BCR-ABL Transcript Levels Research Articles

Therapeutic Challenges in Chronic Myeloid Leukemia: A Case-Based Discussion

Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm characterized by a reciprocal translocation between the long arms of chromosomes 9 and 22 that results in expression of the oncoprotein BCR-ABL1. An optimal response to tyrosine kinase inhibitors (TKIs) requires a BCR-ABL transcript level ≤ 10% at 3 months, ≤ 1% at 6 months, ≤ 0.1% at 1 year, and ≤ 0.01% onwards. Complex scenarios like P190BCR-ABL CML, unusual BCR-ABL transcripts, primary refractory CML, and detection of TKI-resistance mutations during treatment frequently pose a therapeutic challenge. In this article we present some of these clinical scenarios using a case-based approach.

Mechanisms of Disease Progression and Resistance to Tyrosine Kinase Inhibitor Therapy in Chronic Myeloid Leukemia: An Update.

Chronic myeloid leukemia (CML) is characterized by the presence of the BCR-ABL1 fusion gene, which encodes a constitutive active tyrosine kinase considered to be the pathogenic driver capable of initiating and maintaining the disease. Despite the remarkable efficacy of tyrosine kinase inhibitors (TKIs) targeting BCR-ABL1, some patients may not respond (primary resistance) or may relapse after an initial response (secondary resistance). In a small proportion of cases, development of resistance is accompanied or shortly followed by progression from chronic to blastic phase (BP), characterized by a dismal prognosis. Evolution from CP into BP is a multifactorial and probably multistep phenomenon. Increase in BCR-ABL1 transcript levels is thought to promote the onset of secondary chromosomal or genetic defects, induce differentiation arrest, perturb RNA transcription, editing and translation that together with epigenetic and metabolic changes may ultimately lead to the expansion of highly proliferating, differentiation-arrested malignant cells. A multitude of studies over the past two decades have investigated the mechanisms underlying the closely intertwined phenomena of drug resistance and disease progression. Here, we provide an update on what is currently known on the mechanisms underlying progression and present the latest acquisitions on BCR-ABL1-independent resistance and leukemia stem cell persistence.

A Comparison of Two Standardized Quantitative RT-PCRs with CE IVD Kit for Digital PCR in CML Patients with Different Level of BCR-ABL1 Transcripts

The detection and quantification of BCR-ABL1 transcripts play a key role in therapy management of chronic myeloid leukemia (CML) patients treated with tyrosine kinase inhibitors (TKIs). Reverse transcription quantitative PCR (RT-qPCR) is considered the gold standard strategy for monitoring of minimal residual disease (MRD). Recently, digital PCR (dPCR) was introduced as a new quantification method based on determination of absolute target sequence quantity. In connection with the deep molecular response (MR) assessment and the option of TKIs treatment cessation, the dPCR has a potential of high sensitivity, robustness and accuracy of BCR-ABL1 transcripts detection. The aim of present work was to compare the results of two standardized RT-qPCR methods with RT-dPCR detection in clinical samples of CML patients with different BCR-ABL1 fusion transcripts level. In total, 62 peripheral blood samples of CML patients with the level of BCR-ABL1 transcripts (international scale, IS) between 100% and undetectable were enrolled. The samples were analyzed by three methods: (1) CE IVD Xpert BCR-ABL Ultra Kit (GeneXpert, Cepheid), (2) conventional RT-qPCR assay according to ELN guidelines and certified by EUTOS for the level of MR4.5 BCR-ABL1 detection (ABI7300, Applied Biosystems), and (3) RT-dPCR using CE IVD QXDx BCR-ABL %ID Kit (Bio-Rad) on QX200 Droplet Digital PCR System (Bio-Rad). All steps were performed according to manufacturer´s instructions. A linear regression analysis and an overall reporting bias analysis using the Bland-Altman test were used for comparison of the methods. Based on the results of GeneXpert as the determined routine method for BCR-ABL1 transcripts quantification, the samples were divided into two groups: 50/62 samples were scored as BCR-ABL1 positive (the first group), while 12/62 samples were scored as BCR-ABL1 undetectable (the second group). The first group of GeneXpert positive samples was analyzed using both conventional RT-qPCR and RT-dPCR (both in duplicates). The median of the sum of ABL copies per sample was 180,511 copies (range 56,466 - 536,453) by RT-qPCR vs. 39,960 (range 14,360 - 71,690) by RT-dPCR. Both conventional RT-qPCR and RT-dPCR did not detect any BCR-ABL1 transcript in 4/50 samples. In addition, RT-dPCR did not detect any BCR-ABL1 transcript in 5 other samples (Figure 1). Linear regression analysis showed good correlation between both sets of assays: GeneXpert vs. RT-dPCR (R2=0.965, N=41) and conventional RT-qPCR vs. RT-dPCR (R2=0.977, N=41). The slopes of regression curve were not significantly different from the value of 1 for both sets of the compared assays (1.02; 95% CI, range 0.95 - 1.08 and 1.02; 95% CI, range 0.97 - 1.08, respectively). In addition, an overall bias (Bland-Altman analyses) was -0.05 (GeneXpert vs. RT-dPCR) and -0.12 (conventional RT-qPCR vs. RT-dPCR) suggesting good concordance in % IS reporting between RT-dPCR and two standardized quantitative BCR-ABL1 assays. The evaluation of MR level was identical by all three methods in 26/50 samples. The comparison of two methods revealed consistent MR level by GeneXpert vs. RT-dPCR in 29/50 samples and by conventional RT-qPCR vs. RT-dPCR in 28/50 samples. The RT-dPCR scored 12/50 samples (GeneXpert vs. RT-dPCR) and 13/50 samples (conventional RT-qPCR vs. RT-qPCR) to the different level of MR compared to standardized RT-qPCR methods. The second group of samples (12/62) undetectable for BCR-ABL1 transcripts according to GeneXpert was analyzed using conventional RT-qPCR and RT-dPCR in tetraplicates to reach higher sensitivity. The BCR-ABL1 negativity was confirmed in 11/12 samples. One sample was BCR-ABL1 positive by both the conventional RT-qPCR (0.0008% IS) and RT-dPCR (0.0013% IS). We showed that the results of quantitative detection of BCR-ABL1 transcripts (% IS) obtained by the CE IVD RT-dPCR kit are in good correlation with the results of both standardized RT-qPCR methods and all three methods provide comparable sensitivity. RT-qPCR method yielded higher number of copies of control ABL gene per sample compared to RT-dPCR although the input amount of RNA into the RT reaction was the same. The MR level evaluation of RT-dPCR vs. both RT-qPCR methods was identical to the level MR3.0 (category >0.01% IS), while for samples in deep MR (category ≤ 0.01% IS, MR4.0 and below) revealed partial difference in categorization into the individual MR levels. Supported by MH CZ - DRO (FNBr, 65269705). Disclosures Zackova: Novartis: Consultancy; Bristol Myers Squibb: Consultancy; Angelini: Consultancy; Incyte: Consultancy. Mayer:AOP Orphan Pharmaceuticals AG: Research Funding.

