BCR-ABL Mutations Research Articles

Effectiveness of Second-Line (2L) Tyrosine Kinase Inhibitor (TKI) Therapy after Resistance or Intolerance to a Prior TKI in Patients with Philadelphia Chromosome-Positive Chronic Myeloid Leukemia in Chronic Phase (Ph+ CML-CP)

Effectiveness of Second-Line (2L) Tyrosine Kinase Inhibitor (TKI) Therapy after Resistance or Intolerance to a Prior TKI in Patients with Philadelphia Chromosome-Positive Chronic Myeloid Leukemia in Chronic Phase (Ph+ CML-CP)

Sequential Treatments in Chronic Phase Chronic Myeloid Leukemia (CML) Patients without Optimal Response after Frontline Nilotinib or Dasatinib: An Italian CML Campus Study

INTRODUCTION: Frontline therapy with second generation (2G) tyrosine-kinase inhibitors (TKIs) in chronic phase (CP) chronic myeloid leukemia (CML) patients demonstrated higher efficacy as compared to imatinib, with less patients experiencing treatment failure and progression to advanced disease. However, limited information are currently available on the management and outcome of those CML pts not achieving an optimal response to first-line treatment with a 2G-TKI. AIM: To describe the clinical outcome of CP CML patients without an optimal response to a frontline 2G-TKI that switched to alternative TKIs. METHODS: We performed a retrospective analysis in 22 Centers cooperating within the Italian CML Campus Project. Main inclusion criteria were: 1) diagnosis of CP-CML after 2010; 2) first-line treatment with a 2G-TKI; 3) switch to second-line treatment in case of non-optimal response (either following ELN recommendations or as for clinical practice); 4) CML in CP at the time of switching to second-line treatment. The main exclusion criteria were a switch to second-line treatment for intolerance or for low adherence to therapy. RESULTS: The main findings of this analysis are summarized in the table. Seventy-one pts meeting the inclusion/exclusion criteria were identified; the median age of pts at CML diagnosis was 46 (21-80) years. Sokal risk score was low, intermediate, and high in 24 (34%), 30 (42%), and 17 (24%) pts, respectively. First-line treatment was performed with nilotinib in 47 (66%) pts and dasatinib in 24 (34%) pts. According to the ELN 2020 recommendations, 51 (72%) pts fulfilled the criteria for "failure" and 20 (28%) pts those for "warning". BCR-ABL mutations were identified in 12 of 65 (18%) evaluable pts (T315I in 1 pt). Additional chromosomal abnormalities in Ph+ cells were identified in 6 of 54 (11%) evaluable pts. Second-line treatment was started after a median time of 16 (4-72) months, with ponatinib (40 pts, 56%), dasatinib (21 pts, 30%), nilotinib (7 pts, 10%), or bosutinib (3 pts, 4%). Median follow-up from start of second-line treatment was 25 (2-90) months. Best response to second-line treatment was MR2 in 18 (25%) pts and MR3 in 37 (51%) pts. Nineteen (27%) pts (13 for resistance and 6 for intolerance) switched to third-line treatment (ponatinib, 11 pts; nilotinib, 3 pts; dasatinib, 4 pts; imatinib, 1 pt), after a median time of 8 (1-72) months. Mutations were identified in 2 of 17 evaluable pts, and both patients harbored a T315I mutation. MR3 was reached by 9 (47%) of these pts. Lastly, 7 (10%) pts switched (6 for resistance and 1 for intolerance) to fourth-line treatment (asciminib, 4pts; dasatinib, 2 pts, nilotinib, 1 pt). Overall, 44 (62%) patients reached with sequential TKI treatments a MR3 (31/51 pts among "failures"; 13/20 among "warnings"). Allogeneic stem-cell transplantation (SCT) was performed in 7 (9.5%) pts (6 among "failures"), after a median time of 20 (15-60) months from CML diagnosis. Progression to advanced phase occurred in 2 (3%) pts; both pts previously met the ELN2020 "failure" criteria. Estimated 4-y PFS was 92.5%. Death occurred in 3 (4%) pts (1 after progression to blast phase, 2 for cardiovascular adverse events). Estimated 4-y OS was 93.7% CONCLUSION Our findings show that CP-CML patients not achieving an optimal response to frontline 2G-TKI therapy, despite a complex management, still have a favorable prognosis and survival due to the availability of both multiple TKI options and SCT. Figure Disclosures Gugliotta: Novartis: Honoraria; Incyte: Honoraria; Pfizer: Honoraria. Galimberti:Novartis: Speakers Bureau; Incyte: Honoraria. Abruzzese:Pfizer: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Bms: Honoraria; Incyte: Consultancy, Membership on an entity's Board of Directors or advisory committees. Bocchia:CELGENE: Honoraria; Incyte: Honoraria. Castagnetti:Bristol Myers Squibb: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Incyte: Consultancy, Honoraria. Di Raimondo:Amgen, Takeda, Novartis: Honoraria; Janssen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; GILEAD, Incyte: Research Funding; GSK: Consultancy, Honoraria; Takeda: Consultancy, Honoraria; Amgen: Consultancy, Honoraria. Cavo:Jannsen, BMS, Celgene, Sanofi, GlaxoSmithKline, Takeda, Amgen, Oncopeptides, AbbVie, Karyopharm, Adaptive: Consultancy, Honoraria. Rosti:Bristol-Myers Squibb: Speakers Bureau; Incyte: Speakers Bureau; Novartis: Speakers Bureau; Pfizer: Research Funding, Speakers Bureau. Foà:Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Membership on an entity's Board of Directors or advisory committees; Novartis: Speakers Bureau; Incyte: Speakers Bureau. Saglio:Pfizer: Research Funding; Ariad: Research Funding; Roche: Research Funding; Incyte: Research Funding; Bristol-Myers Squibb: Research Funding; Novartis: Research Funding. Breccia:Abbvie: Consultancy; Pfizer: Consultancy, Honoraria; Incyte: Consultancy, Honoraria; Bristol-Myers Squibb/Celgene: Consultancy, Honoraria; Novartis: Consultancy, Honoraria.

