The selection of further treatment following the achievement of a second remission depends on prior treatment as well as individual considerations. Consolidation chemotherapy followed by HSCT is conventionally recommended, though there are no controlled prospective data regarding the contribution of additional courses of therapy once CR2 is obtained. Unrelated donor HSCT has been reported to result in 5-year probabilities of leukemia-free survival of 45%, 20%, and 12% for patients with AML transplanted in second complete remission, overt relapse, and primary induction failure, respectively.[Level of evidence: 3iiA] The optimum type of preparative transplant regimen and source of donor cells has not been determined, although alternative donor sources, including haploidentical donors, are being studied. Importantly, however, there are no data that suggest total-body irradiation (TBI) is superior compared with busulfan-based myeloablative regimens.[16,17]
There is evidence that long-term survival can be achieved in a portion of pediatric patients who undergo a second transplant subsequent to relapse after a first myeloablative transplant. Survival was associated with late relapse (>6 months from first transplant), achievement of complete response prior to the second procedure, and use of a TBI-based regimen (after receiving a non-TBI regimen for the first procedure).
Clinical trials, including new chemotherapy and/or biologic agents and/or novel bone marrow transplant (autologous, matched or mismatched unrelated donor, cord blood) programs, are also considerations. Information about ongoing clinical trials is available from the NCI Web site
Isolated CNS Relapse
Isolated CNS relapse occurs in 3% to 5% of pediatric AML patients.[19,20] Factors associated with an increased risk of isolated CNS relapse include the following:
- Age younger than 2 years at initial diagnosis.
- M5 leukemia.
- Chromosome 11 abnormalities.
- CNS involvement at initial diagnosis.
The outcome of isolated CNS relapse is similar to bone marrow relapse; in one study, the 8-year overall survival for a cohort of children with an isolated CNS relapse was 26% ± 16%.
Recurrent Acute Promyelocytic Leukemia (APL)
Despite the improvement in outcomes for patients with newly diagnosed APL, approximately 10% to 20% of patients relapse.