Giuseppe Saglio

Nilotinib versus Imatinib for Newly Diagnosed Chronic Myeloid Leukemia

BACKGROUND Nilotinib has been shown to be a more potent inhibitor of BCR-ABL than imatinib. We evaluated the efficacy and safety of nilotinib, as compared with imatinib, in patients with newly diagnosed Philadelphia chromosome-positive chronic myeloid leukemia (CML) in the chronic phase. METHODS In this phase 3, randomized, open-label, multicenter study, we assigned 846 patients with chronic-phase Philadelphia chromosome-positive CML in a 1:1:1 ratio to receive nilotinib (at a dose of either 300 mg or 400 mg twice daily) or imatinib (at a dose of 400 mg once daily). The primary end point was the rate of major molecular response at 12 months. RESULTS At 12 months, the rates of major molecular response for nilotinib (44% for the 300-mg dose and 43% for the 400-mg dose) were nearly twice that for imatinib (22%) (P<0.001 for both comparisons). The rates of complete cytogenetic response by 12 months were significantly higher for nilotinib (80% for the 300-mg dose and 78% for the 400-mg dose) than for imatinib (65%) (P<0.001 for both comparisons). Patients receiving either the 300-mg dose or the 400-mg dose of nilotinib twice daily had a significant improvement in the time to progression to the accelerated phase or blast crisis, as compared with those receiving imatinib (P=0.01 and P=0.004, respectively). No patient with progression to the accelerated phase or blast crisis had a major molecular response. Gastrointestinal and fluid-retention events were more frequent among patients receiving imatinib, whereas dermatologic events and headache were more frequent in those receiving nilotinib. Discontinuations due to aminotransferase and bilirubin elevations were low in all three study groups. CONCLUSIONS Nilotinib at a dose of either 300 mg or 400 mg twice daily was superior to imatinib in patients with newly diagnosed chronic-phase Philadelphia chromosome-positive CML. (ClinicalTrials.gov number, NCT00471497.)

Chronic Myeloid Leukemia: An Update of Concepts and Management Recommendations of European LeukemiaNet

PURPOSE To review and update the European LeukemiaNet (ELN) recommendations for the management of chronic myeloid leukemia with imatinib and second-generation tyrosine kinase inhibitors (TKIs), including monitoring, response definition, and first- and second-line therapy. METHODS These recommendations are based on a critical and comprehensive review of the relevant papers up to February 2009 and the results of four consensus conferences held by the panel of experts appointed by ELN in 2008. RESULTS Cytogenetic monitoring was required at 3, 6, 12, and 18 months. Molecular monitoring was required every 3 months. On the basis of the degree and the timing of hematologic, cytogenetic, and molecular results, the response to first-line imatinib was defined as optimal, suboptimal, or failure, and the response to second-generation TKIs was defined as suboptimal or failure. CONCLUSION Initial treatment was confirmed as imatinib 400 mg daily. Imatinib should be continued indefinitely in optimal responders. Suboptimal responders may continue on imatinb, at the same or higher dose, or may be eligible for investigational therapy with second-generation TKIs. In instances of imatinib failure, second-generation TKIs are recommended, followed by allogeneic hematopoietic stem-cell transplantation only in instances of failure and, sometimes, suboptimal response, depending on transplantation risk.

European LeukemiaNet recommendations for the management of chronic myeloid leukemia: 2013

Advances in chronic myeloid leukemia treatment, particularly regarding tyrosine kinase inhibitors, mandate regular updating of concepts and management. A European LeukemiaNet expert panel reviewed prior and new studies to update recommendations made in 2009. We recommend as initial treatment imatinib, nilotinib, or dasatinib. Response is assessed with standardized real quantitative polymerase chain reaction and/or cytogenetics at 3, 6, and 12 months. BCR-ABL1 transcript levels ≤10% at 3 months, <1% at 6 months, and ≤0.1% from 12 months onward define optimal response, whereas >10% at 6 months and >1% from 12 months onward define failure, mandating a change in treatment. Similarly, partial cytogenetic response (PCyR) at 3 months and complete cytogenetic response (CCyR) from 6 months onward define optimal response, whereas no CyR (Philadelphia chromosome-positive [Ph+] >95%) at 3 months, less than PCyR at 6 months, and less than CCyR from 12 months onward define failure. Between optimal and failure, there is an intermediate warning zone requiring more frequent monitoring. Similar definitions are provided for response to second-line therapy. Specific recommendations are made for patients in the accelerated and blastic phases, and for allogeneic stem cell transplantation. Optimal responders should continue therapy indefinitely, with careful surveillance, or they can be enrolled in controlled studies of treatment discontinuation once a deeper molecular response is achieved.

