Treatment-free remission following frontline nilotinib in patients with chronic myeloid leukemia in chronic phase: results from the ENESTfreedom study

Management and outcome of patients with chronic myeloid leukemia in blast phase in the tyrosine kinase inhibitor era - analysis of the European LeukemiaNet Blast Phase Registry

Blast phase (BP) of chronic myeloid leukemia (CML) still represents an unmet clinical need with a dismal prognosis. Due to the rarity of the condition and the heterogeneity of the biology and clinical presentation, prospective trials and concise treatment recommendations are lacking. Here we present the analysis of the European LeukemiaNet Blast Phase Registry, an international collection of the clinical presentation, treatment and outcome of blast phases which had been diagnosed in CML patients after 2015. Data reveal the expected heterogeneity of the entity, lacking a clear treatment standard. Outcomes remain dismal, with a median overall survival of 23.8 months (median follow up 27.8 months). Allogeneic stem cell transplantation (alloSCT) increases the rate of deep molecular responses. De novo BP and BP evolving from a previous CML do show slightly different features, suggesting a different biology between the two entities. Data show that outside clinical trials and in a real-world setting treatment of blast phase is individualized according to disease- and patient-related characteristics, with the aim of blast clearance prior to allogeneic stem cell transplantation. AlloSCT should be offered to all patients eligible for this procedure.

Efficacy and safety of flumatinib in the treatment of newly diagnosed chronic myeloid leukemia in the chronic phase: A real-world single-center retrospective study, with a focus on premature drug discontinuation

PURPOSE

To assess the real-world efficacy and safety of flumatinib as first-line and post-line treatments for chronic myeloid leukemia in the chronic phase (CML-CP).

RESULTS

Among 141 patients receiving flumatinib as first-line and post-line treatment, the 12-month major molecular response (MMR) rates were 69.4% and 67.6%, respectively. The median time to response was 6 and 10.5 months, respectively. In post-line treatment, the early molecular response (EMR) of flumatinib as second-line is significantly superior to that of third-line treatment (3-month EMR rate: 79.2% vs. 39.3%, P<0.001; 3-month MMR rate: 45.8% vs. 21.4%, P=0.033). Contrastively, patients who switched to flumatinib due to intolerance had significantly higher MMR rates at 3, 6, and 12 months compared to patients who switched due to inadequate response (60.6% vs. 24.2%, P=0.003; 66.7% vs. 36.0%, P=0.027; 84.2% vs. 50.0%, P=0.038). Premature drug discontinuation was observed in 28.4% of the patients. Grades 3-4 hematologic adverse events (AEs) were identified as independent risk factors for premature drug discontinuation. Patients who discontinued treatment and those who previously received only imatinib therapy had a poorer molecular response and failure-free survival.

CONCLUSIONS

Flumatinib demonstrates favorable efficacy and safety. Treatment discontinuation can result in a poorer molecular response and long-term prognosis.

Oral arsenic plus imatinib versus imatinib solely for newly diagnosed chronic myeloid leukemia: a randomized phase 3 trial with 5-year outcomes

PURPOSE

The synergistic effects of combining arsenic compounds with imatinib against chronic myeloid leukemia (CML) have been established using in vitro data. We conducted a clinical trial to compare the efficacy of the arsenic realgar-indigo naturalis formula (RIF) plus imatinib with that of imatinib monotherapy in patients with newly diagnosed chronic phase CML (CP-CML).

METHODS

In this multicenter, randomized, double-blind, phase 3 trial, 191 outpatients with newly diagnosed CP-CML were randomly assigned to receive oral RIF plus imatinib (n = 96) or placebo plus imatinib (n = 95). The primary end point was the major molecular response (MMR) at 6 months. Secondary end points include molecular response 4 (MR4), molecular response 4.5 (MR4.5), progression-free survival (PFS), overall survival (OS), and adverse events.

RESULTS

The median follow-up duration was 51 months. Due to the COVID-19 pandemic, the recruitment to this study had to be terminated early, on May 28, 2020. The rates of MMR had no significant statistical difference between combination and imatinib arms at 6 months and any other time during the trial. MR4 rates were similar in both arms. However, the 12-month cumulative rates of MR4.5 in the combination and imatinib arms were 20.8% and 10.5%, respectively (p = 0.043). In core treatment since the 2-year analysis, the frequency of MR4.5 was 55.6% in the combination arm and 38.6% in the imatinib arm (p = 0.063). PFS and OS were similar at five years. The safety profiles were similar and serious adverse events were uncommon in both groups.

CONCLUSION

The results of imatinib plus RIF as a first-line treatment of CP-CML compared with imatinib might be more effective for achieving a deeper molecular response (Chinadrugtrials number, CTR20170221).

Second Treatment-Free Remission Attempt in Patients with Chronic Myeloid Leukemia

Long-term survival outcomes of patients with chronic myeloid leukemia in the chronic phase are now similar to those of the general population, following the introduction of ABL1 tyrosine kinase inhibitors (TKIs). Approximately 40% to 80% of patients with chronic myeloid leukemia successfully achieved treatment-free remission after the first attempt of TKI discontinuation (TFR1), after achieving a durable deep molecular response. However, the possibility of achieving treatment-free remission after a second attempt of TKI discontinuation (TFR2) remains unclear. Therefore, we reviewed current TFR2 studies to clarify the feasibility of achieving TFR2. We identified 5 TFR2 clinical trials and 2 real-world reports. TFR2 attempt may be feasible after retreatment with imatinib, nilotinib, or dasatinib. Patients who have achieved MR4.0 or deeper durable molecular remission are eligible to enter the TFR2 phase. Imatinib is well tolerated and can be administered for consolidative treatment before the TFR2 attempt, whereas drug-related adverse effects of nilotinib or dasatinib affect their tolerability and might lead to discontinuation. Late onset relapse (> 1 year or > 2 year) was often reported, thus careful monitoring is needed.

Treatment-free remission after a second TKI discontinuation attempt in patients with Chronic Myeloid Leukemia re-treated with dasatinib - interim results from the DAstop2 trial

Tyrosine kinase inhibitor (TKI) discontinuation in chronic myeloid leukemia (CML) has become part of routine care for patients with a sustained deep molecular response (DMR). Approximately 50% experience a molecular relapse upon TKI cessation. Most of them quickly regain DMR upon TKI resumption. Whether these patients can achieve a second treatment-free remission (TFR) remains unclear. DAstop2 (ClinicalTrials.gov ID: NCT03573596) is a prospective study including patients with a failed first TFR attempt re-treated with any TKI for ≥ one year. Upon entering the study, patients received the TKI dasatinib for additional two years. Patients with sustained DMR for ≥1 year qualified for a second TKI stop. Ninety-four patients were included between Oct 2017-Dec 2021. At the time of data analysis, 62 patients had attempted a 2nd stop. After a median follow-up of 27 months from 2nd stop, TFR rates were 61, 56 and 46% at 6, 12 and 24 months respectively. No progression to advanced stage disease was seen and 87% had re-achieved MR4 within a median of 3 months from TKI re-initiation. In summary, we show that a 2nd TFR attempt after dasatinib treatment is safe, feasible and TFR rates seem in the range of those reported in trials of a first TKI stop.

Clinical Insights into Structure, Regulation, and Targeting of ABL Kinases in Human Leukemia

Chronic myeloid leukemia is a multistep, multi-lineage myeloproliferative disease that originates from a translocation event between chromosome 9 and chromosome 22 within the hematopoietic stem cell compartment. The resultant fusion protein BCR::ABL1 is a constitutively active tyrosine kinase that can phosphorylate multiple downstream signaling molecules to promote cellular survival and inhibit apoptosis. Currently, tyrosine kinase inhibitors (TKIs), which impair ABL1 kinase activity by preventing ATP entry, are widely used as a successful therapeutic in CML treatment. However, disease relapses and the emergence of resistant clones have become a critical issue for CML therapeutics. Two main reasons behind the persisting obstacles to treatment are the acquired mutations in the ABL1 kinase domain and the presence of quiescent CML leukemia stem cells (LSCs) in the bone marrow, both of which can confer resistance to TKI therapy. In this article, we systemically review the structural and molecular properties of the critical domains of BCR::ABL1 and how understanding the essential role of BCR::ABL1 kinase activity has provided a solid foundation for the successful development of molecularly targeted therapy in CML. Comparison of responses and resistance to multiple BCR::ABL1 TKIs in clinical studies and current combination treatment strategies are also extensively discussed in this article.

