BCR-ABL Inhibitor Research Articles

Efficacy and Safety Results from Ascembl, a Multicenter, Open-Label, Phase 3 Study of Asciminib, a First-in-Class STAMP Inhibitor, Vs Bosutinib in Patients with Chronic Myeloid Leukemia in Chronic Phase after ≥2 Prior Tyrosine Kinase Inhibitors: Update after 48 Weeks

Efficacy and Safety Results from Ascembl, a Multicenter, Open-Label, Phase 3 Study of Asciminib, a First-in-Class STAMP Inhibitor, Vs Bosutinib in Patients with Chronic Myeloid Leukemia in Chronic Phase after ≥2 Prior Tyrosine Kinase Inhibitors: Update after 48 Weeks

A Role for Lipid Metabolism in Tyrosine Kinase Inhibitor (TKI) Resistance of Chronic Myeloid Leukemia (CML)

Tyrosine kinase inhibitors (TKIs) targeting BCR-ABL1 are remarkably effective therapies in chronic myeloid leukemia (CML). Despite success, TKIs do not target the CML leukemic stem cell (LSC), meaning patients must be treated for life at a high economic burden and often with significant side effects. Our previous work demonstrated a tumor suppressor role for G0/G1 switch gene 2 (G0S2) in CML, which is profoundly downregulated in TKI resistance (>3-fold, p<0.02) (Gonzalez MA, et al. Cancer Res 2020 #648). Low G0S2 expression not only correlated with TKI resistance, but also with a shorter overall survival in chronic phase (p=0.036), and transformation from the chronic to the blast phase of disease (p<0.05). G0S2 is known to regulate apoptosis, quiescence, lipid metabolism, oxidative phosphorylation, and also acts as an inhibitor of adipose triglyceride lipase (ATGL), the rate-limiting enzyme in intracellular lipolysis. We hypothesized that G0S2-mediated ATGL inhibition underlies its tumor suppressor activity in CML and TKI resistance.To address this hypothesis, we first assessed ATGL protein expression in CML cell lines (K562 and KU812) in the presence and absence of the BCR-ABL TKI, imatinib. Importantly, ATGL protein expression remained unchanged in graded doses of imatinib, suggesting that ATGL expression occurs in a BCR-ABL1-independent manner. To assess the functional role of ATGL in CML and TKI resistance, we performed shRNA-mediated ATGL knockdown (shATGL) in both cell lines. Although ectopic G0S2 impaired survival of CML cell lines and patient samples, we observed a different phenotype upon ATGL knockdown. Rather, shATGL alone increased colony formation by ~30% in both cell lines in the absence but not presence of imatinib (K562, p=0.04; KU812, p=0.0024). Knockdown of ATGL had no effect on colony formation of normal cord blood CD34 + progenitors (p=0.742). Interestingly, when we ectopically expressed G0S2 into K562 cells with simultaneous ATGL knockdown, the phenotype in colony formation assays mimicked ectopic G0S2 expression, reducing survival by ~50% (p=0.05). These data suggest that the tumor suppressor role of G0S2 in CML is independent of ATGL. However, while ectopic G0S2 expression alone had no effect on apoptosis of CML cell lines, when combined with ATGL knockdown, imatinib-mediated apoptosis was markedly increased. This was similar to data observed in blast phase CML patient samples upon ectopic G0S2 expression. Consistently, RNA sequencing (RNAseq) data for CML patients revealed that ATGL mRNA is highly downregulated in blast phase (n=14) compared with patients in the chronic (n=52) or accelerated (n=11) phases of the disease (p<0.0001). These data suggest that ATGL abrogates G0S2-mediated apoptosis in the presence of imatinib. We next performed colony formation assays of K562 cells with G0S2 knockdown (shG0S2) versus a non-targeting control (shNT) in the absence and presence of an ATGL inhibitor (Atglistatin, 50 µM) and a fatty acid oxidation (FAO) inhibitor (TMZ, 10 µM). Atglistatin had no effect on colony formation in the shNT-expressing cells, but reduced survival by ~40% upon G0S2 knockdown. Similarly, TMZ reduced survival of shNT cells by ~30%, while it reduced survival by ~90% upon G0S2 knockdown. These data suggest that the phenotypic effects of G0S2 knockdown in TKI resistance in part requires FAO.The effect of G0S2 on lipid metabolism was further confirmed with RNAseq and metabolomics/lipidomics analyses. RNAseq revealed no overlapping pathways between K562 cells expressing ectopic G0S2 versus shATGL. Lipidomics analyses revealed that G0S2 knockdown reduced expression of tri- and di-glycerides, whereas ectopic G0S2 promoted triglyceride accumulation in K562 cells. G0S2 knockdown also resulted in substantial changes of phosphatidylethanolamine and phosphatidylcholine expression, implicating G0S2 in the production of lipid bilayer components. Finally, metabolomics data implicated a role for G0S2 as a negative regulator of the mitochondrial electron transport chain. Altogether, these findings suggest that G0S2 and lipid metabolism play a role in regulating leukemic stem and progenitor cell survival as well as TKI response in vitro. Therefore, restoring G0S2 expression and inhibiting FAO, combined with BCR-ABL1 inhibition, may be a novel clinical strategy to induce treatment-free remission in CML patients and eradicate the CML LSC. DisclosuresNo relevant conflicts of interest to declare.

An Update of Safety and Efficacy Results from Phase 1 Dose-Escalation and Expansion Study of Vodobatinib, a Novel Oral BCR-ABL1 Tyrosine Kinase Inhibitor (TKI), in Patients with Chronic Myeloid Leukemia (CML) and Philadelphia Chromosome Positive Acute Lymphoblastic Leukemia (Ph+ ALL) Failing Prior TKI Therapies

An Update of Safety and Efficacy Results from Phase 1 Dose-Escalation and Expansion Study of Vodobatinib, a Novel Oral BCR-ABL1 Tyrosine Kinase Inhibitor (TKI), in Patients with Chronic Myeloid Leukemia (CML) and Philadelphia Chromosome Positive Acute Lymphoblastic Leukemia (Ph+ ALL) Failing Prior TKI Therapies

Real-Life Use of Nilotinib for Chronic Phase CML Demonstrates Similar Efficacy and Rate of Cardiovascular Events As Enestnd

