Assessment of BCR-ABL1 transcript levels at 3 months is the only requirement for predicting outcome for patients with chronic myeloid leukemia treated with tyrosine kinase inhibitors

Chronic myeloid leukemia: 2025 update on diagnosis, therapy, and monitoring

DISEASE OVERVIEW

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm with an annual incidence of two cases/100 000. 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 murine leukemia (ABL1) gene 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 (FDA) for first-line treatment of newly diagnosed CML in the chronic phase (CML-CP). Clinical trials with second and third-generation TKIs in frontline CML-CP therapy reported significantly deeper and faster responses but had no impact on survival prolongation, likely because of their potent efficacy and the availability of effective TKIs salvage therapies for patients who have a cytogenetic relapse with frontline TKI therapy. All four TKIs are equivalent if the aim of therapy is to improve survival. In younger patients with high-risk disease and in whom the aim of therapy is to induce a treatment-free remission status, second-generation TKIs may be favored.

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 and financial status, 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 two 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, and others).

Treatment of chronic-phase chronic myeloid leukemia in patients randomized to dasatinib or imatinib after suboptimal responses to 3 months of imatinib therapy: final 5-year results from DASCERN

Early molecular response at 3 months is predictive of improved overall survival and progression-free survival in patients with chronic myeloid leukemia in the chronic phase. Although about one-third of patients treated with first-line imatinib do not achieve an early molecular response, long-term overall survival and progression-free survival are still observed in most patients. DASCERN (NCT01593254) is a prospective, phase IIb, randomized trial evaluating a switch to dasatinib in patients who have not achieved an early molecular response after 3 months of treatment with first-line imatinib. Early analysis demonstrated an improved major molecular response (MMR) rate at 12 months with dasatinib versus imatinib (29% vs. 13%, P=0.005). Here, we report results from the final 5-year follow-up. In total, 174 patients were randomized to dasatinib and 86 to remain on imatinib. Forty-six (53%) patients who remained on imatinib but subsequently experienced failure were allowed to cross over to dasatinib per protocol. At a minimum follow-up of 60 months, the cumulative MMR rate was significantly higher in patients randomized to dasatinib than those randomized to imatinib (77% vs. 44%, P<0.001). The median time to MMR was 13.9 months with dasatinib versus 19.7 months with imatinib. The safety profile was consistent with previous reports. These results demonstrate that switching to dasatinib after a suboptimal response to imatinib at 3 months leads to faster MMR, provides earlier deep molecular responses, and improves some outcomes in patients with chronic myeloid leukemia in the chronic phase.

Deep Molecular Response Rate in Chronic Phase Chronic Myeloid Leukemia: Eligibility to Discontinuation Related to Time to Response and Different Frontline TKI in the Experience of the Gimema Labnet CML National Network

BACKGROUND

In the last decade, TKIs improved the overall survival (OS) of chronic myeloid leukemia (CML) patients who achieved a deep and sustained molecular response (DMR, defined as stable MR4 and MR4.5). Those patients may attempt therapy discontinuation. In our analysis, we report the differences in eligibility criteria due to time of response and different TKI used as frontline treatment analyzed in a large cohort of CP-CML patients.

METHODS

Data were exported by LabNet CML, a network founded by GIMEMA in 2014. The network standardized and harmonized the molecular methodology among 51 laboratories distributed all over Italy for the diagnosis and molecular residual disease (MRD) monitoring.

RESULTS

Out of 1777 patients analyzed, 774 had all evaluable timepoints (3, 6, and 12 months). At 3 months, 40 patients obtained ≥MR4: of them 14 (3.6%) with imatinib, 8 (5.8%) with dasatinib, and 18 (7.4%) with nilotinib (P = .093); at 6 months, 146 patients were in MR4: 42 (11%) with imatinib, 38 (28%) with dasatinib, and 66 (27%) with nilotinib (P < .001). At 12 months, 231 patients achieved a DMR: 85 (22%) with imatinib, 55 (40%) with dasatinib and 91 (38%) with nilotinib (P < .001). Achieving at least ≥MR2 at 3 months, was predictive of a DMR at any timepoint of observation: with imatinib 67% versus 30% of patients with 2 years was significant for patients who at 3 months had ≥MR2 (18% vs. 9.9% of pts with

CONCLUSION

In conclusion, reaching ≥MR2 and a MR3 at 3 months it seems predictive of a DMR at any time point. Considering the prerequisite for a discontinuation with a sustained DMR only a minority of patients can be eligible for the discontinuation, regardless the frontline treatment received.

Collapse

Key Words

• Chronic myeloid leukemia
• Molecular response
• Outcome
• Treatment free remission
• Tyrosine kinase inhibitors

Collapse

MESH Headings Collapse

Grants Collapse

Affiliation(s)

Massimo Breccia Department of Translational and Precision Medicine, Università Sapienza, Rome, Italy.
Rosalba Cucci GIMEMA Data Center, Rome, Italy
Giovanni Marsili GIMEMA Data Center, Rome, Italy
Fausto Castagnetti Department of Hematology, Istituto Seragnoli, Università di Bologna, Bologna, Italy
Sara Galimberti Department of Hematology, Università di Pisa, Pisa, Italy
Barbara Izzo Department of Hematology, Università Federico II, Napoli, Italy
Federica Sorà Department of Hematology, Università Cattolica, Roma, Italy
Simona Soverini Department of Hematology, Istituto Seragnoli, Università di Bologna, Bologna, Italy
Monica Messina GIMEMA Data Center, Rome, Italy
Alfonso Piciocchi GIMEMA Data Center, Rome, Italy
Massimiliano Bonifacio Department of Hematology, Università di Verona, Verona, Italy
Daniela Cilloni Department of Hematology, Università di Torino, Torino, Italy
Alessandra Iurlo Department of Hematology, Policlinico di Milano, Milano, Italy
Giovanni Martinelli Department of Hematology, Istituto Seragnoli, Università di Bologna, Bologna, Italy
Gianantonio Rosti Department of Hematology, Istituto Amadori, Meldola, Italy
Fabio Stagno Department of Hematology, Università di Messina, Messina, Italy
Paola Fazi GIMEMA Data Center, Rome, Italy
Marco Vignetti GIMEMA Data Center, Rome, Italy
Fabrizio Pane Department of Hematology, Università Federico II, Napoli, Italy

