Equivalence of BCR-ABL transcript levels with complete cytogenetic remission in patients with chronic myeloid leukemia in chronic phase

Higher prevalence of harbouring BCR::ABL1 in first-degree relatives of chronic myeloid leukaemia (CML) patients compared to normal population

BACKGROUND

The role of familial influence in chronic myeloid leukaemia (CML) occurrence is less defined. Previously, we conducted a study to determine the prevalence of harbouring BCR::ABL1 in our local adult normal population (designated as StudyN). We present our current study, which investigated the prevalence of harbouring BCR::ABL1 in the normal first-degree relatives of local CML patients (designated as StudyR). We compared and discussed the prevalence of StudyR and StudyN to assess the familial influence in CML occurrence.

METHODS

StudyR was a cross-sectional study using convenience sampling, recruiting first-degree relatives of local CML patients aged ≥ 18 years old without a history of haematological tumour. Real-time quantitative polymerase chain reaction standardised at the International Scale (BCR::ABL1-qPCRIS) was performed according to standard laboratory practice and the manufacturer's protocol.

RESULTS

A total of 96 first-degree relatives from 41 families, with a mean age of 39 and a male-to-female ratio of 0.88, were enrolled and analysed. The median number of relatives per family was 2 (range 1 to 5). Among them, 18 (19%) were parents, 39 (41%) were siblings, and 39 (41%) were offspring of the CML patients. StudyR revealed that the prevalence of harbouring BCR::ABL1 in the first-degree relatives was 4% (4/96), which was higher than the prevalence in the local normal population from StudyN, 0.5% (1/190). All four positive relatives were Chinese, with three of them being female (p > 0.05). Their mean age was 39, compared to 45 in StudyN. The BCR::ABL1-qPCRIS levels ranged between 0.0017%IS and 0.0071%IS, similar to StudyN (0.0023%IS to 0.0032%IS) and another study (0.006%IS to 0.016%IS).

CONCLUSION

Our study showed that the prevalence of harbouring BCR::ABL1 in the first-degree relatives of known CML patients was higher than the prevalence observed in the normal population. This suggests that familial influence in CML occurrence might exist but could be surpassed by other more dominant influences, such as genetic dilutional effects and protective genetic factors. The gender and ethnic association were inconsistent with CML epidemiology, suggestive of a higher familial influence in female and Chinese. Further investigation into this topic is warranted, ideally through larger studies with longer follow-up periods.

Survival with chronic myeloid leukaemia after failing milestones

Therapy after failing response milestones in CML is controversial. Risks associated with comorbidities, drug toxicities or transplantation may preclude switching to another tyrosine kinase inhibitor (TKI) or other treatments. No information on long-term survival of failing patients is available. To systematically analyse survival after reaching, or not reaching, response milestones, 1342 patients from CML-study IV with newly diagnosed CML in chronic phase and regular molecular tests were studied. Landmark survival analyses were done by <0.1%, 0.1-1%, >1-10% and >10% BCR::ABL1IS at 3, 6, 12 and 24 months up to 14 years. 10- to 12-year survival of patients who failed the failure milestones (>10% BCR::ABL1IS at 6 months, >1% BCR::ABL1IS at 12 months) ranged around 80%, 10% less than in responding patients. These results suggest revision of milestones. Age (more or less than 60 years) had no major impact on survival differences, but on hazard ratios and CML-specific survival. Switching to alternative therapies, which was observed in 26.9% of the patients, did not change the main results. The data show that TKI-treated patients not reaching failure milestones still may derive benefit from continuing TKI-treatment and provide a basis for individualised decisions, if failing patients are confronted with risks of alternative treatments.

European LeukemiaNet laboratory recommendations for the diagnosis and management of chronic myeloid leukemia

From the laboratory perspective, effective management of patients with chronic myeloid leukemia (CML) requires accurate diagnosis, assessment of prognostic markers, sequential assessment of levels of residual disease and investigation of possible reasons for resistance, relapse or progression. Our scientific and clinical knowledge underpinning these requirements continues to evolve, as do laboratory methods and technologies. The European LeukemiaNet convened an expert panel to critically consider the current status of genetic laboratory approaches to help diagnose and manage CML patients. Our recommendations focus on current best practice and highlight the strengths and pitfalls of commonly used laboratory tests.