Introduction:Nilotinib is a second-generation BCR-ABL1 tyrosine kinase inhibitor (TKI) widely used for the treatment of Philadelphia chromosome positive chronic myeloid leukemia (CML). ENESTnd, which compared two doses of nilotinib to imatinib for patients with newly diagnosed CML, demonstrated superior rates of major molecular responses (MMRs) at 12 months in patients treated with nilotinib. However, a relative increase in cardiovascular events (CVE) was observed, including ischemic heart disease, stroke, and/or peripheral artery disease among nilotinib-treated patients. Notably, at a median 5-year follow up, 7.5% of patients on nilotinib 300mg twice daily experienced a CVE (Hochaus, Leukemia, 2016) and by 10-years of follow up, approximately 20% of patients treated with nilotinib developed a CVE (Kantarjian, Leukemia, 2021). The baseline Framingham general cardiovascular risk scores and total dose exposure were predictive of patients' risk of developing CVE.In the province of Quebec, Canada, the GQR LMC-NMP (Groupe Québécois de recherche en leucémie myéloide chronique et néoplasie myéloproliférative) has maintained a registry of nearly all patients with CML since 2011. Using this 900+-patient registry, we examined molecular responses and the rate of CVE among patients receiving nilotinib as frontline therapy for CML, to determine if they were similar to those observed in ENESTnd.Methods:We identified all patients with chronic phase CML in the registry who were initiated on nilotinib for chronic phase CML. Baseline patient characteristics included were age, sex, Sokal index, baseline comorbidities, molecular response, cardiovascular complications, duration of exposure to nilotinib, dose adjustment, dose discontinuation and CVE on therapy.Results:In total, 94 patients received nilotinib as frontline treatment starting in 2008 (Table 1). The median age of the population was 58 years, 50.5% were male. The most common cardiovascular comorbidity prior to nilotinib treatment was hypertension (23.4%) followed by elevated cholesterol (21.3%), and prior CVE (12%). Seventeen patients had a low Sokal index, 26 intermediate and 24 high, 25 missing. Sixty-five patients received nilotinib at a total of 600 mg per day, 29 patients had a dose reduction at some point in their treatment and 18 patients were on either 300 or 400 mg daily. The median follow-up time was 67.0 months (range 0.5 to 159), and median nilotinib exposure time was 38.5 months (range 0.5 to 144). Forty-six patients (48.9%) discontinued nilotinib, 6 for a treatment free remission (TFR). While on nilotinib, 63 patients achieved MMR (72.4%) and 43 achieved MR 4.5 (49.6%) by 5 years of treatment, with 52 (55.3%) and 22 (23.4%) patients achieving MMR or MMR4.5 within a year, respectively.There was a total of 7 CVE in 6 patients: six myocardial infarctions and one ischemic stroke (Table 2). No patients developed peripheral artery disease. The mean time of exposure to nilotinib in these 6 patients was 28.6 months. Two patients had a high Sokal index, 3 intermediate and 1 low. One patient received dose-reduced nilotinib. These patients were co-morbid with diabetes (3), hypertension (3), elevated cholesterol (1) and one had a myocardial infarct prior to starting nilotinib, two patients did not have any risk factors. Only one of these patients has remained on nilotinib. All patients with a CVE were alive at the time of this report.Conclusion:We present real world data on the efficacy and safety of nilotinib in the frontline treatment of CML. Our data indicate that molecular responses and toxicities are similar to the ENESTnd trial. Of the 94 treated patients, the rate of MMR and CVE were 72% and 7.4% at 5.5 years of follow up, respectively, which is similar to that observed in ENESTnd, where 77% of patients experienced MMR and 7.5% CVE at this timepoint (Hochaus, Leukemia, 2016). All but one patient with a CVE in our study continued nilotinib, suggesting a reluctance among physicians to continue in the face of CVE. While there were 11 patients with prior CVE, only one of these developed a CVE on nilotinib. Current GQR-LMC CML management guidelines recommend estimation of Framingham score and management of cardiovascular risk factors for all patients with CML. Future follow up of these registry data may demonstrate a decrease in the rate of CVE among nilotinib treated patients, reflecting local adherence to these guidelines. [Display omitted] DisclosuresBusque: Novartis: Consultancy. Assouline: Eli Lilly: Research Funding; Jewish General Hospital, Montreal, Quebec: Current Employment; Novartis: Honoraria, Research Funding; Amgen: Current equity holder in publicly-traded company, Research Funding; Gilead: Speakers Bureau; Johnson&Johnson: Current equity holder in publicly-traded company; Roche/Genentech: Research Funding; Takeda: Research Funding; BeiGene: Consultancy, Honoraria, Research Funding; F. Hoffmann-La Roche Ltd: Consultancy, Honoraria, Research Funding; AstraZeneca: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria, Research Funding, Speakers Bureau; Janssen: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria.

A Comprehensive Cancer Center Experience with Hyper-CVAD Plus Ponatinib As Frontline Therapy for Adult Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia

BackgroundPonatinib, a third-generation BCR-ABL1 tyrosine kinase inhibitor (TKI), + hyper-CVAD showed remarkable activity against Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph+ ALL), and may be superior to chemotherapy + earlier generation TKIs in terms of depth of remission, event-free survival (EFS), and overall survival (OS). However, this regimen's efficacy and tolerability have yet to be externally validated. Here, we summarize our real-world experience with ponatinib + hyper-CVAD for untreated Ph+ ALL and other Ph+ acute or blast phase leukemias.MethodsWe retrospectively analyzed all adults treated at the University of California, Davis (UCD) from March 2012 to May 2021 with ponatinib + hyper-CVAD upfront. The primary endpoints were 3-year OS and EFS. Secondary endpoints were complete molecular response (CMR), measurable residual disease (MRD) negativity by multiparameter flow cytometry (MFC), complete cytogenetic response (CCyR) rates, and adverse events (AEs). Time to event analyses were done via the Kaplan-Meier method. Patients alive were censored at their last follow-up date. Patients undergoing allogeneic hematopoietic cell transplant (HCT) after 6 months of achieving complete remission (CR) were censored at the time of HCT for the landmark analysis. Patients with missing data were excluded from the response analyses.ResultsWe identified 13 Ph+ ALL patients who received ponatinib + hyper-CVAD for initial induction. The baseline characteristics for the Ph+ ALL patients are summarized in Table 1. The median follow-up was 16 months. The median number of hyper-CVAD cycles completed was 8 (range, 1-8) with ponatinib. Two patients proceeded to HCT in CR1, one at 3.5 months after starting induction, and due to difficulty controlling the patient's concurrent multiple myeloma prior to HCT and recovery from anti-neoplastic therapy, the second was delayed to 46 months after starting induction.The 3-year OS and EFS with ponatinib + hyper-CVAD were each 92% (95% confidence interval, 78.9-100) (Figure 1). Landmark analysis completed 6 months following CR showed a 3-year OS of 100% in patients treated with ponatinib + hyper-CVAD without HCT in first CR (CR1). The CMR, CCyR, and MRD-negativity by MFC rates with ponatinib were all 92.3% (12/13). The median time to CMR, CCyR, and MRD-negativity by MFC were 51 days, 22 days, and 53 days, respectively.Notable AEs with ponatinib include neutropenic fever (92%), bacterial infection (69%), transaminitis (38%), venous thromboembolism (31%), invasive fungal infection (15%), hemorrhage (15%), cerebrovascular accident (CVA) (15%), and tumor lysis syndrome (8%). One patient died during induction with ponatinib due to a bacterial infection. Two patients switched to a different TKI due to a CVA after 4 and 24 months. Only 2 patients did not complete 8 cycles of hyper-CVAD, due to death during induction (n=1) and proceeding to HCT after 3 cycles (n=1).As for similar Ph+ leukemias, 3 chronic myeloid leukemia with lymphoid blast crisis (CML-LBC), 1 CML with mixed phenotype blast crisis (CML-MPBC), and 1 with mixed phenotype acute leukemia (MPAL) were treated with ponatinib + hyper-CVAD. The MPAL patient achieved CMR within 55 days, while the CML-MPBC and 2 CML-LBC patients achieved CMR after HCT. The third CML-LBC patient is in CR with ongoing treatment. After median follow-up of 25 months, all 5 were alive, and only the MPAL patient relapsed 28 months after starting treatment and 1 year after HCT.ConclusionTo our knowledge, this is the first report externally validating the efficacy and tolerability of ponatinib + hyper-CVAD for Ph+ ALL. We also show the feasibility of using this regimen in patients with Ph+ CML-LBC, CML-MPBC and MPAL. Despite the small sample size and retrospective nature, our study supports existing data demonstrating that this regimen challenges both the designation of Ph+ ALL as a high-risk disease and the trend to transplant in CR1. Our findings support that ponatinib + hyper-CVAD should be considered a standard of care for Ph+ ALL. [Display omitted] DisclosuresKaesberg: Incyte: Speakers Bureau. Rosenberg: Takeda, Janssen: Speakers Bureau. Abedi: BMS/Celgene: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Abbvie: Speakers Bureau; Seattle Genetics: Speakers Bureau. Tuscano: Genentech, Pharamcyclics, Abbvie, BMS, Acrotech, Seattle Genetics, Takeda: Research Funding. Jonas: AbbVie, BMS, Genentech, GlycoMimetics, Jazz, Pfizer, Takeda, Treadwell: Consultancy; 47, AbbVie, Accelerated Medical Diagnostics, Amgen, AROG, Celgene, Daiichi Sankyo, F. Hoffmann-La Roche, Forma, Genentech/Roche, Gilead, GlycoMimetics, Hanmi, Immune-Onc, Incyte, Jazz, Loxo Oncology, Pfizer, Pharmacyclics, Sigma Tau, Treadwell: Research Funding; AbbVie: Other: Travel reimbursement. OffLabel Disclosure:Ponatinib is approved for Philadelphia chromosome positive acute lymphoblastic leukemia (Ph+ALL) that is resistant or intolerant to prior tyrosine kinase inhibitor therapy. In this study, we described outcomes with ponatinib in combination with hyperCVAD in the frontline setting, which is off-label.

Updated Safety and Efficacy Results of Phase 1 Study of Olverembatinib (HQP1351), a Novel Third-Generation BCR-ABL Tyrosine Kinase Inhibitor (TKI), in Patients with TKI-Resistant Chronic Myeloid Leukemia (CML)

▪Background: Management of CML using TKIs is often constrained by treatment resistance, which portends a poor prognosis. Treatment failure may be due to therapeutic resistance (BCR-ABL1 mutation-dependent or independent), intolerance, and/or suboptimal adherence. The BCR-ABL1 T315I (“gatekeeper”) genotype is insensitive to first- and second-generation TKIs, while compound mutations complicate management with all TKIs (including third-generation TKI ponatinib). HQP1351 (olverembatinib) is a novel, third-generation, orally active BCR-ABL1 TKI with evidence of antitumor activity against CML regardless of genotype (Ren X et al. Med Chem 2013;56:879-94) and a preliminary favorable safety profile in clinical trials (Jiang Q et al. Blood 2020;136:50-1).Methods: This Chinese, open label, multicenter, phase 1 trial evaluated the safety and efficacy of olverembatinib in adults with CML in chronic phase (CML-CP) or accelerated phase (CML-AP). Eligible patients have CML-CP or CML-AP that is resistant or intolerant to first- or second-generation TKIs. Patients with severe cardiovascular diseases, hypertension, and pulmonary arterial hypertension were excluded. Olverembatinib is orally administered once every other day in 28-day cycles at 11 dose cohorts ranging from 1 to 60 mg. This study reports data on patients with long-term follow-up.Results: From October 26, 2016, through February 2, 2021 (data cutoff date), 101 patients with CP-CML (n = 86) and AP-CML (n = 15) were enrolled and treated with olverembatinib. Seventy-one (70.3%) patients were male, the median age was 40 (range, 20-64) years, and median (range) interval from diagnosis to initial olverembatinib treatment was 6.0 (0.3-15.2) years. Eighty-four (83.2%) patients received ≥ 2 prior lines of TKI-therapy, and 63 (62.4%) harbored T315I mutation. At baseline, compound mutations were detected in 11 (10.9%) patients, of whom 7 (63.6%) had the BCR-ABL1 T315Igenotype. A total of 20 (19.8%) patients had 2 (n = 13) or ≥ 3 (n = 7) mutations. The median follow-up was 30.8 (1.2-51.8) months. As of the data cutoff date, 81 (80.2%) of 101 patients continued on treatment and 20 (14 CP-CML and 6 AP-CML) discontinued because of disease progression, intolerance, or occurrence of a secondary cancer. The cumulative median (range) drug exposure was 13,635 (1,650-20,975) mg. Of 101 patients, 18 (17.8%) were treated for > 3 years and 5 (5%) for > 4 years. Of evaluable patients without baseline responses, 97.0% had complete hematologic responses (CHR), 62.1% complete cytogenetic responses (CCyR), and 51.0% major molecular responses (MMR). Most evaluable patients with T315I mutations experienced 100% for CHR, 83.7% for MCyR, and 71.2% for MMR among patients in CP-CML, as well as 80.0% for CHR and 54.5% each for MCyR and MMR in AP-CML. At 36 months, the PFS rate (95% CI) was 96.3% (89.1%-98.8%) in patients with CP-CML and 71.4% (40.6%‒88.2%) in those with AP-CML. Treatment responses were durable and unaffected by baseline BCR-ABL1 mutational status. Corresponding values in patients with > 4 years of treatment were 100% (CHR), 80% (CCyR), and 60% (MMR). The mean (95% confidence interval) PFS rate was 100% (100%-100%) at 36 months, 100% at 48 months, and not reached (NR-NR) at 60 months. Most treatment-related adverse events were grade 1 or 2. The most frequent nonhematologic adverse event was (mostly grade 1 or 2) skin hyperpigmentation (86.1%). Grade ≥ 3 nonhematologic AEs included hypertriglyceridemia (10.9%), pyrexia (6.9%), and proteinuria (5.0%). The most common hematologic treatment-related adverse event was thrombocytopenia in 78 (77.2%) patients, including 52 (51.5% of total population) with grade ≥ 3 and 6 (5.9%) with serious adverse events. Leukopenia was grade ≥ 3 in 21 (20.8%) patients but not serious, while anemia was grade 3 or higher in 16 (15.8%) patients and serious in 4 (4.0%).Conclusions: In patients with TKI-resistant CML-CP or CML-AP and long-term treatment, olverembatinib was efficacious and well tolerated. Internal study identifier HQP1351-SJ002. [Display omitted] DisclosuresChen: Ascentage Pharma (Suzhou) Co., Ltd: Current Employment, Current equity holder in publicly-traded company. Niu: Ascentage Pharma (Suzhou) Co., Ltd: Current Employment, Current equity holder in publicly-traded company. Men: Ascentage Pharma (Suzhou) Co., Ltd.: Current Employment, Current equity holder in publicly-traded company. Wang: Ascentage Pharma (Suzhou) Co., Ltd: Current Employment, Current equity holder in publicly-traded company. Yang: Ascentage Pharma (Suzhou) Co., Ltd: Current Employment, Current equity holder in publicly-traded company, Other: Leadership and other ownership interests, Patents & Royalties, Research Funding. Zhai: Ascentage Pharma Group Inc.: Current Employment, Current equity holder in publicly-traded company, Other: Leadership and other ownership interests, Patents & Royalties, Research Funding; Ascentage Pharma (Suzhou) Co., Ltd.: Current Employment, Current equity holder in publicly-traded company, Other: Leadership and other ownership interests, Patents & Royalties, Research Funding.

