Individualized Intervention Guided by BCR-ABL Transcript Levels after HLA-Identical Sibling Donor Transplantation Improves HSCT Outcomes for Patients with Chronic Myeloid Leukemia

The aim of this study was to determine the effect of individualized intervention guided by BCR-ABL transcript levels after hematopoietic stem cell transplantation (HSCT) on relapse and leukemia-free survival (LFS) of patients with chronic myelogenous leukemia (CML). Eighty-four consecutive patients who received HLA-identical sibling HSCT were enrolled. The patients were conditioned with a modified busulfan and cyclophosphamide regimen, and received stem cells from a HLA-identical sibling donor. Patients were identified as high risk of relapse based on serial monitoring of post-HSCT BCR-ABL transcript levels, and patients in the high-risk group were given individualized intervention. Interventions included immunosuppressant withdrawal, modified donor lymphocyte infusion, and imatinib mesylate. Engraftment was successful in all patients. Twenty-eight patients were categorized as high risk because of higher post-HSCT BCR-ABL transcript levels and received intervention. The 56 low-risk patients received no intervention. Twenty-five high-risk patients achieved complete molecular remission at a median of 49 days (range: 18-232 days) after intervention. Two high-risk patients and 1 low-risk patient ultimately relapsed, the 4-year relapse rate was 3.9% ± 4.4%. Overall 4-year survival was 89.0% ± 7% and the 4-year LFS was 89.2% ± 6.8%. All surviving patients remains in complete molecular remission after a median of 1481 (1040-1794) days follow-up. Individualized intervention based on the post-HSCT BCR-ABL transcript level can decrease relapse and increase LFS of patients with CML after HLA-identical sibling HSCT.