Cytogenetics in the management of myeloproliferative neoplasms, mastocytosis and myelodysplastic/myeloproliferative neoplasms: Guidelines from the Group Francophone de Cytogénétique Hématologique (GFCH)

Myeloproliferative neoplasms, mastocytosis, myeloid/lymphoid neoplasms with hypereosinophilia and tyrosine kinase gene fusions, and myelodysplastic/myeloproliferative neoplasms are clonal hematopoietic cancers that, with the exception of certain entities, have an indolent course. In addition to their increasingly important role in the diagnosis of these entities, as shown by the recent classification of hematolymphoid tumors in the 5th edition of the World Health Organization and the International Consensus Classification of myeloid neoplasms and acute leukemias, identification of the profile of acquired genetic abnormalities is essential for adapting patient management and early detection of patients at high risk of progression. Alongside molecular abnormalities, cytogenetic abnormalities play an important role in the diagnosis, prognosis and follow-up of these diseases. Here, we review the recent literature on the impact of chromosomal abnormalities in these different entities and provide updated cytogenetic recommendations and guidelines for their management.

Front-Line Tyrosine Kinase Inhibitors in Pediatric Chronic Myeloid Leukemia: A Study on Efficacy and Safety

We conducted a retrospective study on 51 pediatric patients with newly diagnosed chronic myeloid leukemia chronic phase or accelerated phase. The patients were classified into the IMA group (N = 33), treated with imatinib, and the DSA group (N = 18), treated with dasatinib, as front-line tyrosine kinase inhibitors (TKIs). At 12 months, the rates of complete cytogenetic response were similar between the IMA group (92.3%) and DSA group (100%) (p = 0.305). However, the rate of early molecular response was higher in the DSA group than in the IMA group (100.0% vs. 80.0%, p = 0.043). By 12 and 24 months, the DSA group showed faster and higher cumulative rates of both major (DSA group: 72.2% and 100%, respectively; IMA group: 41.2% and 68.7%, respectively; p = 0.002) and deep molecular responses (DSA group: 26.0% and 43.6%, respectively; IMA group: 13.8% and 17.5%, respectively; p = 0.004). Both TKIs were well tolerated. Although the height standard deviation scores decreased in both groups, the height decline was greater in the DSA group between one and two years from the start of TKI therapy. In this study, dasatinib achieved faster and higher molecular responses with an acceptable safety profile. Further follow-up is necessary to assess the long-term outcomes of TKI treatment in children.

Chronic myeloid leukemia without major molecular response after 2 years of treatment with tyrosine kinase inhibitor

Achieving major molecular response (MMR) with BCR::ABL1 tyrosine kinase inhibitors (TKIs) is associated with lower chances of progression to advanced phase disease and higher chances of treatment-free remission (TFR) in patients with chronic myeloid leukemia (CML). Failure to achieve this molecular milestone after 1 year has been highlighted as "suboptimal" or "warning" sign of treatment failure in CML guidelines and recommendations and implied to predict a poor long-term outcome. In this analysis, we report the long-term outcome of 131 patients who did not achieve MMR within the first 2 years of TKI therapy. Patients who achieved a major cytogenetic response (MCyR; roughly equivalent to BCR::ABL1 transcript levels on the International Scale [IS] <10%) had good long-term overall survival (OS) (10-year OS of 88%) and CML-related overall survival (CML-OS) (10-year CML-OS of 95%). The achievement of MCyR within the first 2 years of treatment predicted a better OS (HR = 0.43, p = .03). The value of MMR was even less pronounced among patients aged 60 years or older at diagnosis, in whom mortality was primarily due to comorbidities unrelated to CML (10-year OS of 55% vs. 10-year CML-OS of 100%). In conclusion, achievement of MCyR within 2 years is a reasonable milestone in CML, and these patients can still have good outcomes even when MMR is not achieved.

Long-term outcomes of third-line therapy with tyrosine kinase inhibitors in chronic phase chronic myeloid leukemia: A real-life experience

Introduction

Tyrosine kinase inhibitor (TKI) therapy has greatly improved the prognosis of patients with chronic myeloid leukemia (CML), improving the survival expectancy of patients with chronic phase (CP) CML to that of the general population. However, despite these advances, nearly 50% of patients with CP CML experience failure to respond to frontline therapy, and most fail to respond to the subsequent second-line TKI. Treatment guidelines for patients failing second-line therapy are lacking. This study aimed to determine the efficacy of TKIs as third-line therapy in a “real-world” clinical practice setting and identify factors favorably influencing the long-term outcomes of therapy.