Identification of Patient-Specific Anti-Apoptotic Molecules As Therapeutic Targets in Poor Prognosis Acute Lymphoblastic Leukemia (ALL)

Relapse and refractory ALL shows dismal prognosis despite recent progress in intensive chemotherapy and development of molecular targeting agents. In this study, we aimed to identify vulnerabilities in genetically-diverse ALL and to find additional therapeutic targets in Philadelphia chromosome-positive (Ph+) ALL and chronic myeloid myeloid leukemia (CML) to overcome BCR-ABL tyrosine kinase inhibitor (TKI) resistance.To this end, we performed in vitro drug screening using 23 human ALL samples (9 Ph+ ALL, 5 MLL-ALL, 1 ALL with ETV-RUNX1, 5 B-ALL, not otherwise specified and 4 T-ALL), 10 CML samples and eight mixed phenotype acute leukemia (MPAL) samples (four B-Myeloid and four T-Myeloid). Based on our recent findings in AML (Hashimoto, Saito et al., Nature Cancer 2021), we treated leukemia-engrafting cells with small molecules targeting anti-apoptotic molecules (BCL-2, MCL-1 or BIRC) or molecules associated with cell division (AURKB) in addition to tyrosine kinase inhibitors.Among these compounds, BIRC inhibitor and venetoclax exhibited great efficacy. Responsiveness to each compound was: 28 of 41 for BIRC inhibitor (68.3%), 24 of 40 for venetoclax (60%), 11 of 37 for MCL-1 inhibitor (29.7%) and 4 of 37 for AURKB inhibitor (10.8%). We found differential sensitivity between T-ALL/MPAL T-myeloid and CML. Seven out of eight T-ALL and MPAL T-myeloid samples were highly sensitive to venetoclax (87.5%), while nine out of 10 CML samples were responsive to BIRC inhibition (90%). On the other hand, among Ph+ ALL/MPAL and Ph- B-ALL/MPAL B-myeloid samples, sensitivities to BIRC inhibitor and venetoclax were variable.To identify determinants of sensitivity to compounds, we examined the relation between mutational profile and in vitro leukemia elimination through targeted DNA sequencing for 79 lymphoid and myeloid malignancy-associated somatic mutations. Consistent with our previous study, CBL-mutated leukemia showed higher sensitivity to BIRC inhibitor (four of five cases) compared with venetoclax (two of five cases). Among genes related to RAS signaling pathway, KRAS mutations were most frequent (n=6). While five of six KRAS-mutated cases were BIRC inhibitor sensitive (83.3%), three of six cases were sensitive to venetoclax (50%). For cases with mutations in BCR-ABL1 kinase domain, the sensitivity to BIRC inhibitor and venetoclax was variable.Finally, we went on to setup in vivo experiments to elucidate if targeting the patient-specific vulnerabilities resulted in potent therapeutic efficacy against patient leukemic cells. We created patient-derived xenograft (PDX) models of 5 Ph+ ALL/MPAL, 2 Ph- B-ALL/MPAL, 2 T-ALL/MPAL and 2 CML cases. For Ph+ ALL/MPAL and CML, BIRC inhibitor and/or venetoclax combined with dexamethasone (DEX) and TKI achieved effective in vivo elimination of leukemic cells as predicted by in vitro experiments. Combination therapy showed almost complete elimination of Ph+ leukemic cells even in the presence of T315I mutation. For Ph- B-ALL/MPAL and T-ALL/MPAL, preliminary in vivo experiments showed additional inhibition of BIRC and BCL-2 resulted in more profound reduction of leukemic cells in BM compared with DEX alone (Combination: 2.1% [0.25-8] of hCD45+ leukemic cells, n=13 vs. DEX alone: 67.2% [59-76.5], n=11, median [IQR], p<0.001).We found targeting anti-apoptotic molecules in combination with DEX and/or TKI eradicated human genetically-diverse ALL, MPAL and CML cells both in vitro and in vivo. Inhibition of BIRC and BCL-2 overcame glucocorticoid resistance of Ph- ALL. Altogether, our results may offer precision medicine approach and contribute to improvement of clinical outcome in treatment-resistant ALL, CML and MPAL. DisclosuresUchida: Sumitomo Dainippon Pharma Co., Ltd.: Honoraria; Otsuka Pharmaceutical Co., Ltd.: Honoraria; Astellas Pharma Inc.: Honoraria; Chugai Pharmaceutical Co., Ltd.: Honoraria; Novartis Pharma Inc.: Honoraria. Harigae: Ono pharma: Honoraria, Other: Subsidies or Donations; Astellas Pharma: Other: Subsidies or Donations; Kyowakirin: Other: Subsidies or Donations; Janssen Pharma: Honoraria; Chugai Pharma: Honoraria; Novartis Pharma: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria.