Collapse

The initial molecular response predicts the deep molecular response but not treatment-free remission maintenance in a real-world chronic myeloid leukemia cohort

In chronic myeloid leukemia, the identification of early molecular predictors of stable treatment-free remission (TFR) after tyrosine kinase inhibitor (TKI) discontinuation is challenging. The predictive values of residual disease (BCR::ABL1 quantification) at month 3 and 6 and more recently, BCR::ABL1 transcript halving time (HT) have been described, but no study compared the predictive value of different early parameters. Using a real-world cohort of 408 patients, we compared the performance of the EUTOS long-term survival (ELTS) score, BCR::ABL1 HT, and residual disease at month 3 and 6 to predict the molecular response, achievement of the TKI discontinuation criteria, and TFR maintenance. The performances of BCR::ABL1 HT and residual disease at month 3 were similar. Residual disease at month 6 displayed the best performance for predicting the optimal response (area under the ROC curve between 0.81 and 0.92; cut-off values: 0.11% for MR4 at month 24 and 0.12% for MR4.5 at month 48). Conversely, no early parameter predicted reaching the TKI discontinuation criteria and TFR maintenance. We obtained similar results when patients were divided in subgroups by first-line treatment (imatinib vs. second-generation TKI [2G-TKI]). We identified a relationship between ELTS score, earlier milestones and TFR maintenance only in the 2G-TKI group. In conclusion, this first comparative study of early therapeutic response parameters showed that they are excellent indicators of TKI efficacy (BCR::ABL1 transcript reduction) and best responders. Conversely, they did not predict the achievement of the TKI discontinuation criteria and TFR maintenance, suggesting that other parameters are involved in TFR maintenance.

Measurable residual disease (MRD)-testing in haematological cancers: A giant leap forward or sideways?

Measurable residual disease (MRD)-testing is used in many haematological cancers to estimate relapse risk and to direct therapy. Sometimes MRD-test results are used for regulatory approval. However, some people including regulators wrongfully believe results of MRD-testing are highly accurate and of proven efficacy in directing therapy. We review MRD-testing technologies and evaluate the accuracy of MRD-testing for predicting relapse and the strength of evidence supporting efficacy of MRD-guided therapy. We show that at the individual level MRD-test results are often an inaccurate relapse predictor. Also, no convincing data indicate that increasing therapy-intensity based on a positive MRD-test reduces relapse risk or improves survival. We caution against adjusting therapy-intensity based solely on results of MRD-testing.

JAK2 as Predictor of Therapeutic Response in Patients with Chronic Myeloid Leukemia Treated with Imatinib

Background

Chronic myeloid leukemia (CML) or chronic granulocytic leukemia is a myeloproliferative neoplasm indicated by the presence of the Philadelphia (Ph+) chromosome. First-line tyrosine kinase inhibitor, imatinib, is the gold standard for treatment. However, there has been known unresponsiveness to treatment, especially due to the involvement of other genes, such as the Janus kinase 2 (JAK2) gene. This study aimed to evaluate the relationships between JAK2 levels and complete hematological response (CHR), as well as early molecular response (EMR) after 3 months of imatinib treatment in patients with chronic phase CML.

Methods

Patients with Ph+ CML in the chronic phase (n = 40; mean age, 40 ± 11 years) were recruited to complete assessments consisting of clinical examination and blood test, including evaluation of complete blood counts and the JAK2 levels, at baseline and following 3 months of therapy with imatinib (at an oral dose of 400 mg per day). Subjects were divided into two groups according to the presence of CHR and EMR.

Results

JAK2 gene levels, phosphorylated, and total JAK2 proteins at baseline were significantly lower in the group with the presence of CHR and EMR. In addition, baseline JAK2 levels, including JAK2 gene expression, phosphorylated, and total JAK2 proteins, were negatively correlated with the presence of CHR and EMR.

Conclusions

Based on these findings, JAK2 levels may be a potential indicator for evaluating treatment response on imatinib due to its role in the pathophysiology of CML.

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.

CFL1 is Implicated in Chronic Myeloid Leukemia Response during Imatinib Therapy

Cofilin (CFL1) is one critical member of the actin deploy family (ADF). Overexpression of CFL1 is associated with aggressive features and poor prognosis in malignancies. We evaluated the expression of CFL1 in patients with chronic myeloid leukemia in the chronic phase (CML-CP), acute myelocytic leukemia (AML) and healthy controls. The role of CFL1 in imatinib therapy was also investigated using cell line. We found that the expression of CFL1 was lower in CML patients than that in healthy controls, and was significantly upregulated after imatinib therapy (p<0.05). CML patients with lower CFL1 achieved higher Major molecular response (MMR) rate after 6 months of imatinib therapy (p<0.05). Cofilin, P-cofilin and F-actin, especially branched F-actin were all upregulated after imatinib therapy. The lower CFL1 expression before treatment may predicts a better response to imatinib. Imatinib affects F-actin remodeling in CML patients by regulating CFL1 expression and activity.

The Contemporary Role of Hematopoietic Stem Cell Transplantation in the Management of Chronic Myeloid Leukemia: Is It the Same in All Settings?

Hematopoietic stem cell transplantation (HSCT) for chronic myeloid leukemia (CML) patients has transitioned from the standard of care to a treatment option limited to those with unsatisfactory tyrosine kinase inhibitor (TKI) responses and advanced disease stages. In recent years, the threshold for undergoing HSCT has increased. Most CML patients now have life expectancies comparable to the general population, and therefore, the goal of therapy is shifting toward achieving treatment-free remission (TFR). While TKI discontinuation trials in CML show potential for achieving TFR, relapse risk is high, affirming allogeneic HSCT as the sole curative treatment. HSCT should be incorporated into treatment algorithms from the time of diagnosis and, in some patients, evaluated as soon as possible. In this review, we will look at some of the recent advances in HSCT, as well as its indication in the era of aiming for TFR in the presence of TKIs in CML.

