BCR/ABL level at 6 months identifies good risk CML subgroup after failing early molecular response at 3 months following imatinib therapy for CML in chronic phase

Safety and efficacy of Vitamin D3 supplementation with Imatinib in Chronic Phase- Chronic Myeloid Leukaemia: an Exploratory Randomized Controlled Trial

OBJECTIVES

The study aimed to compare early molecular response (EMR) rates at 3 months of imatinib therapy with and without vitamin D3 supplementation in patients newly diagnosed with chronic-phase chronic myeloid leukaemia (CML-CP). The secondary objective was to assess the effects of vitamin D3 on complete haematological response (CHR) and its safety.

DESIGN

Double-blind, placebo-controlled, exploratory randomised trial.

SETTING

Tertiary care hospital in northern India.

PARTICIPANTS

Treatment-naive patients with chronic phase chronic myeloid leukaemia (n=62) aged >12 years were recruited from January 2020 to January 2021. Patients with progressive disease, pregnancy and hypercalcaemia were excluded.

INTERVENTION

Oral vitamin D3 supplementation (60 000 IU) or matched placebo was given once weekly for an initial 8 weeks along with imatinib after randomisation with 1:1 allocation ratio.

PRIMARY AND SECONDARY OUTCOME MEASURES

The primary outcome was to compare EMR (defined as BCR-ABL1 transcript level ≤10%, international scale) at 3 months. The secondary outcomes were to compare effect of the intervention on CHR, correlation of 25(OH)2D3 levels with treatment response and safety according to Common Terminology Criteria for Adverse Events (CTCAE) version 5.

RESULTS

At baseline, 14.5% of the patients had normal vitamin D3 levels. EMR at 3 months was attained in 24 patients (82.7%) of the vitamin D3 group and 21 (75%) of the placebo group (OR 1.6, 95% CI 0.37 to 7.37, p=0.4). A significant difference in vitamin D3 levels from baseline to the end of study was observed. Patients with vitamin D3 supplementation did not achieve higher CHR in comparison with placebo (OR 1.3, 95% CI 0.25 to 7.23, p=1.0). Vitamin D3 levels were not significantly correlated with BCR-ABL1 levels. No dose-limiting toxicities were observed.

CONCLUSION

Vitamin D3 levels were low among patients with CML-CP in this study. Vitamin D3 supplementation with imatinib therapy did not have significant effect on EMR or CHR. Further clinical trials could be undertaken to assess the effective dosage and duration of vitamin D3 supplementation in these patients.

TRIAL REGISTRATION NUMBER

CTRI/2019/09/021164.

Understanding and Monitoring Chronic Myeloid Leukemia Blast Crisis: How to Better Manage Patients

Chronic myeloid leukemia (CML) is triggered primarily by the t(9;22) (q34.13; q11.23) translocation. This reciprocal chromosomal translocation leads to the formation of the BCR-ABL fusion gene. Patients in the chronic phase (CP) experience a good curative effect with tyrosine kinase inhibitors. However, cases are treatment refractory, with a dismal prognosis, when the disease has progressed to the accelerated phase (AP) or blast phase (BP). Until now, few reports have provided a comprehensive description of the mechanisms involved at different molecular levels. Indeed, the underlying pathogenesis of CML evolution comprises genetic aberrations, chromosomal translocations (except for the Philadelphia chromosome), telomere biology, and epigenetic anomalies. Herein, we provide knowledge of the biology responsible for blast transformation of CML at several levels, such as genetics, telomere biology, and epigenetic anomalies. Because of the limited treatment options available and poor outcomes, only the therapeutic response is monitored regularly, which involves BCR-ABL transcript level assessment and immunologic surveillance, with the optimal treatment strategy for patients in CP adapted to evaluate disease recurrence or progression. Overall, selecting optimal treatment endpoints to predict survival and successful TFR improves the quality of life of patients. Thus, identifying risk factors and developing risk-adapted therapeutic options may contribute to a better outcome for advanced-phase patients.

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.