Methods

We have retrospectively analyzed the medical records of 100 patients with CP CML.

Results

The median age of the patients was 51 (range, 21–88) years, and 36% of the patients were men. The median duration of the third-line TKI therapy was 22 (range, 1– 147) months. Overall, the rate of achieving complete cytogenetic response (CCyR) was 35%. Among the four patient groups with different levels of responses at baseline, the best results were achieved in the groups with any CyR at the baseline of third-line therapy. Thus, СCyR was reached in all 15 and 8/ 16 (50%) patients with partial cytogenetic response (PCyR) or minimal or minor CyR (mmCyR), respectively, whereas CCyR was detected only in 12/69 (17%) patients without any CyR at baseline (p &lt; 0.001). Univariate regression analysis revealed that the factors negatively associated with CCyR achievement in thirdline TKI therapy were the absence of any CyR on first- or second-line TKI therapy (p &lt; 0.001), absence of CHR prior to third-line TKI (p = 0.003), and absence of any CyR prior to third-line TKI (p &lt; 0.001). During the median observation time from treatment initiation to the last visit [56 (4–180) months], 27% of cases progressed into accelerated phase or blast phase CML, and 32% of patients died.

Discussion

Progression-free survival (PFS) and overall survival (OS) were significantly higher in patients with CCyR on third-line than in the group without CCyR on third-line therapy. At the last visit, third-line TKI therapy was ongoing in 18% of patients, with a median time of treatment exposure of 58 (range, 6–140) months; 83% of these patients had stable and durable CCyR, suggesting that patients without CHR at baseline and without CCyR at least by 12 months on third-line TKI should be candidates for allogeneic stem cell transplantation, third-generation TKIs, or experimental therapies.

Guidelines for the treatment of chronic myeloid leukemia from the NCCN and ELN: differences and similarities

Patients diagnosed with chronic myeloid leukemia (CML) in chronic phase can now have a life expectancy comparable to that of the general population thanks to the use of tyrosine kinase inhibitor (TKI) therapies. Although most patients with CML require lifelong TKI therapy, it is possible for some patients to achieve treatment-free remission. These spectacular results have been made possible by the development of superior treatment modalities as well as clinicians' efforts in strictly adhering to clinical guidelines such as the National Comprehensive Cancer Network (NCCN) and European Leukemia Network (ELN). CML treatment recommendations reported in these guidelines are the result of years of selecting and incorporating the most reliable evidence. In this review, we provide a synopsis of the differences and similarities that exist between the NCCN and ELN guidelines.

Late Responses in Patients With Chronic Myeloid Leukemia Initially Refractory to Tyrosine Kinase Inhibitors

BACKGROUND

The introduction of tyrosine kinase inhibitor (TKI) therapy has dramatically improved outcomes for patients with chronic myeloid leukemia (CML); however, the prognosis for those who do not meet treatment milestones remains guarded. Here, we report our experience of patients with CML treated at a single center who did not achieve a complete cytogenetic response (CCyR) at 24 months.

METHODS

We retrospectively evaluated 305 patients who were diagnosed with CML at the University of Michigan between 2001 and 2014 and were treated with TKIs. We assessed rates of CCyR at 24 months correlated to clinical outcomes.

RESULTS

The majority of patients (79%) achieved CCyR at 24 months and were classified as responders. At a median follow-up of 8.1 years from TKI initiation, overall survival among responders was significantly greater than nonresponders (93% vs. 85%, P < .001). Progression to blast phase was more common in nonresponders (1.9% vs. 10.4%, P = .004). However, 34% of nonresponders (at 24 months) went on to achieve CCyR with continued TKI therapy.

CONCLUSION

Here, we re-demonstrate the importance of early CCyR in predicting survival and prevention of progression to blast phase. In addition, late CCyR appears to have prognostic implications, and continued TKI therapy with the goal of achieving a later CCyR may be a reasonable strategy in patients with limited alternate treatment options.