Identification of multivariable microRNA and clinical biomarker panels to predict imatinib response in chronic myeloid leukemia at diagnosis

Imatinib Mesylate (imatinib) was once hailed as the magic bullet for chronic myeloid leukemia (CML) and remains a front-line therapy for CML to this day alongside other tyrosine kinase inhibitors (TKIs). However, TKI treatments are rarely curative and patients are often required to receive life-long treatment or otherwise risk relapse. Thus, there is a growing interest in identifying biomarkers in patients which can predict TKI response upon diagnosis. In this study, we analyze clinical data and differentially expressed miRNAs in CD34+ CML cells from 80 patients at diagnosis who were later classified as imatinib-responders or imatinib-nonresponders. A Cox Proportional Hazard (CoxPH) analysis identified 16 miRNAs that were associated with imatinib nonresponse and differentially expressed in these patients. We also trained a machine learning model with different combinations of the 16 miRNAs with and without clinical parameters and identified a panel with high predictive performance based on area-under-curve values of receiver-operating-characteristic and precision-recall curves. Interestingly, the multivariable panel consisting of both miRNAs and clinical features performed better than either miRNA or clinical panels alone. Thus, our findings may inform future studies on predictive biomarkers and serve as a tool to develop more optimized treatment plans for CML patients in the clinic.

18 months follow-up of deep molecular response 4.5 (MR4.5) with nilotinib in patients with newly diagnosed chronic-phase chronic myeloid leukemia: a prospective, multi-center study in China

Introduction

Early stable deep molecular response (DMR) to nilotinib is associated with goal of treatment-free remission (TFR) in patients with chronic-phase chronic myeloid leukemia (CML-CP). It is important to early distinguish between patients who can achieve a DMR and those who are fit for TFR.

Methods

We performed a multicenter study to explore the early cumulative MR4.5 rate at 18 months with nilotinib in patients with newly diagnosed CML-CP (ND-CML-CP) in China. Of the 29 institutes, 106 patients with ND-CML-CP received nilotinib (300 mg BID).

Results and discussion

The cumulative MR4.5 rate of nilotinib treatment at 18 months was 69.8% (74/106). The cumulative MMR and MR4.0 rates for nilotinib at 18 months were 94.3% (100/106) and 84.9% (90/106), respectively. Patients with an ultra-early molecular response (u-EMR) at 6 weeks were not significantly different in obtaining DMR or MMR by 24 months compared with those without u-EMR (p = 0.7584 and p = 0.9543, respectively). Our study demonstrated that nilotinib treatment in patients with ND-CML-CP contributed to obtain high early MR4.5.

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.

Revisiting six established practices in the treatment of chronic myeloid leukaemia

After two decades of use in chronic myeloid leukaemia, the risks and benefits of established treatment practices for BCR::ABL1 tyrosine kinase inhibitors (TKIs) in the chronic myeloid leukaemia in chronic phase of the disease should be analysed. In this Viewpoint, we suggest that the use of lower than approved TKI doses in both front-line and later-line therapies would result in similar treatment efficacy, less toxicity, better treatment compliance, and reduced cost of care. The absence of an early molecular response might not warrant a change of a TKI, particularly for second-generation TKIs. Among patients in whom reaching a treatment-free remission is not a therapeutic goal or treatment-free remission is unlikely, changing TKIs to improve the depth of molecular response might result in more harm than good. Reducing the TKI dose in response to mild to moderate, or even serious, reversible side-effects might be better than changing the TKI. The availability of generic imatinib, generic dasatinib, and possibly later other generic second-generation TKIs would offer 90% of patients with chronic myeloid leukaemia an effective, safe, and affordable therapy that normalises life expectancy, and results in treatment-free remission status in 30-50% of patients over the long term. Finally, based on treatment value, any TKI that costs more than US$30 000-40 000 per year should be critically evaluated in relation to alternative modalities, such allogeneic haematopoietic stem-cell transplantation.

Adverse outcomes for chronic myeloid leukemia patients with splenomegaly and low in vivo kinase inhibition on imatinib

Variability in the molecular response to frontline tyrosine kinase inhibitor (TKI) therapy in chronic myeloid leukemia may be partially driven by differences in the level of kinase inhibition induced. We measured in vivo BCR::ABL1 kinase inhibition (IVKI) in circulating mononuclear cells after 7 days of therapy. In 173 patients on imatinib 600 mg/day, 23% had low IVKI (<11% reduction in kinase activity from baseline); this was associated with higher rates of early molecular response (EMR) failure; lower rates of major molecular response (MMR), and MR4.5 by 36 months, compared to high IVKI patients. Low IVKI was more common (39%) in patients with large spleens (≥10 cm by palpation). Notably 55% of patients with large spleens and low IVKI experienced EMR failure whereas the EMR failure rate in patients with large spleens and high IVKI was only 12% (p = 0.014). Furthermore, patients with large spleen and low IVKI had a higher incidence of blast crisis, inferior MMR, MR4.5, and event-free survival compared to patients with large spleen and high IVKI and remaining patients. In nilotinib-treated patients (n = 73), only 4% had low IVKI. The combination of low IVKI and large spleen is associated with markedly inferior outcomes and interventions in this setting warrant further studies.

Prognosis in Chronic Myeloid Leukemia: Baseline Factors, Dynamic Risk Assessment and Novel Insights

The introduction of tyrosine kinase inhibitors (TKIs) has changed the treatment paradigm of chronic myeloid leukemia (CML), leading to a dramatic improvement of the outcome of CML patients, who now have a nearly normal life expectancy and, in some selected cases, the possibility of aiming for the more ambitious goal of treatment-free remission (TFR). However, the minority of patients who fail treatment and progress from chronic phase (CP) to accelerated phase (AP) and blast phase (BP) still have a relatively poor prognosis. The identification of predictive elements enabling a prompt recognition of patients at higher risk of progression still remains among the priorities in the field of CML management. Currently, the baseline risk is assessed using simple clinical and hematologic parameters, other than evaluating the presence of additional chromosomal abnormalities (ACAs), especially those at "high-risk". Beyond the onset, a re-evaluation of the risk status is mandatory, monitoring the response to TKI treatment. Moreover, novel critical insights are emerging into the role of genomic factors, present at diagnosis or evolving on therapy. This review presents the current knowledge regarding prognostic factors in CML and their potential role for an improved risk classification and a subsequent enhancement of therapeutic decisions and disease management.

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.