Plasma imatinib levels and ABCB1 polymorphism influences early molecular response and failure-free survival in newly diagnosed chronic phase CML patients

Achieving early molecular response (EMR) has been shown to be associated with better event free survival in patients with chronic phase chronic myeloid leukemia (CP-CML) on Imatinib therapy. We prospectively evaluated the factors influencing the 2-year failure free survival (FFS) and EMR to imatinib therapy in these patients including day29 plasma Imatinib levels, genetic variants and the gene expression of target genes in imatinib transport and biotransformation. Patients with low and intermediate Sokal score had better 2-year FFS compared to those with high Sokal Score (p = 0.02). Patients carrying ABCB1-C1236T variants had high day29 plasma imatinib levels (P = 0.005), increased EMR at 3 months (P = 0.044) and a better 2 year FFS (P = 0.003) when compared to those with wild type genotype. This translates to patients with lower ABCB1 mRNA expression having a significantly higher intracellular imatinib levels (P = 0.029). Higher day29 plasma imatinib levels was found to be strongly associated with patients achieving EMR at 3 months (P = 0.022), MMR at 12 months (P = 0.041) which essentially resulted in better 2-year FFS (p = 0.05). Also, patients who achieved EMR at 3 months, 6 months and MMR at 12 months had better FFS when compared to those who did not. This study suggests the incorporation of these variables in to the imatinib dosing algorithm as predictive biomarkers of response to Imatinib therapy.

Efficacy and safety profile of generic imatinib in patients with newly diagnosed chronic myeloid leukemia-chronic phase: sharing experience of a hemato-oncology center from eastern India

In India, CML is the commonest adult leukemia. Imatinib is the gold standard for frontline treatment of newly diagnosed CML-CP patients. The present study was conducted to assess the efficacy and safety of generic imatinib in newly diagnosed CML-CP patients. In this prospective study, 76 newly diagnosed CML-CP patients received generic imatinib. They were monitored as per the ELN2013 recommendation. Karyotyping and BCR-ABL transcript level were done at specified time points. Adverse effects, if any, were documented as per the NCI-CTCAE criteria v4.03. Statistical analysis was done using standard methods. A total of 76 patients included in the study; median age was 36 years. The most common (71%) presenting symptom was fatigue; splenomegaly was found in all patients. CHR was achieved in 97% cases. At 3 months, 64.5% patients achieved ERM. At 6 months, CCyR and MCyR had seen in 65% and 68% cases, respectively. MMR achieved at 12 months in 44% cases. Most common hematological and non-hematological toxicity were anemia and skin changes seen in 89.5% and 71% cases, respectively. With generic imatinib therapy, the results of treatment outcome and safety profile were comparable with original imatinib. The added advantage was gross reduction in cost of therapy meeting unmet needs in CML patients in countries with resource constraints.

Monitoring Chronic Myeloid Leukemia: How Molecular Tools May Drive Therapeutic Approaches

More than 15 years ago, imatinib entered into the clinical practice as a "magic bullet"; from that point on, the prognosis of patients affected by chronic myeloid leukemia (CML) became comparable to that of aged-matched healthy subjects. The aims of treatment with tyrosine kinase inhibitors (TKIs) are for complete hematological response after 3 months of treatment, complete cytogenetic response after 6 months, and a reduction of the molecular disease of at least 3 logs after 12 months. Patients who do not reach their goal can switch to another TKI. Thus, the molecular monitoring of response is the main consideration of management of CML patients. Moreover, cases in deep and persistent molecular response can tempt the physician to interrupt treatment, and this "dream" is possible due to the quantitative PCR. After great international effort, today the BCR-ABL1 expression obtained in each laboratory is standardized and expressed as "international scale." This aim has been reached after the establishment of the EUTOS program (in Europe) and the LabNet network (in Italy), the platforms where biologists meet clinicians. In the field of quantitative PCR, the digital PCR is now a new and promising, sensitive and accurate tool. Some authors reported that digital PCR is able to better classify patients in precise "molecular classes," which could lead to a better identification of those cases that will benefit from the interruption of therapy. In addition, digital PCR can be used to identify a point mutation in the ABL1 domain, mutations that are often responsible for the TKI resistance. In the field of resistance, a prominent role is played by the NGS that enables identification of any mutation in ABL1 domain, even at sub-clonal levels. This manuscript reviews how the molecular tools can lead the management of CML patients, focusing on the more recent technical advances.

