Chromosome-positive Chronic Myeloid Leukemia Research Articles

Chronic myeloproliferative neoplasms with concomitant CALR mutation and BCR::ABL1 translocation: diagnostic and therapeutic implications of a rare hybrid disease.

Myeloproliferative neoplasms (MPNs) are subdivided into Philadelphia (Ph) chromosome-positive chronic myeloid leukemia (CML) and Ph-negative MPNs. BCR::ABL1 translocation is essential for the development and diagnosis of CML; on the other hand, the majority of Ph-negative MPNs are characterized by generally mutually exclusive mutations of Janus kinase 2 (JAK2), calreticulin (CALR), or thrombopoietin receptor/myeloproliferative leukemia (MPL). CALR mutations have been described essentially in JAK2 and MPL wild-type essential thrombocythemia and primary myelofibrosis. Rarely coexisting CALR and MPL mutations have been found in Ph-negative MPNs. BCR::ABL1 translocation and JAK2 mutations were initially considered mutually exclusive genomic events, but a discrete number of cases with the combination of these genetic alterations have been reported. The presence of BCR::ABL1 translocation with a coexisting CALR mutation is even more uncommon. Herein, starting from a routinely diagnosed case of CALR-mutated primary myelofibrosis subsequently acquiring BCR::ABL1 translocation, we performed a comprehensive review of the literature, discussing the clinicopathologic and molecular features, as well as the outcome and treatment of cases with BCR::ABL1 and CALR co-occurrence.

Co-occurrence of JAK2-V617 F mutation and BCR::ABL1 translocation in chronic myeloproliferative neoplasms: a potentially confounding genetic combination.

Myeloproliferative neoplasms (MPNs) are classified into Philadelphia (Ph) chromosome-positive chronic myeloid leukemia (CML) and Ph-negative MPNs. BCR::ABL1 translocation is the key genetic event of CML, whereas JAK2/MPL/CALR mutations are molecular aberrations of Ph-negative MPNs. Despite initially considered mutually exclusive genetic aberrations, the co-occurrence of BCR::ABL1 and JAK2 has been reported in a limited number of cases. The two genetic alterations may be identified either at the same time or JAK2 aberration may be detected in patients with a previous CML treated with tyrosine kinase inhibitors or, finally, BCR::ABL1 translocation occurs in patients with a history of JAK2-positive MPN. This combination of genomic alterations is potentially confounding with clinical manifestations often misinterpreted either as disease progression or drug resistance, therefore leading to inappropriate patient's treatment. Our systematic review aims to improve hematologist and pathologist knowledge on this rare subset of patients. Starting from the presentation of two additional cases from our routine daily practice, we focus mainly on clinical, laboratory, and bone marrow histological findings, which may represent useful clues of BCR::ABL1 and JAK2 co-occurrence. The interaction between JAK2 and BCR::ABL1 clones during the disease course as well as therapy and outcome are presented.

Dasatinib induced nephrotic range proteinuria in pediatric patient with acute lymphoblastic leukemia with hyper-eosinophilia

Tyrosine kinase inhibitors (TKIs) have improved outcomes for Philadelphia chromosome positive acute lymphoblastic leukemia (ALL) and chronic myeloid leukemia (CML). There has been reports of dasatinib induced proteinuria or nephrotic syndrome. We present a case of a 14-year-old male with high-risk B- ALL who developed nephrotic syndrome due to dasatinib. Proteinuria and nephrotic syndrome should be considered as related adverse effects from dasatinib. This is the first reported case of dasatinib induced nephrotic range proteinuria in a patient with high-risk B-ALL with hyper-eosinophilia.

TKI Dose Optimization Based on Therapeutic Drug Monitoring（TDM) with Encouraging Outcomes and Well-Tolerated for Chronic Myeloid Leukaemia Patients

