HSCT in CML Offers Similar Outcomes to TKI Therapy

In patients with chronic myeloid leukemia (CML), a prospective, long-term study has found that hematopoietic stem cell transplantation (HSCT) and drug therapy yielded similar 10-year survival outcomes. This suggests that even in the era of tyrosine kinase inhibitors (TKIs), HSCT remains a viable option in some patients.

“Use of HSCT has changed over the last decade from an early intervention to a treatment that has been deferred in the lines of therapy,” wrote study authors led by Alois Gratwohl, MD, PhD, of University Hospital Basel in Switzerland. Because TKIs now offer long-lasting remission of the disease, current recommendations now say that HSCT should be considered primarily as a salvage therapy in TKI-resistant or -intolerant patients. But transplant-related mortality has declined, and HSCT may offer a good option for those with advanced disease and low transplant risk.

The study included 669 CML patients enrolled between July 1997 and January 2004 from 143 centers. Of that group, 427 were deemed eligible for HSCT, and were randomized to either HSCT (166 patients) or best available drug treatment (261 patients). The results were published in Leukemia.

The 10-year survival probability for the HSCT group was 0.76, compared with 0.69 for the drug therapy group, which was not significantly different. At the time of analysis, more patients in the HSCT group than in the drug therapy group were in molecular remission (56% vs 39%; P = .005).

Unsurprisingly, significantly more patients who underwent HSCT were free of drug treatment at the time of analysis (56% vs 6%; P < .001).

The causes of death differed between the two groups. In the HSCT group, transplant-related death was the most frequent cause (63%), while disease progression was the most frequent cause in the drug therapy group (60%). There were no significant differences between the groups with regard to how many had a Karnofsky performance score below 80% or how many were reporting symptoms.

The authors noted that disease risk, transplant risk, and treatment allocation were the three key factors in determining outcomes. In patients with a matched donor, when integrating those factors into the analysis, those undergoing HSCT and those with a low European Group for Blood and Marrow Transplantation (EBMT) score had no excess mortality and fared better vs those without a donor. “In contrast, the concept of salvage HSCT in advanced disease despite a high EBMT score failed,” they wrote.

According to the authors, these and other results suggest that patients with a low transplant score and who fail initial TKI therapy could be considered for an early HSCT rather than rescue drug treatment. “Assessment of donor availability will be a prerequisite to achieve this goal; renouncement for HSCT in the absence of a low-risk donor as well,” they concluded.