Safety and Efficacy Profile of Asciminib As Treatment in Chronic Myeloid Leukemia Patients after Several Tyrosine-Kinase Inhibitors Failure

Introduction: Asciminib is a new BCR-ABL1 inhibitor that differs from previous tyrosine kinase inhibitors (TKIs) in that it does not bind to the ATP-binding site of the kinase. Data from different clinical trials has shown an adequate safety and efficacy profile in chronic myeloid leukemia (CML) patients failing previous TKIs. However, no findings have been communicated in real life experience. The aim of our study is to present first results of asciminib in CML patients failing previous TKIs under the current compassionate use program. Methods: We retrospectively collected data from 31 patients treated with asciminib in 25 centers under compassionate use program. Data collecting was performed between October 2018 and June 2020. Patients baseline characteristics are shown in table 1. Most patients were heavily pretreated with 28 patients receiving 3 or more TKIs previous to asciminib. Eleven patients (35.5%) had been treated with ponatinib at some point throughout the disease. Twelve patients showed BCR-ABL1 mutations (only 1 case with T315I mutation). Switch to asciminib was due to intolerance in 22 patients and due to resistance in the remaining 9. Median dose of asciminib was 80mg per day (40mg every 12 hours). Treatment responses were evaluated according to European Leukemia Net recommendations. Data compilation and analysis were performed with REDCap Software and IBM SPSS (Version 25.0). Results: Median time on asciminib for the entire cohort was 35 weeks. Regarding toxicities, 13 patients (42%) experienced mild extra-hematological side effects (grade 1-2) being the most frequent fatigue (19%), joint pain (16%) and nausea (9%). Four patients (12,9%) showed severe (grade 3-4) extra-hematological events: fatigue, hepatotoxicity, hypertension and pericardial effusion (1 patient each). Three patients (9,7%) suffered from grade 4 thrombocytopenia, 2 of them associating grade 4 neutropenia. All toxicities according to previous TKIs adverse effects as well as cross-intolerance data is shown in table 2. Dose reduction had to be carried out in 9 patients (29%), 7 of those with temporary treatment interruptions; most owing to hematological adverse effects. In terms of efficacy (Graph 1), probability of reaching or at least maintaining previous response was 100%, 61.3% and 35.5% for complete hematological response (CHR), complete cytogenetic response (CCyR) and major molecular response (MMR), respectively. Regarding probabilities to improve previous responses, rates of CCyR and MMR were, respectively, 22,2% (2/9) and 22,2% (2/9) for resistant patients and 44% (4/9) and 62,5%. (10/16) for intolerant group. Amid the 11 patients previously treated with ponatinib, 3 patients (27,3%) showed improvement of response achieving at least MMR, 2 of them from the TKI-intolerant group and 1 from the TKI-resistant group. The median follow-up time was 40 weeks, after which 27 patients (87.1%) continued with asciminib. Treatment cessation happened in 2 patients due to progression to blastic phase and in 2 patients due to lack of efficacy. No patients discontinued due to side effects. Conclusion: The data presented, similar to that known from clinical trials, supports the use of asciminib in routine clinical practice in CML patients failing to previous TKIs. Disclosures Garcia-Gutiérrez: Novartis: Consultancy, Other: Travel, Accommodation, Expenses, Research Funding; Bristol-Myers Squibb: Consultancy, Other: Travel, Accommodation, Expenses, Research Funding; Pfizer: Consultancy, Other: Travel, Accommodation, Expenses, Research Funding; Incyte: Consultancy, Other: Travel, Accommodation, Expenses, Research Funding.

Exposure-Response (E-R) Analysis of Olverembatinib (HQP1351) in Chinese Patients with Chronic Myeloid Leukemia (CML)