Exploration of treatment-free remission in CML, based on molecular monitoring

BACKGROUND

Typical chronic myelogenous leukemia (CML) is a myeloproliferative neoplasm caused by t(9; 22)(q34; q11) translocation. This chromosomal translocation forms the BCR::ABL1 fusion gene. The tyrosine kinase encoded by the BCR::ABL1 is considered to be the main pathogenic diver. BCR::ABL1 is not only a therapeutic target, but also a monitoring target. Monitoring of BCR::ABL1 reveals the progression of the disease and guides the next treatment. Now for CML, the target of treatment has been focused on treatment-free remission (TFR).

METHODS

We conducted a literature review of current developments of treatment-free remission and molecular monitoring methods.

RESULTS

More effective and sensitive CML monitoring methods such as digital droplet PCR (ddPCR) and next generation sequencing (NGS) have further studied the measurable residual disease (MRD) and clonal heterogeneity, which provides strong support for the exploration of TFR. We discussed some of the factors that may be related to TFR outcomes at the molecular level, along with some monitoring strategies.

CONCLUSION

Currently, predictive indicators for treatment-free remission outcomes and recurrence are lacking in clinical practice. In future, treatment-free remission research should focus on combining the clinical indicators with molecular monitoring and biological markers to personalize patient conditions and guide clinicians to develop individualized treatment plans, so that more patients with CML can achieve safer and stabler treatment-free remission.

Twenty years of evolution of CML therapy: how the treatment goal is moving from disease to patient

The introduction of imatinib in 2000 opened the era of tyrosine kinase inhibitors (TKIs) for CML therapy and has revolutionized the life expectancy of CML patients, which is now quite like the one of the healthy aged population. Over the last 20 years, both the TKI therapy itself and the objectives have undergone evolutions highlighted and discussed in this review. The main objective of the CML therapy in the first 10 years after TKI introduction was to abolish the disease progression from the chronic to the blastic phase and guarantee the long-term survival of the great majority of patients. In the second 10 years (from 2010 to the present), the main objective of CML therapy moved from survival, considered achieved as a goal, to treatment-free remission (TFR). Two phenomena emerged: no more than 50-60% of CML patients could be candidates for discontinuation and over 50% of them molecularly relapse. The increased cumulative incidence of specific TKI off-target side effects was such relevant to compel to discontinue or reduce the TKI administration in a significant proportion of patients and to avoid a specific TKI in particular settings of patients. Therefore, the treatment strategy must be adapted to each category of patients. What about the patients who do not get or fail the TFR? Should they be compelled to continue the TKIs at the maximum tolerated dose? Alternative strategies based on the principle of minimal effective dose have been tested with success and they are now re-evaluated with more attention, since they guarantee survival and probably a better quality of life, too. Moving from treating the disease to treating the patient is an important change of paradigm. We can say that we are entering a personalized CML therapy, which considers the patients' age, their comorbidities, tolerability, and specific objectives. In this scenario, the new techniques supporting the monitoring of the patients, such as the digital PCR, must be considered. In the present review, we present in deep this evolution and comment on the future perspectives of CML therapy.

Final report of TKI discontinuation trial with dasatinib for the second attempt of treatment-free remission after failing the first attempt with imatinib: Treatment-free Remission Accomplished by Dasatinib (TRAD) study

Multiple studies have reported a significant treatment-free remission (TFR) rate of 50%-60% in patients with chronic myeloid leukaemia (CML) who discontinue tyrosine kinase inhibitor (TKI) therapy. However, the remaining half of these patients still require re-initiation of TKI therapy for leukaemia control. It remains unclear if TKI drugs should be switched for re-therapy in patients who failed the first TFR (TFR1) attempt. Our study attempted to determine whether dasatinib therapy after TFR1 failure post-imatinib discontinuation could improve the likelihood of TFR2. Of 59 patients who lost molecular response after imatinib discontinuation for TFR1, 55 patients (93.2%) were treated with dasatinib, of whom 49 (89.1%) regained MR4.5 or deeper response, with a median time of 1.85 months to achieve MR4.5. Dasatinib was discontinued in 35 patients for TFR2 attempt, of whom 26 patients (74.28%) lost MMR and 6 (17.14%) MR4. Risk factor analysis for the TFR2 after dasatinib discontinuation suggested three significant factors: (1) doubling time of BCR::ABL1 transcript following TFR1 attempt, (2) rapid regaining of molecular response following dasatinib therapy and (3) undetectable BCR::ABL1 transcript prior to TFR2 attempt. The present study showed that dasatinib does not increase the TFR2 rate in general, but a selected group of patients could benefit from this approach.

Importance of TKI treatment duration in treatment-free remission of chronic myeloid leukemia: results of the D-FREE study

Treatment-free remission (TFR) is a new goal for patients with chronic myeloid leukemia in chronic phase (CML-CP) with a sustained deep molecular response (DMR) to treatment with tyrosine kinase inhibitors (TKIs). However, optimal conditions for successful TFR in patients treated with second-generation (2G)-TKIs are not fully defined. In this D-FREE study, treatment discontinuation was attempted in newly diagnosed CML-CP patients treated with the 2G-TKI dasatinib who achieved BCR-ABL1 levels of ≤ 0.0032% (MR4.5) on the international scale (BCR-ABL1IS) and maintained these levels for exactly 1 year. Of the 173 patients who received dasatinib induction therapy for up to 2 years, 123 completed and 60 (48.8%) reached MR 4.5. Among the first 21 patients who maintained MR4.5 for 1 year and discontinued dasatinib, 17 experienced molecular relapse defined as loss of major molecular response (BCR-ABL1IS > 0.1%) confirmed once, or loss of MR4 (BCR-ABL1IS > 0.01%) confirmed on 2 consecutive assessments. The estimated molecular relapse-free survival rate was 16.7% at 12 months. This study was prematurely terminated according to the protocol's safety monitoring criteria. The conclusion was that sustained DMR for just 1 year is insufficient for TFR in CML-CP patients receiving dasatinib for less than a total of 3 years of treatment.

Switching from imatinib to nilotinib plus pegylated interferon-α2b in chronic phase CML failing to achieve deep molecular response: clinical and immunological effects

In order to improve molecular response for a discontinuation attempt in chronic myeloid leukemia (CML) patients in chronic phase, who had not achieved at least a molecular response <0.01% BCR-ABL1^IS (MR^4.0) after at least 2 years of imatinib therapy, we prospectively evaluated whether they could attain MR^4.0 after a switch to a combination of nilotinib and 9 months of pegylated interferon-α2b (PegIFN). The primary endpoint of confirmed MR^4.0 at month 12 (a BCR-ABL1^IS level ≤ 0.01% both at 12 and 15 months) was reached by 44% (7/16 patients, 95% confidence interval (CI): 23- 67%) of patients, with 81% (13/16 patients, 95% CI: 57-93%) of patients achieving an unconfirmed MR^4.0. The scheduled combination was completed by 56% of the patients, with premature discontinuations, mainly due to mood disturbances after the introduction of PegIFN, questioning the feasibility of the combination of nilotinib and PegIFN for this patient population and treatment goal. A comprehensive clinical substudy program was implemented to characterize the impact of the treatment changes on the immunological profile. This trial was registered at www.clinicaltrials.gov as #NCT01866553.

Management of chronic myeloid leukemia in 2023 - common ground and common sense

With the improving knowledge of CML and its management, the goals of therapy need to be revisited to ensure an optimal use of the BCR::ABL1 TKIs in the frontline and later-line therapy of CML. In the frontline therapy of CML in the chronic phase (CML-CP), imatinib and the three second-generation TKIs (bosutinib, dasatinib and nilotinib) are associated with comparable survival results. The second-generation TKIs may produce earlier deep molecular responses, hence reducing the time to reaching a treatment-free remission (TFR). The choice of the second-generation TKI versus imatinib in frontline therapy is based on the treatment aims (survival, TFR), the CML risk, the drug cost, and the toxicity profile with respect to the patient's comorbidities. The TKI dosing is more flexible than has been described in the registration trials, and dose adjustments can be considered both in the frontline and later-line settings (e.g., dasatinib 50 mg frontline therapy; dose adjusted schedules of bosutinib and ponatinib), as well as during an ongoing TKI therapy to manage toxicities, before considering changing the TKI. In patients who are not candidates for TFR, BCR::ABL1 (International Scale) transcripts levels <1% are acceptable, result in virtually similar survival as with deeper molecular remissions, and need not warrant a change of TKI. For patients with true resistance to second-generation TKIs or with the T315I gatekeeper mutation, the third-generation TKIs are preferred. Ponatinib should be considered first because of the cumulative experience and results in the CML subsets, including in T315I-mutated CML. A response-based dosing of ponatinib is safe and leads to high TKI compliance. Asciminib is a third-generation TKI with possibly a better toxicity profile, but lesser activity in T315I-mutated CML. Olverembatinib is another potent third-generation TKI with early promising results.