Background Imatinib, nilotinib, and dasatinib are tyrosine kinase inhibitors (TKIs) that have become first-line treatments for Philadelphia chromosome-positive chronic myeloid leukemia (CML). Series studies indicated TKIs had a high therapeutic index, which led to the registration of these medications at fixed doses. Therapeutic drug monitoring (TDM) is a strategy for dosage optimization to provide individual treatment through dose adjustment to improve efficacy or avoid TKI-related adverse events (AEs). Objective We prospectively analyzed the outcome based on trough plasma concentrations (Cmin) to manage TKI dosage optimization during imatinib, nilotinib, and dasatinib therapy in patients with CML by 12 months. The primary efficacy endpoint was the rate of MMR at 12 months, the secondary endpoints included the cumulative rate of significant AEs defined as grade 3/4 fluid retention, all grade pleural effusion and pulmonary hypertension, grade 3/4 bilirubin increased, and grade 3/4 hematological toxicity related to TKIs within the first 12 months of therapy. Methods We examined 204 CML patients treated with imatinib, nilotinib, or dasatinib in the first line for CML-CP. We used high-performance liquid chromatography-tandem mass spectrometry (UPLC/MS-MS) to detect the Cmin of TKIs. Dasatinib or imatinib Cmin (24±3h post-dose) and nilotinib Cmin (12±3 h post-dose) were assessed after 7~10 days of therapy. We set the Cmin of imatinib at 1000~1500 ng/mL and that of nilotinib at 600~800 ng/mL, dasatinib at 1~3 ng/ml, respectively. Results Imatinib group (n = 67), Nilotinib group (n = 72), and Dasatinib group (n = 65), respectively. The initial dose of imatinib was 400mg qd, based on Cmin of imatinib was 900~1100ng/mL, there were 17 patients with dose reduction(1 case with 100mg qd, 5 cases with 200mg qd, 11 cases with 300mg qd) and 2 patients increased dose to 500mg qd; The initial dose of nilotinib was 300mg bid, based on Cmin of imatinib was 600~800ng/mL, there were 21 patients with dose reduction( 4 cases with 150mg bid, 16 cases with 450mg daily, 1 cases with 150mg qd) and 1 patients increased to 400mg bid; the initial dose of dasatinib was 100mg qd, based on Cmin of dasatinib was1~3 ng/ml, there were 32 patients with dose reduction(1 case with 20mg qd, 4 cases with 40mg qd, 20 cases with 50mg qd, 7 cases with 70mg qd ). Among the patients treated with imatinib, dasatinib, and nilotinib, no statistically significant associations were observed between gender, age, ELT scores, and plasma trough concentration (p>0.05). Early molecular reaction (EMR BCR: ABL(IS) <10%) was achieved by 83.6% (95% confidence interval [CI], 74.6%-92.5%) in the imatinib group, 87.7% (95% CI, 80.0%-95.4%) in the nilotinib group, and 83.3% (95% CI, 75.0%-91.7%) in the dasatinib group of patients at 3 months. The incidence of MMR at 12 months was 82.1% (95% CI, 73.1%-93.0%) in the imatinib group, 73.8% (95% CI, 64.6%-84.6%) in the nilotinib group, and 75.0% (95% CI, 65.3%-84.7%) in the dasatinib group, respectively. The cumulative incidence of grade 3/4 hematological toxicity was 7.8% (16/204), all-grade pleural effusion was 23.1% (15/65) in the dasatinib group, grade 3/4 bilirubin increased was 6.9% (5/72) in the nilotinib group, and there were no patients with pulmonary hypertension. Conclusion There are large individual differences in plasma trough concentrations in CML patients taking TKIs, the TKI dosage should be adjusted based on target plasma concentrations to maximize efficacy and minimize the incidence of adverse events.

Flumatinib for the Treatment of Adult Patients with Resistant or Intolerant Chronic-Phase Chronic Myeloid Leukemia: Results from Real-World Data

Introduction Over the past decades, BCR-ABL1 tyrosine kinase inhibitors (TKIs) as the initial treatment for chronic phase Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia (CML-CP) have dramatically turned CML-CP into a manageable and potentially curable chronic disease. Nonetheless, in spite of the massive improvement in CML treatment over the last years with the introduction of TKIs, some patients (20%-30%) display intrinsic or acquired resistance to treatment during the disease course. Flumatinib Mesylate is a newer and orally available TKI with higher selectivity and potency against BCR-ABL1 kinase versus imatinib. According to the previous data，flumatinib can be an effective first-line treatment for CML-CP. Patients and Methods This study was initiated mainly to observe the safety and efficacy of flumatinib in the treatment of adult patients with resistant or intolerant Chronic-Phase Chronic Myeloid Leukemia, especially in second-line or above treatment in the real world. Efficacy and safety assessments were collected for the intent-to-treat population. Major molecular response (MMR) was defined as BCR-ABL1 transcript level ≤ 0.1% on the International Scale (IS), molecular response (MR4) was defined as BCR-ABL1 transcript level (IS) ≤ 0.01%; MR4.5 was defined as a BCR-ABL1 (IS) transcript level ≤ 0.0032%. DMR was defined as MR 4.0 or MR 4.5. Results Among the 58 evaluable patients with CML-CP, 54% were male, 47% were female. The median age of these patients is 45Y. During the observation period, there were 28 second-line conversion patients (48%), 19 third-line conversion patients (33%), and 11 fourth-line and above patients (19%). Prior therapies included imatinib, dasatinib, nilotinib, olverembatinib, radotinib and ponatinib. All patients converted to treatment of 600mg flumatinib daily. Among the 58 evaluable patients, 20 patients who had been treated with imatinib alone were converted to flumatinib, including 9 cases of IM resistance, 8 cases of IM intolerance and 2 case of personal reasons. During the 1-year follow-up, 52% of patients (n=30) were evaluable for the achievement of MMR. The patients with BCR-ABL1 (IS) > 10% at baseline, 3, 6 and 12 months were 48%, 17%, 23% and 26%, respectively; for patients with BCR-ABL1 (IS) < 0.1% were 26%, 40%, 49% and 52%, respectively; for patients with DMR were 26%, 40%, 49% and 52%, respectively. For imatinib-intolerant or -resistant patients, MMR was 44%. Subgroup analyses showed that the imatinib-intolerant or -resistant patients with BCR-ABL1 (IS) >10% at baseline, 3, 6 and 12 months were 65%, 0%, 10% and 0%, respectively; for patients with BCR-ABL1 (IS) < 0.1% were 10%, 33%, 80% and 44%, respectively; for patients with DMR were 5%, 11%, 30% and 11%, respectively. Meanwhile, 11% of patients could not be detected at molecular level (0.000%). Of the 58 patients, only Grade 1 AEs were reported, including diarrhea, rash and eye edema. Conclusion Flumatinib has good efficacy and safety in the treatment of adult patients with resistant or intolerant Chronic-Phase Chronic Myeloid Leukemia, it will be a good choice for second-line or above treatment for CML-CP In clinical practice.

