UCART19, a first-in-class allogeneic anti-CD19 chimeric antigen receptor T-cell therapy for adults with relapsed or refractory B-cell acute lymphoblastic leukaemia (CALM): a phase 1, dose-escalation trial

The prognosis for adults with relapsed or refractory B-cell acute lymphoblastic leukaemia remains poor. UCART19, an allogeneic genome-edited anti-CD19 chimeric antigen receptor (CAR) T-cell product derived from healthy donors and available for immediate clinical use, offers a potential therapeutic option for such patients. The CALM trial is a first-in-human study evaluating the safety and antileukaemic activity of UCART19 in adult patients with relapsed or refractory B-cell acute lymphoblastic leukaemia. This phase 1, open-label study was conducted at eight centres across France, the UK, the USA, and Japan. Adult patients aged 16–70 years with CD19-positive relapsed or refractory B-cell acute lymphoblastic leukaemia who had morphological relapse or a minimal residual disease level of at least 1 × 10–3 and had exhausted standard treatment options were enrolled in the study, which comprised a dose-escalation phase of up to three UCART19 doses followed by a safety expansion phase. Patients underwent lymphodepletion with fludarabine (30 mg/m2 per day intravenously for 3 days) and cyclophosphamide (500 mg/m2 per day intravenously for 3 days) with or without alemtuzumab (1 mg/kg or 40 mg or 60 mg over 5 days) and received UCART19 doses of 6 × 106, 6–8 × 107, or 1·8–2·4 × 108 total CAR T cells intravenously, followed by safety evaluation and disease response assessments. The primary endpoint was incidence and severity of adverse events. Secondary endpoints were the overall response rate, duration of response, relapse-free survival, progression-free survival, and overall survival. This trial is registered with ClinicalTrials.gov (NCT02746952) and is complete. Between Aug 1, 2016, and June 30, 2020, 25 patients were enrolled in the study and treated with UCART19. Median duration of follow-up was 12·8 months (IQR 2·8–24·8). Median age was 37 years (IQR 28–45). 14 (56%) patients were male and 11 (44%) female. 17 (68%) patients were White, two (8%) Black, two (8%) Asian, and four (16%) from other racial or ethnic groups. Three patients developed dose-limiting toxicities (one at each dose level); one had grade 4 cytokine release syndrome and two had grade 4 prolonged cytopenias. Grade 3 or higher cytokine release syndrome was reported in six (24%) patients and grade 3 or higher neurological toxicity in one (4%) patient. Grade 3 or higher infections occurred in seven (28%) patients, and grade 4 prolonged cytopenia in four (16%) patients. Two (8%) patients developed grad