The Canadian Tyrosine Kinase Inhibitor Discontinuation Trial with Imatinib Discontinuation As a First Attempt and with Dasatinib Discontinuation As a Second Attempt of Treatment-Free Remission: Results of 4 Years of Follow-up

The Canadian Tyrosine Kinase Inhibitor Discontinuation Trial with Imatinib Discontinuation As a First Attempt and with Dasatinib Discontinuation As a Second Attempt of Treatment-Free Remission: Results of 4 Years of Follow-up

Interim Analysis of a Prospective Multicentre Study Using Next Generation Sequencing for Kinase Domain Mutational Analysis in CML Patients on First or Subsequent TKI Therapy

Interim Analysis of a Prospective Multicentre Study Using Next Generation Sequencing for Kinase Domain Mutational Analysis in CML Patients on First or Subsequent TKI Therapy

Prospective Monitoring of Peripheral Blood CD26+ Leukemia Stem Cells in Chronic Myeloid Leukemia Patients from Time of TKI Discontinuation

Prospective Monitoring of Peripheral Blood CD26+ Leukemia Stem Cells in Chronic Myeloid Leukemia Patients from Time of TKI Discontinuation

The Interaction of Tumor Cells and Myeloid-Derived Suppressor Cells in Chronic Myelogenous Leukemia

Chronic myelogenous leukemia (CML) is a malignant myeloproliferative disease characterized by the formation of the BCR-ABL fusion gene. At present, basic studies of the pathogenesis of relapse after stopping tyrosine kinase inhibitors (TKIs) treatment have mainly concentrated on two main aspects: the leukemia stem cells (LSCs) and the tumor microenvironment. However, whether relapse or non-relapse patients who discontinued TKIs therapy, LSCs are still exist. Among a variety of factors that compose the CML microenvironment, myeloid-derived suppressor cells (MDSC) are considered to be a strong contributor to the immunosuppressive tumor microenvironment. Here, we designed the study to investigate the potential relation between tumor cells and MDSC in CML and find risk factors for relapse after discontinuation. We detected the percentage of MDSC and the BCR-ABL (IS) transcript levels in bone marrow of 50 CML patients in chronic phase at our center. The data indicated that the frequency of MDSC had significant positive correlation with BCR-ABL (IS) transcript levels (Figure 1A). In addition, the counts of MDSC had significant difference at different response stages (Figure 1B), especially the M-MDSC, a subtype of MDSC. The percentage of M-MDSC was significantly higher in patients with newly diagnosed or complete hematological response (CHR) or major molecular response (MMR) compared with those of CML patients obtained complete molecular response (CMR) (Figure 1C). When K562 cells or CD34+ cells were cocultured with M-MDSC at a 1:10 ratio, K562 cells or CD34+ cells proliferated significantly at day 3 (Figure 1D and E). K562 subcutaneous tumor formation in BALB/c node mice confirmed that tumors weight and volume of the coculture group were higher than control. Then, we further investigated whether tumor cells have an impact on MDSC through microvesicles (MV). After adding K562-MV to peripheral blood mononuclear cells (PBMCs) from healthy donors, MDSC counts appeared significantly elevated in the different K562 cells counts group compared to the control group (Figure 1F).To analyze the roles of K562-MV collected before and after TKIs discontinuation on MDSC, we established a TKIs discontinuation model using the K562 cell, which emulates the cessation of TKIs treatment of CML patients in some extent. The results showed that regardless of the Imatinib or Dasatinib treatment, a significant increase was observed in the proportion of MDSC after TKIs treatment cessation compared with the TKIs treatment groups (Figure 1G). Experiments in vivo also proved K562-MV after different treatments promoted the proliferation of MDSC (Figure 1H and I). In conclusion, our study introduces the notion of the role of MDSC as mediators in the cross talk between tumor cells and the microenvironment. MDSC would provide a novel and useful model to predict the relapse of CML by establishing a type of new risk stratification system. MDSC could be also act as a promising target in the relapse of CML. In addition, we found a mutual promotion of proliferation of tumor cells and MDSC, this bidirectional interaction results in a vicious cycle by providing a protective niche against immune attacks. Therapeutic interventions modulating this interaction might accelerate the success of treatment-free remission. Figure 1 Disclosures No relevant conflicts of interest to declare.

Nilotinib Vs Nilotinib Plus Pegylated Interferon α (Peg-IFN) Induction and Nilotinib or Peg-IFN Maintenance Therapy for Newly Diagnosed BCR-ABL1 Positive Chronic Myeloid Leukemia Patients in Chronic Phase (TIGER Study): The Addition of Peg-IFN Is Associated with Higher Rates of Deep Molecular Response