Introduction Olverembatinib (HQP1351), a third-generation BCR-ABL1 inhibitor, has been rationally developed to treat patients with CML that is refractory to or intolerant of tyrosine kinase inhibitors (TKIs), including acquired drug-resistant mutations. HQP1351 is effective against a broad spectrum of BCR-ABL1 mutations, including T315I, which confers resistance against all first- and second-generation TKIs. A phase I dose escalation study (SJ-0002) was conducted in Chinese patients with TKI-resistant/refractory CML. A total of 101 patients with CML, including 87 with chronic-phase CML (CML-CP) and 14 with accelerated-phase CML (CML-AP) have been enrolled in 11 dose escalation/expansion cohorts ranging from 1 mg to 60 mg HQP1351 every other day (QOD). The maximum tolerated dose (MTD) has been established as 50 mg, and the recommended phase II dose (RP2D) as 40 mg, QOD. To support selection of RP2D, we performed population pharmacokinetic (PK), exposure-efficacy, and exposure-safety analyses based on data from clinical study SJ-0002. Methods The population PK analysis was performed on the plasma drug concentration data from 65 patients. Exposure-efficacy analysis was performed on the primary clinical endpoint: major cytogenetic response (MCyR) at 6 months in 89 patients with CML. These included 78 individuals with CML-CP and 11 with CML-AP. Using a cell-life-span model in 101 patients with CML, we also performed an exposure-safety analysis on the most frequent adverse event: reduction in platelet count. Results Population PK analysis demonstrated that HQP1351 PK was best described by a two-compartment model with first-order absorption and first-order elimination. Total bilirubin, aspartate aminotransferase, and albumin were found to be significant covariates affecting the PK of HQP1351. In the exposure-response analyses, average dose was selected as the exposure measurement over average concentration at steady state (Cavg,ss) and average trough concentration at steady state (Ctrough,ss) based on the model performance. Exposure-efficacy analysis showed a clear E-R relationship, with the increased probability of achieving MCyR at 6 months with increasing average HQP1351 dose (Figure 1). The highest MCyR rate with HQP1351 was achieved at the MTD (50 mg QOD). In the exposure-safety analysis, there was a significant dose response relationship between average HQP1351 dose and incidence rate of grade 3 or greater (G3⁺) platelet count reductions (Figure 2). Conclusions E-R analyses of HQP1351 in Chinese patients with CML demonstrated a clear positive relationship between average HQP1351 dose and both efficacy and the probability of G3⁺ platelet count reductions. The results of E-R modeling and simulation support the RP2D of 40 mg QOD because it achieved a high rate of MCyR with manageable risk of G3⁺ platelet count reductions. Disclosures Lu: Ascentage Pharma Group: Current Employment, Current equity holder in publicly-traded company. Wang:Ascentage Pharma Group: Current Employment. Xu:Ascentage Pharma Group: Current Employment. Men:Ascentage Pharma Group: Current Employment. Xie:Ascentage Pharma Group: Current Employment. Chen:Ascentage Pharma Group: Current Employment. Niu:Ascentage Pharma Group: Current Employment. Yang:Ascentage Pharma (SuZhou) Co., Ltd: Current Employment, Current equity holder in publicly-traded company, Other: Leadership and other ownership interests. Zhai:Ascentage Pharma (SuZhou) Co., Ltd: Current Employment, Current equity holder in publicly-traded company, Other: Leadership and other ownership interests.

A Patient with Chronic Lymphocytic Leukemia, Chronic Myeloid Leukemia and Multiple Myeloma

Chronic lymphocytic leukemia (CLL) is an indolent lymphoproliferative disorder and is manifested by progressive accumulation of B cells in the blood, bone marrow and lymphatic tissues. Chronic Myeloid Leukemia (CML) is a clonal myeloproliferative disorder characterized by the presence of all the stages of myeloid development in the peripheral blood, and it is believed to be driven by the aberrant protein tyrosine kinase, a product of the mutant BCR-ABL1 gene.Multiple Myeloma (MM) is characterized by the accumulation of clonal plasmcells in the bone marrow with skeletal lesions, anemia, hypercalcemia and renal failure. Our patient is a 78 year-old man. In 2014 diagnosis of CLL and monoclonal gammopathy of undetermined significance (MGUS).At diagnosis: HB 13.5 g/dl; normal renal function;calcium 8.7 mg/dl;IgG 1678 mg/dl,serum immunoelectrophoresis: IgG kappa, Bence Jones kappa; total protein 7.5 g/dl, beta1 6,5%, beta2 24,1%;peripheral blood immunophenotyping showed CLL, FISH:negative;Cariotype: 46, XY; RX skeleton: positive for osteolytic lesions, total body TC scan: adenopathies of 18 mm and 15 mm at bilateral axillary level, norma spleen, adenopathy of 22 cm in the left obturator iliac region; presence of left hip prosthesis; bone marrow biopsy: localization by low-grade plasmacytoma.No CLL.The patient was only observed until April 2015, when there was a presence of myelocytes and metamyelocytes in peripheral blood and an increased spleen (18 cm). So he performed : bone marrow aspirate: diagnosis of CML (Sokal Score: 1,34 H; Eutos Score: 60 L, Hasford Score 1488,5);bone marrow biopsy: suggestive for a myeloproliferative disease (CML), MGUS with a modest lymphoid B component,BCR-ABL: 60;FISH: pathological presence of double fusion signal of the ABL1 and BCR loci in 209 of 271 interphase nuclei examined (77%).The patient started therapy with Imatinib, 400mg/die until July 2015, on the basis of the good response to treatment and the progressive increase of the M component that confirmed the progression to MM: Hb 9.1 g/dL, creatinine 1,1 mg/dl;calcium 10,5 mg/dl;total protein: 8,6 g/dl, gamma 48.02% (CM 4 gr); IgG 3536 mg/dl, cariotype: male with t (9; 22) and Philadelphia chromosome (25%);BCR-ABL: 14,32; bone marrow aspirate: plasmacells 15%;bone marrow biopsy: intermediate-interstitial plasmacytoma, CLL / lymphoma; RMN whole body: hyperintensity at the level of the seventh right rib; PET: osteolytic lesions of the side arch tenth right rib, right iliac bone, left iliac region, right tibia third diaphyseal.RX right hemithorax: osteolytic area at the level of the seventh right rib. So the patient started treatment with Bortezomib, Desamethasone, Alkeran (total 7 cycles).On March 2016, he performed a radiography that showed many osteolytic areas of 45 mm on third distal femur, third proximal and intermediate tibia, third proximal and third distal of fibula.A second PET documented a further MM progression due to new bone localizations and a left tibia biopsy showed localization disease. Radiotherapy colleagues have ruled out the usefulness of a radiation therapy program in consideration of the cerebral damage risk. On June 2016 the patient started a treatment with Lenalidomide for 15 days, interspersed by Glivec, maintaining the disease stable. In September 2017 he developed diplopia and with a nasal surgery, only inflammatory tissue was exported. A revision of the material confirmed plasmacytoma localization. In the same period appearance of a right gluteus sore treated initially with surgical dressing.As blood tests revealed increase of paraprotein levels, bone marrow biopsy resulted negative to myeloma and lymphoma diseases, instead a gluteal skin biopsy revealed plasmacytoma. It was decided to treat cerebral localization due to diplopia and peripherical paralysis. Radiotherapy was started on April 2018 (18 sessions). Bone marrow aspirate test showed plasmacells 15%, BCR-ABL dosage: 213,87, M component increase(5gr), IgG 4440 mg/dl, creatinine and serum calcium: normal. Due to disease progression, a rescue chemotherapy was started according to PAD protocol. After 4 cycles, a bone marrow aspirate documented the presence of plasmacells equal to 80%.The cytogenetic study confirmed the presence of a complex karyotype. So the patient started therapy with Daratumumab, Lenalidomide and Desamethasone which is currently ongoing with an excellent hematological and clinical response Disclosures Ciolli: Janssen: Honoraria; Abbvie: Research Funding.

