ELN 2013 response status criteria: relevance for de novo imatinib chronic phase chronic myeloid leukemia patients?

The response definitions proposed by the European Leukemia Net (ELN) have been recently modified. We evaluated the new criteria for de novo imatinib (400 mg/d) chronic phase chronic myeloid leukemia (CP-CML) patients. Response status according to the 2009 and 2013 criteria were determined in 180 unselected patients. Outcome of the subgroups of patients were then compared. The 180 patients were classified as optimal responders (OR2009; n = 113, 62.7%), suboptimal responders (SOR2009; n = 47, 26.1%) and failures (FAIL2009; n = 20, 11.1%) according to the 2009 ELN criteria and optimal responders (OR2013; n = 77, 42.7%), warnings (WAR2013; n = 59, 32.7%), and failures (FAIL2013; n = 44, 24.4%) according to the 2013 ELN criteria. No difference in terms of outcome was observed between OR2009 patients who became WAR2013 when compared with OR2013 patients. When compared with FAIL2009 patients, SOR2009 patients who became WAR2013 had better EFS, FFS, PFS, and OS. No difference was observed in PFS or OS in SOR2009 patients who became FAIL2013. The 2013 ELN response status criteria have improved patients classification in terms of response status. However, in our patient population this improvement is related to a better definition of failure rather than that of optimal response for CP-CML patients treated with IM frontline therapy.

Achieving deeper molecular response is associated with a better clinical outcome in chronic myeloid leukemia patients on imatinib front-line therapy.

Sustained imatinib treatment in chronic myeloid leukemia patients can result in complete molecular response allowing discontinuation without relapse. We set out to evaluate the frequency of complete molecular response in imatinib de novo chronic phase chronic myeloid leukemia patients, to identify base-line and under-treatment predictive factors of complete molecular response in patients achieving complete cytogenetic response, and to assess if complete molecular response is associated with a better outcome. A random selection of patients on front-line imatinib therapy (n=266) were considered for inclusion. Complete molecular response was confirmed and defined as MR 4.5 with undetectable BCR-ABL transcript levels. Median follow up was 4.43 years (range 0.79-10.8 years). Sixty-five patients (24%) achieved complete molecular response within a median time of 32.7 months. Absence of spleen enlargement at diagnosis, achieving complete cytogenetic response before 12 months of therapy, and major molecular response during the year following complete cytogenetic response was predictive of achieving further complete molecular response. Patients who achieved complete molecular response had better event-free and failure-free survivals than those with complete cytogenetic response irrespective of major molecular response status (95.2% vs. 64.7% vs. 27.7%, P=0.00124; 98.4% vs. 82.3% vs. 56%, P=0.0335), respectively. Overall survival was identical in the 3 groups. In addition to complete cytogenetic response and major molecular response, further deeper molecular response is associated with better event-free and failure-free survivals, and complete molecular response confers the best outcome.

Relevance of treatment-free remission recommendations in chronic phase chronic leukemia patients treated with frontline tyrosine kinase inhibitors.

BACKGROUND: Tyrosine kinase inhibitors (TKI) can be safely discontinued in chronic phase chronic myeloid leukemia (CP-CML) patients who had achieved a sustained deep molecular response. Based on the results of discontinuation trials, recommendations regarding patient selection for a treatment-free remission (TFR) attempt had been proposed. The aims of this study were to evaluate the rate of patients eligible for TKI discontinuation and molecular recurrence-free survival (MRFS) after stop according to recommendations. METHODS: Over a 10-year period, newly diagnosed CP-CML patients and treated with first-line TKI in the nine French participating centers were included. Eligibility to treatment discontinuation and MRFS were analyzed and compared according to selection criteria defined by recommendations and first-line treatments. RESULTS: From January 2006 to December 2015, 398 patients were considered. Among them, 73% and 27% of patients received imatinib or either second or third generation tyrosine kinase inhibitors as frontline treatment, respectively. Considering the selection criteria defined by recommendations, up to 55% of the patients were selected as optimal candidates for treatment discontinuation. Overall 95/398 (24%) discontinued treatment. MRFS was 51.8% [95% CI 41.41-62.19] at 2 years and 43.8% [31.45-56.15] at 5 years. Patients receiving frontline second-generation TKI and fulfilling the eligibility criteria suggested by recommendations had the lowest probability of molecular relapse after TKI stop when compare to others. CONCLUSION: One third of CP-CML patients treated with TKI frontline fulfilled the selection criteria suggested by European LeukemiaNet TFR recommendations. Meeting selection criteria and second-generation TKI frontline were associated with the highest MRFS.

Loss of the Y chromosome in Philadelphia-positive cells predicts a poor response of chronic myeloid leukemia patients to imatinib mesylate therapy.

In chronic myeloid leukemia (CML), cytogenetic abnormalities found in addition to the t(9;22) translocation may impact the response to therapy. Loss of the Y chromosome is generally overlooked in this context, owing to its relatively frequent occurrence in healthy elderly patients. In this multicenter retrospective study, the outcome after imatinib treatment of 30 CML patients with karyotype showing Y chromosome loss (Y-) was compared to 30 Y+ control males diagnosed and treated at the same time in the same institutions. Y- patients had significantly delayed cytogenetic and molecular responses, lower event-free survival and shorter overall survival than Y+ patients. The negative impact of this abnormality was particularly marked when it occurred in a sub-clone (clonal evolution) rather than in all mitoses. These data indicate that loss of the Y chromosome should be taken into account in the prognostic evaluation of chronic myelogenous leukemia patients.

