Pretransplant imatinib can improve the outcome of nonmyeloablative stem cell transplantation without increasing the morbidity in Philadelphia chromosome-positive chronic myeloid leukemia

Prognostic factors for outcomes of allogeneic stem cell transplantation in chronic phase chronic myeloid leukemia in the era of tyrosine kinase inhibitors

The aim of this study was to estimate the prognostic factors for the outcomes of chronic myeloid leukemia (CML) patients receiving allogeneic stem cell transplantation (SCT) in chronic phase (CP) in the era of tyrosine kinase inhibitors (TKIs). Ninety-seven patients who underwent allogeneic SCT in CP were analyzed. Forty-seven were TKI-naïve at the time of transplant, and 50 received TKI(s) treatment before transplantation. After a median follow-up of 115.8 months, the 4-year overall survival and event-free survival were 80.4 and 58.8%, respectively. Multivariate analysis showed that there were no differences in survival outcomes based on prior TKI therapy. Older age was a prognostic factor for higher treatment-related mortality (TRM), and the type of graft source and younger age were associated with relapse, but prior TKI therapy and disease status at the time of transplant were not associated with either TRM or relapse. Additionally, a major molecular response at 1 month and an MR(4.5) at 3 months were important predictors of favorable long-term outcomes. This study demonstrates the prognostic factors for the outcomes of allogeneic SCT in CP CML and shows that survival outcomes were not affected by the administration of long-term multi-TKI treatment prior to transplantation.

Challenges for allogeneic hematopoietic stem cell transplantation in chronic myeloid leukemia in the era of tyrosine kinase inhibitors

Following the introduction of the tyrosine kinase inhibitor (TKI) imatinib in the treatment of chronic myeloid leukemia (CML) patients, the allogeneic hematopoietic stem cell transplantation (HSCT) scene in CML has changed dramatically. The number of patients receiving HSCT in first chronic phase (CP) has declined rapidly, as allogeneic HSCT in CP is now performed in these patients only in case of failure or intolerance of TKIs. Second, those CML patients who undergo allogeneic HSCT represent a selection of high-risk patients due to more advanced disease with high rates of accelerated or blast phase (being associated with an increased relapse risk), advanced age and relevant co-morbidities. Efforts at meeting these special challenges are being developed: treatment with TKIs aims to improve the pre-transplant remission status before HSCT. Dose-reduced conditioning protocols were introduced to decrease transplant-related mortality in patients with co-morbidities or older age. In the post-transplant period, TKIs may be administered for prophylaxis and for treatment of post-transplant relapse. Still, the outcome of patients in advanced CML phases remains guarded, and requires an improvement in current transplant strategies.

Allogeneic stem-cell transplantation provides excellent results in advanced stage chronic myeloid leukemia with major cytogenetic response to pre-transplant imatinib therapy

To determine the impact of imatinib therapy prior to allogeneic stem-cell transplantation in advanced stage chronic myelogenous leukaemia (CML), 30 CML patients who had received imatinib as part of pre-transplant treatment were analysed, with special emphasis on the cytogenetic response to imatinib therapy shortly before transplantation. Median patient age was 51 years (range, 24 - 64). At the time of transplantation all patients were in second or higher chronic phase (CP). The median follow-up after allogeneic transplantation was 360 days (range, 24 - 1524). Cox regression analysis revealed that the quality of cytogenetic response was a prognostic factor for transplant-related mortality (p = 0.050), relapse incidence (p = 0.015), leukaemia-free survival (p = 0.002) and overall survival (p = 0.006). A cytogenetic response with <35%BCR-ABL-positive interphase nuclei in FISH analysis from bone marrow was associated with a probability of overall survival of 81% at 3 years. In conclusion, our data suggest that advanced stage CML has an excellent outcome after allogeneic haematopoietic stem-cell transplantation when transplanted in the phase of cytogenetic response to imatinib.