Abstract IA20: Aberrant leukemic developmental hierarchies and MRD-specific targeting informed by single-cell biophysical and molecular profiling

Abstract Targeted inhibitors of essential oncogenic kinases induce high rates of clinical response but cure few patients due to the persistence of minimal residual disease (MRD). BCR-ABL mutant leukemias are a classic example of this paradigm where patients usually achieve deep remissions followed by near inevitable relapses. Multiple factors have been shown to influence how an individual patient’s leukemic cells will navigate treatment including differentiation state, mutational background, and communication with the microenvironment. Here, we use BCR-ABL-rearranged acute lymphoblastic leukemia (BCR-ABL ALL) to interrogate cell-autonomous features leading to therapeutic resistance using low-input single-cell assays. Specifically, we use a combination of primary samples and PDX models to dissect aberrant developmental hierarchies and monitor leukemic cell transcriptional and biophysical phenotype at pretreatment, MRD, and relapse. Using machine learning, we relate malignant B cells to normal development, allowing us to define leukemic developmental programs and demonstrate that these have consequences for the time to progression as well as the genetic alterations seen at relapse. Further, we determine that there are unique biophysical features tied to leukemic developmental states and that these integrative properties co-evolve with transcriptional state over the course of treatment. Finally, we demonstrate in PDX studies that it may be possible to intercept relapse by targeting specific features of MRD cells. Together, these data suggest that significant developmental hierarchies exist in ALL, tumor subpopulations can be identified directly within MRD, and their phenotypic and molecular characterization can be exploited to therapeutic effect. Citation Format: Peter S. Winter, Andrew Navia, Haley Strouf, Mahnoor Mirza, Jennyfer Galvez-Reyes, Nolawit Mulugeta, Laura Bilal, Nezha Senhaji, Peter Dennis, Catharine S. Leahy, Kay Shigemori, Foster Powers, Alejandro Gupta, Nicholas Calistri, Alex Van Scoyk, Kristen Jones, Huiyun Liu, Kristen E. Stevenson, Robert Kimmerling, Mark Stevens, David M. Weinstock, Scott R. Manalis, Mark A. Murakami, Alex K. Shalek. Aberrant leukemic developmental hierarchies and MRD-specific targeting informed by single-cell biophysical and molecular profiling [abstract]. In: Proceedings of the AACR Virtual Special Conference on Tumor Heterogeneity: From Single Cells to Clinical Impact; 2020 Sep 17-18. Philadelphia (PA): AACR; Cancer Res 2020;80(21 Suppl):Abstract nr IA20.

Frequency of coexistence and kinetics of the BCR-ABL1 transcript level and allele burden of JAK2V617F and CALR Type 1, 2 gene mutations in patients with chronic myeloid leukemia

