The second therapeutic trial for children with hematological malignancies who relapsed after their first allogeneic SCT: long-term outcomes

Donor memory-like NK cells persist and induce remissions in pediatric patients with relapsed AML after transplant

Pediatric and young adult (YA) patients with acute myeloid leukemia (AML) who relapse after allogeneic hematopoietic cell transplantation (HCT) have an extremely poor prognosis. Standard salvage chemotherapy and donor lymphocyte infusions (DLIs) have little curative potential. Previous studies showed that natural killer (NK) cells can be stimulated ex vivo with interleukin-12 (IL-12), -15, and -18 to generate memory-like (ML) NK cells with enhanced antileukemia responses. We treated 9 pediatric/YA patients with post-HCT relapsed AML with donor ML NK cells in a phase 1 trial. Patients received fludarabine, cytarabine, and filgrastim followed 2 weeks later by infusion of donor lymphocytes and ML NK cells from the original HCT donor. ML NK cells were successfully generated from haploidentical and matched-related and -unrelated donors. After infusion, donor-derived ML NK cells expanded and maintained an ML multidimensional mass cytometry phenotype for >3 months. Furthermore, ML NK cells exhibited persistent functional responses as evidenced by leukemia-triggered interferon-γ production. After DLI and ML NK cell adoptive transfer, 4 of 8 evaluable patients achieved complete remission at day 28. Two patients maintained a durable remission for >3 months, with 1 patient in remission for >2 years. No significant toxicity was experienced. This study demonstrates that, in a compatible post-HCT immune environment, donor ML NK cells robustly expand and persist with potent antileukemic activity in the absence of exogenous cytokines. ML NK cells in combination with DLI present a novel immunotherapy platform for AML that has relapsed after allogeneic HCT. This trial was registered at https://clinicaltrials.gov as #NCT03068819.

Second Relapse of Pediatric Patients with Acute Myeloid Leukemia: A Report on Current Treatment Strategies and Outcome of the AML-BFM Study Group

Simple Summary

Children with acute myeloid leukemia (AML) experience high relapse rates of about 30%; still, survival rates following the first relapse are encouraging. Hence, it is critically important to examine the consequences of a second relapse; however, little is known about this subgroup of patients. This retrospective population-based analysis intends to describe response, survival and prognostic factors relevant for the survival of children with second relapse of AML. Treatment approaches include many different therapeutic regimens, including palliation and intensive treatment with curative intent (63% of the patients). Survival is poor; however, patients who respond to reinduction attempts can be rescued with subsequent hematopoietic stem cell transplantation. We deciphered risk factors, such as short time interval from first to second relapse below one year as being associated with a poor outcome. This analysis will help to improve future international treatment planning and patient care of children with advanced AML.

Abstract

Successful management of relapse is critical to improve outcomes of children with acute myeloid leukemia (AML). We evaluated response, survival and prognostic factors after a second relapse of AML. Among 1222 pediatric patients of the population-based AML-Berlin–Frankfurt–Munster (BFM) study group (2004 until 2017), 73 patients met the quality parameters for inclusion in this study. Central review of source documentation warranted the accuracy of reported data. Treatment approaches included palliation in 17 patients (23%), intensive therapy with curative intent (n = 46, 63%) and other regimens (n = 10). Twenty-five patients (35%) received hematopoietic stem cell transplantation (HSCT), 21 of whom (88%) had a prior HSCT. Survival was poor, with a five-year probability of overall survival (pOS) of 15 ± 4% and 31 ± 9% following HSCT (n = 25). Early second relapse (within one year after first relapse) was associated with dismal outcome (pOS 2 ± 2%, n = 44 vs. 33 ± 9%, n = 29; p < 0.0001). A third complete remission (CR) is required for survival: 31% (n = 14) of patients with intensive treatment achieved a third CR with a pOS of 36 ± 13%, while 28 patients (62%) were non-responders (pOS 7 ± 5%). In conclusion, survival is poor but possible, particularly after a late second relapse and an intensive chemotherapy followed by HSCT. This analysis provides a baseline for future treatment planning.

Assessment of chimerism and immunomodulation to prevent post-transplantation relapse in childhood acute myeloblastic leukemia: is it the right approach?

Relapse of acute myeloblastic leukemia (AML) after first allogenic hematopoietic stem-cell transplantation (allo-HSCT) is a fatal complication. Sixty-five children transplanted for AML were included in a prospective national study from June 2005 to July 2008 to explore the feasibility of preemptive immune modulation based on the monitoring of blood chimerism. Relapse occurred in 23 patients (35%). The median time between the last complete chimerism and relapse was 13.5 days (2-138). Prompt discontinuation of cyclosporin and the administration of donor lymphocyte infusions (DLIs) based on chimerism monitoring failed as a preemptive tool, either for detecting relapse or certifying long-term remission.

Feasibility of treating post-transplantation minimal residual disease in children with acute leukemia

Outcomes are poor for patients with hematologic malignancies who experience overt relapse after allogeneic hematopoietic stem cell transplantation (HCT). Data on outcomes of post-transplantation minimal residual disease (MRD) are limited. In this single-institution, retrospective cohort analysis of children with acute leukemia and myelodysplastic syndrome, we document the pattern of relapse with a primary focus on outcomes of post-transplantation MRD. Forty of 93 patients (43%) who underwent a first allogeneic HCT and had systematic pretransplantation and post-transplantation MRD evaluations at +30, +60, +90, +180 days and +1 and +2 years post-transplantation experienced relapse. The median time to relapse was 4.8 months post-transplantation, with a median survival of 4 months post-relapse. Despite frequent, systematic, routine post-HCT disease restaging evaluation, 31 patients (78%) presented with overt disease at the time of relapse. Seven patients with acute leukemia who had post-transplantation MRD presented at a median of 1 month post-transplantation. Owing to rapid disease progression or treatment-related mortality, there was no improvement in survival in those patients whose leukemia was detected in a state of MRD post-transplantation. Our results suggest that early intervention strategies targeting post-transplantation MRD for relapse prevention in acute leukemia may not be feasible.