Novel Tyrosine Kinase Inhibitor Therapy Before Allogeneic Stem Cell Transplantation in Patients with Chronic Myeloid Leukemia: No Evidence for Increased Transplant-related Toxicity

Background: Patients undergoing allogeneic hematopoietic stem cell transplantation (HSCT) for chronic myeloid leukemia (CML) are increasingly likely to have received a novel tyrosine kinase inhibitor (NTKI) after failing imatinib mesylate. It is unknown whether the use of these NTKIs before HSCT increases transplant-related toxicity.

Methods: The outcome of 12 patients with CML (1 in chronic phase, 6 in the accelerated phase, and 5 in the blastic phase) who received dasatinib (n = 2), nilotinib (n = 7), or both (n = 3) before HSCT were retrospectively analyzed.

Results: The median time on treatment was 134 days, and the median time from the end of NTKI therapy to HSCT was 34 days. The preparative regimen was ablative in 8 patients and nonablative in 4. All patients engrafted within 13 days. There was no significant early transplant-related toxicity. One patient developed secondary graft failure after 6 months from the first HSCT that required a second HSCT. Acute and chronic graft-versus-host disease (GVHD) was observed in 7 and 6 patients, respectively. Nine patients achieved a molecular response: 4 complete and 5 major (quantitative reverse transcriptase-polymerase chain reaction <0.05%). Three patients had disease progression by Day 30 after HSCT. Two patients developed disease recurrence after a median of 12 months. After a median follow-up of 10 months, 7 patients were alive in molecular response and 5 patients had died, 4 of disease progression and 1 of extensive chronic GVHD.

Conclusions: Previous treatment with NTKI did not increase transplant-related toxicity in this preliminary experience. Further follow-up and a larger number of patients will be necessary to confirm these observations.