Clinical Implications of Discordant Early Molecular Responses in CML Patients Treated with Imatinib

A reduction in BCR-ABL1/ABL1^IS transcript levels to <10% after 3 months or <1% after 6 months of tyrosine kinase inhibitor therapy are associated with superior clinical outcomes in chronic myeloid leukemia (CML) patients. In this study, we investigated the reliability of multiple BCR-ABL1 thresholds in predicting treatment outcomes for 184 subjects diagnosed with CML and treated with standard-dose imatinib mesylate (IM). With a median follow-up of 61 months, patients with concordant BCR-ABL1/ABL1^IS transcripts below the defined thresholds (10% at 3 months and 1% at 6 months) displayed significantly superior rates of event-free survival (86.1% vs. 26.6%) and deep molecular response (≥ MR⁴; 71.5% vs. 16.1%) compared to individuals with BCR-ABL1/ABL1^IS levels above these defined thresholds. We then analyzed the outcomes of subjects displaying discordant molecular transcripts at 3- and 6-month time points. Among these patients, those with BCR-ABL1/ABL1^IS values >10% at 3 months but <1% at 6 months fared significantly better than individuals with BCR-ABL1/ABL1^IS <10% at 3 months but >1% at 6 months (event-free survival 68.2% vs. 32.7%; p < 0.001). Likewise, subjects with BCR-ABL1/ABL1^IS at 3 months >10% but <1% at 6 months showed a higher cumulative incidence of MR⁴ compared to patients with BCR-ABL1/ABL1^IS <10% at 3 months but >1% at 6 months (75% vs. 18.2%; p < 0.001). Finally, lower BCR-ABL1/GUS^IS transcripts at diagnosis were associated with BCR-ABL1/ABL1^IS values <1% at 6 months (p < 0.001). Our data suggest that when assessing early molecular responses to therapy, the 6-month BCR-ABL1/ABL1^IS level displays a superior prognostic value compared to the 3-month measurement in patients with discordant oncogenic transcripts at these two pivotal time points.

Impact of second decline rate of BCR-ABL1 transcript on clinical outcome of chronic phase chronic myeloid leukemia patients on imatinib first-line

Early molecular response has been associated with clinical outcome in chronic myeloid leukemia (CML) patients treated with tyrosine kinase inhibitors. The BCR-ABL1 transcript rate decline from baseline to 3 months has been demonstrated to be more predictive than a single BCR-ABL1 level at 3 months (M3). However, it cannot be used routinely because ABL1, as an internal gene control, is not reliable for BCR-ABL1 quantification above 10%. This study aimed to compare clinical outcome and molecular response of chronic phase CML patients, depending on the percentage of BCR-ABL1 transcript decrease from month 3 to month 6 using ABL1 as an internal control gene. Two hundred sixteen chronic phase CML patients treated with imatinib 400 mg for whom M3 and month 6 molecular data were available were included in the study. Associations with event-free (EFS), failure-free (FFS), progression-free (PFS), and overall survivals (OS) molecular response 4 log and 4.5 log were assessed. The percentage of BCR-ABL1 decline from month 3 to month 6 was significantly linked to the EFS and the FFS (p < 0.001). A common cut-off of 67% of decline predicted the better risk of event. Patients with a decrease below 67% have worse EFS and FFS as compared to those having a higher decrease (p < 0.001). The impact was confirmed by multivariate analysis. Since the slope between diagnosis and 3 months cannot be reliable using ABL1 as an internal gene control, the second decline rate of BCR-ABL1 transcript between month 3 and month 6 could efficiently identify patients at higher risk of event.