Standardized RT-PCR analysis of fusion gene transcripts from chromosome aberrations in acute leukemia for detection of minimal residual disease. Report of the BIOMED-1 Concerted Action: investigation of minimal residual disease in acute leukemia.

Prospective studies on the detection of minimal residual disease (MRD) in acute leukemia patients have shown that large-scale MRD studies are feasible and that clinically relevant MRD-based risk group classification can be achieved and can now be used for designing new treatment protocols. However, multicenter international treatment protocols with MRD-based stratification of treatment need careful standardization and quality control of the MRD techniques. This was the aim of the European BIOMED-1 Concerted Action ‘Investigation of minimal residual disease in acute leukemia: international standardization and clinical evaluation’ with participants of 14 laboratories in eight European countries (ES, NL, PT, IT, DE, FR, SE and AT). Standardization and quality control was performed for the three main types of MRD techniques, ie flow cytometric immunophenotyping, PCR analysis of antigen receptor genes, and RT-PCR analysis of well-defined chromosomal aberrations. This study focussed on the latter MRD technique. A total of nine well-defined chromosome aberrations with fusion gene transcripts were selected: t(1;19) with E2A-PBX1, t(4;11) with MLL-AF4, t(8;21) with AML1-ETO, t(9;22) with BCR-ABL p190 and BCR-ABL p210, t(12;21) with TEL-AML1, t(15;17) with PML-RARA, inv (16) with CBFB-MYH11, and microdeletion 1p32 with SIL-TAL1. PCR primers were designed according to predefined criteria for single PCR (external primers A ↔ B) and nested PCR (internal primers C ↔ D) as well as for ‘shifted’ PCR with a primer upstream (E5′ primer) or downstream (E3′ primer) of the external A ↔ B primers. The ‘shifted’ E primers were designed for performing an independent PCR together with one of the internal primers for confirmation (or exclusion) of positive results. Various local RT and PCR protocols were compared and subsequently a common protocol was designed, tested and adapted, resulting in a standardized RT-PCR protocol. After initial testing (with adaptations whenever necessary) and approval by two or three laboratories, the primers were tested by all participating laboratories, using 17 cell lines and patient samples as positive controls. This testing included comparison with local protocols and primers as well as sensitivity testing via dilution experiments. The collaborative efforts resulted in standardized primer sets with a minimal target sensitivity of 10−2 for virtually all single PCR analyses, whereas the nested PCR analyses generally reached the minimal target sensitivity of 10−4. The standardized RT-PCR protocol and primer sets can now be used for molecular classification of acute leukemia at diagnosis and for MRD detection during follow-up to evaluate treatment effectiveness.

PML targeting eradicates quiescent leukaemia-initiating cells

The existence of a small population of ‘cancer-initiating cells’ responsible for tumour maintenance has been firmly demonstrated in leukaemia. This concept is currently being tested in solid tumours. Leukaemia-initiating cells, particularly those that are in a quiescent state, are thought to be resistant to chemotherapy and targeted therapies, resulting in disease relapse. Chronic myeloid leukaemia is a paradigmatic haematopoietic stem cell disease in which the leukaemia-initiating-cell pool is not eradicated by current therapy, leading to disease relapse on drug discontinuation. Here we define the critical role of the promyelocytic leukaemia protein (PML) tumour suppressor in haematopoietic stem cell maintenance, and present a new therapeutic approach for targeting quiescent leukaemia-initiating cells and possibly cancer-initiating cells by pharmacological inhibition of PML.

Contribution of ABL Kinase Domain Mutations to Imatinib Resistance in Different Subsets of Philadelphia-Positive Patients: By the GIMEMA Working Party on Chronic Myeloid Leukemia