Comparable b2a2/e13a2 and b3a2/e14a2 Reporting in BCR-ABL Assay When Calibrated By Who Is and By IVT-RNA Copy Number

Introduction: Xpert® BCR-ABL Ultra, automated cartridge-based assay for monitoring BCR-ABL transcript levels, is calibrated by WHO IS to standardize the %reporting for both b2a2/e13a2 BCR-ABL(e13a2) and b3a2/e14a2 BCR-ABL(e14a2) relative to control ABL gene in peripheral blood of patients as a standard management of Chronic Myeloid Leukemia (CML) [1]. Studies have shown differences in patients carrying e13a2 or e14a2 in molecular response to Tyrosine Kinase Inhibitor (TKI) treatment [2-4]. Therefore, it is necessary to understand if there is %reporting differences between two transcripts calibrated by WHO IS[5] and explore the calibration method using breakpoint specific RNA input copy number (CN) for accurate TKI treatment monitoring. Objectives: To establish % reporting method calculated with known CN of e13a2, e14a2 and ABL IVT-RNA within a wide CN range and compare % e13a2 and % e14a2 to WHO IS quantification system. Methods: Three IVT-RNAs, containing e13a2-ABL-BCR, e14a2-ABL-BCR and ABL-BCR, were synthesized as shown in Figure 1. Serial diluted e13a2 RNA, e14a2 RNA and ABL RNA panels were tested on Xpert BCR-ABL Ultra assay to generate individual standard curve of e13a2 Ct, e14a2 Ct and ABL Ct as a function of CN for % reporting calculation. Four levels of IVT-RNA panels with same CN of e13a2 and e14a2 were tested for breakpoint specific % reporting comparison. K562(e14a2), BV173 (e13a2) cell lysates and CML clinical samples carrying e13a2 or e14a2 transcripts were tested to evaluate the %CN reporting compared to WHO IS. Result: Good linearity demonstrated in Ct vs CN input for e13a2, e14a2 and ABL IVT-RNA (Figure2) with comparable efficiency (E) between e13a2 (E=0.992) and e14a2 (E=0.986). %e13a2 reporting was ~1.50-fold (by WHO IS) and ~1.46-fold (by %CN) higher than %e14a2, by testing IVT-RNA panel (Table1). Minor differences in %reporting observed between % CN and WHO IS for e13a2 (84.5%~110.8%) vs e14a2 (82.5%~89.5%) from cell lysates (Table2) and e13a2 (92.6%~105.5%) vs e14a2 (88.1%~92.2%) from clinical samples (Table3). Conclusions: A %CN e13a2/ABL and e14a2/ABL reporting method with known CN of IVT-RNAs has been successfully established in Xpert BCR-ABL Ultra. Both WHO IS and %CN showed very minor differences between e13a2 and e14a2 for % reporting. %CN method demonstrated comparable %reporting to WHO IS in Xpert BCR-ABL Ultra. Recent Publications 1. Dominy KM, Simon IM, Khorashad JS (2021) Evaluation of Xpert® BCR-ABL Ultra for the confirmation of BCR-ABL1 international scale conversion factors for the molecular monitoring of chronic myeloid leukaemia, Int J Lab Hematol, Feb;43(1):e31-e34. 2. Hanfstein B, Lauseker M, Hehlmann R, Saussele S, Erben P, Dietz C (2014) Distinct characteristics of e13a2 versus e14a2 BCR-ABL1 driven chronic myeloid leukemia under first-line therapy with imatinib. Haematologica.99:1441-7. 3. Jain P, Kantarjian H, Patel KP, Gonzalez GN, Luthra R, Shamanna RK (2016) Impact of BCR-ABL transcript type on outcome in patients with chronic-phase CML treated with tyrosine kinase inhibitors. Blood.127:1269-75. 4. Castagnetti F, Gugliotta G, Breccia M, Iurlo A, Levato L, Albano F (2017) The BCR-ABL1 transcript type influences response and outcome in Philadelphia chromosome-positive chronic myeloid leukemia patients treated frontline with imatinib. Am J Hematol. 92:797-805. 5. Matthew S, White HE, Hana Z, Nicholas C.P C (2022) Impact of BCR::ABL1 transcript type on RT-qPCR amplification performance and molecular response to therapy. Leukemia 36(7):1-8

With up to 8 Years of Therapy, Asciminib (ASC) Monotherapy Demonstrated Continued Favorable Efficacy, Safety, and Tolerability in Patients (Pts) with Philadelphia Chromosome-Positive Chronic Myeloid Leukemia in Chronic Phase (Ph+ CML-CP) without the T315I Mutation: Final Results from the Phase 1 X2101 Study