Biochemical Studies of Systemic Lupus Erythematosus-Associated Mutations in Nonreceptor Tyrosine Kinases Ack1 and Brk

Tyrosine kinases (TKs) play essential roles in signaling processes that regulate cell survival, migration, and proliferation. Dysregulation of tyrosine kinases underlies many disorders, including cancer, cardiovascular and developmental diseases, as well as pathologies of the immune system. Ack1 and Brk are nonreceptor tyrosine kinases (NRTKs) best known for their roles in cancer. Here, we have biochemically characterized novel Ack1 and Brk mutations identified in patients with systemic lupus erythematosus (SLE). These mutations are the first SLE-linked polymorphisms found among NRTKs. We show that two of the mutants are catalytically inactive, while the other three have reduced activity. To understand the structural changes associated with the loss-of-function phenotype, we solved the crystal structure of one of the Ack1 kinase mutants, K161Q. Furthermore, two of the mutated residues (Ack1 A156 and K161) critical for catalytic activity are highly conserved among other TKs, and their substitution in other members of the kinase family could have implications in cancer. In contrast to canonical gain-of-function mutations in TKs observed in many cancers, we report loss-of-function mutations in Ack1 and Brk, highlighting the complexity of TK involvement in human diseases.

Association between bariatric surgery and outcomes in chronic myeloid leukemia

BACKGROUND

Bariatric surgery is the most effective weight loss intervention. However, it can also decrease the bioavailability of oral medications. Tyrosine kinase inhibitors, the mainstay treatment for chronic myeloid leukemia (CML), are the most successful example of an oral targeted therapy. The impact of bariatric surgery on CML outcomes is unknown.

METHODS

In a retrospective analysis, we screened 652 patients with CML and identified 22 with prior bariatric surgery, and compared their outcomes to a matched cohort of 44 patients with no prior bariatric surgery.

RESULTS

The rate of early molecular response (3-month BCR::ABL1 < 10% International Scale) was lower in the bariatric surgery group compared with the control group (68% vs. 91%; p = .05), with longer median times to achieve complete cytogenetic (6 vs. 3 months; p = .001) or major molecular responses (12 vs. 6 months; p = .001). Bariatric surgery was associated with inferior event-free survival (5-year, 60% vs. 77%; p = .004) and failure-free survival (5-year, 32% vs. 63%; p < .0001). In a multivariate analysis, bariatric surgery was the only independent predictor for the risk of treatment failure (hazard ratio, 9.40; 95% CI, 2.71-32.55; p = .0004) or event-free survival (hazard ratio, 4.24; 95% CI, 1.67-12.23; p = .008).

CONCLUSIONS

Bariatric surgery is associated with suboptimal responses that require adapted treatment strategies.

Children with chronic myeloid leukaemia treated with front-line imatinib have a slower molecular response and comparable survival compared with adults: a multicenter experience in Taiwan

BACKGROUND

The direct comparison of molecular responses of front-line imatinib (IM) monitored at the same laboratory between children and adults with chronic phase (CP) of chronic myeloid leukaemia (CML) had not been reported. In this multicenter study, we compared the landmark molecular responses and outcomes of paediatric and adult CML-CP cohorts treated with front-line IM in whom the BCR::ABL1 transcript levels were monitored at the same accredited laboratory in Taiwan.

METHODS

Between June 2004 and July 2020, 55 newly diagnosed paediatric and 782 adult CML-CP patients, with molecular diagnosis and monitoring at the same reference laboratory in Taiwan, were enrolled. The criteria of 2020 European LeukemiaNet were applied to evaluate the molecular responses.

RESULTS

By year 5, the cumulative incidences of IS <1%, MMR, MR4.0 and MR4.5 of paediatric patients were all significantly lower than those of adult patients (58 vs 75%, 48 vs 66%, 25 vs 44%, 16 vs 34%, respectively). The 10-year progression-free survival (PFS) (90%) and overall survival (OS) (94%) of paediatric patients did not differ from those (92%) of adult patients.

CONCLUSIONS

We demonstrated the paediatric cohort had slower molecular responses to front-line IM and similar outcomes in 10-year PFS and OS in real-world practice.

Measurable residual disease in chronic myeloid leukemia

Chronic myeloid leukemia is characterized by a single genetic abnormality resulting in a fusion gene whose mRNA product is easily detected and quantified by reverse-transcriptase polymerase chain reaction analysis. Measuring residual disease was originally introduced to identify patients relapsing after allogeneic stem cell transplantation but rapidly adopted to quantify responses to tyrosine kinase inhibitors. Real-time quantitative polymerase chain reaction is now an essential tool for the management of patients and is used to influence treatment decisions. In this review we track this development including the international collaboration to standardize results, discuss the integration of molecular monitoring with other factors that affect patients' management, and describe emerging technology. Four case histories describe varying scenarios in which the accurate measurement of residual disease identified patients at risk of disease progression and allowed appropriate investigations and timely clinical intervention.

Leukemia: Reduction Ratio and Halving Time of BCR: : ABL1 IS Transcript Levels

Objective:

Achieving an early molecular response (EMR) is crucial for improving the prognosis of patients with chronic myeloid leukemia (CML). The halving time (HT) and reduction ratio (RR) of BCR::ABL1 transcript levels have recently emerged as additional prognostic indexes besides the BCR::ABL1 International Scale (IS). We aimed to investigate the prognostic role of BCR::ABL1 transcript levels, HT, and RR on molecular response kinetics at 3 months in patients with newly diagnosed chronic-phase (CP)-CML.

Materials and Methods:

Forty patients with CP-CML who received first-line imatinib treatment were included in this study. BCR::ABL1 transcript levels and molecular responses at baseline and at 3, 6, 12, and 24 months of treatment were evaluated retrospectively. Major molecular response (MMR) at 12 months and event-free survival (EFS) were determined as primary endpoints and the effects of treatment kinetics on these parameters were examined.

Results:

Of the 40 patients, BCR::ABL1 IS was ≤10% at 3 months in 72.5%, representing EMR. The rate of event occurrence was 45.5% in patients with BCR::ABL1 IS of >10%, whereas it was 6.9% in those with BCR::ABL1 IS of ≤10% (p=0.004). MMR was detected in 62.1% of the patients with EMR and in 9.1% of those without EMR (p=0.003). The cut-off value for achieving MMR was 24 days for HT and 0.04 for RR. Deep molecular response (DMR) at 24 months was associated with HT of ≤24 days and RR of ≤0.04. EFS was found to be significantly better in the group with BCR::ABL1 IS of ≤10% and HT of ≤24 days (p=0.001) and in the group with BCR::ABL1 IS of ≤10% and RR of ≤0.04 (p=0.007) compared to others.