SOHO State of the Art Updates and Next Questions | Update on Treatment-Free Remission in Chronic Myeloid Leukemia (CML)

Tyrosine kinase inhibitor (TKI) discontinuation, also known as treatment-free remission (TFR) is currently one of the main goals of chronic myeloid leukemia (CML) therapy. TKI discontinuation should be considered in eligible patients for several reasons. Specifically, TKI therapy is associated with reduced quality of life, long-term side effects, and a heavy financial burden on both the patients and society. TKI discontinuation is a particularly important goal for younger patients diagnosed with CML because of the treatment's effects on their growth and development in addition to potential long-term side-effects. Numerous studies with thousands of patients have demonstrated the safety and feasibility of attempting TKI discontinuation in a select group of patients who have achieved a sustained deep molecular remission. With current TKIs, approximately 50% of patients will be eligible for attempting TFR of which only 50% will achieve a successful TFR. Therefore, in reality, only 20% of patients with newly diagnosed CML will achieve a successful TFR, and the majority of patients will need to continue TKI therapy indefinitely. However, several ongoing clinical trials are investigating treatment options for patients to achieve deeper remission with the ultimate goal of a cure, which is defined as being off drug with no evidence of disease.

Chronic Myeloid Leukemia, from Pathophysiology to Treatment-Free Remission: A Narrative Literature Review

Chronic myeloid leukemia (CML) is one of the most common leukemias occurring in the adult population. The course of CML is divided into three phases: the chronic phase, the acceleration phase, and the blast phase. Pathophysiology of CML revolves around Philadelphia chromosome that constitutively activate tyrosine kinase through BCR-ABL1 oncoprotein. In the era of tyrosine kinase inhibitors (TKIs), CML patients now have a similar life expectancy to people without CML, and it is now very rare for CML patients to progress to the blast phase. Only a small proportion of CML patients have resistance to TKI, caused by BCR-ABL1 point mutations. CML patients with TKI resistance should be treated with second or third generation TKI, depending on the BCR-ABL1 mutation. Recently, many studies have shown that it is possible for CML patients who achieve a long-term deep molecular response to stop TKIs treatment and maintain remission. This review aimed to provide an overview of CML, including its pathophysiology, clinical manifestations, the role of stem cells, CML treatments, and treatment-free remission.

Dasatinib plus Peg-Interferon alpha 2b combination in newly diagnosed chronic phase chronic myeloid leukaemia: Results of a multicenter phase 2 study (DASA-PegIFN study)

Superior rates of deep molecular response (DMR) have been reported with the combination of tyrosine kinase inhibitors and pegylated-interferon-alpha (Peg-IFN) in patients with newly diagnosed chronic phase-chronic myeloid leukaemia (CP-CML). In this setting, this study investigated the efficacy and safety of dasatinib combined to Peg-IFN-α2b (Dasa-PegIFN, NCT01872442). A total of 79 patients (age ≤65 years) started dasatinib; 61 were eligible for Peg-IFNα-2b add-on therapy at month 3 for a maximum 21-months duration. Dasatinib was continued thereafter. The primary endpoint was the cumulative rate of molecular response 4.5 log (MR^4.5 ) by 12 months. The results are reported for the 5-year duration of the study. Grade 3 neutropenia was frequent with the combination but did not induce severe infection (one of grade 3). Other adverse events were generally low grade (4% of grade 3-4) and expected. Seventy-nine per cent and 61% of patients continued the Peg-IFN until months 12 and 24, respectively. Overall, at these time points, MR^4.5 rates were 25% and 38%, respectively. Thereafter, 32% and 46% of patients achieved a sustained (≥2 years) MR^4.5 or MR⁴ , respectively. This work established the feasibility and high rates of achievement of early and sustained DMR (a prerequisite for treatment-free-remission) with dasatinib and Peg-IFNα-2b combination as initial therapy.

Digital PCR as a New Method for Minimal Residual Disease Monitoring and Treatment Free Remission Management in Chronic Myeloid Leukemia Patients: Is It Reliable?

The effective and sensitive monitoring of Minimal Residual Disease or Measurable Residual Disease (MRD) is a very important aspect in the management of patients affected by hematologic malignancies. The recent availability of new technologies has opened to the improvement of MRD monitoring. It is particularly relevant in patients affected by Chronic Myeloid Leukemia (CML). MRD monitoring is key in the management of CML patients thanks to the efficacy of TKIs therapy. Moreover, the policies of TKIs discontinuation aimed at treatment free remission are strongly based on the good selection of patients eligible for stopping TKIs therapy. The recently described application of digital PCR in CML patients monitoring seems to improve the accuracy and precision in the identification of optimal responders. The present review reports an overview on the application of digital PCR in the monitoring of MRD in CML and its impact on TKIs discontinuation trials and, consequently, on TFR success.

Modelling of immune response in chronic myeloid leukemia patients suggests potential for treatment reduction prior to cessation

Introduction

Discontinuation of tyrosine kinase inhibitor (TKI) treatment is emerging as the main therapy goal for Chronic Myeloid Leukemia (CML) patients. The DESTINY trial showed that TKI dose reduction prior to cessation can lead to an increased number of patients achieving sustained treatment free remission (TFR). However, there has been no systematic investigation to evaluate how dose reduction regimens can further improve the success of TKI stop trials.

Methods

Here, we apply an established mathematical model of CML therapy to investigate different TKI dose reduction schemes prior to therapy cessation and evaluate them with respect to the total amount of drug used and the expected TFR success.

Results

Our systematic analysis confirms clinical findings that the overall time of TKI treatment is a major determinant of TFR success, while highlighting that lower dose TKI treatment for the same duration is equally sufficient for many patients. Our results further suggest that a stepwise dose reduction prior to TKI cessation can increase the success rate of TFR, while substantially reducing the amount of administered TKI.

Discussion

Our findings illustrate the potential of dose reduction schemes prior to treatment cessation and suggest corresponding and clinically testable strategies that are applicable to many CML patients.

Early dynamics of chronic myeloid leukemia on nilotinib predicts deep molecular response

Chronic myeloid leukemia (CML) is a myeloproliferative disorder caused by the BCR-ABL1 tyrosine kinase. Although ABL1-specific tyrosine kinase inhibitors (TKIs) including nilotinib have dramatically improved the prognosis of patients with CML, the TKI efficacy depends on the individual patient. In this work, we found that the patients with different nilotinib responses can be classified by using the estimated parameters of our simple dynamical model with two common laboratory findings. Furthermore, our proposed method identified patients who failed to achieve a treatment goal with high fidelity according to the data collected only at three initial time points during nilotinib therapy. Since our model relies on the general properties of TKI response, our framework would be applicable to CML patients who receive frontline nilotinib or other TKIs.

Adverse events and dose modifications of tyrosine kinase inhibitors in chronic myelogenous leukemia

The prognosis of chronic myelogenous leukemia (CML-CP) in chronic phase has improved dramatically since the introduction of imatinib. In addition to imatinib, second- and third-generation tyrosine kinase inhibitors (TKIs) and a novel allosteric inhibitor, asciminib, are now available. During long-term TKI therapy, the optimal selection of TKI therapy for individual patients requires the understanding of specific patterns of toxicity profile to minimize chronic toxicity and the risk of adverse events, including pulmonary arterial hypertension, pleural effusion, and cardiovascular events. Given the high efficacy of TKI therapy, dose modifications of TKI therapy reduce the risk of toxicities and improves quality of life during therapy. In this review article, we summarize the characteristics and adverse event profile of each TKI and dose modifications in patients with CML-CP and discuss future perspectives in the treatment of CML-CP.