Introduction. The pathogenesis of myeloproliferative neoplasms is associated with the chimeric gene BCR-ABL1 or with one of the driver mutations in the genes JAK2, MPL and CALR (Calreticulin). However, the classifi cation of the World Health Organization lists no myeloid neoplasms with more than one driver genetic abnormality. Aim. To search for mutations in the genes JAK2, MPL and CALR in patients with BCR-ABL1-positive chronic myeloid leukemia (CML), as well as to evaluate the kinetics of the discovered mutations during tyrosine kinase inhibitor (TKI) therapy. Materials and methods. mRNA and DNA samples isolated from blood and bone marrow cells of 567 CML patients, who underwent periodic monitoring of the BCR-ABL1 transcript level over the 2012–2019 period were included in the study The BCR-ABL1 transcript level was determined using a highly sensitive quantitative real-time polymerase chain reaction. The mutations JAK2V617F and MPLW515L/K were detected using real-time quantitative allele-specifi c polymerase chain reaction. Mutations in the CALR gene were investigated using fragment analysis followed by Sanger sequencing. Results. The combination of the BCR-ABL1, JAK2 and CALR gene mutations among CML patients receiving TKIs was 1.23 % (7/567). Out of these, the combination of BCR-ABL1 with JAK2V617F and the combination of BCR-ABL1 with CALR gene mutations were detected in 0.88 % (5/567) and 0.35 % (2/567) of cases, respectively. During TKI therapy, in 5 out of 7 patients, the level of BCR-ABL1 reached major molecular response (MR). In 4 of these patients, the therapy was discontinued. These patients are currently in molecular remission. In the remaining 2 patients, major MR was not achieved, despite the use of second-generation TKI preparations. Conclusions. The combination of the BCR-ABL1 chimeric gene with gene mutations Jak2 or CALR was a rare event and amounted to 0.88 and 0.35 % of cases, respectively. The combination of BCR-ABL1 with Jak2V617F and CALR mutations does not always impede the achievement of major MR.

Illuminating novel biological aspects and potential new therapeutic approaches for chronic myeloproliferative malignancies.

This review reflects the presentations and discussion at the 14th post-American Society of Hematology (ASH) International Workshop on Chronic Myeloproliferative Malignancies, which took place on the December 10 and 11, 2019, immediately after the 61st ASH Annual Meeting in Orlando, Florida. Rather than present a resume of the proceedings, we address some of the topical translational science research and clinically relevant topics in detail. We consider how recent studies using single-cell genomics and other molecular methods reveal novel aspects of hematopoiesis which in turn raise the possibility of new therapeutic approaches for patients with myeloproliferative neoplasms (MPNs). We discuss how alternative therapies could benefit patients with chronic myeloid leukemia who develop BCR-ABL1 mutant subclones following ABL1-tyrosine kinase inhibitor therapy. In MPNs, we focus on efforts beyond JAK-STAT and the merits of integrating activin receptor ligand traps, interferon-α, and allografting in the current treatment algorithm for patients with myelofibrosis.

CML-366: Baseline Cytogenetic Response Level Impact on Survival of Chronic Phase Chronic Myeloid Leukemia Patients Treated with Tyrosine Kinase Inhibitors as Third-Line Therapy: Real-World Data in Five Russian Centers

Context Tyrosine kinase inhibitors in third-line therapy (TKI-3L) in chronic-phase chronic myelogenous leukemia (CP CML) is effective in a portion of patients. Meanwhile, it is unclear which patients may benefit from TKI-3L. Objective To identify the factors affecting the outcome of TKI-3L therapy in CP CML. Design A retrospective study was conducted in five centers of St. Petersburg and Leningrad Region in 2019. All CP CML patients who ever obtained TKI-3L in these centers were included, except patients (pts) with complete cytogenetic response (CCyR). Results Seventy-three pts (male=26) with baseline median age 51 (25–88) were included in the study. There were 51 (70%) pts without any CyR, including 27 (37%) cases without complete hematologic response in baseline. For other patients, the best baseline cytogenetic response was minimal or minor (mmCyR) in 12 (16%) and partial (PCyR) in 10 (14%). BCR-ABL mutations were detected in 30/73 (42%) cases at any time before TKI-3L. Reasons for switching to TKI-3L were resistance in 56 (77%) or intolerance in 17 (23%). Dasatinib, Nilotinib, Bosutinib, or Ponatinib were used as TKI-3L in 43 (59%), 18 (25%), 9 (12%), and 3 (4%) pts, respectively. The median time of TKI-3L treatment duration was 15 (1–120) months. CCyR was achieved in 8/51 (16%) and 14/22 (64%) pts without CyR and with mmCyR/PCyR, respectively(p=0.001). CCyR subsequently had been lost 5/8 (62.5%) and 5/14 (29%) pts initially without or with any CyR (p=0.01). MMR was achieved in 3/51 (6%) and 6/22 (27%) pts without or with any CyR (p>0.05). Estimated overall 1-year, 3-year, and 5-year OS were 95%, 81%, and 65%, respectively. The median follow-up was 26 (3–136) months. There were 14 (19%) death: 11 due to CML progression and 3 after allo-SCT. All deaths occurred in pts without any CyR at baseline. Transformation to accelerated phase and blast crisis was occurred in 13 (18%) pts only in pts group without any CyR initially. The median time to progression was 15 (6–102) months. The only relevant baseline factor for CCyR, OS, and PFS probability in multivariant analysis was the presence of any CyR at baseline (p Conclusion Initial presence of any CyR was a favorable factor for long-term results of TKI third-line treatment in CP CML. TKI-3L should be considered as an appropriate tool in CML treatment for this group.