Conclusion:

Our findings revealed that MMR could be predicted via EMR as well as by HT and RR. Additionally, HT of ≤24 days and RR of ≤0.04 were more important thanBCR::ABL1 IS of ≤10% in achieving DMR at 24 months, and the combination of BCR::ABL1 IS of ≤10% with both HT of ≤24 days and RR of ≤0.04 has the best predictive value for EFS.

Bosutinib in Japanese patients with newly diagnosed chronic-phase chronic myeloid leukemia: final 3-year follow-up results of a phase 2 study

Bosutinib has been evaluated for treatment of chronic-phase chronic myeloid leukemia (CP-CML) in several clinical studies, including in Japan. This open-label, single-arm, phase 2 study evaluated the efficacy and safety of bosutinib at a starting dose of 400 mg once daily in Japanese patients (n = 60) with newly diagnosed CP-CML. The minimum follow-up period was 3 years and median duration of treatment was 35.9 months. At study completion, 60% of patients were still on treatment. Cumulative rates of major molecular response (MMR), molecular response⁴ (MR⁴), and MR^4.5 at any time were 70.0%, 53.3%, and 48.3%, respectively. No patient who achieved MMR or MR⁴ had a confirmed loss of response. No patient experienced on-treatment transformation to accelerated/blast phase or died within 28 days of the last bosutinib dose. Any-grade treatment-emergent adverse events (TEAEs) occurred in 100% (grade ≥ 3: 81.7%) of patients. The most common TEAEs were diarrhea (86.7%), increased alanine aminotransferase (55.0%), and increased aspartate aminotransferase (46.7%). No new safety signals emerged during the follow-up period. Bosutinib continues to demonstrate a favorable benefit/risk profile and is an important treatment option for Japanese patients with newly diagnosed CP-CML. Optimal management of TEAEs during initial treatment with bosutinib should be prioritized.

Trial Registration: ClinicalTrials.gov ID: NCT03128411.

EAHP 2020 workshop proceedings, pediatric myeloid neoplasms

The first section of the bone marrow workshop of the European Association of Haematopathology (EAHP) 2020 Virtual Meeting was dedicated to pediatric myeloid neoplasms. The section covered the whole spectrum of myeloid neoplasms, including myelodysplastic syndromes (MDS), myeloproliferative neoplasms (MPN), myelodysplastic/myeloproliferative neoplasms (MDS/MPN), and acute myeloid leukemia (AML). The workshop cases are hereby presented, preceded by an introduction on these overall rare diseases in this age group. Very rare entities such as primary myelofibrosis, pediatric MDS with fibrosis, and MDS/MPN with JMML-like features and t(4;17)(q12;q21); FIP1L1::RARA fusion, are described in more detail.

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.

The Impact of SKP2 Gene Expression in Chronic Myeloid Leukemia

Introduction: The prognosis of chronic myeloid leukemia (CML) patients has been dramatically improved with the introduction of imatinib (IM), the first tyrosine kinase inhibitor (TKI). TKI resistance is a serious problem in IM-based therapy. The human S-phase kinase-associated protein 2 (SKP2) gene may play an essential role in the genesis and progression of CML. Aim of the study: We try to explore the diagnostic/prognostic impact of SKP2 gene expression to predict treatment response in first-line IM-treated CML patients at an early response stage. Patients and methods: The gene expression and protein levels of SKP2 were determined using quantitative RT-PCR and ELISA in 100 newly diagnosed CML patients and 100 healthy subjects. Results: SKP2 gene expression and SKP2 protein levels were significantly upregulated in CML patients compared to the control group. The receiver operating characteristic (ROC) analysis for the SKP2 gene expression level, which that differentiated the CML patients from the healthy subjects, yielded a sensitivity of 86.0% and a specificity of 82.0%, with an area under the curve (AUC) of 0.958 (p < 0.001). The ROC analysis for the SKP2 gene expression level, which differentiated optimally from the warning/failure responses, yielded a sensitivity of 70.59% and a specificity of 71.21%, with an AUC of 0.815 (p < 0.001). Conclusion: The SKP2 gene could be an additional diagnostic and an independent prognostic marker for predicting treatment responses in first-line IM-treated CML patients at an early time point (3 months).

Expression dynamics of the immune mediators ARG1, TBET, CIITA, IL10 and TGFB1 in chronic myeloid leukaemia patients during the first year of imatinib therapy

The use of tyrosine kinase inhibitors seems to restore the broadly compromised immune system described in chronic myeloid leukaemia (CML) patients at diagnosis leading to a re-activation of the effector-mediated immune surveillance. Here, we describe the expression dynamics of immune factors during the first year on imatinib therapy. Gene expression was evaluated in 132 peripheral blood samples from 79 CML patients, including 34 who were serially followed. An aliquot of the stored sample used to monitor BCR-ABL1 levels was retro-transcribed to cDNA and gene expression was quantified by real-time PCR. An elevated expression of ARG1 was observed at diagnosis, while TBET, CIITA, IL10 and TGFB1 were significantly decreased. Once on therapy, each gene displayed a particular behaviour. ARG1 normalized to control levels at 3 months only in optimal molecular responders and was identified as the major contributor to the difference among patients. TBET reached normal levels after 12 months in optimal responders and non-responders, regardless the Th1-response previously associated, and CIITA continued downregulated. IL10 and TGFB1 achieved normal levels early at 3 months in both groups, afterwards IL10 was sustained while TGFB1 was slightly increased after 1 year in responders. Our findings are in agreement with an immune re-activation after imatinib initiation; however, some immune mediators may require a longer exposition. The follow-up of novel and reliable biomarkers, such as ARG1, one of the principal mechanisms of myeloid-derived-suppressor cells to inhibit immune system, may be useful to deepen the characterization of early responder patients.