Introduction: The TIGER (CML V)-study* (NCT01657604) is a multicenter, randomized phase III trial to evaluate efficacy and tolerability of nilotinib (NIL) 2*300mg/d monotherapy vs NIL 2*300mg/d + pegylated interferon α2b (Peg-IFN) 30-50μg/week as first line therapy for chronic myeloid leukemia (CML) patients (pts) in chronic phase and discontinuation of therapy after Peg-IFN maintenance (Figure). Methods: In August 2012, recruitment started with a pilot phase, aiming to validate the recommended dose of Peg-IFN. 25 pilot phase patients were treated with the combination of NIL 2*300 mg daily and Peg-IFN (30-50μg/week according to tolerability and commenced after ≥6 weeks NIL monotherapy). During the main phase of the study, 692 newly diagnosed pts were randomized between NIL 2*300 mg/d and NIL/Peg-IFN combination according to the outcome of the pilot phase. Results: Within 5 years, a total of 717 pts (429 male; median age 51 years, range 18-85; 12.9% EUTOS high risk) were recruited from 109 sites in Germany, Switzerland, and the Czech Republic. 702 pts with typical BCR-ABL1 transcripts (97.9%) were eligible for molecular follow-up assessments according to the international scale (IS). Fifteen pts (2.1%) expressed atypical BCR-ABL1 transcripts. 692 pts were randomized after EUTOS risk stratification to receive NIL monotherapy (n=353) or NIL/PEG-IFN combination therapy (n=339). Median observation time since recruitment was 41 months. Up to now, 477 pts concluded the induction phase by achieving a confirmed major molecular response, MMR (BCR-ABL1 transcript levels ≤0.1% IS, which qualified for entering the maintenance phase of the study using NIL or Peg-IFN monotherapy. During the maintenance phase, 199 pts achieved or sustained MR4 (BCR-ABL1 ≤0.01% IS) for at least one year and then discontinued all therapy. While the rate of MMR at 12 and 18 mo - the first primary endpoint of the study - was not different between the treatment arms, adding Peg-IFN to upfront NIL significantly improved rates of MR4 and MR4.5, BCR-ABL1 ≤0.0032% IS) (Table). In competing risk analysis, median time to MMR was 5.7 vs 5.4 mo, to MR4 20.9 vs 12.5 mo, and to MR4.5 33.8 vs 23.2 mo for NIL vs NIL/Peg-IFN, respectively. After NIL discontinuation, during Peg-IFN maintenance therapy, rate of molecular recurrence (BCR-ABL1 >1% IS) after 18 mo was 28%. From 199 pts who discontinued all therapy, 63 experienced a molecular relapse (BCR-ABL1 >0.1%). Relapse free survival by 18 mo after treatment discontinuation was 61% in the total cohort. By protocol, it is too early to assign relapse rates to the randomized treatment arm. Frequencies of adverse events after 24 mo of therapy were 90 and 92% (grade 1-5) and 36 and 42% (grade 3-5) for NIL vs NIL/Peg-IFN, respectively. Adverse events of special interest (all grades) were fatigue in 34.6 vs 40.4%, thrombocytopenia in 13.3 vs 18.9% and elevation of the alanin aminotransferase (ALAT) in 11.0 vs 18.9% of pts in the NIL vs NIL/Peg-IFN arms, respectively. Fifteen pts (2.1%) progressed to accelerated phase or blast crisis; 22 pts (3.1%) received an allogeneic stem cell transplantation, 10 of them after disease progression. In total, 22 pts (3.1%) died, 16 during the induction phase, 4 in the maintenance phase and 2 in treatment free remission. Four deaths were related to CML, 3 to vascular complications. Conclusions: This per protocol interim analysis demonstrates feasibility of the first-line treatment with NIL 2*300 mg/d combined with PEG-IFN 30-50 μg/week. Peg-IFN, when added upfront to NIL further increases the rates of MR4 and MR4.5, which may translate into higher rates oftreatment free remission. *The study is being conducted on behalf of the German CML Study Group, the Swiss Group for Clinical Cancer Research (SAKK) and the East German Study Group on Hematology and Oncology (OSHO). Disclosures Hochhaus: Pfizer: Research Funding; Novartis: Research Funding; BMS: Research Funding; Incyte: Research Funding; MSD: Research Funding. Burchert:Novartis: Research Funding. Saussele:Novartis: Honoraria, Research Funding; Incyte: Honoraria, Research Funding; BMS: Honoraria, Research Funding; Pfizer: Honoraria. Baerlocher:Novartis: Research Funding. Brümmendorf:Janssen: Consultancy; Ariad: Consultancy; University Hospital of the RWTH Aachen: Employment; Pfizer: Consultancy, Research Funding; Merck: Consultancy; Novartis: Consultancy, Research Funding. La Rosée:Novartis: Research Funding; Bristol-Myers-Squibb: Consultancy, Other: Travel support, Speakers Bureau. Heim:Novartis: Research Funding. Krause:Siemens: Research Funding; Takeda: Honoraria; MSD: Honoraria; Gilead: Other: travel; Celgene Corporation: Other: Travel. le Coutre:Bristol-Myers Squibb: Honoraria, Speakers Bureau; Incyte: Honoraria, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; Pfizer: Honoraria, Speakers Bureau. Niederwieser:Daichii: Speakers Bureau; Cellectis: Consultancy. Lange:Novartis: Research Funding. Fabarius:Novartis: Research Funding. Hänel:Novartis: Honoraria; Amgen: Honoraria; Takeda: Other: advisory board; Celgene: Other: advisory board; Roche: Honoraria. Stegelmann:Novartis: Consultancy, Honoraria; Incyte: Consultancy, Honoraria. Mayer:AOP Orphan Pharmaceuticals AG: Research Funding. Hasford:Novartis: Research Funding. Hehlmann:Novartis: Research Funding. Ernst:Novartis: Research Funding. OffLabel Disclosure: Combination of Nilotinib and PEG-IFN alpha is being tested is off-label and being tested in the TIGER study.

The Relationship between Molecular Response of BCR-ABL1 Transcripts within 6 Months and Deep Molecular Response at 18 Months to Dasatinib Treatment for Newly Diagnosed Patients with CML-CP

BACKGROUND: The overall survival of patients with newly diagnosed chronic myeloid leukemia (CML) has improved significantly since the introduction of tyrosine kinase inhibitors (TKIs), and recently, some patients with CML who achieve stable deep molecular response (DMR) to TKI therapy could safely suspend treatment. In addition to European LeukemiaNet criteria (ELN), the European Society for Medical Oncology (ESMO) proposed that less than 0.01% of BCR-ABL1 transcript (MR4.0) on the International Scale (IS) after 18 months is optimal for patients to achieve treatment-free remission. Branford et al. indicated that major molecular response (MMR; less than or equal to 0.1% of BCR-ABL1 IS ; MR3.0) at three months predicts stable undetectable BCR-ABL1 transcript levels during imatinib treatment. However, second-generation TKIs induce more rapid and deeper responses at early time points compared to imatinib; however, whether early molecular response predicts MR4.0 by 18 months to second-generation TKI therapy, remains unclear. AIMS: We retrospectively analyzed BCR-ABL1 transcript levels in patients with CML in chronic phase (CML-CP) at 3, 6, 12, and 18 months after initiating dasatinib treatment to identify molecular milestones that would predict MR4.0 by 18 months. METHODS: Fifty-nine newly diagnosed patients with CML-CP were included in this study. The median age was 61 years (18-81 years), 72% of whom were males, and patients older than 65 years comprised 31% of the overall enrollment. Eighty-six percent of them had low and intermediate Sokal scores. Patients received 100 mg of dasatinib once daily. Dose interruption or reduction was allowed if drug-related grade 3 non-hematological toxicity or grade 3 or worse hematological toxicity occurred.BCR-ABL1/ ABL ratio IS (BCR-ABL1 IS) was performed at approximately 3-month intervals. To assess the kinetics of response, we calculated halving time (HT) of BCR-ABL1 IS. HT-BCR-ABL1 was calculated as described by Branford et al. We used a receiver-operating characteristic (ROC) curve to identify the cut-offs in transcript levels at three and six months. Mann-Whitney test was used to determine statistical significance. Categorical variables were compared using Fisher's exact test. Factors were subjected to multivariate analysis using Cox regression; differences with p<0.05 were considered statistically significant. RESULTS: The median BCR-ABL1 IS level before therapy was 82.1% (range 13.5-157.9 %). The estimated MMR by 12 months and MR4.0 by 18 months were 86.4% and 50.8%, respectively. We analyzed each into a cohort that achieved MR4.0 by 18 months (MR4.0 cohort) and a cohort that did not achieve MR4.0 (non-MR4.0 cohort). The BCR-ABL1 IS level in each cohort is indicated in the Table. Median HT-BCR-ABL1 IS 0-3 months was 10.8 days (6.5-71.3 days) in MR4.0 cohort, and 13.0 days (8.5- 169.6 days, p<0.05) in non-MR4.0 cohort, whereas that of 3-6 months was 24.4 days (6.5-228.9 days) in MR4.0 cohort and 47.3 days (18.0- 154.9 days, p<0.01) in non-MR4.0 cohort. The shape of BCR-ABL1 IS descent was biphasic in MR4.0 cohort. The cut-off values of BCR-ABL1 IS at 3 months and 6 months for prediction of MR4.0 by 18 months were 0.122% (specificity 0.964, sensitivity 0.586, AUC 0.784) and 0.048% (0.852, 0.833, 0.909), respectively. We determined the optimal threshold for predicting MR4.0 by 18 months using these parameters. Some of them (BCR-ABL1 IS 3 months ≤0.122%,BCR-ABL1 IS 6 months ≤ 0.048%, BCR-ABL1 IS 6 months ≤1%: ELN optimal criteria) were identified as predictive cut-off values for MR4.0 by 18 months in univariate analysis (BCR-ABL1 IS 3 months ≤0.122%; 94.4% vs. 30.7%, p<0.01, BCR-ABL1 IS 6 months ≤ 0.048%; 85.7% VS. 20.7%, p<0.01 and BCR-ABL1 IS 6 months <1.0%; 58.8% vs. 0%, p<0.01). However, BCR-ABL1 IS 3 months ≤ 10% (ELN optimal criteria at three months) was not identified as predictive cut-off value for MR4.0 (54.7% vs. 20%, N.S.). Multivariate analysis indicated that BCR-ABL1 IS 6 months ≤ 0.048% was a significant independent factor for achievement of MR4.0 by 18 months (hazard ratio 0.05, p<0.01). CONCLUSION: Even though dasatinib is highly-priced, dasatinib treatment results in higher rates of molecular responses in newly diagnosed patients with CML-CP. Assessment of molecular reduction within six months has become an important landmark to predict MR4.0 by 18 months during dasatinib treatment for patients with the aim to achieve treatment-free remission. Disclosures Oyake: Astellas: Speakers Bureau; Celgene: Honoraria; Chugai: Honoraria; Kyowa-Hakko Kirin: Honoraria. Ito:Bristol-Myers Squibb: Honoraria; Celgene: Honoraria; Ono: Honoraria.