CML-245: Central Nervous System Restricted Lymphoid Blast Phase Transformation of CML

Objective We describe the clinical manifestations and management of a patient with lymphoid blast transformation of CML with sole compromise of central nervous system. Design case report Setting Hematology ward of Hospital San Juan de Dios, Caja Costarricense Seguro Social, Costa Rica Patients or other participants A 65-year-old male with chronic myelogenous leukemia with a history of non-adherence to TKI. Due to not reaching the European LeukemiaNet milestones, the patient was switched from imatinib to nilotinib. After three months on nilotinib, the patient complained of leg weakness and deafness. Due to persisting neurological symptoms, lumbar puncture was performed. Cerebrospinal fluid flow cytometry demonstrated 92% lymphoblasts. Interventions Full blood count was normal. Bone marrow aspiration showed no evidence of blast phase transformation, polymerase chain reaction showed 17% of BCR ABL transcripts. Head and spine CT and MRI showed no lesions. Tyrosine kinase inhibitor change to dasatinib was solicited. Systemic combination chemotherapy was started. The patient received induction with weekly vincristine and dexamethasone. Anthracycline was omitted due to cardiac disfunction. Triple intrathecal chemotherapy with was administered twice a week until the spinal tap analysis showed no blast presence by flow cytometry. The patient continued on a BFM-like protocol with high dose methotrexate of which he has received four courses. Results In his last follow-up visit the patient had a normal blood count. His last PCR for BCR ABL transcripts had failed to achieve molecular response. BCR ABL mutation study showed no evidence of mutations, medication non-adherence was suspected and addressed. His last spinal tap showed no evidence of blast presence by flow cytometry, his bone marrow aspiration showed no evidence of lymphoblasts. Conclusions The progression to blast phase is a rare event, most of the time related to the development of resistance to tyrosine kinase inhibitors. Less than 20 cases are described in the literature. Central nervous system is the most frequent location. Blast crisis usually presents with a lymphoid phenotype, the frequency of ABL mutations is usually low. The prognosis in these cases is usually dismal with overall survival less than six months.

Further Analytical, Pharmacokinetic, and Clinical Observations on Low-Dose Ponatinib in Patients with Philadelphia Chromosome-Positive Acute Lymphoblastic Leukemia

Introduction: Ponatinib (PNT) is a tyrosine kinase inhibitor approved for treating patients with Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph + ALL), or chronic myeloid leukemia, resistant or intolerant to other tyrosine kinase inhibitor or showing T315I mutation of BCR-ABL. Unfortunately, the clinical use of PNT is limited by the possible occurrence of vascular occlusive events. The incidence of vascular events seems to correlate with PNT dose intensity and plasma exposure. Dose reductions from 45 mg to 30 or 15 mg/day are increasingly considered to improve PNT safety but a plasma threshold of ∼40 nM must be achieved to ensure that antileukemic activity is preserved. Therapeutic drug monitoring (TDM) would be appropriate for patients treated by PNT. We, therefore, developed and validated a liquid chromatography tandem mass spectrometry (HPLC-MS/MS) assay to measure PNT plasma levels. Methods: PNT and its deuterated internal standard were extracted from human plasma by one-step protein precipitation. PNT was separated and quantified by HPLC-MS/MS operating in the multiple reaction monitoring acquisition mode. Results: The method was linear from 9.4 to 940 nM PNT. Limits of detection and lower limits of quantification (LLOQ) were, respectively, 1 and 9.4 nM. Selectivity, sensitivity, matrix effect, short-, and long-term stability met criteria of international guidelines for bioanalytical method validation. Intra- and inter-day accuracy and precision were calculated on 4 different concentrations (QCLow, QCMedium, QCHigh, and LLOQ), with all values being <15%. The method was successfully probed in leukemia Ph + ALL patients to show that PNT doses <45 mg/day caused lower plasma exposure but still achieved PNT levels at or above the 40 nM threshold. Conclusions: We developed a highly sensitive and selective HPLC-MS/MS method to quantify PNT in human plasma. This method might be used for TDM and to guide dose reductions if unnecessary high PNT levels are detected in a patient.

The impacts of BCR-ABL1 mutations in patients with Philadelphia chromosome-positive acute lymphoblastic leukemia who underwent allogeneic hematopoietic cell transplantation

The prognostic impacts of BCR-ABL1 fusion gene mutations in Philadelphia chromosome-positive acute lymphoblastic leukemia (Ph + ALL) remain unknown. Using data from a nationwide Japanese registry, we have evaluated the prognostic impact of BCR-ABL1 mutations prior to the first allogeneic hematopoietic cell transplantation (HCT). The cohort included 289 patients with a median of 48 years of age (range: 16-70). Point mutations were detected in 110 patients. Of these, 90 (82%) harbored T315I mutations, while 20 had other mutations. With a median follow-up period of 29 months (range: 1-125), outcomes after 2 years were worse with mutations than without (overall survival [OS]: 34% vs 68%, p < 0.001; relapse rate [RR]: 48% vs 18%, p < 0.001), particularly with the presence of the T315I mutation (OS: 29% vs 68%, p < 0.001; RR: 54% vs 18%, p < 0.001). OS was significantly worse in the T315I group even among the cohort with hematological (p < 0.001) or molecular complete remission (p = 0.025) as compared to the no mutation group. Multivariate analysis determined the prognostic impact of the T315I mutation (OS: hazard ratio [HR] = 2.19, 95% confidence interval [CI]: 1.5-3.3, p < 0.001; RR: HR = 2.51, 95% CI: 1.5-4.2, p < 0.001). This study is the first to report on the prognostic significance of BCR-ABL1 mutations in Ph + ALL.