Updated Results of Pivotal Phase 2 Trials of Olverembatinib (HQP1351) in Patients (Pts) with Tyrosine Kinase Inhibitor (TKI)-Resistant BCR-ABL1 T315I-Mutated Chronic- and Accelerated-Phase Chronic Myeloid Leukemia (CML-CP and CML-AP)

Background: Management of CML with TKIs is constrained by treatment resistance, which portends a poor prognosis particularly in pts failing 2 nd-generation TKIs. Cells with BCR-ABL1 T315I mutations are insensitive to 1 st- and 2 nd -generation TKIs, and compound BCR-ABL1 mutations complicate management with all TKIs (including 3 rd-generation ponatinib). Olverembatinib is a novel, potent, 3 rd-generation, orally active BCR-ABL1 TKI with promising activity against CML , largely irrespective of genotype and has a preliminary favorable safety profile.Methods: HQP1351-CC201 and HQP1351-CC202 are Chinese open, single-arm, multicenter phase 2 trials evaluating the safety and efficacy of olverembatinib in adults with TKI-resistant (BCR-ABL1 T351-mutated) CML-CP and CML-CP, respectively. Olverembatinib was administered at 40 mg orally on alternate days for 28-day cycles. The primary outcome measure is major cytogenetic response (MCyR) and major hematologic response (MaHR) by the end of Cycle 12 in CML-CP and CML-AP, respectively. Secondary study endpoints include : complete CyR (CCyR), complete hematologic response (CHR), major molecular response (MMR), progression-free survival (PFS), overall survival (OS), and safety, including treatment-related adverse events (TRAEs) and serious AEs (SAEs).Results:Baseline characteristicsStudy CC201（CML-CP）On the study cutoff date of August 25,2020, 41 pts were enrolled, of whom 32 (78%) completed ≥ 12 cycles and 21 (51.2%) were male. The median (range) follow-up was 13 (3.1-16.3) months, age was 47 (22-70) years, and interval from CML diagnosis to first olverembatinib dose was 5.31 (0.6-23.2) years. In all, 32 (78.1%) pts had received ≥ 2 prior TKIs and 9 pts withdrew because of progressive disease (PD), intolerance, or consent withdrawal before Cycle 12.Study CC202（CML-AP）On the cut-off date of July 27, 2020, 23 pts were enrolled, of whom 14 (61%) had completed ≥ 12 cycles and 18 (78.3%) were male. The median (range) follow-up was 13.5 (1.4-15.2) months, age was 41 (21-74) years, and interval from CML diagnosis to first olverembatinib dose was 4.96 (0.4-10.2) years. In all, 18 (78.3%) pts had received ≥ 2 prior TKIs, and 11 pts withdrew because of PD or intolerance before Cycle 12.EfficacyStudy CC201（CML-CP）After ≥ 12 treatment cycles in pts without responses at baseline, all 31 (100%) experienced CHR (10 other pts had CHR at baseline); 31/41 (75.6%) MCyR; 28/41 (68.3%) CCyR; and 23/41 (56.1%) MMR (Figure 1). The median time to CHR was 1 (95% CI = 1.0-1.9) month, the median time to MCyR was 2.8 (95% CI = 2.8-5.6) months, and the median time to MMR was 6.5 (95% CI = 2.8 to not reached [NR]) months. At 12 months, the PFS rate was 89.3% (95% CI = 73.9%-95.8%), and the OS was 100% (95% CI = 100%-100%).Study CC202（CML-AP）After ≥ 12 treatment cycles in pts without responses at baseline, 17/23 (73.9%) experienced MaHR (65.2% CHR and 8.7% no evidence of leukemia [NEL]); 12/23 (52.2%) MCyR; 11/23 (47.8%) CCyR; and 9/23 (39.1%) MMR (Figure 1). The median time to MaHR was 2.8 (95% CI = 1.0-4.7) months, the median time to MCyR was 5.6 (95% CI = 2.00-NR) months, and the median time to MMR was 13.1 (95% CI = 5.6-NR) months. At 12 months, the PFS rate was 74.1% (95% CI = 48.2%-88.4%), and the OS was 91.3% (95% CI = 69.5%-97.8%).SafetyStudy CC201（CML-CP）Frequent TRAEs (all grades; grade 3-4; SAEs) included thrombocytopenia (70.7%; 48.8%; 7.3%), followed by anemia (61%; 26.8%; 2.4%), leukopenia (43.9%; 17.1%; 0), and neutropenia (36.6%; 19.5%; 0). Common nonhematologic TRAEs (all grades; G3-4) included skin pigmentation (56.1%, 0%) and elevations in creatine kinase (51.2%, 14.6%), ALT (39%, 2.4%) and AST (34.1%, 0) (Table 1). No deaths occurred.Study CC202（CML-AP）Common TRAEs (all grades; G3-4; SAEs) included thrombocytopenia (73.9%; 56.5%; 17.4%), anemia (60.9%; 34.8%; 13.0%), leukopenia (56.5%; 30.4%; 0), and neutropenia (26.1%; 21.7%; 0). Common nonhematologic AEs included skin pigmentation (69.6%), hypocalcemia (52.2%), proteinuria (47.8%), hypertriglyceridemia (56.5%), hyperphosphatemia (47.8%), hyperuricemia (21.7%), and arthralgia (34.8%), of which most were grade 1-2 (Table 2).Conclusions: Olverembatinib was efficacious and well tolerated when administered as monotherapy in pts with TKI-resistant CP-CML and AP-CML and the BCR-ABL1 T315Imutation. Internal study identifiers: HQP1351-CC201-CC202. ClinicalTrials.gov identifiers: NCT03883087 and NCT03883100. [Display omitted] DisclosuresChen: Ascentage Pharma (Suzhou) Co., Ltd: Current Employment, Current equity holder in publicly-traded company. Niu: Ascentage Pharma (Suzhou) Co., Ltd: Current Employment, Current equity holder in publicly-traded company. Men: Ascentage Pharma (Suzhou) Co., Ltd.: Current Employment, Current equity holder in publicly-traded company. Yang: Ascentage Pharma (Suzhou) Co., Ltd: Current Employment, Current equity holder in publicly-traded company, Other: Leadership and other ownership interests, Patents & Royalties, Research Funding. Zhai: Ascentage Pharma Group Inc.: Current Employment, Current equity holder in publicly-traded company, Other: Leadership and other ownership interests, Patents & Royalties, Research Funding; Ascentage Pharma (Suzhou) Co., Ltd.: Current Employment, Current equity holder in publicly-traded company, Other: Leadership and other ownership interests, Patents & Royalties, Research Funding.