Randomized, Open-Label, Multicenter, Phase 2 Study of Asciminib (ABL001) As an Add-on to Imatinib Versus Continued Imatinib Versus Switch to Nilotinib in Patients with Chronic Myeloid Leukemia in Chronic Phase Who Have Not Achieved a Deep Molecular Response with Frontline Imatinib

Background: In patients with chronic myeloid leukemia in chronic phase (CML-CP), the efficacy of ATP-competitive tyrosine kinase inhibitors (TKIs) has resulted in treatment-free remission (TFR) as a primary treatment goal for those with a sustained deep molecular response (DMR). However, most patients treated with imatinib fail to achieve a sustained DMR, meaning that they cannot benefit from TFR. Asciminib is a potent and specific inhibitor of BCR-ABL1. Unlike BCR-ABL1 TKIs that target the ATP binding site, asciminib binds to the myristate pocket of ABL1. Preclinical data showed that the combination of asciminib with ATP-competitive TKIs may provide more potent BCR-ABL1 inhibition and prevent emergence of resistance mutations (Wylie et al. Nature. 2017;543:733-737). In an ongoing phase 1 study (NCT02081378), asciminib demonstrated clinical activity and was well tolerated as a single agent (Hughes et al. Blood. 2016;128 [abstract 625]). In the same study, asciminib in combination with imatinib showed promising preliminary efficacy and a good safety profile in patients resistant/intolerant of ≥2 prior TKIs (Cortes et al. HemaSphere. 2019;3(S1) [abstract S388]). These findings informed the dose of asciminib to be further evaluated in combination with imatinib. An ongoing phase 3 study (NCT03106779) is evaluating asciminib vs bosutinib in patients previously treated with ≥2 ATP-binding site TKIs (Mauro et al. J Clin Oncol. 2019;37 [abstract TPS7070]). Here, we describe the ASCiminib add-on 4-arm study evaluating MOlecular REsponse (ASC4MORE) in patients. This is a phase 2 study evaluating the efficacy of adding asciminib to ongoing imatinib therapy in patients with CML-CP who have not achieved DMR with long-term frontline imatinib (CABL001E2201; NCT03578367). Methods: Study participants are aged ≥18 years, have CML-CP, and have been treated with frontline imatinib for ≥12 months. Study entry requires patients to be receiving imatinib 400 mg once daily (QD) at randomization, have BCR-ABL1 transcript levels in the range of ≤1% to >0.01% on the International Scale (IS), no prior achievement of MR4 (BCR-ABL1IS ≤0.01%) confirmed by two consecutive tests, and no prior treatment failure. Overall, ~80 patients will be randomized 1:1:1:1 to one of four arms (Figure): either asciminib 40 mg QD or 60 mg QD added to imatinib 400 mg QD; continued treatment with imatinib 400 mg QD; or switch to nilotinib 300 mg twice daily. Study treatment will continue until treatment resistance or intolerance, or up to 96 weeks after the last randomized patient has begun treatment. The primary objective of this study is to assess whether asciminib add-on to imatinib is more effective than imatinib continuation; the primary endpoint is the rate of MR4.5 (BCR-ABL1IS ≤0.0032%) at 48 weeks. Secondary objectives include: to estimate the efficacy of switch to nilotinib; to estimate the difference in efficacy between asciminib add-on to imatinib and switch to nilotinib; and to characterize the safety of asciminib add-on to imatinib. Exploratory objectives include TFR eligibility at the end of the study and patient-reported outcomes. Patients in the imatinib continuation arm who have not achieved MR4.5 at 48 weeks may cross over to receive add-on asciminib. This study is ongoing, with 23 patients randomized as of 22 July 2019. Disclosures Saglio: BMS: Consultancy; Novartis: Consultancy; Ariad: Consultancy; Incyte: Consultancy; Pfizer: Consultancy; Jansen: Consultancy; Celgene: Consultancy. Hughes:Novartis, Bristol-Myers Squibb, Celgene: Research Funding; Novartis, Bristol-Myers Squibb: Consultancy, Other: Travel. Geissler:Novartis: Consultancy, Research Funding, Speakers Bureau; Pfizer: Consultancy, Research Funding, Speakers Bureau; Roche: Consultancy; Amgen: Consultancy; Incyte: Research Funding; Takeda: Research Funding; Biomarin: Consultancy; Bristol-Myers Squibb: Consultancy, Research Funding, Speakers Bureau; Janssen: Consultancy, Speakers Bureau; UCB: Consultancy, Speakers Bureau; Servier: Consultancy. Kapoor:Novartis: Employment. Longin:Novartis: Employment. Mukherjee:Novartis: Employment. Cortes:Novartis: Consultancy, Honoraria, Research Funding; Daiichi Sankyo: Consultancy, Honoraria, Research Funding; BiolineRx: Consultancy; Jazz Pharmaceuticals: Consultancy, Research Funding; Merus: Consultancy, Honoraria, Research Funding; Forma Therapeutics: Consultancy, Honoraria, Research Funding; Immunogen: Consultancy, Honoraria, Research Funding; Astellas Pharma: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Biopath Holdings: Consultancy, Honoraria; Sun Pharma: Research Funding; Pfizer: Consultancy, Honoraria, Research Funding.

