Retrospective Study of Allogeneic Hematopoietic Stem Cell Transplantation in Philadelphia Chromosome-Positive Leukemia: 25 Years' Experience at Gustave Roussy Cancer Campus

The introduction of tyrosine kinase inhibitor (TKI) therapy has markedly reduced the use of allogeneic (allo) hematopoietic stem cell transplantation (HSCT), which is no longer standard practice in the first chronic phase in chronic myelogenous leukemia and is currently reserved after failure of TKI or in advanced phase of disease. We compared the outcome of Philadelphia chromosome-positive (Ph+) leukemia patients who received a first allo-HSCT in our center in both the pre-TKI era and the TKI era. The primary end point was to compare the 2 groups' overall survival (OS), leukemia-free survival (LFS), cumulative incidence of nonrelapse mortality, and relapse incidence. The secondary end point was to underline in the TKI era the impact of the pretransplantation minimal residual disease (MRD) on the outcomes. A total of 69 patients with Ph+ leukemia were included and their outcomes analyzed. For the purpose of this analysis, we defined 2 groups: group A (n = 39) included patients treated in the pre-TKI era, treated from January 1989 until December 2001, and group B (n = 30) included patients treated in the TKI era, treated from January 2002 until December 2013. Additional analysis was performed in group B for whom detailed TKIs and MRD data were collected. The study took place in our cancer center in the department of HSCT, Villejuif, France. The median follow-up duration for group A was 116.1 months (range, 1.1 to 240.1 months) and for group B was 8.3 months (range, 3.5 to 141.7 months). At 3 years, the LFS and OS were higher in group B (respectively, 66% and 71%) than in group A (respectively, 63% and 57%) (P >.05). The LFS and OS at 3 years of the pretransplantation MRD-negative (< 0.01%) patients were significantly (P <.05) higher (respectively, 83% and 94%) than the pretransplantation MRD-positive patients (respectively, 43% and 46%). Our data, although statistically not significant, suggest better outcomes for Ph+ leukemia patients undergoing allo-HSCT in the TKI era. Mostly TKI does not adversely affect the transplantation outcomes and can be used successfully as a bridge to allo-HSCT, especially in advanced disease. In addition, we highlight the importance of obtaining deep pretransplantation MRD negativity.