Purpose: ABL kinase domain mutations have been implicated in the resistance to the BCR-ABL inhibitor imatinib mesylate of Philadelphia-positive (Ph+) leukemia patients. Experimental Design: Using denaturing high-performance liquid chromatography and sequencing, we screened for ABL kinase domain mutations in 370 Ph+ patients with evidence of hematologic or cytogenetic resistance to imatinib. Results: Mutations were found in 127 of 297 (43%) evaluable patients. Mutations were found in 27% of chronic-phase patients (14% treated with imatinib frontline; 31% treated with imatinib post-IFN failure), 52% of accelerated-phase patients, 75% of myeloid blast crisis patients, and 83% of lymphoid blast crisis/Ph+ acute lymphoblastic leukemia (ALL) patients. Mutations were associated in 30% of patients with primary resistance (44% hematologic and 28% cytogenetic) and in 57% of patients with acquired resistance (23% patients who lost cytogenetic response; 55% patients who lost hematologic response; and 87% patients who progressed to accelerated phase/blast crisis). P-loop and T315I mutations were particularly frequent in advanced-phase chronic myeloid leukemia and Ph+ ALL patients, and often accompanied progression from chronic phase to accelerated phase/blast crisis. Conclusions: We conclude that (a) amino acid substitutions at seven residues (M244V, G250E, Y253F/H, E255K/V, T315I, M351T, and F359V) account for 85% of all resistance-associated mutations; (b) the search for mutations is important both in case of imatinib failure and in case of loss of response at the hematologic or cytogenetic level; (c) advanced-phase chronic myeloid leukemia and Ph+ ALL patients have a higher likelihood of developing imatinib-resistant mutations; and (d) the presence of either P-loop or T315I mutations in imatinib-treated patients should warn the clinician to reconsider the therapeutic strategy.

Nilotinib versus imatinib for the treatment of patients with newly diagnosed chronic phase, Philadelphia chromosome-positive, chronic myeloid leukaemia: 24-month minimum follow-up of the phase 3 randomised ENESTnd trial

BACKGROUND Nilotinib has shown greater efficacy than imatinib in patients with newly diagnosed Philadelphia chromosome-positive chronic myeloid leukaemia (CML) in chronic phase after a minimum follow-up of 12 months. We present data from the Evaluating Nilotinib Efficacy and Safety in clinical Trials-newly diagnosed patients (ENESTnd) study after a minimum follow-up of 24 months. METHODS ENESTnd was a phase 3, multicentre, open-label, randomised study. Adult patients were eligible if they had been diagnosed with chronic phase, Philadelphia chromosome-positive CML within the previous 6 months. Patients were randomly assigned (1:1:1) to receive nilotinib 300 mg twice a day, nilotinib 400 mg twice a day, or imatinib 400 mg once a day, all administered orally, by use of a computer-generated randomisation schedule, using permuted blocks, and stratified according to Sokal score. Efficacy results are reported for the intention-to-treat population. The primary endpoint was major molecular response at 12 months, defined as BCR-ABL transcript levels on the International Scale (BCR-ABL(IS)) of 0·1% or less by real-time quantitative PCR in peripheral blood. This study is registered with ClinicalTrials.gov, number NCT00471497. FINDINGS 282 patients were randomly assigned to receive nilotinib 300 mg twice daily, 281 to receive nilotinib 400 mg twice daily, and 283 to receive imatinib. By 24 months, significantly more patients had a major molecular response with nilotinib than with imatinib (201 [71%] with nilotinib 300 mg twice daily, 187 [67%] with nilotinib 400 mg twice daily, and 124 [44%] with imatinib; p<0·0001 for both comparisons). Significantly more patients in the nilotinib groups achieved a complete molecular response (defined as a reduction of BCR-ABL(IS) levels to ≤0·0032%) at any time than did those in the imatinib group (74 [26%] with nilotinib 300 mg twice daily, 59 [21%] with nilotinib 400 mg twice daily, and 29 [10%] with imatinib; p<0·0001 for nilotinib 300 mg twice daily vs imatinib, p=0·0004 for nilotinib 400 mg twice daily vs imatinib). There were fewer progressions to accelerated or blast phase on treatment, including clonal evolution, in the nilotinib groups than in the imatinib group (two with nilotinib 300 mg twice daily, five with nilotinib 400 mg twice daily, and 17 with imatinib; p=0·0003 for nilotinib 300 mg twice daily vs imatinib, p=0·0089 for nilotinib 400 mg twice daily vs imatinib). At 24 months, survival was comparable in all treatment groups, but fewer CML-related deaths had occurred in both the nilotinib groups than in the imatinib group (five with nilotinib 300 mg twice daily, three with nilotinib 400 mg twice daily, and ten with imatinib). Overall, the only grade 3 or 4 non-haematological adverse events that occurred in at least 2·5% of patients were headache (eight [3%] with nilotinib 300 mg twice daily, four [1%] with nilotinib 400 mg twice daily, and two [<1%] with imatinib) and rash (two [<1%], seven [3%], and five [2%], respectively). Grade 3 or 4 neutropenia was more common with imatinib than with either dose of nilotinib (33 [12%] with nilotinib 300 mg twice daily, 30 [11%] with nilotinib 400 mg twice daily, and 59 [21%] with imatinib). Serious adverse events were reported in eight additional patients in the second year of the study (four with nilotinib 300 mg twice daily, three with nilotinib 400 mg twice daily, and one with imatinib). INTERPRETATION Nilotinib continues to show better efficacy than imatinib for the treatment of patients with newly diagnosed CML in chronic phase. These results support nilotinib as a first-line treatment option for patients with newly diagnosed disease. FUNDING Novartis.