Abstract 4682: Influence of PI3K/AKT pathway on imatinib mesylate treatment outcome in chronic myeloid leukemia patients

Abstract Chronic myeloid leukemia (CML) is a common myeloproliferative disorder characterized by cytogenetic abnormality [t(9;22)(q34;q11)] that generates BCR-ABL oncogene with aberrant tyrosine kinase activity, the driver event in CML origin. Tyrosine kinase inhibitors (TKIs) are remarkably effective; yet, treatment failure is common in some cases due to the accumulation of mutations in BCR-ABL itself and other genes causing drug resistance/relapse, which indicates that BCR-ABL inhibition alone may not be sufficient to combat CML. The PI3K/Akt/mTOR signaling pathway downstream of BCR-ABL has been proven to be an important survival mechanism in leukemias. In vitro studies demonstrated that targeting this pathway could be a viable strategy, but needs further validation in CML patients. In this study, we examined the critical PI3K/AKT/mTOR pathway genes (PIK3CA, PTEN, AKT1, SHIP1, mTOR, and FOXO3A) in CML patients (n=51) using qPCR method at diagnosis and after treatment, and analyzed with respect to BCR-ABL status, and JAK2, STAT5, and STAT3 levels. Interestingly, significant upregulation of AKT1 (p=0.012) and PIK3CA (p=0.026) and downregulation of PTEN (P=0.06) and SHIP1 (p=0.039) was observed in samples at diagnosis compared to their post imatinib treated. Remarkably, these elevated AKT1 and PI3KCA transcript levels were significantly associated with increased BCR-ABL and JAK2 transcript levels, but not STAT3 and STAT5 suggesting PI3K pathway as a prominent target in CML. However, with respect to the clinical phase and imatinib response, none of the genes showed significant differences except for PTEN, which was significantly downregulated in advanced phase (p&amp;lt;0.042) and in cases with poor imatinib response. Overall, these results indicate a critical role for PI3K pathway in CML and its maintenance. Citation Format: Swathi Banapuram, Manjula Gorre, Raghunadha Rao Digumarti, Vishnupriya Satti, Komaraiah Palle, Sandhya Annamaneni. Influence of PI3K/AKT pathway on imatinib mesylate treatment outcome in chronic myeloid leukemia patients [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4682.

"All Our Wisdom is Stored in the Trees" - Degrading BCR-ABL with Berberis Vulgaris.

Treating BCR-ABL-positive chronic myeloid leukemia remains impeded by the development of clinical resistance to imatinib. It has been demonstrated that berberine, a plant alkaloid, has activity against imatinib-resistant BCR-ABL mutants by inducing autophagic degradation of BCR-ABL, thereby preventing the acquisition of drug-resistant mutations.See related article by Yin et al., p. 4040.

PVR and ICAM-1 on Blast Crisis CML Stem and Progenitor Cells with TKI Resistance Confer Susceptibility to NK Cells.

The BCR-ABL1 fusion gene generating an oncogenic tyrosine kinase is a hallmark of chronic myeloid leukemia (CML), which can be successfully targeted by BCR-ABL1 tyrosine kinase inhibitors (TKIs). However, treatment-free remission has been achieved in a minority of patients due to evolving TKI resistance and intolerance. Primary or acquired resistance to the approved TKIs and progression to blast crisis (BC), thus, remain a major clinical challenge that requires alternative therapeutic strategies. Here, we first demonstrate that donor natural killer (NK) cells prepared using a protocol adopted in clinical trials can efficiently eliminate CML-BC blasts, with TKI resistance regardless of BCR-ABL1 mutations, and preferentially target CD34+CD38− leukemic stem cells (LSC), a potential source of disease relapse. Mechanistically, the predominant expression of PVR, a ligand for the NK cell-activating DNAM-1 receptor, in concert with ICAM-1, a ligand for NK cell adhesion, confer this susceptibility to NK cells, despite the lack of ligands for NKG2D, a principal NK cell activating receptor, as an immune evasion mechanism. With these mechanistic insights, our findings provide a proof-of-concept that donor NK cell-based therapy is a viable strategy for overcoming TKI resistance in CML, particularly the advanced, multi-TKI-resistant CML with dismal outcome.

Cytogenetic Pattern in Adult Patients with de novo Acute Myeloid Leukaemia: A Single Centre Study in Bangladesh

Background: Cytogenetic analysis performed at diagnosis is considered to be the most important prognostic factor in AML. Objective: The purpose of this study was to observe the pattern of cytogenetic abnormalities in adult patients with de novo AML. Method: Total fifty-two newly diagnosed de novo AML patients were selected for the study. Six cytogenetic abnormalities including t(8;21), t(15;17), inv(16), BCR-ABL1, FLT3-ITD &amp; NPM1 mutations were detected by Real-Time PCR. Results: In this study, 36 (69.2%) patients showed different cytogenetic abnormalities. The t(15;17) was found to be the most common. t(15;17), t(8;21) and inv(16) were found only in M3, M2 and M4 FAB subtypes, respectively. Significant association was found with increasing age and cytogenetic risk groups. BCR-ABL1 mutation showed significant relation with increased age. FLT3-ITD mutation showed significant association with increased WBC count and inv16 was significantly associated with relatively less bone marrow blast percentage. Conclusion: Cytogenetic study should be performed routinely in all cases of AML for proper diagnosis, prediction of prognosis and implementation of effective therapeutic measures.