Comparison of 3-month cytogenetic and molecular assays for early assessment of long-term clinical impact after BCR-ABL1 tyrosine kinase inhibitor treatment in chronic myeloid leukemia

To compare the clinical significance of 3-month cytogenetic and molecular monitoring, we analyzed 1,410 paired cytogenetic and molecular data from 705 chronic-phase chronic myeloid leukemia patients. Based on early cytogenetic response (ECyR, Ph+≤35 %) and molecular response (EMR, BCR-ABL1^IS≤10 %) at 3 months, the patients were divided into four groups (group 1: ECyR + EMR, n = 560; group 2: no ECyR + EMR, n = 27; group 3: ECyR + no EMR, n = 55; group 4: no ECyR + no EMR, n = 63). By 10 years, major molecular response (MMR), deep molecular response (MR4.5), overall survival (OS), and progression-free survival (PFS) rates were significantly high in group 1 (P < 0.001). Comparing groups 2 and 3, the MMR (P = 0.096), MR4.5 (P = 0.945), OS (P = 0.832), and PFS (P = 0.627) rates tended to be higher in group 2, although not significantly. Thus, the cytogenetic assay can not only be useful but its addition may also provide a more precise prediction of MR4.5.

Clinical outcome of chronic myeloid leukemia patients who switch from first-line therapy with a second generation tyrosine kinase inhibitor to an alternative TKI

While second generation tyrosine kinase inhibitors (2GTKIs) are highly effective therapies for chronic myeloid leukemia (CML), a significant minority of patients who initiate a 2GTKI will require a switch to an alternative TKI. The long-term outcomes of those who require a change in therapy after front-line 2GTKI therapy are largely undescribed. Here we describe the clinical outcomes associated with switch to an alternative TKI after first-line therapy with a 2GTKI. Of 232 patients who initiated a 2GTKI during the study period, 76 (33 %) switched to an alternative TKI. Reasons for switching included intolerance (79 %) and resistance (21 %). Among the 60 patients who switched due to intolerance, 53 (88 %) were able to achieve or maintain a major molecular response (MMR) with 5-year progression-free survival (PFS) 90.5 % (95 % CI 90.4-90.6 %). Amongst the 16 patients who switched due to resistance, 8 patients (50 %) were able to achieve MMR with 5-year PFS 80.4 % (95 % CI 80.2-80.6 %). Most patients who switched due to intolerance remained on their second-line TKI. Approximately 25 % of patients who initiate first-line 2GTKI in a real world setting will ultimately switch to an alternate TKI due to intolerance. Patients who switch for intolerance continue to enjoy excellent clinical outcomes.

The New ELN Recommendations for Treating CML

After normal survival has been achieved in most patients with chronic myeloid leukemia (CML), a new goal for treating CML is survival at good quality of life, with treatment discontinuation in sustained deep molecular response (DMR; MR4 or deeper) and treatment-free remission (TFR). Four tyrosine kinase inhibitors (TKIs) have been approved for first-line therapy: imatinib, dasatinib, nilotinib, bosutinib. Unexpectedly, the outcome of long-term randomized trials has shown that faster response as achieved by higher doses of imatinib, imatinib in combination, or second-generation (2G)-TKIs, does not translate into a survival advantage. Serious and frequent, and in part cumulative long-term toxicities, have led to a reevaluation of the role of 2G-TKIs in first-line therapy. Generic imatinib is the current most cost-effective first-line therapy in the chronic phase. A change of treatment is recommended when intolerance cannot be ameliorated or molecular milestones are not reached. Patient comorbidities and contraindications of all TKIs must be considered. Risk profile at diagnosis should be assessed with the EUTOS score for long-term survival (ELTS). Monitoring of response is by polymerase chain reaction (PCR). Cytogenetics is still required in the case of atypical translocations, atypical transcripts, and additional chromosomal aberrations. TKIs are contraindicated during pregnancy. Since the majority of patients are at risk of lifelong exposure to TKIs, amelioration of chronic low-grade side effects is important.

Chronic Myeloid Leukemia in 2020

New insights have emerged from maturing long-term academic and commercial clinical trials regarding optimum management of chronic myeloid leukemia (CML). Velocity of response has unexpectedly proved less important than hitherto thought, does not predict survival, and is of unclear relevance for treatment-free remission (TFR). Serious and cumulative toxicity has been observed with tyrosine kinase inhibitors that had been expected to replace imatinib. Generic imatinib has become cost-effective first-line treatment in chronic phase despite chronic low-grade side-effects in many patients. Earlier recognition of end-phase by genetic assessment might improve prospects for blast crisis (BC). TFR has become an important new treatment goal of CML. To reflect this new situation ELN has recently revised and updated its recommendations for treating CML. After a brief review of 175 years of CML history this review will focus on recent developments and on current evidence for treating CML in 2020.