CONCLUSIONS Tyrosine kinase inhibitors (TKIs) have extended the life expectancy for pts with CML, approximating that of the general population, and established BCR::ABL1-targeted therapies as the standard of care for CML. However, multi-TKI resistance and intolerance remain challenges that may lead to treatment (Tx) discontinuation. ASC is the first and only approved BCR::ABL1 inhibitor that Specifically Targets the ABL Myristoyl Pocket (STAMP) with higher selectivity for ABL, reducing off-target effects seen with TKIs. A follow-up analysis (median exposure: 4.2 y) of the phase 1 ASC study in pts with CML-CP without T315I after receiving ≥2 TKIs demonstrated durable efficacy and favorable tolerability, with nearly one-third of pts achieving deep molecular response by cutoff (Jan 6, 2021). Here we present final end-of-study (EOS) efficacy and safety results from the phase 1 ASC study in pts with CML-CP without the T315I mutation (cutoff: Mar 14, 2023). This analysis included adults with Ph+ CML-CP without the T315I mutation and an ECOG performance status of 0-2 who had relapsed disease or were refractory to or intolerant of ≥2 prior TKIs. Pts received ASC monotherapy at starting doses of 10-200 mg twice daily (BID) or 80-200 mg once daily (QD). The study started with dose escalation to estimate the maximum tolerated dose (MTD), followed by expansion to establish safety and tolerability of ASC. Dose adjustments were allowed if pts did not tolerate the dosing schedule. The EOS was declared when all pts completed ≥64 wks within the study or discontinued Tx; pts continuing to receive ASC at the EOS were provided continued access to ASC. A total of 115 pts were enrolled between Apr 2014 and Mar 2023. Across all starting doses, the median exposure duration was 5.9 y, with a maximum exposure of 8.4 y; 112 pts (97.4%) had received ≥2 prior TKIs and 82 (71.3%) had received ≥3 prior TKIs. By data cutoff, 70 pts (60.9%) who completed the study on ASC were provided continued access to ASC. Among 45 pts who ended Tx early, 15 (13.0%) and 8 (7.0%) ended due to adverse events (AEs) and disease progression, respectively. Efficacy of ASC at EOS was sustained and consistent with previous reports, with the majority of pts (65.1%) achieving major molecular response (MMR) by the cutoff. While most responses were observed by wk 48, cumulative MMR rates continued to increase up to wk 144 (Figure 1). The median time to MMR (range) was 58.3 (2-360) wks among pts who achieved MMR but were not in MMR at screening. Among the 56 pts who achieved MMR, 50 maintained or improved the response up to data cutoff. At wks 24, 48, and 96, respectively, 18.9%, 17.9%, and 23.6% of pts achieved MR 4 and 13.2%, 15.1%, and 18.9% achieved MR 4.5. Safety and tolerability of ASC improved with longer durations of exposure. The most frequent all-grade AEs included arthralgia (40.9%), increased lipase (39.1%), fatigue (38.3%), and headache (38.3%), and only 13.0% of pts experienced AEs leading to Tx discontinuation. Even with longer durations of Tx, AEs were less likely to occur after the first year on ASC (Figure 2). The safety and tolerability of ASC remained consistent with prior analyses; there were no new or worsening safety issues compared with those already known for ASC and no new on-Tx deaths. The MTD of ASC was not reached. Based on safety, tolerability, efficacy, and pharmacokinetic data, ASC 40 mg BID was selected as the recommended dose for expansion in adults with CML-CP without the T315I mutation. In this final analysis of the phase 1 ASC trial in pts with CML-CP without the T315I mutation, ASC continued to show favorable efficacy and sustained safety and tolerability over a median exposure duration of 5.9 y, with a maximum exposure of 8.4 y. Pts achieved high rates of MMR with nearly one-fourth of pts achieving deep molecular responses at wk 96, demonstrating durable efficacy of ASC over time. Even with longer exposures, the risk of AEs did not increase and there were no new or worsening safety issues. With ASC, most AEs occurred early, and no new late-emerging safety issues were seen, supporting ASC as a safe and tolerable long-term Tx, highly clinically relevant in the management of resistant/intolerant CML-CP. Based on results from this and the ASCEMBL study, 40 mg BID and 80 mg QD have since been approved for use in this pt population.

ASC4START and ASC4FIRST: Two Ongoing Phase 3 Trials Investigating Asciminib Monotherapy As First-Line Therapy Versus Tyrosine Kinase Inhibitors in Patients with Newly Diagnosed Philadelphia Chromosome-Positive Chronic Myeloid Leukemia in Chronic Phase

