Predicting complete cytogenetic response and subsequent progression-free survival in 2060 patients with CML on imatinib treatment: the EUTOS score. Blood. 2011;118:686-692. [PMID: 21536864 DOI: 10.1182/blood-2010-12-319038]

EUTOS score is not predictive for survival and outcome in patients with early chronic phase chronic myeloid leukemia treated with tyrosine kinase inhibitors: a single institution experience

To validate the recently reported European Treatment and Outcomes Study (EUTOS) score, we applied it to 465 patients with early chronic phase chronic myeloid leukemia treated with standard-dose imatinib (n=71), high-dose imatinib (n=208), or second-generation tyrosine kinase inhibitors (n=186), and assessed its ability to predict event-free survival (EFS), transformation-free survival (TFS), and overall survival (OS). The median follow-up was 69 months. The overall complete cytogenetic response and major molecular response rates were 92% and 85%, respectively. The 3-year EFS, TFS, and OS rates were 86%, 95%, and 97%, respectively. Of the 465 patients, 427 (92%) were in low EUTOS score category. There was no difference in the major molecular response, TFS, EFS, and OS rates between patients with low and high EUTOS score, overall and within specific therapies. In conclusion, 8% of patients with chronic phase chronic myeloid leukemia treated at our institution are in the high EUTOS score; in this population, the EUTOS score was not predictive for outcome.

Selection of therapy: rational decisions based on molecular events

This article reviews to what extent molecular data can be used to rationalize therapeutic choices in the treatment of chronic myeloid leukemia. Two categories of data are discussed: markers that globally measure risk but do not provide a molecular rationale for therapy selection; and biomarkers with a causal link to a clinical phenotype, such as certain mutations of the BCR-ABL kinase domain. As therapy selection is still mainly based on clinical criteria, molecular biomarkers are discussed in the context of available clinical prognostication tools, focusing on biomarkers that do not reflect disease burden as a surrogate of responsiveness to treatment.

Analysis of outcomes in adolescents and young adults with chronic myelogenous leukemia treated with upfront tyrosine kinase inhibitor therapy

BACKGROUND

Outcomes in chronic myeloid leukemia have improved with tyrosine kinase inhibitor treatment. However, little is known about outcomes of chronic myeloid leukemia in adolescent and young adult patients.

DESIGN AND METHODS

We reviewed all 468 chronic myeloid leukemia patients treated at our institution with tyrosine kinase inhibitors as initial therapy: imatinib (n=281), nilotinib (n=98) or dasatinib (n=89).

RESULTS

Median age was 47 years, median follow up 71 months and median treatment time with initial tyrosine kinase inhibitors 48 months. Adolescent and young adult was defined as aged 15-29 years. Sixty-one adolescent and young adult patients were identified. The only significant differences between adolescent and young adult and older patients were incidence of splenomegaly and distribution in Sokal risk groups. Only 3 adolescent and young adult patients have died. Rates of complete cytogenetic, major molecular and complete molecular response were significantly higher in older patients compared to adolescent and young adult patients, with a favorable trend in event-free survival for older patients. Transformation-free and overall survival were similar for the two groups.

CONCLUSIONS

The unfavorable trend in outcome for adolescent and young adult patients with chronic myeloid leukemia is unexpected. Additional research in this population is required to better define outcomes, understand the cause of this difference, and to help make better treatment recommendations.

Leukemic spleen cells are more potent than bone marrow-derived cells in a transgenic mouse model of CML

Spleen size ranks among the most important risk factors in chronic myeloid leukemia (CML), but the pathogenic mechanisms of splenic hematopoiesis in CML remain poorly defined. Here, we studied the biology of Bcr-Abl positive leukemia-initiating cells in the spleen, using an inducible transgenic mouse model of CML. Disease kinetics showed greater increases of immature leukemic cells in spleen vs bone marrow (BM). To assess how Bcr-Abl alters the behavior of spleen-derived CML cells, we transplanted these cells either before ('pre-uninduced') or 44 days after ('pre-induced') expression of the oncogene. Mice transplanted with pre-induced spleen cells showed significantly increased neutrophilia and splenomegaly compared with mice receiving pre-uninduced spleen cells, suggesting that Bcr-Abl expression in the donors had increased splenic tumor burden. However, pre-induction also altered the biology of these cells, as shown by a striking increase in erythropoietic potential. These results differ from those of BM-derived CML stem cells where pre-induction of Bcr-Abl had previously been shown to decrease disease transplantability. Moreover, splenic cells were less sensitive to imatinib than BM cells. In conclusion, Bcr-Abl alters the biology of splenic leukemic stem cells by a cell-autonomous mechanism, but the disease phenotype is also influenced by the microenvironment of these cells.

Impact of additional cytogenetic aberrations at diagnosis on prognosis of CML: long-term observation of 1151 patients from the randomized CML Study IV

The prognostic relevance of additional cytogenetic findings at diagnosis of chronic myeloid leukemia (CML) is unclear. The impact of additional cytogenetic findings at diagnosis on time to complete cytogenetic (CCR) and major molecular remission (MMR) and progression-free (PFS) and overall survival (OS) was analyzed using data from 1151 Philadelphia chromosome-positive (Ph(+)) CML patients randomized to the German CML Study IV. At diagnosis, 1003 of 1151 patients (87%) had standard t(9;22)(q34;q11) only, 69 patients (6.0%) had variant t(v;22), and 79 (6.9%) additional cytogenetic aberrations (ACAs). Of these, 38 patients (3.3%) lacked the Y chromosome (-Y) and 41 patients (3.6%) had ACAs except -Y; 16 of these (1.4%) were major route (second Philadelphia [Ph] chromosome, trisomy 8, isochromosome 17q, or trisomy 19) and 25 minor route (all other) ACAs. After a median observation time of 5.3 years for patients with t(9;22), t(v;22), -Y, minor- and major-route ACAs, the 5-year PFS was 90%, 81%, 88%, 96%, and 50%, and the 5-year OS was 92%, 87%, 91%, 96%, and 53%, respectively. In patients with major-route ACAs, the times to CCR and MMR were longer and PFS and OS were shorter (P < .001) than in patients with standard t(9;22). We conclude that major-route ACAs at diagnosis are associated with a negative impact on survival and signify progression to the accelerated phase and blast crisis.

Recommendations to meet statistical challenges arising from endpoints beyond overall survival in clinical trials on chronic myeloid leukemia

The aim of this work was to provide guidelines for appropriate statistical analyses regarding most common endpoints in clinical trials on chronic myeloid leukemia: hematologic, cytogenetic and molecular results, failure-free and event-free survival, and progression-free and overall survival. The reasons for the specified recommendations are explained and important issues are outlined by comprehensive examples. Particular attention is paid to the warning of the application of suboptimal methods that may lead to seriously biased results and conclusions. In the presence of a competing risk like death, Kaplan-Meier analysis should not be applied for time-to-remission endpoints. The appropriate method to estimate the probabilities of a time-to-remission endpoint is the calculation of its cumulative incidence function. However, the exact date of remission is hardly known. Detection of remission depends strongly on evaluation frequencies. Complex composite endpoints comprising many events with considerably heterogeneous severity imply difficulties with interpretation. Time-to-remission and complex composite endpoints are not recommended for primary judgment on efficacy. It is rather advisable to investigate remission status at a fixed time point as a primary endpoint, followed by progression-free and overall survival. For patients with the intended remission success at the time point of interest, relapse-free survival provides an additional primary outcome.