Determine White Blood Cell Count (WBCC) Limits and ABL Ct Cut-Off with ABL Copy Number (CN) Calibration for the Xpert® BCR-ABL Ultra Assay

Introduction Monitoring BCR-ABL transcript levels in peripheral blood of patients using real-time quantitative PCR is standard of care in the management of Chronic Myeloid Leukemia. Xpert BCR-ABL Ultra is an automated cartridge-based assay developed by Cepheid for sensitive assessment of BCR-ABL transcript levels. However, in clinical situations the total RNA isolated from white blood cell (WBC) in the patient's blood is insufficient to ensure assay LoD of 0.003% (IS)/MR4.52, or high WBCC in specimen can overload the Ultra cartridge, resulting in inaccurate test results. Therefore, it is necessary to determine proper WBCC input, to ensure accurate assay quantification results. Objectives The objective of this study was to determine the correlation between ABL copy number input and Ct value, determine lower and upper WBCC input limits for the Xpert BCR-ABL Ultra assay and establish the ABL Ct cut-offs. Methods To establish an upper ABL Ct limit that corresponds to a minimal ABL CN input of 32,000 for supporting LoD, a BCR-ABL plasmid DNA (pDNA, ERM-AD623) was serially diluted and tested in an EDTA whole blood background to make a calibration panel. A standard curve was generated against which the ABL Ct could be estimated as a function of ABL copy number. To estimate the lower WBCC limit, CML negative EDTA lysate with normal WBCC was serially diluted with WBC depleted EDTA lysate. To estimate the upper WBCC limit, EDTA lysate from a specimen with high WBCC (69.9×106cells/mL) was diluted with CML negative lysate with normal WBCC (3.5×106 cells/mL). To validate the WBCC limit, CML positive lysate with high WBCC (40×106cells/mL) was diluted with high WBCC (40×106cells/mL) CML negative lysate to produce five BCR-ABL levels within 0.03% (IS)/MR3.52 to 65% (IS)/MR0.19. Each level was further diluted with PBS lysate to achieve 8 levels of WBCC from 40×106 to 0.04×106 cells/mL. Results ABL Ct value of ~19 corresponding to a minimum ABL copy number input of 32,000 was established to support assay LoD of 0.003% (IS)/MR4.52 (Figure.1). To allow for a one Ct buffer, the upper ABL Ct cut-off was set at 18. The lower WBCC input limit, corresponding to the upper ABL Ct limit of ~18 with estimated ABL copy number greater than 64,000, was established to be 0.15×106 cells/mL (Figure.2) The upper WBCC input limit was established to be 30×106 cells/mL. This corresponds approximately to a Ct value of 10 (Figure.3). The Xpert BCR-ABL Ultra test monitors RNA expression levels of the BCR-ABL fusion transcript and the ABL transcript. Unlike a gene DNA marker, RNA expression levels are variable and can fluctuate. To accommodate for the variability in RNA expression levels and based on results from this study, the upper ABL Ct cut-off was lowered to 8. The lower and upper WBCC input limit, together with ABL Ct cut-off, were validated with CML patient specimens with WBCC input ranging from 0.04 to 40 × 106 /ml within IS% range of 0.03% to 65% (Table.1). The normal WBCC of 4 to 10 × 106/mL across all tested concentrations yielded ABL Ct range from 13.2 to 11.7 with estimated ABL copy number of 2.5×106 to 7.8×106. Conclusions A correlation between ABL copy number input and ABL Ct value was established with the standard curve generated from a pDNA calibration panel. The lower WBCC limit was set at 1.5×105 cells/mL and upper WBCC limit was set at 3.0×107 cells/mL, together with ABL Ct cut-offs of 18 and 8 and ABL copy number of 6.4×104 to 1.4×108, to support Xpert BCR-ABL Ultra assay performance. The normal WBCC of 4 to10×106/mL across all tested concentrations yielded an ABL Ct range from 13.2 to 11.7 with estimated ABL copy number of 2.5×106 to 7.8×106, indicating Xpert BCR-ABL Ultra assay normally provided more than 10 times the required minimum ABL Copy number to support the assay LoD claim at 0.003% (IS). *Product in development. Not for use in diagnostic procedures. Not reviewed by any regulatory body. Disclosures No relevant conflicts of interest to declare.

Prospective Evaluation of ABL Kinase Domain Mutational Analysis By Next-Generation-Sequencing in Newly Diagnosed CP CML Patients Undergoing First-Line Treatment with Nilotinib Alone or Nilotinib + Pegylated Interferon-α2a in a Prospective Phase III Trial

Prospective Evaluation of ABL Kinase Domain Mutational Analysis By Next-Generation-Sequencing in Newly Diagnosed CP CML Patients Undergoing First-Line Treatment with Nilotinib Alone or Nilotinib + Pegylated Interferon-α2a in a Prospective Phase III Trial

Ten-Year Follow-up of Patients with Chronic Myeloid Leukemia Treated with Nilotinib in First-Line: Final Results of the Gimema CML 0307 Trial

Ten-Year Follow-up of Patients with Chronic Myeloid Leukemia Treated with Nilotinib in First-Line: Final Results of the Gimema CML 0307 Trial

Long-Term Outcomes of Chronic Myeloid Leukemia Patients Who Lost Undetectable Molecular Residual Disease (UMRD) after Imatinib Discontinuation: Korean Imatinib Discontinuation Study (KIDS)