A Small Molecule Inhibitor, OGP46, Is Effective against Imatinib-Resistant BCR-ABL Mutations via the BCR-ABL/JAK-STAT Pathway

Chronic myeloid leukemia (CML) is caused by the Philadelphia (Ph+) chromosome carrying the BCR-ABL oncogene, a constitutively active tyrosine kinase. The discovery of imatinib represents a major success story in the treatment against CML. However, mutations in the BCR-ABL kinase domain are a major cause of resistance to imatinib, demonstrating that BCR-ABL remains a critical drug target. Here, we investigate a novel small molecule inhibitor, OGP46, for its inhibitory activity against K562, a panel of murine BaF3 cell lines stably expressing either wild-type BCR-ABL or its mutant forms, including T315I. OGP46 exhibits potent activity against imatinib-resistant BCR-ABL mutations, including T315I. OGP46 induced cell differentiation accompanied by G0/G1 cell-cycle arrest and suppressed the colony formation capacity of cells. Treatment with OGP46 significantly decreased the mRNA and protein expression of BCR-ABL in K562 and BaF3-p210-T315I cells. Mechanistically, the anti-cancer activity of OGP46 induced by cell differentiation is likely through the BCR-ABL/JAK-STAT pathway in native BCR-ABL and mutant BCR-ABL, including T315I, of CML cells. Our findings highlight that OGP46 is active against not only native BCR-ABL but also 11 clinically relevant BCR-ABL mutations, including T315I mutation, which are resistant to imatinib. Thus, OGP46 may be a novel strategy for overcoming imatinib-resistance BCR-ABL mutations, including T315I.

Ponatinib-based therapy in adults with relapsed or refractory Philadelphia chromosome-positive acute lymphoblastic leukemia: results of the real-life OPAL study

The OPAL study is a French multicenter observational retrospective analysis of adults with relapsed/refractory Philadelphia chromosome-positive acute lymphoblastic leukemia treated in a real-life setting by ponatinib. Twenty-nine patients were included since 2012. Median age was 55 years. The initial dose of ponatinib, combined to chemotherapy in half of the patients, was 45 mg/day in most instances. The remission rate was 90% and seven patients received allogeneic stem cell transplantation. Median disease-free and overall survival were only 3.5 and 9.9 months respectively. The outcome of patients with BCR-ABL mutation was similar to that of unmutated patients. With a median duration of exposure to ponatinib of 4 months, only 3 cardio-vascular events were recorded despite a high incidence of risk factors, and overall safety was acceptable. These results underline the place of ponatinib to induce early response in advanced disease and the need of new combinations to improve long-term outcome.

Variables associated with BCR-ABL kinase domain mutation in TKI-resistant patients with chronic myeloid leukemia

目的分析酪氨酸激酶抑制剂（TKI）耐药的慢性髓性白血病（CML）患者BCR-ABL激酶区突变状况、类型和影响因素。方法回顾性分析2001年6月至2019年9月就诊于北京大学人民医院并发生TKI耐药的CML患者的BCR-ABL激酶区突变状况。采用Sanger测序法检测BCR-ABL激酶区突变，二元Logistic回归模型进行多因素分析。结果共纳入804例CML患者，发生1 093例次TKI耐药，其中对伊马替尼、尼洛替尼、达沙替尼耐药分别为576（52.7%）、238（21.8%）、279（25.5%）例次。伊马替尼、尼洛替尼和达沙替尼耐药患者BCR-ABL突变检出率分别为50.5%、63.9%和57.3%，T315I突变检出率均最高，分别为12.3%、27.3%和34.1%。此外，检出率≥5%的突变类型在伊马替尼耐药患者中为Y253F/H（7.5%）和F359V/C/I（5.6%），在尼洛替尼耐药患者中为F359V/C/I（12.2%）、Y253F/H（11.8%）和E255K/V（10.5%），在达沙替尼耐药患者中为F317L/V/I/C（11.5%）和E255K/V（5.4%）。多因素分析显示，TKI减停用药史是影响BCR-ABL突变检出的共同因素，无TKI减停用药史患者突变检出率更高。此外，男性、年龄小、无共存疾病、诊断至服用当前TKI间隔较长、开始服用当前TKI时为进展期、继发耐药、耐药时处于进展期或血液学耐药与较高比例检出BCR-ABL突变相关。发生治疗失败至筛查BCR-ABL突变时间间隔、耐药时当前TKI和总TKI服用时间也与突变检出率相关。服用达沙替尼或尼洛替尼、继发耐药与检出T315I突变相关。结论CML患者发生TKI耐药时，半数以上的患者检测出BCR-ABL突变，其中T315I突变比例最高，人口学、疾病状态和TKI用药等临床特征与BCR-ABL突变的检出率和类型相关。

A patient with maculopapular rash and lichenoid skin damage caused by ponatinib.

Tyrosine kinase inhibitors (TKIs) are invaluable for the treatment of patients with chronic myelogenous leukemia. Although TKIs are generally better tolerated than traditional chemotherapy, dermatologic side effects are common and present a significant cause of concern for both patients and physicians. Ponatinib is a third-generation TKI and the only kinase inhibitor effective in patients with certain BCR-ABL1 mutations, including the T315I mutation. However, ponatinib is associated with an increased risk of serious side effects, and severe cutaneous reactions have increasingly been reported. We present a patient who developed a cutaneous lichenoid eruption following the initiation of ponatinib, which resolved after treatment with a topical retinoid. This case demonstrates that cutaneous side effects caused by ponatinib can be managed relatively easily, allowing patients to continue treatment with ponatinib. This is important considerting the limited alternative treatment approaches available for BCR-ABL1 T315I chronic myelogenous leukemia.