Influence of Telomere Length on the Achievement of Deep Molecular Response With Imatinib in Chronic Myeloid Leukemia Patients

Tyrosine kinase inhibitors have dramatically changed the outcome of chronic myeloid leukemia (CML), and nowadays, one of the main treatment goals is the achievement of deep molecular responses (DMRs), which can eventually lead to therapy discontinuation approaches. Few biological factors at diagnosis have been associated with this level of response. Telomere length (TL) in peripheral blood cells of patients with CML has been related to disease stage, response to therapy and disease progression, but little is known about its role on DMR. In this study, we analyzed if age-adjusted TL (referred as “delta-TL”) at diagnosis of chronic phase (CP)-CML might correlate with the achievement of DMR under first-line imatinib treatment. TL from 96 CP-CML patients had been retrospectively analyzed at diagnosis by monochrome multiplex quantitative PCR. We observed that patients with longer age-adjusted telomeres at diagnosis had higher probabilities to achieve DMR with imatinib than those with shortened telomeres (P = 0.035 when delta-TL was studied as a continuous variable and P = 0.047 when categorized by the median). Moreover, patients carrying long telomeres also achieved major molecular response significantly earlier (P = 0.012). This study provides proof of concept that TL has a role in CML biology and when measured at diagnosis of CP-CML could help to identify patients likely to achieve DMR to first-line imatinib treatment.

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.

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.

A Novel System for Semiautomatic Sample Processing in Chronic Myeloid Leukaemia: Increasing Throughput without Impacting on Molecular Monitoring at Time of SARS-CoV-2 Pandemic

Molecular testing of the BCR-ABL1 transcript via real-time quantitative-polymerase-chain-reaction is the most sensitive approach for monitoring the response to tyrosine-kinase-inhibitors therapy in chronic myeloid leukaemia (CML) patients. Each stage of the molecular procedure has been standardized and optimized, including the total white blood cells (WBCs) and RNA isolation methods. Here, we compare the performance of our current manual protocol to a newly semiautomatic method based on the Biomek i-5 Automated Workstations integrated with the CytoFLEX Flow Cytometer, followed by the automatic QIAsymphony system to facilitate high-throughput processing samples and reduce the hands-on time and the risk associated with SARS-CoV-2. The recovery efficiency was investigated in blood samples from 100 adults with CML. We observe a 100% of concordance between the two methods, with similar total WBCs isolated (median 1.137 × 10⁶ for manual method vs. 1.076 × 10⁶ for semiautomatic system) and a comparable quality and quantity of RNA extracted (median 103 ng/μL with manual isolation kit vs. 99.95 ng/μL with the QIAsymphony system). Moreover, by stratifying patients according to their BCR-ABL1 transcript levels, we obtained similar BCR-ABL1/ABL1^IS values and ABL1 copies, and matched samples were assigned to the same group of molecular response. We conclude that this newly semiautomatic workflow has a performance comparable to our more laborious standard manual, which can be replaced, particularly when specimens from patients with suspected or confirmed SARS-CoV-2 infection need to be processed.

Circulating miRNAs can serve as potential diagnostic biomarkers in chronic myelogenous leukemia patients

Introduction

Chronic Myelogenous Leukemia (CML) is a myeloproliferative disorder described as a malignant blood disorder by accounts for 15–20% of all adult leukemia. MicroRNAs (miRNAs) play an important role in post-transcriptional regulation of gene expressions. Expression level of tumor suppressor-miRNAs, described as miRNAs that target the oncogens, can contribute to diagnosis and prognosis of some malignant disorders including CML. We theorized that according to the excessive proliferation and alteration in miRNA expressions, there could be a change in the expression of miRNAs in plasma carried by exosomes.

Methods

We consequently decided to detect the differences between normal and aberrant miRNA expression in human plasma sample to find out the possibility of diagnosis by these alterations. The expression of candidate miRNAs were compared using RNA extracted from the plasma of 50 patients, as well as 30 healthy individuals. We analysed the plasma miR-16-1, miR-20, miR-106, miR-126, miR-155, miR-222, and miR-451 expression levels in CML patients by individual real-time quantitative RT-PCR.

Results

All selected miRNAs were found to be upregulated in newly diagnosed CML patients compared to the control, while upregulation of only three (miR-20, 106 and 222) were significant (17.4, 19 and 74.95 fold change, respectively; p<0.0001).

In conclusion

microRNAs have a potential use in treatment of CML, as they can target the genes involved in cell cycle, MAPK, growth inhibition, TGF beta, and p53 signaling pathways. Therefore, these miRNA signatures provide the basis for their utilization as biomarkers in CML.

Early prediction of stable MR4.5 by depth of molecular response at 6 months in patients with chronic myeloid leukemia treated with frontline imatinib

Treatment-free remission is achievable in approximately half of patients with chronic myeloid leukemia who attain a sustained, deep molecular response with tyrosine-kinase inhibitor (TKI) therapy. We aimed to identify potential predictors of future achievement of stable MR^4.5, defined as a sustained 4.5-log reduction in BCR-ABL1 transcripts for a minimum of 2 years, in 593 patients treated with imatinib as first-line TKI therapy. In multivariable analyses of patient and disease variables including baseline blood counts, disease phase, additional cytogenetic abnormalities, prior therapy, depth and rapidity of molecular response, the only predictor for future achievement of stable MR^4.5 was molecular response at 6 months. In this study, patients failing to attain a molecular response of BCR-ABL1≤ 0.16%^IS after 6 months of imatinib therapy were unlikely to subsequently achieve stable MR^4.5 with imatinib. Our data suggest that achievement of BCR-ABL1≤ 0.16%^IS at 6 months is predictive of future stable MR^4.5.

MiR-150 Expression in Chronic Myeloid Leukemia: Relation to Imatinib Response

OBJECTIVE

To assess the circulating micro-RNA-150 (miR-150) expression in patients with chronic myeloid leukemia (CML) in relation to imatinib response.

METHODS

Sixty patients with CML and 20 age- and sex-matched control subjects were enrolled. Circulating miR-150 levels were assessed by quantitative real-time polymerase chain reaction on days 0, 14, and 90 of imatinib therapy for patients and once for control subjects.

RESULTS

The baseline miR-150 expression was significantly lower in patients with CML than in control subjects with subsequent elevation at 14 and 90 days after the start of imatinib treatment. Early treatment response (ETR) at 90 days was the main study outcome. The miR-150 expression had a significantly higher level in patients with CML with ETR. On multivariate analysis, miR-150 on day 14 was significantly related to ETR in patients with CML with predictive efficacy (area under the curve = 0.838, 72.9% sensitivity, and 84.2% specificity).