European LeukemiaNet 2020 recommendations for treating chronic myeloid leukemia

The therapeutic landscape of chronic myeloid leukemia (CML) has profoundly changed over the past 7 years. Most patients with chronic phase (CP) now have a normal life expectancy. Another goal is achieving a stable deep molecular response (DMR) and discontinuing medication for treatment-free remission (TFR). The European LeukemiaNet convened an expert panel to critically evaluate and update the evidence to achieve these goals since its previous recommendations. First-line treatment is a tyrosine kinase inhibitor (TKI; imatinib brand or generic, dasatinib, nilotinib, and bosutinib are available first-line). Generic imatinib is the cost-effective initial treatment in CP. Various contraindications and side-effects of all TKIs should be considered. Patient risk status at diagnosis should be assessed with the new EUTOS long-term survival (ELTS)-score. Monitoring of response should be done by quantitative polymerase chain reaction whenever possible. A change of treatment is recommended when intolerance cannot be ameliorated or when molecular milestones are not reached. Greater than 10% BCR-ABL1 at 3 months indicates treatment failure when confirmed. Allogeneic transplantation continues to be a therapeutic option particularly for advanced phase CML. TKI treatment should be withheld during pregnancy. Treatment discontinuation may be considered in patients with durable DMR with the goal of achieving TFR.

Defining therapy goals for major molecular remission in chronic myeloid leukemia: results of the randomized CML Study IV

Major molecular remission (MMR) is an important therapy goal in chronic myeloid leukemia (CML). So far, MMR is not a failure criterion according to ELN management recommendation leading to uncertainties when to change therapy in CML patients not reaching MMR after 12 months. At monthly landmarks, for different molecular remission status Hazard ratios (HR) were estimated for patients registered to CML study IV who were divided in a learning and a validation sample. The minimum HR for MMR was found at 2.5 years with 0.28 (compared to patients without remission). In the validation sample, a significant advantage for progression-free survival (PFS) for patients in MMR could be detected (p-value 0.007). The optimal time to predict PFS in patients with MMR could be validated in an independent sample at 2.5 years. With our model we provide a suggestion when to define lack of MMR as therapy failure and thus treatment change should be considered. The optimal response time for 1% BCR-ABL at about 12–15 months was confirmed and for deep molecular remission no specific time point was detected. Nevertheless, it was demonstrated that the earlier the MMR is achieved the higher is the chance to attain deep molecular response later.

Assessment of imatinib as first-line treatment of chronic myeloid leukemia: 10-year survival results of the randomized CML study IV and impact of non-CML determinants

Chronic myeloid leukemia (CML)-study IV was designed to explore whether treatment with imatinib (IM) at 400 mg/day (n=400) could be optimized by doubling the dose (n=420), adding interferon (IFN) (n=430) or cytarabine (n=158) or using IM after IFN-failure (n=128). From July 2002 to March 2012, 1551 newly diagnosed patients in chronic phase were randomized into a 5-arm study. The study was powered to detect a survival difference of 5% at 5 years. After a median observation time of 9.5 years, 10-year overall survival was 82%, 10-year progression-free survival was 80% and 10-year relative survival was 92%. Survival between IM400 mg and any experimental arm was not different. In a multivariate analysis, risk group, major-route chromosomal aberrations, comorbidities, smoking and treatment center (academic vs other) influenced survival significantly, but not any form of treatment optimization. Patients reaching the molecular response milestones at 3, 6 and 12 months had a significant survival advantage. For responders, monotherapy with IM400 mg provides a close to normal life expectancy independent of the time to response. Survival is more determined by patients' and disease factors than by initial treatment selection. Although improvements are also needed for refractory disease, more life-time can currently be gained by carefully addressing non-CML determinants of survival.

