A Phase I Open Label Dose Escalation Study of MB-CART19.1 in Relapsed and Refractory CD19+ B Cell Malignancies, Interim Preliminary Results in Pediatric ALL, Adult ALL Including CLL Cohorts

• Published in: Blood 2021-11, Vol.138 (Supplement 1), p.3836-3836
• Main Authors: Mackensen, Andreas, Hanssens, Linda, Stelljes, Matthias, Bethge, Wolfgang A, Feuchtinger, Tobias, Künkele, Annette, Aigner, Michael, Yakushina, Alisa, Karitzky, Sandra, Holtkamp, Silke, Assenmacher, Mario, Jurk, Marion, Rauser, Georg, Schneider, Dina, Rossig, Claudia
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2021-152452

Introduction This phase I first-in-human clinical study assesses the safety and preliminary efficacy of a CD19-directed, CAR (4-1BBz) gene-modified, autologous T-cell immunotherapy (MB-CART19.1) intended for use in pediatric and adult patients with relapsed or refractory B-cell acute lymphoblastic leukemia (ALL) and Non-Hodgkin lymphoma (NHL). The study also evaluates the feasibility of a hybrid manufacturing model, combining central and academic manufacturing capabilities with central QP oversight. Methods MB-CART19.1 is evaluated in a Phase I (EudraCT 2017-002848-32) multi-center, open label, dose escalation trial enrolling 33 to 48 patients in three disease cohorts, defined by disease biology and age. Pediatric (1-17 years) and adult patients are eligible if diagnosed with relapsed/refractory (r/r) CD19-expressing B-cell ALL or B-cell high-grade and low-grade (adults) NHL, including chronic lymphocytic leukemia (CLL). Enrollment is still ongoing. The starting material, a fresh patient leukapheresis product, is enriched for CD4/CD8 T-cells, transduced with a lentiviral vector (LV) and expanded using the CliniMACS Prodigy System allowing a high degree of control and consistency of the manufacturing process in both a central and decentralized facilities. MB-CART19.1 is presented as fresh cellular dispersion for single infusion and undergoes central release. Subjects undergo lymphodepletion with fludarabine (25 mg/m 2 daily for 3 days) and cyclophosphamide (1000 mg/m 2 on day -3). Dose escalation includes 3 dose levels (DL) 5x10 5 (DL I), 1x10 6 (DL II), 3x10 6 (DL III) CAR T cells/kg BW, respectively, and a safety dose level 0. The primary objective is to determine the recommended dose of MB-CART19.1. Secondary objectives are preliminary efficacy parameters evaluation of as well as CART persistence. Results Disease cohort I: pediatric ALL and aggressive NHL, 1-17 years. Up to the data lock point for interim analysis (DLP, 02 June 2021), 9 pediatric ALL patients were treated, 6 at DL I and 3 at DL II. All 9 patients completed the 28 days safety follow-up. At DL I, 5 of 6 patients experienced CRS (4 grade I-II, 1 grade III,) starting 5 to 7 days after IMP infusion. Two CRS cases were managed with tocilizumab and resolved within 1-2 weeks. 1 patient developed signs of neurotoxicity (grade IV seizure) concurrently with grade II CRS, which was effectively managed and fully resolved within 48 hours. The event was evaluated as DLT and led to the extension of the