CONCLUSION

We found that miR-150 expression on day 14 of imatinib treatment is a useful early predictive candidate for imatinib response in patients with CML.

Long-term outcome of imatinib 400 mg compared to imatinib 600 mg or imatinib 400 mg daily in combination with cytarabine or pegylated interferon alpha 2a for chronic myeloid leukaemia: results from the French SPIRIT phase III randomised trial

The STI571 prospective randomised trial (SPIRIT) French trial is a four-arm study comparing imatinib (IM) 400 mg versus IM 600 mg, IM 400 mg + cytarabine (AraC), and IM 400 mg + pegylated interferon alpha2a (PegIFN-α2a) for the front-line treatment of chronic-phase chronic myeloid leukaemia (CML). Long-term analyses included overall and progression-free survival, molecular responses to treatment, and severe adverse events. Starting in 2003, the trial included 787 evaluable patients. The median overall follow-up of the patients was 13.5 years (range 3 months to 16.7 years). Based on intention-to-treat analyses, at 15 years, overall and progression-free survival were similar across arms: 85%, 83%, 80%, and 82% and 84%, 87%, 79%, and 79% for the IM 400 mg (N = 223), IM 600 mg (N = 171), IM 400 mg + AraC (N = 172), and IM 400 mg + PegIFN-α2a (N = 221) arms, respectively. The rate of major molecular response at 12 months and deep molecular response (MR4) over time were significantly higher with the combination IM 400 mg + PegIFN-α2a than with IM 400 mg: p = 0.0001 and p = 0.0035, respectively. Progression to advanced phases and secondary malignancies were the most frequent causes of death. Toxicity was the main reason for stopping AraC or PegIFN-α2a treatment.

Haematology in the UK: A 60-year personal perspective

The advances in understanding the pathogenesis, in the diagnosis and classification of blood diseases and in their treatment that have been achieved over the six decades from 1960 to 2020, are reviewed. Emphasis is given to the new techniques, especially in immunology and molecular biology, that have enabled this remarkable progress. The review also highlights the major contributions of UK haematologists and non-clinical scientists to these advances.

Analisi di Budget Impact di ponatinib per il management di pazienti affetti da leucemia mieloide cronica

Background:

The current clinical practice for patients affected by chronic myeloid leukemia (CML) is based on the evaluation of second generation alternatives following therapeutic failure that leads to a lengthening of patients’ management times and a consequent negative impact in terms of quality of life.

Objective:

To determine the economic absorption of resources associated to the management of patients with CML in a scenario in which an early recourse to ponatinib is considered as compared with a scenario based on the current Italian clinical practice characterized by a cyclical recourse to the available therapies.

Methods:

A Budget Impact model was developed to compare the resources absorbed in the scenarios under assessment considering a 3-year time horizon and the perspective of the Italian National Health Service. Results are expressed in terms of differential resources absorbed in the alternative scenarios.

Results:

The increase in the recourse to ponatinib allowed a saving of resources for the Italian NHS over the 3-year time horizon of –€ 1,979,322 (€ 825,104,350 vs € 823,125,028). The parameter affecting the most of the results achieved in the base-case is the monthly cost of bosutinib used as a third-line treatment.

Conclusions:

The increase in the recourse to ponatinib in patients affected by CML that failed to respond to a previous pharmacological therapy resulted to be associated to a lower level of resources’ absorption in the Italian NHS allowing to re-allocate health founds to other fields of the care sector ensuring greater sustainability of the system.

Chronic Myeloid Leukemia: Modern therapies, current challenges and future directions

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm caused by a reciprocal translocation [t(9;22)(q34;q11.2)] that leads to the fusion of ABL1 gene sequences (9q34) downstream of BCR gene sequences (22q11) and is cytogenetically visible as Philadelphia chromosome (Ph). The resulting BCR/ABL1 chimeric protein is a constitutively active tyrosine kinase that activates multiple signaling pathways, which collectively lead to malignant transformation. During the early (chronic) phase of CML (CP-CML), the myeloid cell compartment is expanded, but differentiation is maintained. Without effective therapy, CP-CML invariably progresses to blast phase (BP-CML), an acute leukemia of myeloid or lymphoid phenotype. The development of BCR-AB1 tyrosine kinase inhibitors (TKIs) revolutionized the treatment of CML and ignited the start of a new era in oncology. With three generations of BCR/ABL1 TKIs approved today, the majority of CML patients enjoy long term remissions and near normal life expectancy. However, only a minority of patients maintain remission after TKI discontinuation, a status termed treatment free remission (TFR). Unfortunately, 5-10% of patients fail TKIs due to resistance and are at risk of progression to BP-CML, which is curable only with hematopoietic stem cell transplantation. Overcoming TKI resistance, improving the prognosis of BP-CML and improving the rates of TFR are areas of active research in CML.

Chronic myeloid leukemia-from the Philadelphia chromosome to specific target drugs: A literature review

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm and was the first neoplastic disease associated with a well-defined genotypic anomaly - the presence of the Philadelphia chromosome. The advances in cytogenetic and molecular assays are of great importance to the diagnosis, prognosis, treatment, and monitoring of CML. The discovery of the breakpoint cluster region (BCR)-Abelson murine leukemia (ABL) 1 fusion oncogene has revolutionized the treatment of CML patients by allowing the development of targeted drugs that inhibit the tyrosine kinase activity of the BCR-ABL oncoprotein. Tyrosine kinase inhibitors (known as TKIs) are the standard therapy for CML and greatly increase the survival rates, despite adverse effects and the odds of residual disease after discontinuation of treatment. As therapeutic alternatives, the subsequent TKIs lead to faster and deeper molecular remissions; however, with the emergence of resistance to these drugs, immunotherapy appears as an alternative, which may have a cure potential in these patients. Against this background, this article aims at providing an overview on CML clinical management and a summary on the main targeted drugs available in that context.