Withdrawal syndrome after tyrosine kinase inhibitors discontinuation in patients with chronic myeloid leukemia

Background. Withdrawal syndrome (WS) a musculoskeletal pain after discontinuation of tyrosine kinase inhibitors (TKI) in patients with chronic myeloid leukemia (CML) has been described in the treatment-free remission (TFR) studies. The pathophysiological mechanisms and predisposing factors of WS have not been well established. Aim. Our aim was to evaluate clinical features and factors associated with WS in the Russian cohort of CML patients who discontinued TKI therapy. Materials and methods. WS was evaluated in total of 183 CML patients with chronic phase and sustained deep molecular response (DMR). WS was defined as a musculoskeletal pain newly observed after TKI cessation or as a worsening of previously observed symptoms. Results. DMR loss free survival at 36 months was 49% and 43% in prospective and retrospective groups respectively (p=0.96) with mеdian (Me) time of observation 33 months (range 1136). WS was observed in 49 (27%) patients: grade 12 was in 45 (92%) patients, grade 3 in 4 (8%) patients. Me time to WS occurrence was 2 months (range 17), Ме duration of WS was 5 months (range 135). WS was resolved in 14 of 15 patients with molecular relapse after 13 months of TKI re-initiation and was decreased in 1 patient. WS was completely resolved in 31 of 34 patients who continued remained in TFR and decreased in 3 patients. WS was resolved spontaneously or with nonsteroidal anti-inflammatory drugs in 14 (45%) and 17 (55%) patients accordingly. Older age (p0.0001), longer duration of TKI therapy (p0.0001) and presence of locomotion system diseases (p=0.022) were observed in patients with WS. No WS was observed in pregnant patients (р0.001). Survival without DMR loss at 12 months after TKI stop was 66 and 42% in patients with and without WS accordingly (р=0.095). Conclusion. The rate of WS was 27% that is in a good concordance with the data of the other TFR studies. A longer period of TKI exposure, older age and the history of locomotion system diseases were associated with the development of the WS. We found for the first time that WS was not observed in patients with pregnancy. There was no association of WS development and the rate of molecular relapses.

Discontinuation of tyrosine kinase inhibitors in pediatric chronic myeloid leukemia

BACKGROUND

The feasibility of tyrosine kinase inhibitor (TKI) discontinuation in pediatric chronic myeloid leukemia (CML) remains to be fully elucidated.

PROCEDURES

TKI was prospectively discontinued in patients who were diagnosed with CML at <20 years of age, treated with TKI for ≥3 years, and sustained molecular response 4.0 (MR4.0) for ≥2 years. Molecular relapse was defined as a single loss of major molecular response (MMR) (BCR-ABL1^IS >0.1%). Relapsed patients resumed the same TKI therapy administered before discontinuation.

RESULTS

Twenty-two patients with chronic-phase CML were enrolled, and the median ages at diagnosis and at TKI discontinuation were 9 (range: 1-14) years and 16 (5-26) years, respectively. The median follow-up time after TKI discontinuation was 37 months (range: 24-41 months). The median duration of TKI treatment before discontinuation was 100 (42-178) months, and that of MR4.0 was 53.5 (25-148) months. The treatment-free remission (TFR) rate at 12 months was 50.0% (90% confidence interval: 31.7%-65.8%). Eleven patients experienced loss of MMR within 4 months after TKI discontinuation and resumed TKI as originally prescribed. No progression was observed, and all 11 patients regained MR4.0 after TKI resumption. No patient had a withdrawal syndrome. The quality-of-life analysis suggested that successful TFR may improve academic performance in some patients. In patients who discontinued TKI therapy before puberty, the possibility of improvement in growth velocity upon TKI discontinuation was observed.

CONCLUSIONS

TKI could be discontinued safely in patients with pediatric CML showing a sustained deep MR.

[Observational study of chronic myeloid leukemia Chinese patients who discontinued tyrosine kinase inhibitors in the real-world]

Objective: This study aimed to observe whether the treatment-free remission (TFR) of second-generation tyrosine kinase inhibitors (TKI) in chronic myeloid leukemia (CML) is better than imatinib (IM) . Methods: The clinical data of 274 CML patients who discontinued treatment and with complete clinical data were retrospectively studied from June 2013 to March 2021. Using both univariate and multivariate Cox proportional hazards regression models, risk factors influencing TFR outcomes after drug withdrawal in CML patients were assessed. Results: A total of 274 patients were enrolled, 140 patients were women (51.1%) , with a median age of 48 (9-84) years at the time of TKI discontinuation. Prior to TKI discontinuation, 172 (62.8%) patients were treated with IM, and 102 (37.2%) had received second-generation TKI treatment, including 73 patients who had shifted from IM to a second-generation TKI and 29 patients who used second-generation TKI as the first-line treatment. The rationale for converting to a second-generation TKI are as follows: 37 patients aimed deep molecular response (DMR) to achieve TFR, seven patients changed due to IM intolerance, and 29 patients changed because of failure to achieve the optimal treatment response. The use of the last type of TKI included 96 patients (94.1%) with nilotinib, three patients (2.9%) with dasatinib, and two patients (2%) with flumatinib, including one patient who changed to IM due to second-generation TKI intolerance. No statistical differences were found in the median age at diagnosis and TKI discontinuation, sex, Sokal score, IFN treatment before TKI, median time of TKI treatment to achieve DMR, and the reasons for TKI discontinuation between the second TKI and IM (P>0.05) .The median cumulative treatment time of TKI (71.5 months vs 88 months, P<0.001) , the last TKI median treatment time (60 months vs 88 months, P<0.001) , and the median duration of DMR (58 months vs 66 months, P=0.002) were significantly shorter in the second-generation TKI compared with IM. In the median follow-up of 22 (6-118) months after TKI discontinuation, 88 patients (32.1%) had lost their MMR at a median of 6 (1-91) months; of the 53 patients (60.2%) who lost MMR within 6 months, the overall TFR rate was 67.9%, and the cumulative TFR rates at 12 and 24 months were 70.5% and 67.5%, respectively. Withdrawal syndrome occurred in 26 patients (9.5%) . For patients who restarted TKI treatment, 72 patients (83.7%) achieved DMR again at a median treatment of 4 (1 to 18) months. The univariate analysis showed that the TFR rate of patients treated with second-generation TKI was significantly higher than those who were treated with IM (77.5% vs 62.2%, P=0.041) . A further subgroup analysis found that the TFR rate of the second-generation TKI patients was significantly higher than those treated with IM (80.8% vs 62.2%, P=0.026) . No significant difference was found in the second-generation TKI used as the first line treatment compared with those who were treated with IM (69.0% vs 62.2%, P=0.599) . The multivariate analysis results showed that second-generation TKI treatment was an independent prognostic factor affecting TFR in patients who discontinued TKI (RR=1.827, 95%CI 1.015-3.288, P=0.044) . Conclusion: In the clinical setting, more CML patients rapidly achieved TFR using second-generation TKI than IM treatment.

Tyrosine Kinase Inhibitor discontinuation in Chronic Myeloid Leukemia: eligibility criteria and predictors of success

TKI discontinuation proved to be safe and feasible in patients with CML with deep and durable molecular responses, introducing an additional treatment goal for these patients beyond overall survival. However, treatment interruption is a safe procedure only with appropriate patient selection and monitoring. Clinical and biological factors associated with better outcomes do not yet offer a precise stratification of patients according to their risk of relapse. This article aims at reviewing the leading studies present in the field in order to define eligibility criteria for discontinuation and predictors of success.

Brazilian chronic myeloid leukemia working group recommendations for discontinuation of tyrosine kinase inhibitors in chronic myeloid leukemia in clinical practice

Introduction

Treatment-free remission (TFR) is a new goal of chronic myeloid leukemia (CML) therapy. TFR is feasible when the patient has achieved a deep and stable molecular response and met the criteria required to ensure its success. Treatment discontinuation should not be proposed to the CML patient if minimum conditions are not met. In Brazil, for example, molecular tests (BCR::ABL1) are not broadly available, making it difficult to monitor the patients adequately.

Objective

In this sense, providing TFR recommendations for Brazilian physicians are therefore necessary. These recommendations include the main criteria checklist to start the TKIs treatment discontinuing process in patients diagnosed with CML and the population-eligible characteristics for treatment discontinuation.