Background The recent discontinuation clinical trials have demonstrated that IM discontinuation can be employed based on clinical study in patients who had enough IM therapy and undetectable molecular residual disease (UMRD) durations prior to IM discontinuation. Moreover, treatment rechallenge in patients with molecular recurrence lead a second deep molecular response, suggesting that IM discontinuation is safe. However, the issues on the definition of molecular relapse requiring treatment resumption and the occurrence of late relapse with a long-term follow-up after IM discontinuation are important. Therefore, here we analyzed the long-term follow-up results of the patients who lost UMRD after IM discontinuation Methods CP CML patients who were treated with IM for more than 3 years and had undetectable levels of BCR-ABL1 transcripts determined by quantitative reverse transcriptase polymerase chain reaction (PCR) for at least 2 years were eligible for KID study and in cases of MMR loss after 2 consecutive assessments, IM treatment was re-introduced. After IM resumption for MMR loss, the molecular response was evaluated every month until MMR was re-achieved and every 3 months thereafter. The second stop was permitted in the patients who were in second UMRD for at least 2 years. Results Between October 2010 and June 2015, a total of 126 patients (70 females, 56 males) were enrolled on KID Study, with a median age of 47 years (range, 18-82), the percentages of patients with low, intermediate and high Sokal risk scores were 33%, 25% and 15%, respectively with unknown Sokal risk scores in 27%. And the median time on IM therapy and the median duration of sustained UMRD prior to discontinuation were 83 months (range, 32-141) and 41 months (range, 22-131), respectively. After a median follow-up of 62.6 months (range, 4.9-100.8 months) after IM discontinuation, 83 patients (65.9%) lost UMRD. Among them, 56 (67.5%) patients lost MMR in 2 consecutive analyses. The other 27 (32.5%) patients who lost UMRD but not MMR exhibited different patterns of BCR-ABL1 kinetics: 8 patients spontaneously re-achieved UMRD after a median time of 2.8 months (range, 0.9-3.0 months), and 19 patient showed fluctuation of BCR-ABL1 transcript under the level of 0.1% on IS for a median 19 months (range, 3-34), and then spontaneously returned and maintained UMRD for a median 31 months (range, 2-64). Of 73 patients who lost MR4.0, the rate of MMR loss was 76.7%. Out of 56 patients with molecular relapse, 54 patients (except two patients who restart radotinib) were re-treated with IM, all patients (except one patient lost follow-up) re-achieved MMR at a median of 1.9 months (range, 0.0 - 5.4 months) after resuming treatment. Among them, two patients who re-achieving of MMR after resuming IM therapy lost MMR again; One patient who relapsed at 53.2 months after IM discontinuation, despite re-achieving MMR 1.4 later after IM restarting, suddenly progressed to blast crisis at 6 months after restarting IM and in spite of switching to dasatinib and ponatinib, she died. Another patient lost MMR at 7.4 months after IM discontinuation and re-achieved MMR 1.7 later after IM restarting, but progressed to AP on the assessment 32 months later. The patient switched to dasatinib and lost follow-up. Among the patients who maintained a second UMRD for at least 2 years after IM resumption, 23 patients entered into a second IM stop. With a median follow-up of 29.5 months (range, 9-63 months) since second IM stop, 15/23 patients (65%) lost MMR after a median 2.9 months (range, 1.8-30.7 months), which was similar to those of the first IM discontinuation [median 3.7 (range, 1.8-20.8 months)]. The patients who lost MMR were retreated with IM for a median of 24.5 months (range, 1.2-49.7 months); 14 patients re-achieved MMR and one patient was in therapy for 1.2 months. Conclusions Our results showed that 67.5% and 76.7% of patients who lost UMRD and MR4.0, respectively resulted in MMR loss, and the other patients were below MMR without re-treatment, suggesting loss of MMR can be chosen for treatment re-challenge. Overall, IM discontinuation could be applied with approximately 55% of probability of sustained MMR in the long term. In addition, we demonstrated that a second attempt might be possible. Further studies on the predictors to select patients for a trial of second stop are warranted. Disclosures Kim: Il-Yang co.: Research Funding; Pfizer: Research Funding; Takeda: Research Funding; BMS: Research Funding; Novartis: Research Funding.

Combination of Nilotinib and Pegylated Interferon Alfa-2B Results in High Rates of MR4.5 at 24 Months - Primary Analysis of the ALLG CML 11 Pinnacle Study

Combination of Nilotinib and Pegylated Interferon Alfa-2B Results in High Rates of MR4.5 at 24 Months - Primary Analysis of the ALLG CML 11 Pinnacle Study

A Comparison of Droplet Digital PCR and RT-qPCR for BCR-ABL1 Monitoring in Chronic Myeloid Leukemia

Background: Monitoring of BCR-ABL1 molecular levels is essential for the management of Chronic Myeloid Leukemia (CML) patients treated with Tyrosine Kinases Inhibitors (TKIs). Real Time Quantitative PCR (RT-qPCR) is currently the standard method for assessing molecular remission (MR) in patients with CML. Recently, droplet digital PCR (ddPCR) has emerged to provide a more accurate detection of minimal residual disease (MRD). In order to hypothesize the use of this new technology in the clinical practice, in the era of TKI discontinuation, we designed a multi-centric study to evaluate the potential value of ddPCR in diagnostic routine. Aims of the study were:1) the evaluation of the agreement between the measures obtained by ddPCR and RT-qPCR and 2) the assessment of the repeatability of the two methods. Methods: Total RNA was extracted from 37 CML patients using Maxwell 16 LEV simplyRNA Blood kit (Promega), following the manufacturer's instructions. Samples were divided in 5 groups based on molecular response (MR) as follow: group 1, MR<3, n=5; group 2, MR 3, n=5; group 3, MR 4, n=9; group 4, MR 4.5, n=9 and group 5, MR 5, n=9. BCR-ABL1 p210 was quantified by RT-qPCR and ddPCR in 3 different Italian laboratories namely Lab A, Lab B and Lab C. Lab B and C performed 1 amplification session each, while Lab A performed 3 independent sessions. All ddPCR experiments were performed using Kit QXDxTM BCR-ABL%IS (Bio-Rad) on the QX200 system (Bio-Rad), according to the manufacturer's instructions. For RT-qPCR experiments, BCR-ABL1 p210 was quantified with three different methods: by using the One-Step BCR-ABL P210 ELITe MGB Kit (ELITech Group), according to manufacturer's protocol (Lab A); by using the One-Step Philadelphia SensiQuant Kit (Bioclarma), according to the manufacturer's instructions (Lab B) and as described in Gabert et al (Lab C). The results obtained were corrected for the laboratory-specific conversion factor, as recommended by Standard Operating Procedures of Labnet CML network (GIMEMA group). The target quantification for each sample was expressed as BCR-ABL1/ABL1 %IS for both RT-qPCR and ddPCR. Statistical analysis: Bland-Altman analysis was performed. For the measurement of the agreement we reported the bias, which is the mean of the difference between the methods, the 95% limits of agreement and the coefficient of variation. Residual variance and coefficients of repeatability (i.e. the upper limits of a prediction interval for the absolute difference between two measurements by the same method on the same item) were computed to achieve the second endpoint. An analysis of sensitivity on the labs was also carried out. All analyses were stratified by the level of disease. Results: A total of 370 measures were included in the analysis, 185 for ddPCR and 185 for RT-qPCR divided as follow: 50 for group 1 and for group 2, 90 for group 3, 4 and 5. In Table 1 we reported the median and interquartile range (IQR) for all levels of disease. Results of the Bland-Altman analysis are shown in Table 2. The coefficients of variation, which expresses the standard deviation as a percentage of the mean, were 2.35, 2.31, 1.10, 1.34, 39.12 in group 1, 2, 3, 4 and 5 respectively. The repeatability coefficients of ddPCR were smaller than qRT-PCR across all the levels of disease, showing a slightly better precision of ddPCR (Table 2). Conclusions: Higher coefficients of variation in group 1 and 2 were probably due to a greater heterogeneity of the patients. In fact, BCR-ABL1/ABL1 levels by RT-qPCR ranged between 1.43 and 6.94 and between 0.10 and 0.25 in group 1 and in group 2 respectively (Table 1). Sensitivity analysis showed that the high coefficient of variation in group 5 can be explained almost all by the variability observed in Lab B. Coefficient of repeatability of ddPCR was always smaller than RT-qPCR for all level of disease showing a slightly better precision. Our results showed that ddPCR has a good agreement with RT-qPCR and it is more precise to quantify BCR-ABL1 transcript levels, particularly for MR 4 and MR 4.5. Thus, ddPCR may be valuable in diagnostic routine. Disclosures Fava: Novartis: Honoraria; BMS: Honoraria; Pfizer: Honoraria; Incyte: Honoraria. Martino:Bio-Rad: Employment. Saglio:Ariad: Consultancy; Incyte: Consultancy; Pfizer: Consultancy; Jansen: Consultancy; Celgene: Consultancy; Novartis: Consultancy; BMS: Consultancy. Martinelli:Roche: Consultancy; BMS: Consultancy; Novartis: Consultancy; ARIAD: Consultancy; Pfizer: Consultancy. Pane:Novartis: Membership on an entity's Board of Directors or advisory committees, Other: research founding; Janssen: Membership on an entity's Board of Directors or advisory committees; GSK: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; BMS: Membership on an entity's Board of Directors or advisory committees. Cilloni:Novartis: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees.