Post Hoc Analysis of Responses to Ponatinib in Patients with Chronic-Phase Chronic Myeloid Leukemia (CP-CML) By Baseline BCR-ABL1 Level and Baseline Mutation Status in the Optic Trial

Post Hoc Analysis of Responses to Ponatinib in Patients with Chronic-Phase Chronic Myeloid Leukemia (CP-CML) By Baseline BCR-ABL1 Level and Baseline Mutation Status in the Optic Trial

Trial in Progress: Phase 1b Bridging Study of the Pharmacokinetics (PK), Safety, and Efficacy of Orally Administered Olverembatinib (HQP1351) in Patients with Refractory Chronic Myeloid Leukemia (CML) and Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia (Ph⁺ ALL)

Background: Management of CML using tyrosine kinase inhibitors (TKIs) is often constrained by treatment failure, which portends a poor prognosis, particularly among patients who fail second-generation TKIs because of resistance. Treatment failure may be due to therapeutic resistance (whether BCR-ABL1 mutation-dependent or independent), intolerance, and/or suboptimal adherence. The BCR-ABL1 T315I (“gatekeeper”) genotype is insensitive to first- and second-generation TKIs, and compound mutations complicate management with all members of the class (including third-generation TKI ponatinib). Olverembatinib (HQP1351) is a novel, potent, orally active BCR-ABL1 TKI with promising activity against CML, including antitumor activity regardless of genotype, and a preliminarily favorable safety profile.Methods: This open-label bridging trial is evaluating the PK, efficacy, and safety of olverembatinib administered orally every other day (QOD) in adults who have chronic-phase, accelerated-phase, or blast-phase CML (CP-CML, AP-CML, or BP-CML) and Ph⁺ ALL, with or without the T315I mutation, and have experienced resistance to or intolerance (including NCI CTCAE v5.0 grade ≥ 2 adverse events) of at least 3 TKIs. Eligible patients have no residual grade ≥ 2 adverse events (other than alopecia or skin pigmentation change) due to prior treatments, a maximum ECOG performance status of 2, and a minimum life expectancy of 3 months. Study participants are being randomly allocated in a 1:1:1 ratio to 3 dose cohorts: 30, 40, or 50 mg of oral olverembatinib QOD over a cycle length of 28 days, with 10 patients per cohort and randomization stratified according to CML phase (CP-CML, AP-CML, or BP-CML) or Ph⁺ ALL and T315I mutational status. Study endpoints comprise the PK profile of olverembatinib at Cycle 1 Day 1 and Day 27; efficacy endpoints of major cytogenetic and hematologic responses; and safety. The recommended phase 2 dose of olverembatinib will be determined based on a comprehensive assessment of PK, safety, and efficacy data in US and Chinese patients. As of July 14, 2021, 14 of 30 patients have been enrolled. Internal study identifier HQP1351-CU-101. Clinicaltrial.gov identifier: NCT04260022. DisclosuresJabbour: Amgen, AbbVie, Spectrum, BMS, Takeda, Pfizer, Adaptive, Genentech: Research Funding. Kantarjian: Aptitude Health: Honoraria; Daiichi-Sankyo: Research Funding; Ascentage: Research Funding; Astra Zeneca: Honoraria; Ipsen Pharmaceuticals: Honoraria; Immunogen: Research Funding; Pfizer: Honoraria, Research Funding; KAHR Medical Ltd: Honoraria; BMS: Research Funding; NOVA Research: Honoraria; Astellas Health: Honoraria; Novartis: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Jazz: Research Funding; AbbVie: Honoraria, Research Funding; Precision Biosciences: Honoraria; Taiho Pharmaceutical Canada: Honoraria. Issa: Kura Oncology: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Syndax Pharmaceuticals: Research Funding. Mukherjee: Genentech: Membership on an entity's Board of Directors or advisory committees; Blueprint Medicines: Membership on an entity's Board of Directors or advisory committees; Acceleron: Membership on an entity's Board of Directors or advisory committees; Partnership for Health Analytic Research: Honoraria; AbbVie: Membership on an entity's Board of Directors or advisory committees; BioPharm: Consultancy; AAMDS in Joint Partnership with Cleveland Clinic Taussig Cancer Institute: Honoraria; Eusa Pharma: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Teaching and Speaking; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Research/Independent Contractor, Research Funding; McGraw Hill: Honoraria, Other: Editor of Hematology Oncology Board Review (ongoing); Bristol-Myers Squibb Co.: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Research/Independent Contractor, Research Funding; Jazz Pharmaceuticals: Research Funding. Oehler: OncLive: Honoraria; Pfizer: Research Funding; Takeda: Consultancy; BMS: Consultancy. Chen: Ascentage Pharma (Suzhou) Co., Ltd: Current Employment, Current equity holder in publicly-traded company. Lu: Ascentage Pharma Group Inc.: Current Employment, Current equity holder in publicly-traded company. Fu: Ascentage Pharma Group Inc: Current Employment, Current equity holder in publicly-traded company. Zhai: Ascentage Pharma (Suzhou) Co., Ltd.: Current Employment, Current equity holder in publicly-traded company, Other: Leadership and other ownership interests, Patents & Royalties, Research Funding; Ascentage Pharma Group Inc.: Current Employment, Current equity holder in publicly-traded company, Other: Leadership and other ownership interests, Patents & Royalties, Research Funding. Yang: Ascentage Pharma (Suzhou) Co., Ltd: Current Employment, Current equity holder in publicly-traded company, Other: Leadership and other ownership interests, Patents & Royalties, Research Funding.

Arsenic Trioxide Suppresses Growth of BCR-ABL1 Positive Cells with “Gatekeeper” or Compound Mutation