Method

Age, risk score at diagnosis, TKI treatment duration, BCR::ABL1 transcripts type, depth of the molecular response for treatment discontinuation, treatment adherence, patient monitoring and withdrawal syndrome are essential factors to consider in TFR. After TKI discontinuation, BCR::ABL1 transcripts monitoring should be more frequent. When a major molecular response loss is observed during the monitoring of a patient in TFR, the TKI treatment should be resumed.

Conclusion

These recommendations should serve as a basis for medical professionals interested in proposing TKI discontinuation for CML patients in clinical practice. It is important to highlight that, despite the benefits of TFR for the patients and the health system, it should only be feasible following the minimum standards proposed in this recommendation.

The prognostic role of NKG2A expression for patients with chronic myeloid leukemia after treatment discontinuation

This study aims to evaluate the possibility of tyrosine kinase inhibitors (TKIs) discontinuation in chronic myeloid leukemia (CML) patients who obtained sustained deep molecular response (DMR) and to explore the prognostic role of NK cells in treatment-free remission (TFR). Sixty CML patients who discontinued TKI treatment were enrolled, and we also investigated the immune profiles in 27 CML patients after TKI cessation. Of the 60 patients, the estimated TFR rate was 60.8% [95% CI: 49.5-74.8%] at 12 months. Patients who had longer TKI duration, major molecular response, and DMR maintenance time had a significantly higher TFR rate. And a higher percentage of NKG2A⁺NK cells and NKG2A⁺CD56^brightCD16^-NK cells were independent prognostic factors of TFR in multivariate analysis. These results indicate the practicality of the cessation of TKIs and patients with stable NK cell counts accompanied by higher cytotoxicity and increased killing capacity are more inclined to get sustained treatment-free survival.

Chronic Myeloid Leukemia: 2022 Update on Diagnosis, Therapy and Monitoring

DISEASE OVERVIEW

Chronic Myeloid Leukemia (CML) is a myeloproliferative neoplasm with an incidence of 1-2 cases per 100,000 adults. It accounts for approximately 15% of newly diagnosed cases of leukemia in adults DIAGNOSIS: CML is characterized by a balanced genetic translocation, t (9;22) (q34;q11.2), involving a fusion of the Abelson gene (ABL1) from chromosome 9q34 with the breakpoint cluster region (BCR) gene on chromosome 22q11.2. This rearrangement is known as the Philadelphia chromosome. The molecular consequence of this translocation is the generation of a BCR::ABL1 fusion oncogene, which in turn translates into a BCR::ABL1 oncoprotein.

FRONTLINE THERAPY

Four tyrosine kinase inhibitors (TKIs), imatinib, dasatinib, bosutinib, and nilotinib are approved by the United States Food and Drug Administration for first-line treatment of newly diagnosed CML in chronic phase (CML-CP). Clinical trials with second generation TKIs reported significantly deeper and faster responses but had no impact on survival prolongation, likely because of the availability of effective TKIs salvage therapies for patients who have a cytogenetic relapse with frontline TKI therapy.

SALVAGE THERAPY

For CML post failure on frontline therapy, second-line options include second and third generation TKIs. Although potent and selective, these TKIs exhibit unique pharmacological profiles and response patterns relative to different patient and disease characteristics, such as patients' comorbidities, disease stage, and BCR::ABL1 mutational status. Patients who develop the T315I "gatekeeper" mutation display resistance to all currently available TKIs except ponatinib, asciminib, and olverembatinib. Allogeneic stem cell transplantation remains an important therapeutic option for patients with CML-CP and failure (due to resistance) of at least 2 TKIs, and for all patients in advanced phase disease. Older patients who have a cytogenetic relapse post failure on all TKIs can maintain long-term survival if they continue a daily most effective/least toxic TKI, with or without the addition of non-TKI anti-CML agents (hydroxyurea, omacetaxine, azacitidine, decitabine, cytarabine, busulfan, others). This article is protected by copyright. All rights reserved.

Management of Myeloproliferative Neoplasms in the Molecular Era: From Research to Practice

The 1960 discovery of the Philadelphia chromosome in chronic myeloid leukemia (CML) marked the beginning of the modern genomic era of oncology. In the following years, the molecular underpinnings of CML were unraveled, culminating in the development of the first molecularly targeted therapy: imatinib. Imatinib revolutionized CML management, inducing deep molecular responses for most patients and aligning survival curves with those of age-matched control participants. Five additional tyrosine kinase inhibitors are now approved for CML: dasatinib, nilotinib, bosutinib, ponatinib, and asciminib (approved October 2021). The 2005 discovery of JAK2 mutations in myelofibrosis (MF) sparked enthusiasm that molecularly targeted therapies could have a similar impact in that disease. Three JAK inhibitors are now available for MF: ruxolitinib, fedratinib, and pacritinib (approved February 2022). JAK inhibitors are helpful for improving symptoms and splenomegaly but still only scratch the surface of MF pathophysiology. Clinical research testing novel agents, next-generation JAK inhibitors, and combinations of JAK inhibitors plus novel agents is moving at a tremendous pace in the hope that outcomes for patients with MF may mirror those with CML one day. This review provides an update on the status of clinical care and research for MF and addresses ongoing issues related to CML management.

Relationship between achievement of major molecular response or deep molecular response and nilotinib plasma concentration in patients with chronic myeloid leukemia receiving first-line nilotinib therapy

PURPOSE

We evaluated the plasma exposure and response relationships of nilotinib for patients with newly diagnosed chronic myeloid leukemia (CML) in real-world practice.

METHODS

For the 26 patients enrolled in this study, at 3, 6, 12, and 24 months after nilotinib administration, the trough plasma concentrations (C_trough) of nilotinib were analyzed. The relationships between nilotinib C_trough and the molecular response to nilotinib treatment at each point (each n = 26) were evaluated.

RESULTS

Median nilotinib C_trough values were significantly higher in patients with a major molecular response (MMR) at 3 months than in patients without an MMR (809 and 420 ng/mL, respectively; P = 0.046). Based on the area under the receiver-operating characteristic curve, the threshold value of the nilotinib C_trough at 3 months for predicting MMR achievement was 619 ng/mL at the best sensitivity (71.4%) and specificity (77.8%). Patients with a nilotinib C_trough of above 619 ng/mL had a significantly shorter time to achievement of a deep molecular response (DMR; 9.0 and 18.0 months, respectively; P = 0.020) and higher rates of DMR by 2 years in Kaplan-Meier plots (P = 0.025) compared with that in patients with a nilotinib C_trough of less than 619 ng/mL.

CONCLUSION

For patients with newly diagnosed CML, the nilotinib dose may be adjusted using a C_trough of above 619 ng/mL as the minimum effective concentration, i.e., the lowest concentration required for MMR or DMR achievement within a shorter time, during early stages after beginning therapy to obtain faster and deeper clinical responses.

Targeting DNMT1 by demethylating agent OR-2100 increases tyrosine kinase inhibitors-sensitivity and depletes leukemic stem cells in chronic myeloid leukemia

ABL1 tyrosine kinase inhibitors (TKIs) dramatically improve the prognosis of chronic myeloid leukemia (CML), but 10-20% of patients achieve suboptimal responses with low TKIs sensitivity. Furthermore, residual leukemic stem cells (LSCs) are involved in the molecular relapse after TKIs discontinuation. Aberrant DNA hypermethylation contributes to low TKIs sensitivity and the persistence of LSCs in CML. DNMT1 is a key regulator of hematopoietic stem cells, suggesting that aberrant DNA hypermethylation targeting DNMT1 represents a potential therapeutic target for CML. We investigated the efficacy of OR-2100 (OR21), the first orally available single-compound prodrug of decitabine. OR21 exhibited anti-tumor effects as a monotherapy, and in combination therapy it increased TKI-induced apoptosis and induction of tumor suppressor genes including PTPN6 encoding SHP-1 in CML cells. OR21 in combination with imatinib significantly suppressed tumor growth in a xenotransplant model. OR21 and combination therapy decreased the abundance of LSCs and inhibited engraftment in a BCR-ABL1-transduced mouse model. These results demonstrate that targeting DNMT1 using OR21 exerts anti-tumor effects and impairs LSCs in CML. Therefore, combination treatment of TKIs and OR21 represents a promising treatment strategy in CML.

