Anti-CD19 chimeric antigen receptor (CAR) T-cell therapy yields a high rate of complete remission (CR) for patients with relapsed or refractory (R/R) B-cell acute lymphoblastic leukemia (B-ALL), including those who have high-risk features, according to a study published in Blood Advances.

The phase 1/2 study (IM19CAR-T; ClinicalTrials.gov Identifier: NCT03173417), conducted at the Lu Daopei Hospital in China, aimed to assess the efficacy and safety of anti-CD19 CAR T cells in patients with R/R B-ALL, including patients with the following high-risk features: extramedullary disease, TP53 mutation, BCR-ABL1+, or relapse after allogeneic hematopoietic stem cell transplantation (allo-HSCT).

The primary endpoints measured short-term efficacy (CR and minimum residual disease [MRD]-negative CR on day 30) and safety (CAR T-cellrelated cytokine release syndrome and neurotoxicity). The secondary endpoints included 1-year overall survival (OS) and leukemia-free survival (LFS) after CAR T-cell therapy.

Of the 115 patients with CD191 B-ALL who were enrolled in the study, 110 participants (62% male) were successfully infused with anti-CD19 CAR T cells. The median patient age was 12 years (range, 2-61 years); however, most patients (71 participants) were between ages 2 and 14 years.

Overall, 93% of patients achieved a morphologic CR. Among these, 87% became MRD-negative at 30 days. Efficacy was observed across all high-risk feature subgroups as well. Among the 110 patients, the 1-year LFS and OS was 58% and 64%, respectively.

A subset of 75 patients (73.5%) received allo-HSCT after CAR T-cell infusion. These patients demonstrated longer LFS (76.9% vs 11.6%; P <.0001) and OS (79.1% vs 32.0%; P <.0001) than those who received CAR T-cell therapy alone, and this was confirmed in a multivariate analysis (hazard ratio [HR], 16.546).

Notably, patients with TP53 mutation had a lower OS (51.9% vs 89.0%; P <.0001 and LFS (42.4% vs 82.6%; P =.0002) than those without TP53 mutation, and this was also confirmed in a multivariate analysis (HR, 0.235).

Age did not significantly affect CR rate, OS, or LFS when comparing patients aged 2 to 14 years with those older than 14 years.

The authors reported mild cytokine release syndrome and neurotoxicity. Cytokine release syndrome occurred in most patients (92%); however, most of these cases (76%) were grade 1 to 2, with a minority (16%) having grade 3 to 4. Overall, neurotoxicity was less common (any grade, 21%; grade 2 to 3, 14%; grade 1, 7%).

The primary limitations of the study were that it was conducted at a single center and the allo-HSCT recipients were not randomly selected.

Despite the high rates of CR, the authors concluded, The relapse rate for subgroups with high-risk features after CAR T-cell treatment alone remains high, and CAR T-cell therapy followed by subsequent consolidative allo-HSCT has showed better LFS and OS in our study. However, the benefit of a subsequent allo-HSCT transplant requires confirmation with randomized allocation.

Disclosures: Some authors have declared affiliations with the pharmaceutical industry. Please refer to the original study for a full list of disclosures.

Zhang X, Lu X, Yang J, et al. Efficacy and safety of anti-CD19 CAR T-cell therapy in 110 patients with B-cell acute lymphoblastic leukemia with high-risk features. Blood Adv. 2020;4(10):2325-2338.

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Benefit From CD19 CAR T-Cell Therapy in Relapsed/Refractory B-Cell ALL - Hematology Advisor