Incidences of Deep Molecular Responses and Treatment-Free Remission in de Novo CP-CML Patients.

Background: Tyrosine Kinase Inhibitors (TKIs) discontinuation in patients who had achieved a deep molecular response (DMR) offer now the opportunity of prolonged treatment-free remission (TFR). Patients and Methods: Aims of this study were to evaluate the proportion of de novo chronic-phase chronic myeloid leukemia (CP-CML) patients who achieved a sustained DMR and to identify predictive factors of DMR and molecular recurrence-free survival (MRFS) after TKI discontinuation. Results: Over a period of 10 years, 398 CP-CML patients treated with first-line TKIs were included. Median age at diagnosis was 61 years, 291 (73%) and 107 (27%) patients were treated with frontline imatinib (IMA) or second- or third-generation TKIs (2-3G TKI), respectively. With a median follow-up of seven years (range, 0.6 to 13.8 years), 182 (46%) patients achieved a sustained DMR at least 24 months. Gender, BCR-ABL1 transcript type, and Sokal and ELTS risk scores were significantly associated with a higher probability of sustained DMR while TKI first-line (IMA vs. 2-3G TKI) was not. We estimate that 28% of CML-CP would have been an optimal candidate for TKI discontinuation according to recent recommendations. Finally, 95 (24%) patients have entered in a TFR program. MRFS rates at 12 and 48 months were 55.1% (95% CI, 44.3% to 65.9%) and 46.9% (95% CI, 34.9% to 58.9%), respectively. In multivariate analyses, first-line 2-3G TKIs compared to IMA and TKI duration were the most significant factors of MRFS. Conclusions: Our results suggest that frontline TKIs have a significant impact on TFR in patients who fulfill the selection criteria for TKI discontinuation.

Incidence and outcome of BCR-ABL mutated chronic myeloid leukemia patients who failed to tyrosine kinase inhibitors.

PURPOSE: To assess the incidence of BCR-ABL kinase domain (KD) mutation detection and its prognostic significance in chronic phase chronic myeloid leukemia (CP-CML) patients treated with tyrosine kinase inhibitors (TKIs). PATIENTS AND METHODS: We analyzed characteristics and outcome of 253 CP-CML patients who had at least one mutation analysis performed using direct sequencing. Of them, 187 patients were early CP (ECP) and 66 were late CP late chronic phase (LCP) and 88% were treated with Imatinib as first-line TKI. RESULTS: Overall, 80 (32%) patients harbored BCR-ABL KD mutations. A BCR-ABL KD mutation was identified in 57% of patients, who progressed to accelerated or blastic phases (AP-BP), and 47%, 29%, 35%, 16% and 26% in patients in CP-CML at the time of mutation analysis who lost a complete hematologic response, failed to achieve or loss of a prior complete cytogenetic and major molecular response, respectively. Overall survival and cumulative incidence of CML-related death were significantly correlated with the disease phase whatever the absence or presence of a mutation was and for the latter the mutation subgroup (T315I vs P-loop vs non-T315I non-P-loop) (P<.001). Considering patients who were in CP at the time of mutation analysis, LCP mutated patients had a significantly worse outcome than ECP-mutated patients despite a lower incidence of T315I and P-loop mutations (P<.001). With a median follow-up from mutation analysis to last follow-up of 5 years, T315I and P-loop mutations were not associated with a worse outcome in ECP patients (P = .817). CONCLUSION: Our results suggest that early mutation detection together with accessibility to 2nd and 3rd generation TKIs have reversed the worst outcome associated with BCR-ABL KD mutations whatever the mutation subgroup in CP-CML patients.

Molecular remission in chronic myeloid leukemia patients with sustained complete cytogenetic remission after imatinib mesylate treatment.

BACKGROUND AND OBJECTIVES: Imatinib mesylate induces a complete cytogenetic response (CCR) in many patients with chronic myeloid leukemia (CML). However, the ultimate goal of therapy for CML is complete elimination of Philadelphia chromosome positive cells or BCR-ABL rearrangements. We studied molecular responses in CML patients in CCR after imatinib treatment. DESIGN AND METHODS: Real-time quantitative reverse transcriptase polymerase chain reaction analysis were used to monitor BCR-ABL levels in 59 CCR patients. Negative results were confirmed by two different techniques performed in two different laboratories. Patients were considered in complete molecular remission if they had four undetectable analyses from two separate samples taken three months apart. RESULTS: The median follow-up was 41 months (17-53). The median BCR-ABL/ABL ratio at the time of CCR was 0.3 % (0-9.88). Patients were split into two groups: group A (n=43) comprised patients with a detectable BCR-ABL/ABL ratio throughout the follow-up and group B (n=16) included those with an undetectable level of BCR-ABL/ABL (< 10(-5)) i.e. in complete molecular remission. No relapses were observed in group B, while 13 group A patients lost their CCR. The probability of losing CCR in this group was 33.2 % >+/-18.0. By Cox regression analysis the best factor for predicting the probability of achieving molecular remission was having a CCR at 6 months (p=0.038) or at 3 months (p=0.024). INTERPRETATION AND CONCLUSIONS: Molecular remission after imatinib treatment, i.e. BCR-ABL/ABL< 10-5 in peripheral blood, is not a rare event, particularly in patients achieving CCR at 6 months.