Introduction:Chronic myeloid leukemia (CML) and 30% of adult acute lymphatic leukemia (ALL) are characterized by the Philadelphia chromosome (Ph +), having a (9;22) chromosomal translocation. The BCR-ABL1 fusion protein is the hallmark of Ph + leukemia. BCR-ABL1 is characterized by constitutively activated ABL1 tyrosine kinase activity that determines its transformation potential. Tyrosine kinase inhibitors (TKI) have greatly improved the overall prognosis of these diseases. However, unsatisfactory responses in advanced disease stages, resistance and long-term tolerability of BCR-ABL1 inhibitors represent major clinical problems. The most important resistance mechanism against TKIs is the acquisition of point mutations within the BCR-ABL1 kinase domain that impair drug binding, restoring the oncoprotein's constitutively active tyrosine kinase activity. The selection of leukemic clones driven by BCR-ABL1 harboring point mutations, such as the E255K, Y253F/H (P-loop), H396R (activation loop) or the T315I (gatekeeper).Second- and third generation TKIs such as nilotinib, dasatinib, and ponatinib effectively overcome point mutation-mediated resistance. Ponatinib is the only U.S. Food and Drug Administration approved TKI with activity against all known BCR-ABL1 point mutations, including BCR-ABL1-T315I. However, the emergence of compound mutations (two mutations within the same BCR-ABL1 allele) has been linked to resistance to all approved TKIs, including ponatinib, posing a clinical challenge with limited treatment options.The anti-cancer agent arsenic trioxide (ATO) has been used to treat patients with acute promyelocytic leukemia (APL). APL patients respond very well to ATO therapy and achieve complete remission, possibly through induction of apoptosis and differentiation. In addition, it has been demonstrated that combined treatment of ATO with interferon or nilotinib significantly suppressed cell proliferation. However, the potential effects of ATO on BCR-ABL1 mutations and especially on compound mutation is not apparent. This study aimed to investigate the role of ATO in BCR-ABL1 resistant mutations, including compound mutation in Ph + leukemias.Methods:We undertook preclinical evaluation of ATO and compared it with approved TKIs e.g. imatinib, nilotinib, dasatinib, ponatinib and ABL inhibitor asciminib, in vitro models of CML and primary patient-derived long term cultures (PD-LTC) of Ph + ALL patients with or without mutation. The effects on mutational resistance were investigated in Ba/F3 cells expressing BCR-ABL1 with T315I mutation and T315I-E255K mutation. For non-mutational resistance, we used PD-LTCs from Ph + ALL patients with different levels of non-mutational drug resistance. Cell proliferation was assessed by XTT.Results:ATO efficiently inhibited the growth of all PD-LTCs in cellular assays at dosages of 200-500nM. It also suppressed the growth of Ph + PD-LTC with non- mutational resistance (BV) and the BCR-ABL1-T315I positive PD-LTC (KO) in this dosage range. In all modelsWe treated Ba/F3 cells expressing native BCR-ABL1, BCR-ABL1-T315I mutation and BCR-ABL1-T315I-E255K (compound mutation) with increasing concentrations of imatinib (250, 500 and 1000nM), nilotinib (100, 200 and 400nM), dasatinib (10, 25 and 50nM), ponatinib (10, 50 and 100nM), asciminib) (ABL allosteric inhibitor) (5, 10 and 20nM) and ATO (0.5, 1.0 and 2.0 µM). We found that all the inhibitors significantly inhibited the proliferation of Ba/F3 cells expressing wild type BCR-ABL1 in a dose-dependent manner. In contrast, the growth of Ba/F3 cells expressing BCR-ABL1-T315I was inhibited by increasing concentration of ponatinib, asciminib and ATO. ATO potently inhibited the most challenging mutation (T315I-E255K) with a clinically relevant concentration (IC50 250nM). All approved ABL kinase inhibitors (AKIs) and allosteric inhibitors like asciminib could not inhibit the growth of Ba/F3 cells expressing BCR-ABL1 compound mutation.Conclusions:Our findings indicate that ATO significantly suppressed the proliferation of cells expressing non-mutated BCR-ABL1, single and compound mutated BCR-ABL1. These results support including ATO in treating patients with Ph + leukemias having BCR-ABL1 resistant single or compound mutati DisclosuresOttmann: Novartis: Honoraria; Amgen: Honoraria, Research Funding; Celgene/BMS: Honoraria, Research Funding; Fusion: Honoraria; Incyte: Honoraria, Research Funding.

Discovery of novel BCR-ABL PROTACs based on the cereblon E3 ligase design, synthesis, and biological evaluation.

Protein degradation is a promising strategy for drug development. Proteolysis-targeting chimeras (PROTACs) hijacking the E3 ligase cereblon (CRBN) exhibit enormous potential and universal degradation performance due to the small molecular weight of CRBN ligands. In this study, the CRBN-recruiting PROTACs were explored on the degradation of oncogenic fusion protein BCR-ABL, which drives the pathogenesis of chronic myeloid leukemia (CML). A series of novel PROTACs were synthesized by conjugating BCR-ABL inhibitor dasatinib to the CRBN ligand including pomalidomide and lenalidomide, and the extensive structure-activity relationship (SAR) studies were performed focusing on optimization of linker parameters. Therein, we uncovered that pomalidomide-based degrader 17 (SIAIS056), possessing sulfur-substituted carbon chain linker, exhibits the most potent degradative activity invitro and favorable pharmacokinetics invivo. Besides, degrader 17 also degrades a variety of clinically relevant resistance-conferring mutations of BCR-ABL. Furthermore, degrader 17 induces significant tumor regression against K562 xenograft tumors. Our study indicates that 17 as an efficacious BCR-ABL degrader warrants intensive investigation for the future treatment of BCR-ABL+ leukemia.

Activated na\xefve \u03b3\u03b4 T cells accelerate deep molecular response to BCR-ABL inhibitors in patients with chronic myeloid leukemia

Tyrosine kinase inhibitors (TKIs) that target BCR-ABL are the frontline treatments in chronic myeloid leukemia (CML). Growing evidence has shown that TKIs also enhance immunity. Since gamma-delta T (γδT) cells possess the potent anticancer capability, here we investigated the potential involvement of γδT cells in TKI treatments for CML. We characterized γδT cells isolated from chronic-phase CML patients before and during TKI treatments. γδT expression increased significantly in CML patients who achieved major molecular response (MMR) and deep molecular response (DMR). Their Vδ2 subset of γδT also expanded, and increased expression of activating molecules, namely IFN-γ, perforin, and CD107a, as well as γδT cytotoxicity. Mechanistically, TKIs augmented the efflux of isopentenyl pyrophosphate (IPP) from CML cells, which stimulated IFN-γ production and γδT expansion. Notably, the size of the IFN-γ+ naïve γδT population in TKI-treated CML patients was strongly correlated with their rates to reach DMR and with the duration on DMR. Statistical analysis suggests that a cutoff of 7.5% IFN-γ+ naïve subpopulation of γδT in CML patients could serve as a determinant for MR4.0 sustainability. Our results highlight γδT cells as a positive regulator for TKI responses in CML patients.

Is COVID-19 less severe in CML patients than in those with other haematological cancers?

Is COVID-19 less severe in CML patients than in those with other haematological cancers?

