CD19-CAR-T cells are an effective therapy of post-transplant relapse in B- ALL patients: Real-World Data from Germany.

Patients with precursor B cell acute lymphoblastic leukemia (pB-ALL) who have relapsed subsequent to allogeneic stem cell transplantation (alloHSCT), have relapsed more than once, or are resistant upfront have a dismal prognosis. CD19-targeted CAR-T cells have evolved as potent immune therapies. Tisagenlecleucel (Tisa-cel) is a commercial autologous CD19-directed CAR-T cell product. We performed a retrospective study inviting all CAR-T cell centers in Germany to participate. Eighty-one patients with pB-ALL were included. Twenty-eight days after CAR-T cell infusion, 71 patients (87.7%) were in CR, and 8 (9.9%) were in NR. At two years, the probabilities of event-free, relapse-free and overall survival were 45.3% (pEFS), 51.7% (pRFS) and 53.2% (pOS), respectively. pEFS was not different in patients without (n=16, 55.0%) vs. with prior alloHSCT (n=65, 43.4%). In patients treated after alloHSCT, the time to relapse after alloHSCT was a strong predictor of outcome. Patients relapsing within 6 months of alloHSCT had a disappointing pEFS (pOS) of 18.4% (16.0%); pEFS (pOS) for those relapsing later was 55.5% (74.8%). Our study provides real-world experience in pediatric, adolescent and young adult patients with ALL treated with Tisa-cel, where the majority of patients were treated after having relapsed post-alloHSCT. A total of 45.3% were rescued with a single dose of Tisa-cel. Our novel finding that ALL patients post-alloHSCT had by far a better pEFS if relapse occurred beyond 6 months might be helpful in clinical decision-making and motivates studies to uncover the reasons.