Tyrosine Kinase Inhibitors in the Treatment of Chronic-Phase CML: Strategies for Frontline Decision-making

PURPOSE OF REVIEW

Over the past two decades, the introduction of tyrosine kinase inhibitors (TKIs) has transformed the treatment of chronic myeloid leukemia (CML). With four agents currently approved for frontline use in chronic-phase (CP) disease, it follows that treatment decision-making has been rendered more challenging. Here we will review recent advances that help inform the selection of a first-line TKI.

RECENT FINDINGS

Extended follow-up of the seminal CML trials has demonstrated the long-term efficacy of TKIs, while also highlighting significant differences in their respective toxicity profiles and potency. Dasatinib and nilotinib generate deeper molecular responses than imatinib, particularly among patients with higher risk disease, but this has not translated into a significant survival advantage. Similar results have been obtained at 1 year with bosutinib; its efficacy and toxicity were well balanced at a dose of 400 mg daily, prompting its recent approval for this indication. Lastly, multiple studies have demonstrated that TKIs can be safely discontinued in select individuals who have maintained deep responses for extended periods, establishing treatment-free remission as a novel goal in CP CML. The careful consideration of parameters such as disease risk, the potency, and toxicity profile of each TKI, as well as each patient's unique comorbidities and preferences, enables truly individualized therapeutic decision-making in CP CML, with the goal of ensuring that a high quality of life accompanies the survival advantage conferred by these agents.

Molecular monitoring in CML: how deep? How often? How should it influence therapy?

With the advent of tyrosine kinase inhibitors (TKIs), the goals of therapy in chronic myeloid leukemia (CML) are steadily shifting. Long-term disease control on TKI therapy has been the goal and expectation for most patients. More recently, treatment-free remission (TFR) has entered mainstream practice and is increasingly being adopted as the main goal of therapy. This therapeutic shift not only influences TKI selection but also, has necessitated the refinement and dissemination of highly sensitive and accurate molecular monitoring techniques. Measurement of BCR-ABL1 messenger RNA expression through reverse transcription quantitative polymerase chain reaction, reported according to the International Scale, has become the primary tool for response assessment in CML. Achieving specific time-dependent molecular milestones, as defined by global therapeutic guidelines, has been established as critical in maximizing optimal outcomes while identifying patients at risk of therapy failure. Depth and duration of a deep molecular response have become the new therapeutic targets in patients considered for TFR. Consequently, molecular monitoring in CML has become even more critical to ongoing response assessment, identifying patients with TKI resistance and poor drug adherence, and enabling TFR to be attempted safely and effectively.

Molecular monitoring in CML: how deep? How often? How should it influence therapy?

With the advent of tyrosine kinase inhibitors (TKIs), the goals of therapy in chronic myeloid leukemia (CML) are steadily shifting. Long-term disease control on TKI therapy has been the goal and expectation for most patients. More recently, treatment-free remission (TFR) has entered mainstream practice and is increasingly being adopted as the main goal of therapy. This therapeutic shift not only influences TKI selection but also, has necessitated the refinement and dissemination of highly sensitive and accurate molecular monitoring techniques. Measurement of BCR-ABL1 messenger RNA expression through reverse transcription quantitative polymerase chain reaction, reported according to the International Scale, has become the primary tool for response assessment in CML. Achieving specific time-dependent molecular milestones, as defined by global therapeutic guidelines, has been established as critical in maximizing optimal outcomes while identifying patients at risk of therapy failure. Depth and duration of a deep molecular response have become the new therapeutic targets in patients considered for TFR. Consequently, molecular monitoring in CML has become even more critical to ongoing response assessment, identifying patients with TKI resistance and poor drug adherence, and enabling TFR to be attempted safely and effectively.

