Servier, Pfizer Inc. and Cellectis presented at the 59th American Society of Hematology (ASH) Annual Meeting and Exposition in Atlanta preliminary results from two phase 1 studies of UCART19, an investigational allogeneic anti-CD19 CAR T-cell product, in adult and pediatric patients with relapsed or refractory (R/R) CD19-positive B-cell acute lymphoblastic leukemia (B-ALL). These first-in-human data demonstrated the safety and tolerability of UCART19, resulting in an 83% complete remission rate across the adult and pediatric patient population. Results from the CALM (UCART19 in Advanced Lymphoid Malignancies) Trial: The CALM study (UCART19 in Advanced Lymphoid Malignancies) is an open label, dose-escalation study designed to evaluate the safety, tolerability and anti-leukemic activity of UCART19 in adult patients with R/R B-ALL.

Five out seven patients treated achieved molecular remission at Day 28 post UCAR19. Molecular remission is defined by negative minimal residual disease (MRD). MRD is a measurement of the number of residual leukemic cells that remain after treatment.

Only one Grade 1 cutaneous acute graft versus host disease (GvHD) occurred. No severe neurotoxicity was observed. Cytokine release syndromes (CRS) were mild and manageable except in one patient treated with UCART19 at the first dose level, who developed CRS Grade 4 and neutropenic sepsis leading to death at Day 15.

Results from the PALL (Pediatric Acute Lymphoblastic Leukemia) Trial: The PALL (Pediatric Acute Lymphoblastic Leukemia) study is a phase 1, open label study designed to evaluate the safety and ability of UCART19 to induce molecular remission defined by MRD negativity at Day 28 to enable allogeneic stem cell transplantation in pediatric patients with high-risk R/R B-ALL. Results showed all five children achieved MRD negativity, enabling them to proceed to allogeneic stem cell transplant. Only one Grade 1 cutaneous acute GvHD occurred.

No severe neurotoxicity was observed. Cytokine release syndromes were mild in the majority of cases and were all manageable. Servier is the sponsor of both studies that are active in Europe and the United States.