Background: The current standard of care (SoC) for newly diagnosed patients (pts) with chronic myeloid leukemia in chronic phase (CML-CP) is treatment with 1 of the 4 tyrosine kinase inhibitors (TKIs) approved for this use (first generation [1G] imatinib [IMA] and second generation [2G] bosutinib [BOS], dasatinib [DAS], and nilotinib [NIL]). Although TKIs have vastly improved treatment outcomes, pts with newly diagnosed CML-CP experience lack of efficacy and intolerance to available treatments. A large number of pts treated with IMA do not achieve major molecular response (MMR) and even fewer pts achieve deep molecular response, a key requirement to attempt treatment-free remission. Treatment with 2G TKIs results in larger proportions of pts achieving deep responses albeit still with a sizeable minority not reaching this goal. Also, many pts are intolerant to 2G TKIs, resulting in therapy switching, frequently multiple times. For pts who remain on treatment, even low-grade adverse events (AEs) may significantly impact quality of life (QoL) given the long-term nature of treatment. Improved treatments with high efficacy and improved tolerability are needed to limit therapy switching, reduce treatment discontinuation, maintain, or improve pt QoL, and allow pts to remain on treatment at an optimal dose for longer duration to achieve deep responses. Asciminib is the first and only approved BCR::ABL1 inhibitor that works by specifically targeting the ABL myristoyl pocket (STAMP). This unique mechanism of action (MoA) has no confirmed overlapping mutation-driven resistance profile with ATP-competitive TKIs. Asciminib shows better selectivity compared to other TKIs, with no known off-target kinase-mediated effects due to its MoA; this translates into improved tolerability. In clinical trials (Hughes et al. N Engl J Med. 2019; Rea et al. Blood 2021), asciminib has demonstrated sustained efficacy and a favorable safety profile over time in pts with Philadelphia chromosome positive (Ph+) CML-CP previously treated with ≥2 TKIs as well as in pts with T315I mutation. Asciminib as monotherapy and in combination with ATP-competitive TKIs is being studied as first-line (1L) treatment in CML. The ongoing ASC4FIRST (NCT04971226) study is investigating the efficacy and safety of asciminib 80 mg once daily (QD) monotherapy vs investigator-selected 1G or 2G TKI in adults with newly diagnosed Ph+ CML-CP ( Table 1). The primary endpoint of ASC4FIRST is MMR rate at 48 weeks. The ongoing ASC4START (NCT05456191) study is focused on pt-centric objectives, assessing the tolerability and efficacy of asciminib vs 2G TKI NIL in adults with newly diagnosed Ph+ CML-CP. The primary endpoint of ASC4START is time to treatment discontinuation due to an AE ( Table 1). Current Status: As of December 20, 2022, the ASC4FIRST study completed recruitment, with 405 pts enrolled worldwide. The end of study (EOS) will occur 5 years from the last pt first treatment in the study. Pts will continue to receive the assigned treatment until the EOS, or until premature discontinuation due to treatment failure, disease progression or intolerance, or due to investigator or participant decision. Between 21 November 2022 and 25 July 2023, 180 pts have been screened for the ASC4START study, with 147 pts randomized to treatment (n=52 France, n=40 Germany, n=9 Bulgaria, n=7 Czechia, n=7 Hungary, n=6 Korea, n=6 Singapore, n=2 Slovakia, n=5 Argentina, n=3 Greece, n=2 each from Slovakia, Malaysia, and Oman, and n=1 each from the USA, Italy, Romania, UK, Jordan, and Canada). Recruitment is ongoing. Patients will be treated until approximately 64 discontinuations of either study treatment due to an AE have been recorded. Conclusions: With demonstrated efficacy and improved tolerability compared to ATP-binding TKIs, asciminib has the potential to become the therapy of choice for CML in 1L, enabling newly diagnosed patients to remain on therapy with improved QoL and overall survival, and reducing the need for therapy switching, ultimately allowing patients to achieve optimal milestone responses and reach treatment goals. Findings from these two trials will provide comprehensive evidenceon the use of asciminib as 1L therapy for newly diagnosed pts with Ph+ CML-CP.

Flumatinib for Newly Diagnosed Chronic Phase Chronic Myeloid Leukemia: An Open-Label, Multi-Center Study

Background Tyrosine kinase inhibitors (TKIs) ushered in the era of targeted therapy for chronic myeloid leukemia(CML), which greatly improved the prognosis of patients with CML. Flumatinib is a second-generation tyrosine kinase inhibitor (TKI), which is currently approved for patients with Philadelphia chromosome-positive chronic myeloid leukemia (Ph+ CML) in China. And some current clinical trials revealed that flumatinib has been shown to be a more potent inhibitor of BCR::ABL than imatinib. Methods In this open label, single-arm, multicenter study, 127 patients with newly diagnosed chronic-phase chronic myeloid leukemia (CP-CML) treated with flumatinib were enrolled. The primary endpoint of this study was early molecular response (EMR) rates at 3 months. The secondary were the rates of complete cytogenic response (CCyR), major molecular response (MMR) at 3, 6, 12 months and treatment-related adverse events (AEs). The trial is registered with ClinicalTrials.gov NCT04591197. Results From October 2020 to December 2022, a total of 158 patients with CP-CML were assessed for eligibility, of whom 127 were followed up for more than 3 months. 79(62%) patients were men and 48 (38%) were women. The median age was 47 years (range, 19-82 years), The median time from diagnosis to treatment was 6 days (0-176 days) and the median follow-up was 9.7 months (range 3.1-26.6 months). Of evaluable 127 patients, EMR was achieved by 85% (95% confidence interval [CI], 77.6%-90.7%) of patients at 3 months. After the initiation of flumatinib treatment, the incidence of MMR at 3, 6, and 12 months was 24%, 59%, and 73%, respectively. Patients receiving flumatinib had higher rates of CCyR at 6 months and MMR 12 months than the data from DASISION (dasatinib) and ENESTnd (nilotinib) therapy (85% vs 73% vs 67% and 73% vs 46% vs 44%). Progression-free survival (PFS) rate at 1-year was 97.2%. Diarrhea (34%) were the most commonly reported adverse events. Most treatment-related adverse events were grade 1/2. None of the patients discontinued or died due to AEs. Conclusion Flumatinib as first-line therapy in patients with newly diagnosed CP-CML was not inferior to nilotinib and dasatinib and well tolerated.