Nilotinib vs imatinib in patients with newly diagnosed Philadelphia chromosome-positive chronic myeloid leukemia in chronic phase: ENESTnd 3-year follow-up

Evaluating Nilotinib Efficacy and Safety in Clinical Trials Newly Diagnosed Patients compares nilotinib and imatinib in patients with newly diagnosed chronic myeloid leukemia in chronic phase (CML-CP). With a minimum follow-up of 3 years, major molecular response, molecular response of BCR-ABL⩽0.01% expressed on the international scale (BCR-ABLIS; MR4) and BCR-ABLIS⩽0.0032% (MR4.5) rates were significantly higher with nilotinib compared with imatinib, and differences in the depth of molecular response between nilotinib and imatinib have increased over time. No new progressions occurred on treatment since the 2-year analysis. Nilotinib was associated with a significantly lower probability of progression to accelerated phase/blast crisis vs imatinib (two (0.7%) progressions on nilotinib 300 mg twice daily, three (1.1%) on nilotinib 400 mg twice daily and 12 (4.2%) on imatinib). When considering progressions occurring after study treatment discontinuation, the advantage of nilotinib over imatinib in preventing progression remained significant (nine (3.2%) progressions on nilotinib 300 mg twice daily, six (2.1%) on nilotinib 400 mg twice daily and 19 (6.7%) on imatinib). Both nilotinib and imatinib were well tolerated, with minimal changes in safety over time. Nilotinib continues to demonstrate superior efficacy in all key response and outcome parameters compared with imatinib for the treatment of patients with newly diagnosed CML-CP.

Desirable performance characteristics for BCR-ABL measurement on an international reporting scale to allow consistent interpretation of individual patient response and comparison of response rates between clinical trials

An international basis for comparison of BCR-ABL mRNA levels is required for the common interpretation of data derived from individual laboratories. This will aid clinical decisions for individual patients with chronic myeloid leukemia (CML) and assist interpretation of results from clinical studies. We aligned BCR-ABL values generated by 38 laboratories to an international scale (IS) where a major molecular response (MMR) is 0.1% or less. Alignment was achieved by application of laboratory-specific conversion factors calculated by comparisons performed with patient samples against a reference method. A validation procedure was completed for 19 methods. We determined performance characteristics (bias and precision) for consistent interpretation of MMR after IS conversion. When methods achieved an average BCR-ABL difference of plus or minus 1.2-fold from the reference method and 95% limits of agreement within plus or minus 5-fold, the MMR concordance was 91%. These criteria were met by 58% of methods. When not met, the MMR concordance was 74% or less. However, irrespective of precision, when the bias was plus or minus 1.2-fold as achieved by 89% of methods, there was good agreement between the overall MMR rates. This indicates that the IS can deliver accurate comparison of molecular response rates between clinical trials when measured by different laboratories.

Nilotinib is effective in patients with chronic myeloid leukemia in chronic phase after imatinib resistance or intolerance: 24-month follow-up results

Nilotinib is a potent selective inhibitor of the BCR-ABL tyrosine kinase approved for use in patients with newly diagnosed chronic myeloid leukemia in chronic phase (CML-CP), and in CML-CP and CML-accelerated phase after imatinib failure. Nilotinib (400 mg twice daily) was approved on the basis of the initial results of this phase 2 open-label study. The primary study endpoint was the proportion of patients achieving major cytogenetic response (CyR). All patients were followed for ≥ 24 months or discontinued early. Of 321 patients, 124 (39%) continue on nilotinib treatment. Overall, 59% of patients achieved major CyR; this was complete CyR (CCyR) in 44%. Of patients achieving CCyR, 56% achieved major molecular response. CyRs were durable, with 84% of patients who achieved CCyR maintaining response at 24 months. The overall survival at 24 months was 87%. Adverse events were mostly mild to moderate, generally transient, and easily managed. This study indicates that nilotinib is effective, with a manageable safety profile, and can provide favorable long-term benefits for patients with CML-CP after imatinib failure.