The cure of leukemia through the optimist's prism

Progress is occurring at a dizzying rate across all leukemias. Since the authors' review of the topic in Cancer in 2018, numerous discoveries have been made that have improved the therapy and outcomes of several leukemia subsets. Hairy cell leukemia is potentially curable with a single course of cladribine followed by rituximab (10-year survival, ≥90%). Acute promyelocytic leukemia is curable at a rate of 80% to 90% with a nonchemotherapy regimen of all-trans retinoic acid and arsenic trioxide. The cure rate for core-binding factor acute myeloid leukemia (AML) is ≥75% with fludarabine, high-dose cytarabine, and gemtuzumab ozogamicin. Survival for patients with chronic myeloid leukemia is close to that for an age-matched normal population with BCR-ABL1 tyrosine kinase inhibitors (TKIs). Chronic lymphocytic leukemia, a previously incurable disease, may now be potentially curable with a finite duration of therapy with Bruton tyrosine kinase inhibitors and venetoclax. The estimated 5-year survival rate for patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (ALL) exceeds 70% with intensive chemotherapy and ponatinib, a third-generation BCR-ABL1 TKI, and more recent nonchemotherapy regimens using dasatinib or ponatinib with blinatumomab are producing outstanding results. Survival in both younger and older patients with ALL has improved with the addition of antibodies targeting CD20, CD19 (blinatumomab), and CD22 (inotuzumab) to chemotherapy. Several recent drug discoveries (venetoclax, FLT3 and IDH inhibitors, and oral hypomethylating agents) are also improving outcomes for younger and older patients with AML and for those with higher risk myelodysplastic syndrome.

Development of Asciminib, a Novel Allosteric Inhibitor of BCR-ABL1

Chronic myeloid leukemia (CML) is driven by a translocation event between chromosomes 9 and 22, leading to the formation of a constitutively active BCR-ABL1 oncoprotein. Approved tyrosine kinase inhibitors (TKIs) for CML inhibit BCR-ABL1 by competitively targeting its adenosine triphosphate (ATP)-binding site, which significantly improves patient outcomes. However, resistance to and intolerance of TKIs remains a clinical challenge. Asciminib is a promising investigational agent in development that allosterically targets BCR-ABL1 in a non-ATP-competitive manner. It binds to the ABL1 myristoyl-binding pocket and is effective against most ABL1 kinase domain mutations that confer resistance to ATP-competitive TKIs, including the T315I mutation. This review discusses unmet needs in the current CML treatment landscape, reports clinical data from asciminib trials that support the use of single-agent asciminib as third-line therapy and beyond, and explores the potential benefit of asciminib in combination with approved TKIs in earlier lines.

Discontinuation of tyrosine kinase inhibitors based on BCR-ABL1 monitoring by digital droplet PCR in pediatric chronic myeloid leukemia

Lifelong treatment of pediatric chronic myeloid leukemia (CML) patients with tyrosine kinase inhibitors (TKIs) can affect their growth and development. For these reasons, clinical trials have explored the feasibility of TKI discontinuation in children with a sufficient TKI response. We evaluated the analytical performance of digital droplet PCR (ddPCR) to quantify BCR-ABL1 and compared the results with reverse transcription quantitative polymerase chain reaction (RT-qPCR). We further investigated whether ddPCR could be used to determine TKI discontinuation in a clinical setting. Performance of ddPCR was evaluated using standard materials for BCR-ABL1, and a total of 197 clinical samples from 45 pediatric CML patients was included for comparison with RT-qPCR. ddPCR showed excellent analytical sensitivity with 0.001% international scale (IS) and linearity with R ² > 0.99 in log scale. BCR-ABL1 % IS results correlated well with those of RT-qPCR (R ² = 0.9435), however, they showed a moderate strength for agreement with a Cohen's kappa of 0.41 due to higher sensitivity of ddPCR. Among 45 pediatric CML patients, 42 were treated with first-line TKIs including imatinib (n = 27, 64%) and dasatinib (n = 12, 29%), and three patients that were started with imatinib were switched to dasatinib. When we evaluated whether follow-up samples fulfilled ABL1 copies ≥ 10,000 required for deep molecular response (DMR), all samples were acceptable by ddPCR, whereas 18% by RT-qPCR did not reached acceptable ABL1 copies. Moreover, 52 and 13% reached ABL1 copies ≥ 32,000 required for MR4.5 by ddPCR and RT-qPCR, respectively. Seven patients discontinued TKI and the median TKI treatment duration was 73 months prior to discontinuation. Prior to discontinuation, the median duration of sustained undetected BCR-ABL1 was 60 months. Two patients experienced loss of major MR (MMR) during follow-up and restarted dasatinib 5 months after discontinuation. They achieved MMR again and maintained better than DMR afterward. Results from those patients demonstrated that RT-qPCR did not match the need for adequate ABL1 copies for MR4.5 while majority of ddPCR could. Therefore, ddPCR was technically more acceptable to decide and monitor pediatric CML patients before and after TKI discontinuation.

Emerging concepts for assessing and predicting treatment-free remission in chronic myeloid leukemia patients

INTRODUCTION

In chronic myeloid leukemia (CML) patients who have reached a deep and sustained reduction of residual disease can attempt a discontinuation. The 'treatment-free remission' (TFR) has become a real long-term endpoint for 30-40% of chronic phase patients.

AREAS COVERED

In this review, we focus our attention on possible prognostic features who can predict the success of tyrosine kinase inhibitors discontinuation and how we can assess the minimal residual disease (MRD) during the TFR phase. Broad research was made on Medline, Embase and archives from EHA and ASH congresses.

EXPERT OPINION

Median duration of TKI therapy and of deep molecular response are the main prognostic factors identified in most trials and real-life experiences on discontinuation. Immunological pathways have been proposed as possible control on successful TFR as also early molecular response dynamics. Appropriate molecular monitoring by RQ-PCR in the TFR phase has been proposed by several international recommendations and digital droplet PCR (ddPCR) seems to have a possible role in the future for a better identification of candidate to this possible therapeutic strategy.

Second-Generation Tyrosine Kinase Inhibitor Discontinuation in Chronic Myeloid Leukemia Patients with Stable Deep Molecular Response: A Systematic Review and a Meta-Analysis

The treatment with 2nd-generation tyrosine kinase inhibitors (2G-TKIs), namely, dasatinib and nilotinib, has been reported to have faster and deeper responses in newly diagnosed chronic phase-chronic myeloid leukemia (CP-CML) patients as compared with imatinab. A number of studies on the discontinuation of 2G-TKIs have been conducted and recently published. A meta-analysis was conducted in this study to assess the rate of treatment-free remission (TFR) rate as well as the long-term safety of 2G-TKI discontinuation in CML patients with stable deep molecular response (DMR). 517 patients were recruited in 5 single-armed, prospective cohort studies. The overall weighted mean TFR rate at the follow-up of 12 months reached 57% (95% CI 51-64%; I 2 = 56.4%). The weighted mean TFR rate at the 24-month follow-up was 53% (95% CI 47-60%; I 2 = 47.1%). The loss of TFR was primarily concentrated in the first 12 months. 96.5% of patients, having restarted TKI therapy after a molecular relapse, achieved major molecular response (MMR) rapidly. There were four deaths at the two-year follow-up. As suggested from the results of the final study, 2G-TKI discontinuation in CML patients with stable DMR was reported to be feasible. Relapsed patients were retreated with 2G-TKI, and over 95% of patients could reach MMR. Almost no deaths occurred due to adverse events in two years after discontinuation, and more than half of the patients could maintain a TFR.

Treatment-free remission in patients with chronic myeloid leukemia: recommendations of the LALNET expert panel

Discontinuing TKIs in LA is the new goal, and LALNET TFR recommendations for CML patients are an unmet need.

TFR recommendations adapted to LA needs will make discontinuation feasible and safe in real life in the region.