Canadian chronic myeloid leukemia outcomes post-transplant in the tyrosine kinase inhibitor era

The majority of patients with TKI failure respond to HCT. However, the relapse risk remains high. This study has evaluated transplant outcomes in 223 CML patients with TKI failure due to resistance (n = 132) or intolerance (n = 29), as well as those that were TKI naïve/responding with advanced disease (n = 35) or with chronic phase (CP, n = 27). We studied outcomes according to post-transplant BCR-ABL transcript level within 3 months. With respect to transplant outcomes according to the post-transplant BCR/ABLtranscript level within 3 months, the group failing to achieve a 1.3 log reduction (n = 14, 12.4%) showed the highest relapse rate of 78.6% at 5 years, compared to 26.2% and 24.1% in the groups achieving 1.3-4.0 log reduction (n = 45, 39.8%), and ≥4.1 log reduction (n = 54, 47.8%) respectively (p < 0.001). Multivariate analysis confirmed that the group failing to achieve a 1.3 log reduction had a 2.3-fold higher risk of death and 6.6 times higher risk of relapse. Poor overall survival after HCT was associated with advanced disease at diagnosis, but not disease status prior to HCT. Of 61 patients who relapsed after HCT, 47 were treated with post-transplant TKI therapy; those receiving TKI after loss of MR2 or MMR showed higher rates of response and survival compared to those receiving TKI after hematologic relapse (p < 0.001). QPCR log reduction level within 3 months post transplantation is prognostic in this population.

The Role of Early Molecular Response in the Management of Chronic Phase CML

Purpose of Review

Although tyrosine kinase inhibitors (TKIs) spectacularly improve the disease burden and the overall survival of chronic myeloid leukemia patients, early identification of a subset of poor TKI responders has been recognized as a critical goal to prevent disease progression in these patients. We herein review the past and recent evidence on the impact of early response.

Recent Findings

In the recent years, the achievement of an early molecular response (EMR, defined as 3-month BCR-ABL1 transcript <10% IS) has emerged as a useful tool to identify poor-risk patients. Although several groups have reported the importance of such milestone, clinical intervention based on it remains controversial partly due to its low specificity to predict progression, which may be partially improved by using the rate of decline in BCR-ABL1 transcript level (halving time or velocity of ratio reduction).

Summary

Standardization of halving time or velocity of ratio reduction will likely help establishing more stringent recommendation and modify current clinical practices.

[Comparison of generic and original imatinib in the treatment of newly diagnosed patients with chronic myelogenous leukemia in chronic phase: a multicenter retrospective clinical study]

Objective: To evaluate the efficacy and safety of generic imatinib (Genike, Chiatai Tianqing Pharmaceutical Group Co., Ltd.) and imatinib (Glevic, Novartis, Switzerland) in newly diagnosed patients with chronic myeloid leukemia in chronic phase (CML-CP) . Methods: A retrospective study of 323 CML-CP patients (205 in Glivec treatment group and 118 in Genike group) who were ≥ 18 years old receiving imatinib monotherapy over the period of June 2013 to March 2016 was done to compare the differences of cytogenetics, molecular curative effect, survival, and adverse reactions between the two groups. The beginning dosage of imatinib was 400mg per day. There was no statistically difference between the two groups of patients on baseline. Results: ①The median duration of imatinib treatment was 13 (0.5-36) months in Glevic group and 11 (1-31) months in Genike group. ②The rate of complete hematological remission (CHR) had no statistically difference between Glivec and Genike treatment groups[98% (201/205) vs 97.5% (115/118) , χ(2)=0.123, P=0.725]. ③Cumulative rates of major cytogenetic responses (MCyR) at 3, 6 and 12 months after imatinib treatment in Gleevec and Genike groups were (59.7±3.5) % vs (79.8±3.1) %, (89.2±2.6) % vs (59.1±4.7) %, (80.3±4.1) % vs (87.1±4.3) %, respectively, the difference was not statistically significant (χ(2)=0.084, P=0.772) . Cumulative rates of complete cytogenetic response (CCyR) at 3, 6 and 12 months after imatinib treatment in Gleevec and Genike groups were (32.9±3.4) % vs (58.3±3.7) %, (87.4±3.0) % vs (35.2±4.5) %, (64.8±4.8) % vs (87.3±4.7) %, respectively, the difference was not statistically significant (χ(2)=0.660, P=0.417) . ④Cumulative rates of major molecular responses at 6, 12 months after imatinib treatment in Glevic and Genike groups were (24.9±3.3) % vs (57.0±4.1) %, (16.3±4.0) % vs (55.3±7.7) %, respectively, there was no statistical significance (χ(2)=1.617, P=0.204) . Cumulative rates of molecular response 4.5 (MR4.5) at 12 months after imatinib treatment in Glevic and Genike groups were (14.9±3.2) % vs (8.1±2.1) % (χ(2)=3.628, P=0.057) , respectively. ⑤At a median follow-up of 12 months, the difference of progression-free survival (PFS) in Glevic and Genike groups had no statistical significance[ (96.6±1.4) % vs (93.3±2.5) %, χ(2)=2.293, P=0.130]. The difference of event-free survival (EFS) had no statistical significance, either[ (95.6±1.5) % vs (93.3±2.4) %, χ(2)=2.124, P=0.145]. ⑥Genike was well tolerated in patients with CML-CP and had no statistically significant difference in adverse events compared with Glevic group. Conclusion: There were no statistically significant differences in efficacy and safety between Glevic and Genike treatment in newly diagnosed patients with CML-CP.

