Outcomes in children with first-relapsed acute lymphoblastic leukemia in Japan: Results from JCCG Study JPLSG-ALL-R08.

BACKGROUND/OBJECTIVES: The Berlin-Frankfurt-Münster (BFM)-S classification is a crucial prognostic indicator in children experiencing first-relapsed acute lymphoblastic leukemia (ALL). Early molecular response to therapy, evaluated by measurable/minimal residual disease (MRD), has a significant impact on the survival of patients with childhood ALL. Applying risk stratification based on the BFM-S classification and MRD response after induction, the first nationwide prospective multicenter study, ALL-R08, was conducted in children with first-relapsed ALL in Japan.

METHODS

The ALL-R08 study comprised two parts: ALL-R08-I, an observational study aimed at obtaining an overall picture of outcomes in first-relapsed childhood ALL, and ALL-R08-II, a clinical trial for the non-T-ALL S2 risk group. In ALL-R08-II, patients with an MRD level of ≥10 at the end of induction therapy were assigned to undergo allogeneic hematopoietic stem cell transplantation (allo-HCT), whereas those with an MRD level less than 10 and isolated extramedullary relapse continued to receive chemotherapy.

RESULTS

In total, 163 patients were enrolled in the ALL-R08 study, and 82 and 81 patients were enrolled in the ALL-R08-I and the ALL-R08-II, respectively. In ALL-R08-I, the probability of 3-year event-free survival (EFS) for patients with S1, S2, S3, S4, and post-HCT groups was 83% ± 15%, 37% ± 11%, 28% ± 8%, 14% ± 7%, and 0%, respectively. In the ALL-R08-II trial, 3-year EFS in patients with post-induction MRD less than 10 and ≥10 was 70% ± 9% (n = 27) and 68% ± 8% (n = 31) (p = .591), respectively.

CONCLUSIONS

ALL-REZ BFM-type treatment is equally effective for children with first-relapsed ALL treated according to the Japanese frontline protocols and for children with first-relapsed ALL treated according to the BFM-type frontline protocols.