CML Chapter

The discovery of the tyrosine kinase inhibitor (TKI) imatinib in the early 2000's revolutionized the treatment and prognosis of patients with chronic myeloid leukemia (CML) [Hochhaus et al. in N Engl J Med 376:917-927, 2017]. The treatment of patients with CML has changed dramatically since the approval of imatinib and other TKIs. Before the TKI era, newly diagnosed patients would undergo HLA typing to try to identify a well-matched donor, and then proceed quickly to allogeneic hematopoietic cell transplantation (HCT). With the introduction of imatinib followed a few years later by dasatinib, nilotinib, then bosutinib, treatment approaches changed in a dramatic way. Transplantation is no longer an upfront treatment option for newly diagnosed CML patients, and in fact, it is very rarely used in the management of a patient with CML currently. The management of CML patients has been a model of personalized medicine or targeted therapy that is being emulated in the treatment of many other hematologic malignancies and solid tumors such as lung cancer [Soverini et al. in Mol Cancer 17:49, 2018]. The Philadelphia Chromosome (Ph) which leads to the formation of the BCR-ABL fusion gene and its product the BCR-ABL protein is the cause of CML. With effective targeting of this protein with the available TKIs, the disease is completely controllable if not curable for most patients. Life expectancy for patients with CML is essentially normal. Quality of life becomes an important goal including the potential for pregnancy, and ultimately the chance to discontinue all TKI therapy permanently. The three cases outlined below serve to highlight some of the important issues in the management of patients with CML in the post-TKI era.

Why is it critical to achieve a deep molecular response in chronic myeloid leukemia?

The primary goal of tyrosine kinase inhibitor (TKI) therapy for patients with chronic myeloid leukemia is survival, which is achieved by the vast majority of patients. The initial response to therapy provides a sensitive measure of future clinical outcome. Measurement of BCR-ABL1 transcript levels using real-time quantitative polymerase chain reaction standardized to the international reporting scale is now the principal recommended monitoring strategy. The method is used to assess early milestone responses and provides a guide for therapeutic intervention. When patients successfully traverse the critical first 12 months of TKI therapy, most will head towards another milestone response, deep molecular response (DMR, BCR-ABL1 ≤0.01%). DMR is essential for patients aiming to achieve treatment-free remission and a prerequisite for a trial of TKI discontinuation. The success of discontinuation trials has led to new treatment strategies in order for more patients to reach this milestone response. DMR has been incorporated into endpoints of clinical trials and is considered by some expert groups as the optimal treatment response. But is DMR a stable response and does it provide the ultimate protection against TKI resistance and death? Do we need to increase the sensitivity of detection of BCR-ABL1 to better identify the patients who would likely remain in treatment-free remission after TKI discontinuation? Is it necessary to switch current TKI therapy to a more potent inhibitor if the goal is to achieve DMR? These are issues that I will explore in this review.

Digital PCR for BCR-ABL1 Quantification in CML: Current Applications in Clinical Practice

Molecular monitoring of the BCR-ABL1 transcript for patients with chronic phase chronic myeloid leukemia (CML) has become increasingly demanding. Real-time quantitative PCR (qPCR) is the routinely used method, but has limitations in quantification accuracy due to its inherent technical variation. Treatment recommendations rely on specific BCR-ABL1 values set at timed response milestones, making precise measurement of BCR-ABL1 a requisite. Furthermore, the sensitivity of qPCR may be insufficient to reliably quantify low levels of residual BCR-ABL1 in patients in deep molecular response (DMR) who could qualify for an attempt to discontinue Tyrosine Kinase Inhibitor (TKI) therapy. We reviewed the current use of digital PCR (dPCR) as a promising alternative for response monitoring in CML. dPCR offers an absolute BCR-ABL1 quantification at various disease levels with remarkable precision and a clinical sensitivity reaching down to at least MR5.0. Moreover, dPCR has been validated in multiple studies as prognostic marker for successful TKI treatment discontinuation, while this could not be achieved using classical qPCR. dPCR may thus prospectively be the preferred method to reliably identify patients achieving treatment milestones after initiation of TKI therapy as well as for the selection and timing for TKI discontinuation.

Overlooking the obvious? On the potential of treatment alterations to predict patient-specific therapy response

Prognostic or therapeutic classification of diseases is often based on clinical or genetic characteristics at diagnosis or response landmarks determined at a certain time point of treatment. On the other hand, there are more and more means, such as molecular markers and sensor data, that allow for quantification of disease or therapeutic parameters over time. Although a general value of time-resolved disease monitoring is widely accepted, the full potential of using the available information on disease and treatment dynamics in the context of outcome prediction or individualized treatment optimization still seems to be, at least partially, overlooked. Within this Perspective, we summarize the conceptual idea of using dynamic information to obtain a better understanding of complex pathophysiological processes within their particular "host environment," which also allows us to intrinsically map patient-specific heterogeneity. Specifically, we discuss to which extent treatment alterations can provide additional information to understand a patient's individual condition and use this information to further adapt the therapeutic strategy. This conceptual discussion is illustrated by using examples from myeloid leukemias to which we recently applied this concept using statistical and mathematical modeling.

On the road to treatment-free remission in chronic myeloid leukemia: what about 'the others'?

INTRODUCTION

The treatment of chronic myeloid leukemia (CML) has been drastically changed by the approval of tyrosine kinase inhibitors (TKIs). CML is now managed as a chronic disease requiring both long-term treatment and close molecular monitoring in the majority of patients.

AREAS COVERED

Evidence suggests that in a substantial number of patients who have achieved a stable deep molecular response (DMR), TKI treatment can be safely discontinued without loss of response. Therefore, treatment-free remission (TFR), through the achievement of a DMR, is increasingly regarded as a feasible treatment goal in about 20% to 40% CML patients. Nevertheless, a proportion of patients with chronic-phase CML treated with TKIs remain in stable MMR and do not achieve a DMR.

EXPERT OPINION

We provide prospective views on how it is possible to optimize treatment for patients in stable MMR but not in DMR in order to finalize the therapeutic strategy.

Chronic Myeloid Leukemia, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology

Chronic myeloid leukemia (CML) is defined by the presence of Philadelphia chromosome (Ph) which results from a reciprocal translocation between chromosomes 9 and 22 [t(9;22] that gives rise to a BCR-ABL1 fusion gene. CML occurs in 3 different phases (chronic, accelerated, and blast phase) and is usually diagnosed in the chronic phase. Tyrosine kinase inhibitor therapy is a highly effective first-line treatment option for all patients with newly diagnosed chronic phase CML. This manuscript discusses the recommendations outlined in the NCCN Guidelines for the diagnosis and management of patients with chronic phase CML.