Asciminib (ASC) in Combination with Imatinib (IMA), Nilotinib (NIL), or Dasatinib (DAS) May be a Potential Treatment (Tx) Option in Patients (Pts) with Philadelphia Chromosome-Positive Chronic Myeloid Leukemia in Chronic Phase or Accelerated Phase (Ph+ CML-CP/AP): Final Results from the Asciminib Phase 1 Study

Asciminib (ASC) in Combination with Imatinib (IMA), Nilotinib (NIL), or Dasatinib (DAS) May be a Potential Treatment (Tx) Option in Patients (Pts) with Philadelphia Chromosome-Positive Chronic Myeloid Leukemia in Chronic Phase or Accelerated Phase (Ph+ CML-CP/AP): Final Results from the Asciminib Phase 1 Study

Physiologically Based Pharmacokinetic Modeling of Nilotinib for Drug-Drug Interactions, Pediatric Patients, and Pregnancy and Lactation.

Nilotinib is a second-generation BCR-ABL tyrosine kinase inhibitor for the treatment of Philadelphia chromosome-positive chronic myeloid leukemia in both adult and pediatric patients. The pharmacokinetics (PK) of nilotinib in specific populations such as pregnant and lactating people remain poorly understood. Therefore, the objectives of the current study were to develop a physiologically based pharmacokinetic (PBPK) model to predict nilotinib PK in virtual drug-drug interaction (DDI) studies, as well as in pediatric, pregnant, and lactating populations. The nilotinib PBPK model was built in PK-Sim, which is part of the free and open-source software Open Systems Pharmacology. The observed clinical data for the validation of the nilotinib models were obtained from the literature. The model reasonably predicted nilotinib concentrations in the adult population; the DDIs between nilotinib and rifampin or ketoconazole in the adult population; and the PK in the pediatric, pregnant, and lactating populations, although in the latter 2 populations plasma concentrations were slightly underestimated. The ratio of predicted versus observed PK parameters for the adult model ranged from 0.71 to 1.11 for area under the concentration-time curve and 0.55 to 0.95 for maximum concentration. For the DDI, the predicted area under the concentration-time curve ratio and maximum concentration ratio fell within the Guest criterion. The current study demonstrated the utility of using PBPK modeling to understand the mechanistic basis of PK differences between adults and specific populations, such as pediatrics, and pregnant and lactating individuals, indicating that this technology can potentially inform or optimize dosing conditions in specific populations.

Asciminib - ABL Kinase Inhibitor in the Treatment of Philadelphia Chromosome Positive Chronic Myeloid Leukemia: Chemistry and Pharmacology Perspectives

Abstract: Asciminib, also known as ACP-196, is the FDA-approved low-molecular ABL kinase inhibitor. The ABL kinase is a non-receptor tyrosine kinase that helps in cell growth and survival and is a key player in the development of chronic myeloid leukemia (CML) and Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ALL). The BCR-ABL fusion protein, which is formed by chromosomal translocation in CML and Ph+ ALL, results in the constitutive activation of ABL kinase, leading to uncontrolled cell growth and proliferation. To have a high binding affinity for the active site of the enzyme, structural biology and computer-aided drug design (CADD) concepts were applied to the design of asciminib so that it could specifically target the ABL kinase enzyme. The drug was synthesized and characterized in a laboratory. In its pharmacological studies, it has shown that asciminib is a potent and selective inhibitor of ABL kinase. Phase I clinical trials assessed its safety and efficacy, revealing that it is effective against tumors while causing minimal discomfort to patients. In addition to this, it was able to induce apoptosis and a cytogenetic response as well as inhibit the proliferation of CML and Ph+ALL cells in patients with CML. As this trial gave a positive response, phase II and III trials were conducted. In that sense, asciminib has shown to be highly effective, with response rates of over 90% in patients with these diseases. The safety and efficacy of asciminib were also evaluated in combination with other drugs, such as tyrosine kinase inhibitors and immunomodulatory drugs, and the results were promising. Overall, the discovery and development of asciminib showed that by using the concepts of pharmacology and CADD, a drug with a 90% positive rate response can be developed with a high tolerance level and lower side effects

Outcome of Philadelphia chromosome-positive chronic myeloid leukemia in the United States since the introduction of imatinib therapy-The Surveillance, Epidemiology, and End Results database, 2000-2019.

Since the introduction of BCR::ABL1 tyrosine kinase inhibitors (TKIs) in 2000, the treatment of Philadelphia chromosome (Ph)-positive chronic myeloid leukemia (CML) has improved significantly. This study aimed to evaluate Ph-positive CML outcomes in the TKI therapy era, considering factors like age, ethnicity, and income. Using the Surveillance, Epidemiology, and End Results (SEER) database, 2857 patients with Ph-positive CML diagnosed from 2000 to 2019 were analyzed. The overall 5-year survival rates in Ph-positive CML increased to above 80%, compared with pre-TKIs historical data reporting 5-year overall survival (OS) rates of less than 50%. The 5-year OS rate was 73% for patients diagnosed in 2000-2004, 82% in 2005-2009, and 78% in 2010-2014; the 4-year OS rate was 83% in 2015-2019. The 5-year OS rate for younger patients (<60years old) was 88% in 2000-2009 and 90% in 2010-2019 (p value .426). In older patients (60+ years old), the 5-year OS rates were 64% and 65%, respectively (p value, .303). Lower household income was associated with inferior survival across the 2000-2019. These results are inferior to European studies where TKIs are universally available and affordable, and relative OS in CML is similar to age-matched normal populations. Although the outcome of Ph-positive CML has improved significantly since 2000, the SEER data still shows differences in outcomes among patient subsets, some anticipated (worse OS in older patients accounted by the relative OS), but others that suggest less than universal access and affordability of this therapy (among poorer patients) in the United States.

