Outcomes of patients with chronic myeloid leukemia (CML) who undergo blood or bone marrow transplantation (BMT) may not be negatively affected by previous exposure to BCR-ABL tyrosine kinase inhibitor (TKI) therapy, study results published in Cancer have shown.

Prior to the availability of BCR-ABL TKIs, BMT was the preferred treatment for patients with CML and human leukocyte antigens (HLA)-matched donors. For patients unable to tolerate long-term TKI therapy, or those not achieving a durable remission on such treatment, allogeneic BMT remains a potential therapeutic option.

This study was conducted to assess late mortality in patients with chronic CML undergoing allogeneic BMT with or without prior exposure to a TKI.

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Data for the cohort of patients with chronic CML enrolled in The Blood or Marrow Transplant Survivor Study who had undergone BMT between 1974 and 2010 and survived for at least 2 years post-BMT were utilized for this analysis.

Of the 447 patients included in the study, 76 (17%) had been exposed to a TKI prior to BMT and 371 (83%) had not.  Some of the clinical characteristics that differed between the 2 groups included the percentages of patients classified as having high-risk disease (51.3% with prior TKI exposure and 28.6% without prior TKI exposure), and the prevalence of graft-versus-host disease (GvHD; 81.6% with prior TKI exposure and 62.8% without prior TKI exposure). Whereas almost all patients not previously exposed to a TKI underwent bone marrow transplant, the majority of those with prior TKI exposure underwent transplantation with peripheral stem cells.

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A comparison of the 10-year overall survival (OS) for these 2 groups showed no significant difference (65.7% with prior TKI exposure vs 73% without prior TKI exposure; P =.3). Similarly, there was no significant different in 10-year OS rates between these 2 groups when patients were categorized according to whether they had undergone BMT within or following the first year of disease diagnosis.

Limitations of this study included the absence of data on TKI use following BMT, as well as information on preventive and management approaches related to GvHD. In addition, data related to TKI resistance mutations were not available.

The study authors noted that “these findings suggest that, for patients who do not tolerate TKI therapy, are nonadherent to TKIs, or develop resistance to TKIs, allogeneic BMT may offer a viable strategy, especially when combined with aggressive efforts at preventing non–CML mortality.”

Reference Wu J, Chen Y, Hageman L, et al. Late mortality after bone marrow transplant for chronic myelogenous leukemia in the context of prior tyrosine kinase inhibitor exposure: a Blood or Marrow Transplant Survivor Study (BMTSS) report [published online August 14, 2019]. Cancer. doi: 10.1002/cncr.32443