Tyrosine kinase inhibitors (TKIs) have dramatically changed the survival of chronic myeloid leukemia (CML) patients, and treatment-free remission (TFR) has recently emerged as a new goal of CML treatment. The aim of this work was to develop recommendations for TKI discontinuation in Latin America (LA), outside of clinical trials. A working group of CML experts from LA discussed 22 questions regarding TFR and reached a consensus for TFR recommendations in the region. TFR is indicated in patients in first chronic phase, with typical BCR-ABL transcripts, under TKI treatment of a minimum of 5 years, in sustained deep molecular response (DMR; molecular response 4.5 [MR4.5]) for 2 years. Sustained DMR must be demonstrated on at least 4 international reporting scale quantitative polymerase chain reaction (PCR) tests, separated by at least 3 months, in the immediate prior 2 years. After second-line therapy, TFR is indicated in previously intolerant, not resistant, patients. Molecular monitoring is recommended monthly for the first 6 months, every 2 to 3 months from months 7 to 12, and every 3 months during the second year, indefinitely. Treatment should be reintroduced if major molecular response is lost. Monitoring of withdrawal syndrome, glucose levels, and lipid profile is recommended after discontinuation. After TKI reintroduction, molecular monitoring is indicated every 2 to 3 months until MR4.0 achievement; later, every 3 to 6 months. For the TFR attempt, having standardized and reliable BCR-ABL PCR tests is mandatory. These recommendations will be useful for safe discontinuation in daily practice and will benefit patients who wish to stop treatment in emergent regions, in particular, with TKI-related chronic adverse events.

Predictive value of clinical examination parameters for cardiovascular adverse events during treatment of chronic myeloid leukemia with tyrosine kinase inhibitors

Treatment of chronic myelogenous leukemia (CML) requires management of long-term use of tyrosine kinase inhibitors (TKIs). Although cardiovascular adverse events (CAEs) caused by off-target effects of TKIs can be life-threatening, the optimal method of monitoring for CAEs has not been established. Here, we comprehensively evaluated the clinical utility of various cardiovascular parameters, including ankle-brachial blood pressure index (ABI), cardiac ankle vascular index (CAVI), and carotid ultrasonography and electrocardiogram measurements, for monitoring and predicting CAEs in 74 patients with CML receiving TKIs. Based on concordance statistics, the predictive value of established risk factor models was significantly improved by addition of both ABI and CAVI, as follows: model 1 (hypertension, smoking history, and dyslipidemia), 0.680 versus 0.817 (p = 0.041); model 2 (hypertension, dyslipidemia, and diabetes mellitus), 0.685 vs. 0.830 (p = 0.047); and model 3 (age, hypertension, dyslipidemia and diabetes mellitus) 0.737 versus 0.818 (p = 0.044). However, no single cardiovascular parameter independently improved the predictive value of established risk factor models. In conclusion, addition of combined assessment of ABI and CAVI to established risk factors can improve prediction of future CAEs and may enable better clinical management of patients with CML receiving TKIs.

Making Treatment-Free Remission (TFR) Easier in Chronic Myeloid Leukemia: Fact-Checking and Practical Management Tools

In chronic-phase chronic myeloid leukemia (CML), tyrosine kinase inhibitors (TKIs) are the standard of care, and treatment-free remission (TFR) following the achievement of a stable deep molecular response (DMR) has become, alongside survival, a primary goal for virtually all patients. The GIMEMA CML working party recently suggested that the possibility of achieving TFR cannot be denied to any patient, and proposed specific treatment policies according to the patient's age and risk. However, other international recommendations (including 2020 ELN recommendations) are more focused on survival and provide less detailed suggestions on how to choose first and subsequent lines of treatment. Consequently, some grey areas remain. After literature review, a panel of Italian experts discussed the following controversial issues: (1) early prediction of DMR and TFR: female sex, non-high disease risk score, e14a2 transcript and early MR achievement have been associated with stable DMR, but the lack of these criteria is not sufficient to exclude any patient from TFR; (2) criteria for first and subsequent line therapy choice: a number of patient and drug characteristics have been proposed to make a personalized decision; (3) monitoring of residual disease after discontinuation: after the first 6 months, the frequency of molecular tests can be reduced based on MR4.5 persistence and short turnaround time; (4) prognosis of TFR: therapy and DMR duration are important to predict TFR; although immunological control of CML plays a role, no immunological predictive phenotype is currently available. This guidance is intended as a practical tool to support physicians in decision making.

Treatment-Free Remission in Chronic Myeloid Leukemia and New Approaches by Targeting Leukemia Stem Cells

The therapeutic landscape for chronic myeloid leukemia (CML) has improved significantly with the approval of tyrosine kinase inhibitors (TKIs) for therapeutic use. Most patients with optimal responses to TKIs can have a normal life expectancy. Treatment-free remission (TFR) after discontinuing TKI has increasingly become a new goal for CML treatment. However, TKI only "control" CML, and relapse after discontinuation has become a key factor hindering patient access to attempt TFR. In this study, we reviewed studies on TKI discontinuation, including both first and second-generation TKI. We also reviewed predictors of relapse, new monitoring methods, and strategies targeting leukemic stem cells.

Challenges in Chronic Myeloid Leukemia Management in South America

PURPOSE OF REVIEW

Chronic myeloid leukemia (CML) management in developing countries has improved in the last years, but the availability of therapeutic resources, monitoring, reimbursement, and financial issues may be a challenge and interfere with the best practices and results of CML treatment. This review points out the main challenges in CML management in South America.

RECENT FINDINGS

In this review, we describe the access to tyrosine kinase inhibitors and monitoring in different countries of South America. We also address the ongoing discontinuation trials, the progress, and limitations of hematopoietic stem cell transplantation in the last years. There are still many challenges for achieving the best outcomes for CML patients in South America. The continuous efforts to provide continuous education, access to tyrosine kinase inhibitors, and monitoring, providing reference centers for CML management and hematopoietic stem cell transplantation may improve patients' outcomes.

Health-Related Quality of Life of Patients with Chronic Myeloid Leukemia as Measured by Patient-Reported Outcomes: Current State and Future Directions

PURPOSE OF REVIEW

Tyrosine kinase inhibitors (TKIs) allow many patients with chronic myeloid leukemia (CML) to live normal life spans but have the potential to impact patients' health-related quality of life (HRQOL). Patient-reported outcome (PRO) measures can provide valuable information to inform treatment decision-making. Here, we review pivotal studies that used PRO measures to evaluate HRQOL of patients with CML in the first-line and treatment-free remission (TFR), and identify areas for future research.

RECENT FINDINGS

PRO measures commonly studied in patients with CML include the SF-36, FACT-Leu, EORTC QLQ-CML24, and MDASI CML. Cohort or cross-sectional studies provide the most data on PRO measures in patients with CML, with less information available from randomized controlled trials (RCTs). Patients with CML taking TKIs have worse HRQOL compared to matched controls, with a few studies seeing a larger effect in younger patients (< 60 years old). No single TKI consistently has better HRQOL compared to other agents. Fatigue is a predominant symptom associated with impaired HRQOL across many studies. Studies evaluating TFR show stable or improved HRQOL after TKI discontinuation. There are areas of HRQOL detrimental to patients with other types of cancer (e.g., cognition, sexuality) that warrant further evaluation in patients with CML. Understanding the HRQOL of patients with CML is increasingly important as patients live near-normal life expectancies. PRO measures have the potential to inform treatment decisions in this patient population. Future research opportunities include using PRO measures in RCTs and expanding the HRQOL topics studied in patients with CML.

Which Tyrosine Kinase Inhibitors Should Be Selected as the First-Line Treatment for Chronic Myelogenous Leukemia in Chronic Phase?

Simple Summary

This review discusses the optimal selection of BCR-ABL1 tyrosine kinase inhibitors (TKIs) as the first-line treatment for newly diagnosed chronic myelogenous leukemia in chronic phase (CML-CP). With the advent of TKIs, the treatment goals for CML-CP patients have changed from “simply survival” to “survival with adequate quality of life”, hence the number of CML-CP patients aiming to achieve treatment-free remission has increased, irrespective of age or comorbidities. Therefore, optimal selection of TKIs for maximizing the number of patients to achieve treatment-free remission is an important factor for consideration in future studies. To this end, we must understand the advantages and disadvantages of each TKI in terms of treatment response, disease risk at diagnosis, comorbidities, and medical expenses, and use of effective 2GTKIs based on patient background. This review provides insights into “shared decision-making” in individual cases, including the elderly population.