Conventional Real Time Quantitative Polymerase Chain Reaction Method Yields Similar Level of Sensitivity to Digital Droplet Polymerase Chain Reaction for Detection of BCR-ABL p210 Transcripts in Patients with Chronic Phase Chronic Myeloid Leukemia

Introduction: Several studies have investigated the utility of digital droplet polymerase chain reaction (ddPCR) in the detection of p210 BCR-ABL fusion transcripts in chronic myeloid leukemia (CML), and have suggested greater sensitivity compared to real-time quantitative PCR (RT-qPCR). There is limited data regarding the utility and sensitivity of ddPCR in patients with chronic phase CML (CP-CML) who are candidates for tyrosine kinase inhibitor (TKI) discontinuation. We aimed to investigate the capability of ddPCR to detect p210 BCR-ABL transcript levels in CP-CML patients and compare the sensitivity to RT-qPCR. Methods: We analyzed 103 different peripheral blood (n=98) and bone marrow (n=5) samples from 36 patients with CP-CML treated at Moffitt Cancer Center between 2013 and 2018. Samples were from patients who either met clinical criteria for TKI discontinuation or were enrolled in a phase I dose-escalation study evaluating combination therapy with nilotinib plus ruxolitinib who had at least a complete cytogenetic response (CCyR) to TKI therapy with detectable BCR-ABL transcripts by RT-PCR at the time of enrollment(1, 2). BCR-ABL levels were assessed by RT-qPCR at the time of collection with level of transcript reported as % International Standard (%IS). Samples collected from 2013 to 2014 were reported as p210 to ABL and converted to %IS per lab-specific conversion factor. Stored purified RNA samples were obtained retrospectively and ddPCR was performed using the QX-200 Droplet Digital PCR System and QXDx BCR-ABL %IS Kit (Bio-Rad). Droplets were analyzed by QXDx BCR-ABL reporter software to determine p210 transcript level (%IS). Analysis for RNA degradation of stored samples was performed via High Sensitivity RNA ScreenTape (Agilent). Samples that did not pass quality check upon performing ddPCR were excluded from further analysis. Correlation coefficient was calculated with p-value of <0.05 being significant. Results: Of the 36 patients, 28 were in the TKI discontinuation cohort and 10 were enrolled in the clinical trial of nilotinib plus ruxolitinib. Two patients who participated in the clinical trial subsequently also met criteria for TKI discontinuation. In the TKI discontinuation cohort, 46% of patients (n=13) lost major molecular response (MMR) with a median time to loss of MMR of 88 days. We observed a statistically significant correlation between RT-qPCR and ddPCR levels when comparing %IS (correlation coefficient R2=0.42; p<0.0001) as well as calculated molecular response (MR) logarithm values of all available samples (R2=0.67; p <0.0001) (Figure 1). There was a weaker correlation between patients determined to have MMR by RT-qPCR (MR≥3.0) compared to ddPCR (R2=0.55; p <0.0001) (Figure 2). A total of 91 different samples were consistent with MMR when tested by RT-PCR. Of these samples, 85.7% (n=78) were consistent with MMR when tested by ddPCR and the remaining 14.3% (n=13) appeared to have higher detectable levels of p210 transcripts (MR<3.0). When investigating deeper molecular responses, 62 samples were consistent with MR≥4.0 by RT-PCR, and 20.9% (n=13) of these samples did not achieve a deep molecular response (MR<4.0) when tested by ddPCR. Of note, 5 representative samples were also evaluated for potential RNA degradation and 3 were noted to have significant degradation present. Conclusion: Compared to RT-PCR, ddPCR represents a viable method for detection of p210 transcripts for patients with CP-CML. The two methods yield similar efficacy when detecting varying levels of molecular response, however further research is warranted for the ability to detect deeper molecular responses for patients in MMR. Our study is limited by inherent retrospective bias and quality of RNA in stored samples. 1. National Comprehensive Cancer Network. Chronic Myeloid Leukemia (Version 1.2019). 2. Sweet K, Hazlehurst L, Sahakian E, Powers J, Nodzon L, Kayali F, et al. A phase I clinical trial of ruxolitinib in combination with nilotinib in chronic myeloid leukemia patients with molecular evidence of disease. Leuk Res. 2018;74:89-96. Disclosures Talati: Jazz Pharmaceuticals: Honoraria, Speakers Bureau; Daiichi-Sankyo: Honoraria; Astellas: Honoraria, Speakers Bureau; Pfizer: Honoraria; Celgene: Honoraria; Agios: Honoraria. Shelton:Bio-Rad: Employment. Nodzon:Pharmacyclics: Consultancy; Abbvie: Other: Speaker Fees; Genentech: Consultancy, Other: Speaker Fees; Pfizer: Consultancy. Sweet:Stemline: Consultancy; Pfizer: Consultancy; Abbvie: Membership on an entity's Board of Directors or advisory committees; Celgene: Speakers Bureau; Bristol Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Incyte: Research Funding; Jazz: Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Agios: Membership on an entity's Board of Directors or advisory committees. Pinilla Ibarz:Novartis: Consultancy; Abbvie: Consultancy, Speakers Bureau; Takeda: Consultancy, Speakers Bureau; Bristol-Myers Squibb: Consultancy; Janssen: Consultancy, Speakers Bureau; Bayer: Speakers Bureau; TG Therapeutics: Consultancy; Teva: Consultancy; Sanofi: Speakers Bureau.