Treating the chronic-phase chronic myeloid leukemia patient: which TKI, when to switch and when to stop?

INTRODUCTION

With the discovery of imatinib mesylate nearly 20 years ago, tyrosine kinase inhibitors (TKIs) were found to be effective in chronic myeloid leukemia (CML). TKI therapy has since revolutionized the treatment of CML and has served as a paradigm of success for targeted drug therapy in cancer. Several new TKIs for CML have been approved over the last two decades that exhibit improved potency over imatinib and have different off-target profiles, providing options for individualized therapy selection. Areas covered: Current management of chronic phase CML, including guidance on the sequential use of imatinib and newer-generation TKIs and evolving treatment strategies such as TKI discontinuation. Relevant literature was identified by searching biomedical databases (i.e. PubMed) for primary research material. Expert commentary: Although survival outcomes have drastically improved for CML patients, treatment for CML has grown more complex with the introduction of next-generation TKIs and the advent of treatment-free remissions (TFR). Goals of therapy have shifted accordingly, with increased focus on improving quality of life, managing patient expectations and optimizing patient adherence.

Factors Affecting Early Molecular Response in Chronic Myeloid Leukemia

OBJECTIVES

There is controversy about whether 3- or 6-month molecular assessment predicts progression-free and overall survival in those with chronic myeloid leukemia (CML). The factors predicting molecular response at 3, 6, and 12 months have not been studied extensively. The study objective was to study the factors affecting molecular response at 3 and 6 months in patients with CML who are receiving imatinib mesylate.

METHODS

We prospectively enrolled patients with newly diagnosed CML who were receiving imatinib mesylate as the initial therapy for CML. The diagnosis of CML was based on clinical examination, bone marrow, and demonstration of BCR ABL(IS) transcripts by polymerase chain reaction. The molecular response(IS) was assessed at 3, 6, and 12 months by GeneXpert (Cepheid, Sunnyvale, CA) and co-related with various baseline characteristics of patients. We also looked at whether early achievement of a complete hematologic response within 6 weeks predicts molecular response at 3 or 6 months. The study took place at a tertiary care hospital in Northwest India catering to patients belonging to low-middle socioeconomic status.