Abstract

With the use of tyrosine kinase inhibitors (TKIs), chronic myelogenous leukemia in chronic phase (CML-CP) has been transformed into a non-fatal chronic disease. Hence, “treatment-free remission (TFR)” has become a possible treatment goal of patients with CML-CP. Currently, four types of TKIs (imatinib, nilotinib, dasatinib, and bosutinib) are used as the first-line treatment for newly diagnosed CML-CP. However, the second-generation TKI (2GTKI), the treatment response of which is faster and deeper than that of imatinib, is not always recommended as the first-line treatment for CML-CP. Factors involved in TKI selection in the first-line treatment of CML-CP include not only patients’ medical background, but also patients’ choice regarding the desired treatment goal (survival or TFR?). Therefore, it is important that clinicians select an appropriate TKI to successfully achieve the desired treatment goal for each patient, while minimizing the development of adverse events. This review compares the pros and cons of using imatinib and 2GTKI for TKI selection as the first-line treatment for CML-CP, mainly considering treatment outcomes, medical history (i.e., desire for pregnancy, aging factor, and comorbidity), and cost. The optimal use of 2GTKIs is also discussed.

BCR-ABL1 transcript doubling time as a predictor for treatment-free remission failure after imatinib discontinuation in chronic myeloid leukaemia in chronic phase

The doubling time (DT) of the BCR-ABL1 quantitative polymerase chain reaction (qPCR) transcript level reflects the re-growing fraction of leukaemic cells after discontinuation of tyrosine kinase inhibitor (TKI). The present study analyzed monthly DT within six months after imatinib discontinuation in 131 patients. Monthly DT was calculated as x = ln(2)/K, where x is the DT and K is the fold BCR-ABL1 change from the previous value divided by the number of days between each measurement. The optimal DT value was determined as 12·75 days at two months using a recursive partitioning method. The patients were stratified into three groups: the high-risk group (DT<12·75 days but >0, with rapidly proliferating chronic myeloid leukaemia (CML) cells; n = 26) showed the lowest molecular relapse-free survival (mRFS) of 7·7% at 12 months, compared to 53·6% in the intermediate-risk group (DT≥12·75 days, with slowly proliferating CML cells; n = 16) or 90·0% in the low-risk group (DT≤0, i.e., without proliferating CML cells; n = 71; P < 0·001). Monthly assessment of DT helps identify high-risk patients for treatment-free remission failure with an imminent risk of molecular recurrence, and to define low-risk patients who can be spared the frequent monitoring of monthly molecular tests.

Long-term tolerability and efficacy after initial PegIFN-α addition to dasatinib in CML-CP: Five-year follow-up of the NordCML007 study

OBJECTIVES

Treatment-free remission (TFR) has emerged as a treatment goal in chronic myeloid leukemia in the chronic phase (CML-CP). Attempts to increase proportion of patients achieving TFR include combination of tyrosine kinase inhibitors (TKI) and other drugs. Interferon-α in addition to TKI has shown promising efficacy but with dose-dependent toxicity and discontinuations. NordCML007 was initiated to study the efficacy and safety of low dose pegylated IFN-α (PegIFN-α) in combination with dasatinib (DAS) in CML-CP.

METHODS

Forty patients with newly diagnosed CML-CP were given DAS upfront. After month 3 (M3) 15 μg/wk of PegIFN-α was added and increased to 25 μg/wk from M7 until M15. DAS treatment was continued and adverse events and BCR-ABL1 qRT-PCR values were reported yearly after M24. Results from M1 to M18 have previously been published, and here we present long-term data.

RESULTS

After 5 years of follow-up, there were no suspected unexpected serious adverse reactions, no increase in serosal effusions, no disease progressions and no CML-related deaths. Rates of MR^3.0 (MMR), MR^4.0 and MR^4.5 were 84.6%, 64.1% and 51.3% respectively at M60, and 95% of patients reached MMR at some point during the study.

CONCLUSION

Initial addition of PegIFN-α to DAS shows good long-term efficacy without increased toxicity.

Treatment-Free Remission in Chronic Myeloid Leukemia: Can We Identify Prognostic Factors?

Simple Summary

Chronic myeloid leukemia (CML) is a blood cancer. Unlike other cancers CML treatment is lifelong and many patients experience side effects. For those patients who respond well to treatment and achieve deep molecular remission, quality of life is impacted because of continuous treatment. In this review, we look at emerging clinical trials which aim to investigate which patients can safely stop treatment. Treatment-free remission is the ultimate goal for CML patients, but there is still a gap in our knowledge as to why some patients can achieve treatment-free remission, while others relapse when treatment is stopped. Here we discuss if there are any prognostic factors that can predict the best candidates who qualify for treatment discontinuation, with a view to keeping them in remission.

Abstract

Following the development of tyrosine kinase inhibitors (TKI), the survival of patients with chronic myeloid leukaemia (CML) drastically improved. With the introduction of these agents, CML is now considered a chronic disease for some patients. Taking into consideration the side effects, toxicity, and high cost, discontinuing TKI became a goal for patients with chronic phase CML. Patients who achieved deep molecular response (DMR) and discontinued TKI, remained in treatment-free remission (TFR). Currently, the data from the published literature demonstrate that 40–60% of patients achieve TFR, with relapses occurring within the first six months. In addition, almost all patients who relapsed regained a molecular response upon retreatment, indicating TKI discontinuation is safe. However, there is still a gap in understanding the mechanisms behind TFR, and whether there are prognostic factors that can predict the best candidates who qualify for TKI discontinuation with a view to keeping them in TFR. Furthermore, the information about a second TFR attempt and the role of gradual de-escalation of TKI before complete cessation is limited. This review highlights the factors predicting success or failure of TFR. In addition, it examines the feasibility of a second TFR attempt after the failure of the first one, and the current guidelines concerning TFR in clinical practice.

Discontinuation of Imatinib in Children with Chronic Myeloid Leukemia: A Study from the International Registry of Childhood CML

Within the International Registry of Childhood Chronic Myeloid Leukemia (CML), we identified 18 patients less than 18 years old at diagnosis of CML who were in the chronic phase and exhibiting a sustained deep molecular response (DMR) to imatinib defined as BCR-ABL1/ABL1 < 0.01% (MR4) for at least two years followed by discontinuation of imatinib. Before discontinuation, the median duration of imatinib was 73.2 months (range, 32-109) and the median duration of MR4 was 46.2 months (range, 23.9-98.6). Seven patients experienced loss of major molecular response (MMR) 4.1 months (range, 1.9-6.4) after stopping and so restarted imatinib. The median molecular follow-up after discontinuation was 51 months (range, 6-100) for the nine patients without molecular relapse. The molecular free remission rate was 61% (95% CI, 38-83%), 56% (95% CI, 33-79%) and 56% (95% CI, 33-79%) at 6, 12 and 36 months, respectively. Six of the seven children who experienced molecular relapse after discontinuation regained DMR (median, 4.7 months; range, 2.5-18) after restarting imatinib. No withdrawal syndrome was observed. In univariate analysis, age, sex, Sokal and ELTS scores, imatinib treatment and DMR durations before discontinuation had no influence on treatment free remission. These data suggest that imatinib can be safely discontinued in children with sustained MR4 for at least two years.

Treatment-Free Remission-A New Aim in the Treatment of Chronic Myeloid Leukemia

Tyrosine kinases inhibitors (TKIs) revolutionized chronic myeloid leukemia (CML) treatment for many years, prolonging patients' life expectancy to be comparable to age-matched healthy individuals. According to the latest the European LeukemiaNet (ELN) recommendations, CML treatment aims to achieve long-term remission without treatment (TFR), which is feasible in more than 40% of patients. Nearly all molecular relapses occur during the first 6 months after TKI withdrawal and do not progress to clinical relapse. The mechanisms that are responsible for CML relapses remain unexplained. It is suggested that maintaining TFR is not directly related to the total disposing of the gene transcript BCR-ABL1, but it might be a result of the restoration of the immune surveillance in CML. The importance of the involvement of immunocompetent cells in the period of TKI withdrawal is also emphasized by the presence of specific symptoms in some patients with "withdrawal syndrome". The goal of this review is to analyze data from studies regarding TFRs in order to characterize the elements of the immune system of patients that might prevent CML molecular relapse. The role of modern droplet digital polymerase chain reaction (ddPCR) and next-generation sequencing (NGS) in better identification of low levels of BCR-ABL1 transcripts was also taken into consideration for refining the eligibility criteria to stop TKI therapy.