Population Pharmacokinetics and Pharmacogenetics Analyses of Dasatinib in Chinese Patients with Chronic Myeloid Leukemia.

Dasatinib, a second-generation tyrosine kinase inhibitor of BCR-ABL 1, used for first-line treatment of Philadelphia chromosome-positive chronic myeloid leukemia (CML), exhibits high pharmacokinetic (PK) variability. However, its PK data in Chinese patients with CML remains rarely reported to date. Thus, we developed a population pharmacokinetic (PPK) model of dasatinib in Chinese patients and identified the covariate that could explain the individual variability of PK for optimal individual administration. PPK modeling for dasatinib was performed based on 754 plasma concentrations obtained from 140 CML patients and analysis of various genetic and physicochemical parameters. Modeling was performed with nonlinear mixed-effects (NLME) using Phoenix NLME. The finally developed model was evaluated using internal and external validation. Monte Carlo simulations were used to predict drug exposures at a steady state for various dosages. The PK of dasatinib were well described by a two-compartment with a log-additive residual error model. Patients in the current study had a relatively low estimate of CL/F (126 L/h). A significant association was found between the covariate of age and CL/F of dasatinib, which was incorporated into the final model. None of the genetic factors was confirmed as a significant covariate for dasatinib. The results of external validation with 140 samples from 36 patients were acceptable. Simulation results showed significantly higher exposures in elderly patients. This study's findings suggested that low-dose dasatinib would be better suited for Chinese patients, and the dosage can be appropriately reduced according to the increase of age, especially for the elderly.

Chloroquine Intervenes Nephrotoxicity of Nilotinib through Deubiquitinase USP13-Mediated Stabilization of Bcl-XL.

Nephrotoxicity has become prominent due to the increase in the clinical use of nilotinib, a second-generation BCR-ABL1 inhibitor in the first-line treatment of Philadelphia chromosome-positive chronic myeloid leukemia. To date, the mechanism of nilotinib nephrotoxicity is still unknown, leading to a lack of clinical intervention strategies. Here, it is found that nilotinib could induce glomerular atrophy, renal tubular degeneration, and kidney fibrosis in an animal model. Mechanistically, nilotinib induces intrinsic apoptosis by specifically reducing the level of BCL2 like 1 (Bcl-XL) in both vascular endothelial cells and renal tubular epithelial cells, as well as in vivo. It is confirmed that chloroquine (CQ) intervenes with nilotinib-induced apoptosis and improves mitochondrial integrity, reactive oxygen species accumulation, and DNA damage by reversing the decreased Bcl-XL. The intervention effect is dependent on the alleviation of the nilotinib-induced reduction in ubiquitin specific peptidase 13 (USP13) and does not rely on autophagy inhibition. Additionally, it is found that USP13 abrogates cell apoptosis by preventing excessive ubiquitin-proteasome degradation of Bcl-XL. In conclusion, the research reveals the molecular mechanism of nilotinib's nephrotoxicity, highlighting USP13 as an important regulator of Bcl-XL stability in determining cell fate, and provides CQ analogs as a clinical intervention strategy for nilotinib's nephrotoxicity.

Asciminib (Scemblix) for chronic myeloid leukemia.

Asciminib (Scemblix – Novartis), an oral kinase inhibitor, has been approved by the FDA for treatment of adults with Philadelphia chromosome-positive chronic myeloid leukemia (Ph+ CML) in chronic phase (CP) previously treated with ≥2 tyrosine kinase inhibitors and for adults with Ph+ CML in CP with a T315I mutation.

The EMA Assessment of Asciminib for the Treatment of Adult Patients With Philadelphia Chromosome-Positive Chronic Myeloid Leukemia in Chronic Phase Who Were Previously Treated With At Least 2 Tyrosine Kinase Inhibitors.

Asciminib is an allosteric high-affinity tyrosine kinase inhibitor (TKI) of the BCR-ABL1 protein kinase. This kinase is translated from the Philadelphia chromosome in chronic myeloid leukemia (CML). Marketing authorization for asciminib was granted on August 25, 2022 by the European Commission. The approved indication was for patients with Philadelphia chromosome-positive CML in the chronic phase which have previously been treated with at least 2 TKIs. Clinical efficacy and safety of asciminib were evaluated in the open-label, randomized, phase III ASCEMBL study. The primary endpoint of this trial was major molecular response (MMR) rate at 24 weeks. A significant difference in MRR rate was shown between the asciminib treated population and the bosutinib control group (25.5% vs. 13.2%, respectively, P = .029). In the asciminib cohort, adverse reactions of at least grade 3 with an incidence ≥ 5% were thrombocytopenia, neutropenia, increased pancreatic enzymes, hypertension, and anemia. The aim of this article is to summarize the scientific review of the application which led to the positive opinion by the European Medicines Agency's Committee for Medicinal Products for Human Use.