The effects of imatinib mesylate treatment before allogeneic transplantation for chronic myeloid leukemia

The impact of imatinib mesylate (IM) treatment for chronic myeloid leukemia (CML) on subsequent allogeneic transplantation is uncertain. To better understand this relationship, we retrospectively compared 145 patients with CML receiving IM for a minimum of 3 months before allogeneic hematopoietic cell transplantation (HCT) to 231 patients with CML who did not. IM treatment was associated with no increase in early hepatotoxicity or engraftment delay after HCT compared with the historical cohort. In addition, there was no statistically significant difference in the IM-treated cohort compared with the historical cohort with regard to overall survival, disease-free survival, relapse, and nonrelapse mortality. For chronic-phase (CP) patients, IM response prior to HCT was associated with post-HCT outcome. Patients who underwent transplantation in CP with a suboptimal response or a loss of response on IM had a statistically significant higher hazard of mortality when compared with CP patients who achieved a complete cytogenetic response (CCR) or major cytogenetic response (MCR) on IM (HR=5.31, 95% confidence interval [CI] 1.13-25.05, P=.03). These data indicate that pre-HCT IM is not associated with increased transplant-related morbidity (TRM) or poorer outcomes. However, patients with a suboptimal or loss of IM response before HCT do worse, suggesting a more aggressive disease course for these patients.

Role of Allogeneic Stem Cell Transplantation for Adult Chronic Myeloid Leukemia in the Imatinib Era

Due to superior survival in the short to medium term, the first-generation ABL kinase inhibitor imatinib mesylate has generally supplanted all other therapies as the initial treatment of choice in chronic phase chronic myeloid leukemia. The role of allogeneic stem cell transplantation (alloSCT) has shifted from a preferred first-line therapy to a possible second- or third-line therapy. However, despite generally excellent responses to imatinib, some patients respond poorly or lose response, and the risk-benefit equation in these cases may rapidly shift in favor of the alloSCT option. These patients need to be identified as soon as possible so that the alloSCT option can be applied while they are still in controlled chronic phase. Monitoring of imatinib response in patients who have suitable donors and are potentially eligible for alloSCT needs to be frequent, sensitive, and accurate. Clear criteria for switching from imatinib therapy to the alloSCT option should be established for each patient according to the specific risk profile of the transplant. The potential efficacy and safety of clinical trials combining reduced intensity alloSCT with ABL kinase inhibitor therapy warrants further consideration.

Allogeneic haematopoietic cell transplantation for chronic myelogenous leukaemia in the era of imatinib: a retrospective multicentre study

OBJECTIVE

To analyse the results of allogeneic haematopoietic cell transplantation (HCT) in patients with advanced stages of Philadelphia chromosome-positive chronic myelogenous leukaemia (CML) who had previously been treated with imatinib mesylate (IM).

METHODS

We analysed the outcome of 61 patients with CML who had received allogeneic HCT from sibling (n = 18) or unrelated (n = 43) donors after having been treated with IM. Forty-one patients had received IM because of accelerated or blast phase CML. Conditioning therapy contained standard doses of busulfan (n = 25) or total-body irradiation (n = 20) in conjunction with cyclophosphamide in the majority of cases. Sixteen patients received dose-reduced conditioning with fludarabine-based regimens.

RESULTS

The incidence of grades II-IV and III-IV graft-versus-host disease was 66% and 38% respectively. The probability of overall survival (OS), disease-free survival (DFS) and relapse at 18 months for the whole patient cohort were 37%, 33% and 24% respectively. The probability of non-relapse mortality (NRM) at 100 d and 12 months was 30% and 46% respectively. Univariate analysis showed that fludarabine-based conditioning therapy, age > or = 40 yr and >12 months interval between diagnosis and transplantation were associated with a significantly lower OS and DFS and a higher NRM.

CONCLUSION

These data suggest that although pretreatment with IM is not an independent negative prognostic factor, it cannot improve the dismal prognosis of CML patients at high risk for transplant-related mortality.