Concordant optimal molecular and cytogenetic responses at both 3 and 6 months predict a higher probability of MR4.5 achievement in patients with chronic myeloid leukemia treated with imatinib

To investigate the impact of the combination of early molecular and cytogenetic responses on the achievement of MR4.5, 228 newly diagnosed chronic phase chronic myeloid leukemia patients treated with imatinib were categorized into 3-month and 6-month concordant optimal, discordant, concordant warning, and failure groups. Among them, 85.3% at 3 months and 78.1% at 6 months had concordant molecularly and cytogenetically defined responses. At both 3 and 6 months, patients with discordant, concordant warning and failure responses had similar 3-year MR4.5 rates, and all were significantly lower than the rate in patients with concordant optimal responses. Patients with concurrent 3-month and 6-month concordant optimal responses had a significantly higher 3-year MR4.5 rate than those with other responses, and 3-month and 6-month concurrent molecular optimal, but not cytogenetic optimal responses. Therefore, achieving concordant optimal molecular and cytogenetic responses at both 3 and 6 months with imatinib treatment are associated with MR4.5 achievement.

Flow Cytometric Immunobead Assay for Detection of BCR-ABL1 Fusion Proteins in Chronic Myleoid Leukemia: Comparison with FISH and PCR Techniques

Chronic Myeloid Leukemia (CML) is characterized by a balanced translocation juxtaposing the Abelson (ABL) and breakpoint cluster region (BCR) genes. The resulting BCR-ABL1 oncogene leads to increased proliferation and survival of leukemic cells. Successful treatment of CML has been accompanied by steady improvements in our capacity to accurately and sensitively monitor therapy response. Currently, measurement of BCR-ABL1 mRNA transcript levels by real-time quantitative PCR (RQ-PCR) defines critical response endpoints. An antibody-based technique for BCR-ABL1 protein recognition could be an attractive alternative to RQ-PCR. To date, there have been no studies evaluating whether flow-cytometry based assays could be of clinical utility in evaluating residual disease in CML patients. Here we describe a flow-cytometry assay that detects the presence of BCR-ABL1 fusion proteins in CML lysates to determine the applicability, reliability, and specificity of this method for both diagnosis and monitoring of CML patients for initial response to therapy. We show that: i) CML can be properly diagnosed at onset, (ii) follow-up assessments show detectable fusion protein (i.e. relative mean fluorescent intensity, rMFI%>1) when BCR-ABL1IS transcripts are between 1-10%, and (iii) rMFI% levels predict CCyR as defined by FISH analysis. Overall, the FCBA assay is a rapid technique, fully translatable to the routine management of CML patients.

Response-related predictors of survival in CML

The assessment of response to tyrosine kinase inhibitor (TKI) treatment in chronic myeloid leukemia (CML) does not only reflect tumor burden at a given time but has been shown to be linked to long-term survival outcomes as well. Therefore, the quantification of molecular or cytogenetic response as early as 3 months on treatment allows a prognostic stratification of a patient's individual risk. With competing TKI regimens available, a timely switch of treatment can be considered if unfavorable outcome has to be expected due to early response failure. Numerous studies have demonstrated the association of long-term outcome with early response for first-line treatment with imatinib, with second-generation TKI and for second-line TKI treatment as well.

Safety and efficacy of imatinib in CML over a period of 10 years: data from the randomized CML-study IV

Tyrosine kinase inhibitors (TKI) have changed the natural course of chronic myeloid leukemia (CML). With the advent of second-generation TKI safety and efficacy issues have gained interest. The randomized CML - Study IV was used for a long-term evaluation of imatinib (IM). 1503 patients have received IM, 1379 IM monotherapy. After a median observation of 7.1 years, 965 patients (64%) still received IM. At 10 years, progression-free survival was 82%, overall survival 84%, 59% achieved MR(5), 72% MR(4.5), 81% MR(4), 89% major molecular remission and 92% MR(2) (molecular equivalent to complete cytogenetic remission). All response levels were reached faster with IM800 mg except MR(5). Eight-year probabilities of adverse drug reactions (ADR) were 76%, of grades 3-4 22%, of non-hematologic 73%, and of hematologic 28%. More ADR were observed with IM800 mg and IM400 mg plus interferon α (IFN). Most patients had their first ADR early with decreasing frequency later on. No new late toxicity was observed. ADR to IM are frequent, but mostly mild and manageable, also with IM 800 mg and IM 400 mg+IFN. The deep molecular response rates indicate that most patients are candidates for IM discontinuation. After 10 years, IM continues to be an excellent initial choice for most patients with CML.