Asciminib vs bosutinib in chronic-phase chronic myeloid leukemia previously treated with at least two tyrosine kinase inhibitors: longer-term follow-up of ASCEMBL

Asciminib, the first BCR::ABL1 inhibitor that Specifically Targets the ABL Myristoyl Pocket (STAMP), is approved worldwide for the treatment of adults with Philadelphia chromosome–positive chronic myeloid leukemia in chronic phase (CML-CP) treated with ≥2 prior tyrosine kinase inhibitors (TKIs). In ASCEMBL, patients with CML-CP treated with ≥2 prior TKIs were randomized (stratified by baseline major cytogenetic response [MCyR]) 2:1 to asciminib 40 mg twice daily or bosutinib 500 mg once daily. Consistent with previously published primary analysis results, after a median follow-up of 2.3 years, asciminib continued to demonstrate superior efficacy and better safety and tolerability than bosutinib. The major molecular response (MMR) rate at week 96 (key secondary endpoint) was 37.6% with asciminib vs 15.8% with bosutinib; the MMR rate difference between the arms, after adjusting for baseline MCyR, was 21.7% (95% CI, 10.53–32.95; two-sided p = 0.001). Fewer grade ≥3 adverse events (AEs) (56.4% vs 68.4%) and AEs leading to treatment discontinuation (7.7% vs 26.3%) occurred with asciminib than with bosutinib. A higher proportion of patients on asciminib than bosutinib remained on treatment and continued to derive benefit over time, supporting asciminib as a standard of care for patients with CML-CP previously treated with ≥2 TKIs.

Severe persistent marrow aplasia in chronic myeloid leukemia (CML): An unusual complication of imatinib.

Imatinib has changed the treatment of chronic myeloid leukemia (CML) drastically since 15 years. It is usually well tolerated, but severe persistent marrow aplasia is an unusual complication of imatinib while using it in CML. The aim of this study is to describe our experience confronting this rare side effect and review the available data worldwide. It was a retrospective analysis conducted at a center from February 2002 to February 2015. This study was endorsed by our Institutional Review Board (IRB) and written consent was taken from all patients. Patients diagnosed as Philadelphia (Ph) chromosome-positive CML either in chronic phase (CP), accelerated phase (AP), or blastic crisis (BC) were included. There were a total of 1,576 patients with CML treated with imatinib during this period. Karyotyping and quantitative reverse transcriptase polymerase chain reaction (RT-qPCR) were done at the time of pancytopenia for all patients. In total, 11 (males = 5, females = 6) patients met our inclusion criteria from 1,576 patients of CML. The median age was 58 years (range 32-76). Out of 11 patients 8, 2, and 1 patients were in CP, AP, and BC phases, respectively. The median time of administration of imatinib was 3.3 months (range 1.5-6). The average time of marrow recovery was 10.4 months (range 5-15). Two patients expired (one from septicemia and the other from intracranial hemorrhage). BCR-ABL transcripts level by RT-PCR revealed the existence of the disease in all patients. Imatinib is a very well-tolerated tyrosine kinase inhibitor (TKI), but is associated with persistent myelosuppression when used in older age, advanced phase of the disease, and treated previously. After confirming persistent marrow aplasia, the treatment is mainly supportive. It is striking that the disease is still persistent, which is confirmed by RT-PCR. There is no consensus regarding recalling imatinib at lower doses or the use of second-generation TKI (nilotinib, dasatinib) in these patients.

Single-cell resolution reveals RalA GTPase expanding hematopoietic stem cells and facilitating of BCR-ABL1-driven leukemogenesis in a CRISPR/Cas9 gene editing mouse model.

BCR-ABL oncogene-mediated Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia (CML) is suggested to originate from leukemic stem cells (LSCs); however, factors regulating self-renewal of LSC and normal hematopoietic stem cells (HSCs) are largely unclear. Here, we show that RalA, a small GTPase in the Ras downstream signaling pathway, has a critical effect on regulating the self-renewal of LSCs and HSCs. A RalA knock-in mouse model (RalARosa26-Tg/+) was initially constructed on the basis of the Clustered Regularly Interspaced Short Palindromic Repeats/Cas9 (CRISPR/Cas9) assay to analyze normal hematopoietic differentiation frequency using single-cell resolution and flow cytometry. RalA overexpression promoted cell cycle progression and increased the frequency of granulocyte-monocyte progenitors (GMPs), HSCs and multipotent progenitors (MPPs). The uniform manifold approximation and projection (UMAP) plot revealed heterogeneities in HSCs and progenitor cells (HSPCs) and identified the subclusters of HSCs and GMPs with a distinct molecular signature. RalA also promoted BCR-ABL-induced leukemogenesis and self-renewal of primary LSCs and shortened the survival of leukemic mice. RalA knockdown prolonged survival and promoted sensitivity to imatinib in a patient-derived tumor xenograft model. Immunoprecipitation plus single-cell RNA sequencing of the GMP population confirmed that RalA induced this effect by interacting with RAC1. RAC1 inhibition by azathioprine effectively reduced the self-renewal, colony formation ability of LSCs and prolonged the survival in BCR-ABL1-driven RalA overexpression CML mice. Collectively, RalA was detected to be a vital factor that regulates the abilities of HSCs and LSCs, thus facilitating BCR-ABL-triggered leukemia in mice. RalA inhibition serves as the therapeutic approach to eradicate LSCs in CML.