RESULTS

We enrolled 131 patients with CML in the chronic phase from July 1, 2013, to August 31, 2014. The median age of the patients was 40 years (range, 13-67) with a male preponderance (61% were male). Most patients presented with symptoms of low-grade fever (52.7%) and abdominal fullness (26.7%). Spleen was palpable in 84.7% of patients. The median hemoglobin at presentation was 10.8 g/dL (range, 4.8-18.4 g/dL), white cell count was 138.3 × 10(9)/L (4.1-697 × 10(9)/L), and platelet count was 326 × 10(9)/L (85-1819 × 10(9)/L). The median number of peripheral blood basophils was 3% (range, 0%-20%), and blasts were 3% (range, 0%-10%). Myelofibrosis of more than grade 1 was present in 30% of patients. Most patients belonged to intermediate Sokal (45.8%) and Hasford (55%) scores and low EUropean Treatment Outcome Study (78.6%) score. Of 128 evaluable patients at 3 months, 96.9% achieved complete hematologic remission (CHR) and 82.3% achieved BCR ABL(IS) of less than 10%. None of the patients who had BCR ABL(IS) > 10% at 3 months achieved BCR ABL(IS) < 1% at 6 months or < 0.1% at 12 months. Early achievement of CHR (< 6 weeks), peripheral blood blast count of < 5%, and lactate dehydrogenase < 851 U/L were significantly associated with achievement of BCR ABL(IS) < 10% at 3 months and BCR ABL(IS) < 1% at 6 months.

CONCLUSIONS

We found that BCR ABL(IS) assessment at 3 months is superior to assessment at 6 months. Patients with CML in the chronic phase who achieve CHR within 6 weeks are more likely to achieve BCR ABL(IS) < 10% at 3 months and < 1% at 6 months than patients who achieve CHR between 7 and 12 weeks.

Chronic myeloid leukemia: reminiscences and dreams

With the deaths of Janet Rowley and John Goldman in December 2013, the world lost two pioneers in the field of chronic myeloid leukemia. In 1973, Janet Rowley, unraveled the cytogenetic anatomy of the Philadelphia chromosome, which subsequently led to the identification of the BCR-ABL1 fusion gene and its principal pathogenetic role in the development of chronic myeloid leukemia. This work was also of major importance to support the idea that cytogenetic changes were drivers of leukemogenesis. John Goldman originally made seminal contributions to the use of autologous and allogeneic stem cell transplantation from the late 1970s onwards. Then, in collaboration with Brian Druker, he led efforts to develop ABL1 tyrosine kinase inhibitors for the treatment of patients with chronic myeloid leukemia in the late 1990s. He also led the global efforts to develop and harmonize methodology for molecular monitoring, and was an indefatigable organizer of international conferences. These conferences brought together clinicians and scientists, and accelerated the adoption of new therapies. The abundance of praise, tributes and testimonies expressed by many serve to illustrate the indelible impressions these two passionate and affable scholars made on so many people's lives. This tribute provides an outline of the remarkable story of chronic myeloid leukemia, and in writing it, it is clear that the historical triumph of biomedical science over this leukemia cannot be considered without appreciating the work of both Janet Rowley and John Goldman.

[A prospective, multi-centre clinical trial to evaluate the early clinical efficacy and safety of a generic imatinib in treating patients with chronic phase of chronic myelogenous leukemia]

OBJECTIVE

To evaluate the early hematologic, cytogenetic and molecular responses in newly diagnosed patients with chronic myelogenous leukemia in chronic phase（CML-CP）and initially treated with a generic imatinib（Xinwei）, manufactured by Jiansu Hansoh Pharmaceutical Group Co., Ltd.

METHODS

107 newly diagnosed patients of CML-CP, whose ages were above 18- year- old and who had never received any tyrosine kinase inhibitor（TKI）were treated with Xinwei 400 mg QD. The hematologic, cytogenetic and molecular responses were assessed at 3- and 6-month, and adverse effects were evaluated throughout the study.