Dasatinib-induced diffuse alveolar hemorrhage

The BCR-ABL tyrosine kinase inhibitor dasatinib is a potent treatment for chronic myeloid leukemia (CML). However, it is associated with pulmonary toxicities. Commonly reported dasatinib related pulmonary toxicities include pleural effusion, lung parenchymal abnormalities, and pulmonary hypertension. Diffuse alveolar hemorrhage (DAH) during treatment with dasatinib is very rare. To the best of our knowledge there are only two cases reported. Here we report a 57-year-old Caucasian woman who developed acute hypoxic respiratory failure while on dasatinib for treatment of CML. She was diagnosed with DAH suspected to be secondary to dasatinib, after other common etiologies were ruled out. There was full recovery after stopping dasatinib and treatment with corticosteroids.&#x0D; Keywords: Dasatinib, pulmonary toxicity, diffuse alveolar hemorrhage, chronic myeloid leukemia

JKST6, a novel multikinase modulator of the BCR-ABL1/STAT5 signaling pathway that potentiates direct BCR-ABL1 inhibition and overcomes imatinib resistance in chronic myelogenous leukemia

Chronic myelogenous leukemia (CML) is a hematological malignancy that highly depends on the BCR-ABL1/STAT5 signaling pathway for cell survival. First-line treatments for CML consist of tyrosine kinase inhibitors that efficiently target BCR-ABL1 activity. However, drug resistance and intolerance are still therapeutic limitations in Ph+ cells. Therefore, the development of new anti-CML drugs that exhibit alternative mechanisms to overcome these limitations is a desirable goal. In this work, the antitumoral activity of JKST6, a naphthoquinone-pyrone hybrid, was assessed in imatinib-sensitive and imatinib-resistant human CML cells. Live-cell imaging analysis revealed JKST6 potent antiproliferative activity in 2D and 3D CML cultures. JKST6 provoked cell increase in the subG1 phase along with a reduction in the G0/G1 phase and altered the expression of key proteins involved in the control of mitosis and DNA damage. Rapid increases in Annexin V staining and activation/cleavage of caspases 8, 9 and 3 were observed after JKST6 treatment in CML cells. Of interest, JKST6 inhibited BCR-ABL1/STAT5 signaling through oncokinase downregulation that was preceded by rapid polyubiquitination. In addition, JKST6 caused a transient increase in JNK and AKT phosphorylation, whereas the phosphorylation of P38-MAPK and Src was reduced. Combinatory treatment unveiled synergistic effects between imatinib and JKST6. Notably, JKST6 maintained its antitumor efficacy in BCR-ABL1-T315I-positive cells and CML cells that overexpress BCR-ABL and even restored imatinib efficacy after a short exposure time. These findings, together with the observed low toxicity of JKST6, reveal a novel multikinase modulator that might overcome the limitations of BCR-ABL1 inhibitors in CML therapy.

The cure of leukemia through the optimist's prism.

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

Ponatinib Exerts an Inhibitory Effect on Collagen-induced Platelet Aggregation and Generation of Coated-Platelets

BCR-ABL tyrosine kinase inhibitors (TKIs) are exceptionally effective drugs in the treatment of chronic myeloid leukemia, nevertheless, TKIs have also an effect on platelets. We aimed to investigate the effect of a third-generation TKI, ponatinib on platelet functions. Collagen-induced platelet aggregation and coated-platelet formation were examined using in vitro and in ex vivo samples of patients on ponatinib therapy. In platelet rich plasma of healthy volunteers, ponatinib at a supra-therapeutic concentration (1,000 nM) significantly impaired collagen induced platelet aggregation (p≤0.01) and reduced the formation of coated-platelets at 150 nM ponatinib concentration (p≤0.05). In addition, upon glycoprotein VI (GPVI) receptor activation, a significantly lower percentage of PAC1 binding platelets (p≤0.05) was observed at 1,000 nM final concentration of ponatinib. Platelets, isolated from patients on ponatinib therapy showed impaired collagen elicited aggregation response, already in pre-dose samples compared to healthy donors. The therapeutic concentration of ponatinib impairs platelet activation processes elicited by GPVI receptor agonists.

Combination of tyrosine kinase inhibitors and the MCL1 inhibitor S63845 exerts synergistic antitumorigenic effects on CML cells

Tyrosine kinase inhibitor (TKI) treatment has dramatically improved the survival of chronic myeloid leukemia (CML) patients, but measurable residual disease typically persists. To more effectively eradicate leukemia cells, simultaneous targeting of BCR-ABL1 and additional CML-related survival proteins has been proposed. Notably, several highly specific myeloid cell leukemia 1 (MCL1) inhibitors have recently entered clinical trials for various hematologic malignancies, although not for CML, reflecting the insensitivity of CML cell lines to single MCL1 inhibition. Here, we show that combining TKI (imatinib, nilotinib, dasatinib, or asciminib) treatment with the small-molecule MCL1 inhibitor S63845 exerted strong synergistic antiviability and proapoptotic effects on CML lines and CD34+ stem/progenitor cells isolated from untreated CML patients in chronic phase. Using wild-type BCR-ABL1-harboring CML lines and their T315I-mutated sublines (generated by CRISPR/Cas9-mediated homologous recombination), we prove that the synergistic proapoptotic effect of the drug combination depended on TKI-mediated BCR-ABL1 inhibition, but not on TKI-related off-target mechanisms. Moreover, we demonstrate that colony formation of CML but not normal hematopoietic stem/progenitor cells became markedly reduced upon combination treatment compared to imatinib monotherapy. Our results suggest that dual targeting of MCL1 and BCR-ABL1 activity may efficiently eradicate residual CML cells without affecting normal hematopoietic stem/progenitors.

Effects of the FOXO3a rs 4946936 Gene Polymorphism on the FOXO3a Transcription Factor in Chronic Granulocytic Leukemia Patients

Introduction : FOXO3a has an important role in the maintenance of leukemic stem cells. BCR-ABL inhibition therapy by TKI dasatinib aims to reduce the phosphorylation of the transcription factor FOXO3a, promote localization of FOXO3a in the nucleus and restore transcriptional activity. However, some studies showed that the TKI dasatinib, in addition to increase the relocation of Foxo3a to the intranuclear, also increase the expression of CDKN1c/p57 and Bcl6 genes that became the down target for Foxo3a intra nucleus ATM. Therefore, current therapy is mostly directed at personalized therapy (personalized medicine). The aim of this study was to investigate the effect of the FOXO3a rs4946936 gene polymorphism on the Foxo3a transcription factor in chronic granulocytic leukemia patients treated with Imatinib mesylate.&#x0D; Method : This is a cross-sectional study in patients with chronic granulocytic leukemia (CGL) with positive Bcr-ABL. The aim was to prove the effect of the FOXO3a gene polymorphism rs4946936 on the Foxo3a transcription factor. The data analysis test used was a correlation test and a regression test.&#x0D; Result : There were three polymorphisms of the FOXO3a gene, namely CC polymorphism, TC polymorphism, and TT polymorphism with a p-value of 0.026 and an r of 0.287, so it can be concluded that there was a significant correlation between the FOXO3a gene polymorphism and the Foxo3an transcription factor with a sufficient correlation value. In the regression test between the FOXO3a gene polymorphisms and the transcription factor FOXO3a, the p value was 0.029 and the B value was -0.294. This means that it has a negative and significant effect on the Foxo3a transcription factor variable.&#x0D; Conclusion : There was a significant correlation between the gene polymorphism FOXO3a rs4946936 and the transcription factor FOX3a. The FOXO3a gene polymorphism of the TT genotype had a negative effect on the FOXO3a transcription factor. The TT gene in the FOXO3a gene polymorphism was the most effective in reducing the FOXO3a transcription factor.