Multicenter, Open-Label, Single Arm, Phase II Exploratory Study to Evaluate the Effect of a One-Year Consolidation Treatment with Ponatinib 15 Mg on Treatment Free-Remission Rate in Patients with Philadelphia-Positive Chronic Myeloid Leukemia, Who Had Previously Achieved a Deep Molecular Response with Imatinib (PonaZero_study)

Study Rationale The present study with ponatinib is based on previous studies on the potential role of imatinib discontinuation, to achieve a stable treatment-free remission (TFR) of patients with Philadelphia-positive Chronic Myeloid Leukemia (CML). As ponatinib has shown to induce deeper molecular responses compared with imatinib, the rationale is that ponatinib treatment could increase the proportion of patients who could discontinue treatment successfully. Purpose The purpose is to determine the successful TFR within the first 48 weeks following cessation of treatment in patients who achieved MR4 on imatinib, and maintained MR4 on ponatinib, after a switch from imatinib. Eligible patients have been previously treated with imatinib as unique tyrosine kinase inhibitor (TKI) therapy, for at least 4 years, and have documented MR4 (at least 12 months) at the time of ponatinib to study entry. Objectives The Primary Objective is to evaluate the proportion of patients without confirmed loss of MR4 or loss of MMR (do not require confirmation). The Key Secondary Objectives are: To evaluate the proportion of patients without confirmed loss of MR4 or loss of MMR within 72 and 96 weeks following ponatinib cessation.To estimate progression-free survival (PFS) from the date of ponatinib cessation to the date of the earliest event. Treatment-free survival (TFS) defined as a lack of any of the following: loss of MMR, confirmed loss of MR4, re-start of imatinib treatment, progression of AP/BP, or death from any cause.Overall survival (OS), defined as the time from the date of cessation of ponatinib therapy to the date of death from any cause.Proportion of patients who regain MR4 within 48 weeks of imatinib treatment re-initiation, following confirmed loss of MR4 within 48 weeks subsequent to ponatinib cessation.Kinetics of BCR-ABL transcript level (IS) after re-start of imatinib therapy. Other Secondary Objectives include adverse events, laboratory data for hematology, biochemistry, and urinary test, vital signs and ECGs. Exploratory Objectives include phenotypic and genotypic biomarkers, as well as functional analysis of cytotoxic cell activation. Plasma monitoring of ponatinib levels will also be performed. Study Design This is a single-arm, open label study, open label study in 40 patients who achieved and maintained MR4, to determine the rate of successful TFR in both gender patients, treated with 15 mg/day of ponatinb for 48 weeks. Ten Spanish sites will participate. The study has two main phases: ponatinib consolidation (48 weeks) and ponatinib TFR phase (96 weeks). Inclusion criteria are patients who had received a minimum of 4 years imatinib as unique TKI therapy, have documented MR4 at least 12 months prior to study entry, and will continue with MR4 before the discontinuation of ponatinib. After stopping ponatinb (TFR phase), BCR-ABL wil be monitored every 4 weeks during the first 48 weeks, and every 12 weeks during the last period of 48 weeks. Exclusion criteria include patients with transplant, atypical transcripts, CML treatment resistant mutation, or having cardiovascular or pancreatitis diseases. Figure 1: Current State of the Study First Visit First Patient: 17 JUL 2019 Patients Enrolled: 4 Patients Recruited: 3 Screening Failure: 0 In Screening: 1 patient Figure 1 Disclosures Sanchez-Guijo: Novartis: Consultancy, Honoraria, Research Funding; BMS: Consultancy, Honoraria; Incyte: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Amgen: Honoraria; Roche: Honoraria. Hernandez Boluda:Incyte: Other: Travel expenses paid. Steegmann:BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

A Phase I-II Study of Ruxolitinib (INCB18424) for Patients with Chronic Myeloid Leukemia with Minimal Residual Disease While on Therapy with Imatinib

A Phase I-II Study of Ruxolitinib (INCB18424) for Patients with Chronic Myeloid Leukemia with Minimal Residual Disease While on Therapy with Imatinib

Evaluation of Medication Adherence and Pharmacokinetics of Dasatinib for Earlier Molecular Response in Japanese Patients With Newly Diagnosed Chronic Myeloid Leukemia: A Pilot Study.

Tyrosine kinase inhibitors markedly improve the survival for patients with chronic myeloid leukemia (CML). However, a decrease in adherence leads to undesired therapeutic outcomes. In this study, the relationships among adherence, pharmacokinetics, response, and adverse effects for dasatinib treatment were prospectively investigated. This study was a prospective cohort study of patients with newly diagnosed CML at 4 general hospitals and 1 university hospital. Patients started to receive dasatinib 100 mg once daily. A Medication Event Monitoring System was used to assess medication adherence and the medication possession ratio during the 12 months. Plasma concentrations of dasatinib were measured using liquid chromatograph-tandem mass spectrometry (LC-MS/MS), and therapy responses were assessed at 3, 6, and 12 months after treatment. Ten patients were included. An extremely high medication adherence for dasatinib was observed; the median medication possession ratio was 99.4%. All 9 CML patients with breakpoints in the major BCR-ABL achieved major molecular response (MMR; major BCR-ABL transcript level below 0.1% on the International Scale) within 12 months, and 5 achieved MMR within 6 months. The receiver operating characteristic curve analysis revealed that the cutoff value for the dasatinib area under the concentration-time curve was 336.1 ng × h/mL (accuracy 88.9%, sensitivity 80.0%, specificity 100%, and receiver operating characteristic curve-area under the concentration-time curve 0.800) for achieving MMR within 6 months. Two patients had interrupted dasatinib treatment because of pleural effusion and diarrhea with intestinal edema, respectively. These edematous adverse events developed after plasma dasatinib Cmin surpassed 3.0 ng/mL. A Medication Event Monitoring System was applied for the direct evaluation of oral dasatinib adherence for the first time, and the clinical effect of dasatinib was investigated under the strict monitoring of patient adherence. Although this study had a small sample size, the plasma concentration monitoring of dasatinib is considered to be useful to predict an earlier molecular response with fewer edematous adverse events.