RESULTS

107 patients were treated with Xinwei for at least 3 months, 54 of them were treated for 6 months or more. At 3- month, the complete hematologic responses（CHR）rate were 98.1%（105/107）; 47/57（82.5%） patients achieved major cytogenetic response（MCyR）, and 20/57 （35.1%） patients complete cytogenetic response（CCyR）; BCR- ABLIS was ≤10% in 77/106 patients （72.6%）, 11 of them（10.4%）achieved major molecular response（MMR, BCR-ABLIS was ≤0.1%）. At 6-month, the CHR rate was 100%（54/54）; 28/39 patients（71.8%）achieved CCyR; BCR-ABLIS was ≤1% in 37/54 patients （68.5% ）, 18 of them （33.3% ） achieved MMR. The grade Ⅲ leukopenia, thrombocytopenia and anemia rates were 19.5%, 23.0% and 13.8%, respectively. No grade Ⅳ hematologic toxicity occurred. The common non- hematologic toxicities were edema（74.7%）, nausea（48.3%）, bone pain（42.5%）, rash（36.8%）, diarrhea（34.5%）, fever（23.0%）, cramp（11.5%）and impaired liver function （3.4%）. No patient experienced grade Ⅳ non- hematologic toxicity. No adverse effects related death occurred.

CONCLUSION

Our results revealed the excellent early haematology, cytogenetic and molecular responses and safety of Xinwei in treating patients with CML-CP.

Response-related predictors of survival in CML

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

Molecular monitoring in CML and the prospects for treatment-free remissions

Monitoring treatment responses in chronic myeloid leukemia (CML) is based on complete blood counts (CBCs) to determine hematologic response, karyotyping of bone marrow metaphase cells to delineate cytogenetic response and quantitative reverse transcription polymerase chain reaction (qPCR) to quantify expression of BCR-ABL1 mRNA (molecular response; MR) in peripheral blood. Fluorescence in situ hybridization (FISH) to identify BCR-ABL1 in interphase nuclei and mutational analysis of the BCR-ABL1 kinase domain (KD) are used in certain clinical circumstances. As most patients treated with tyrosine kinase inhibitors (TKIs) achieve complete cytogenetic responses (CCyRs), qPCR with its increased sensitivity and dynamic range has become the main tool used to monitor CML patients. Landmark analyses of large TKI trials have established MR milestones that identify patients with high risk of failure, are the basis of consensus management guidelines, and have led to a strong push toward qPCR test standardization. Today many laboratories report BCR-ABL1 qPCR results on the international scale (IS), a system based on the conversion of laboratory-specific numerical values to conform to a universal scale. The fact that qPCR is technically demanding and liable to assay variations poses considerable challenges for its routine clinical use. This is important as the prevalence of patients on chronic TKI therapy increases and critical clinical decisions are made based on qPCR results, for example if discontinuation of TKI therapy should be considered. Here we will review the current state of molecular monitoring in CML, focusing on qPCR, the definition of TKI failure and the results of TKI discontinuation studies.

Prognostic significance of early molecular response in chronic myeloid leukemia patients treated with tyrosine kinase inhibitors

A 55-year-old man presented with splenomegaly (10 cm below left costal margin) and leucocytosis (145 × 10(9)/L). Differential showed neutrophilia with increased basophils (2%), eosinophils (1.5%), and left shift including myeloblasts (3%). A diagnosis of chronic myeloid leukemia in chronic phase was established after marrow cytogenetics demonstrated the Philadelphia chromosome. Molecular studies showed a BCR-ABL1 qPCR result of 65% on the International Scale. Imatinib therapy at 400 mg daily was initiated due to patient preference, with achievement of complete hematological response after 4 weeks of therapy. BCR-ABL1 at 1 and 3 months after starting therapy was 37% and 13%, respectively (all reported on International Scale). Is this considered an adequate molecular response?

Goals for chronic myeloid leukemia TK inhibitor treatment: how little disease is too much?

Tyrosine kinase inhibitors, now numbering 5 for the treatment of Philadelphia chromosome-positive leukemia, have proven ability to reduce clonal disease burden rapidly, dramatically, and durably, especially in chronic myeloid leukemia in the chronic phase. Deep molecular remissions are likely in most chronic phase patients and expectations on timing of response have been developed, validated as best as possible, and evolved over time. Increasing attention has been given to the initial decline of Bcr-Abl1 transcripts and the ultimate depth of molecular remission, overshadowing but not displacing the traditional role of cytogenetic response. This chapter reviews the evolution of response milestones for chronic phase chronic myeloid leukemia and tries to answer the question of how little disease is too much.