prockop
Journal: Annals of Oncology (2018)

Background: EBV+ LMS is a rare cancer that develops in patients with immune deficiency. EBV+ LMS responds poorly to radiation and chemotherapy resulting in limited treatment options and poor outcomes.1 Tabelecleucel is an investigational, off-the-shelf, genetically unmodified, allogeneic T-cell immunotherapy targeting EBV antigens. Here we report the efficacy and safety of tabelecleucel in a subgroup of EBV+ LMS patients from 3 clinical trials. Methods: Tabelecleucel was evaluated in 2 single-center, open-label studies (NCT00002663 [Study 1], NCT01498484 [Study 2]) and a multi-center expanded access protocol (NCT02822495 [Study 3]). Tabelecleucel was given at 1.0–2.0 x 106 cells/kg/dose on days 1, 8, and 15 of every 4-6-week cycle, and imaging was performed before the 1st dose of each cycle. Results: A total of 12 patients with EBV+ LMS received ≥ 1 dose of tabelecleucel, 10 of whom were assessed for responses (1 patient was not evaluable and 1 patient was too early to assess). Using CT-based RECIST 1.1 criteria, 2 patients achieved a partial response (objective response rate = 17%) and 8 patients achieved stable disease. In studies 1 and 2 where longer follow-up is available, 6 of 8 patients survived ≥ 27 months. The median survival (95% CI) is 77.4 (18, NE) months. At the time of this analysis, metabolic responses were available in study 3: 3 of the 4 patients (75%) achieved a metabolic response. The safety profile is consistent with previously reported data;2 no new safety signals have been identified. Conclusions: This analysis represents one of the larger prospective studies of patients with EBV+ LMS. The combination of CT-based and metabolic responses to tabelecleucel, in the context of prolonged survival, demonstrate that tabelecleucel (also known as tab-cel™) may provide clinical benefit in this typically radiation- and chemotherapy-resistant disease. Tabelecleucel is well tolerated in this population of patients. References: 1. Wang Z et al. Cancer Med. 2016;5(12):3437-3444. 2. Prockop SE et al. Blood. 2017;130:4520. Editorial acknowledgement: Editorial assistance in the writing of this abstract was provided by Kathryn Boorer, PhD of KB Scientific Communications, LLC. Clinical trial identification: NCT00002663, NCT01498484, NCT02822495. Legal entity responsible for the study: Atara Biotherapeutics and Memorial Sloan Kettering Cancer Center. Funding: Atara Biotherapeutics and Memorial Sloan Kettering Cancer Center. Disclosure: S. Suser: Research funding: Atara Biotherapeutics. E. Doubrovina: Royalties following licensure of the EBV-specific T-cell bank: Atara Biotherapeutics; Research support and consultant fees: Atara Biotherapeutics. A. Sudhindra, Y. Wei, M. Hiremath, W. Navarro: Employee and stock holder: Atara Biotherapeutics. R. O'Reilly: Royalties following licensure of the EBV-specific T-cell bank: Atara Biotherapeutics; Research support and consultant fees: Atara Biotherapeutics. S. Prockop: Research funding: Atara Biotherapeutics. All other authors have declared no conflicts of interest.