Phase Chronic Myeloid Leukemia Patients Research Articles

International, Prospective Study Comparing Nilotinib Versus Imatinib with Early Switch to Nilotinib to Obtain Sustained Treatment-Free Remission in Patients with Chronic Myeloid Leukemia (SUSTRENIM trial): Analysis of the Eligibility to Treatment Discontinuation

Background. Treatment free remission (TFR) is one of the most important aims of CML treatment but, so far, the best treatment strategy to obtain a durable deep molecular response (DMR) and the overall rate of patients able to achieve a successful TKI discontinuation based on intention-to-treat principle from CML diagnosis are still debated. In November 2016 we launched an international, prospective, randomized, two arms study to evaluate both the depth of the molecular response and the rate of TFR in newly diagnosed CP-CML patients treated with a second generation TKI (Nilotinib, NIL) or with imatinib (IM) followed by switching to NIL in absence of optimal response (Clinical Trial number 02602314). Patients were randomized 1:1 between NIL and IM, stratifying on the Sokal score. All the patients achieving a MR4.0 or better by three years and maintaining this level of response up to the end of the fourth year of therapy were qualified for the discontinuation phase. We recently reported that patients enrolled in the NIL arm had a rate of MR4.5 at two years (primary co-endpoint of the study), significantly higher than those in the IM arm (32 vs 22%, p = 0.023 Pane F. et al, EHA 2022). The aim of the present analysis is to assess, in both arms of the trial, the percentage of patients achieving the eligibility to treatment discontinuation, defined as a MR4 maintained in 4 consecutive MRD analysis within the fourth year of therapy. Methods. In this pilot analysis, we first examined the rate of patients eligible to discontinuation and their baseline features (i.e. age, gender, ELTS and Sokal risk, BCR::ABL1 isoform) compared to patients without sustained MR4, using Fisher's exact test or Wilcoxon according to variable type. In patients discontinuing TKIs at 48 months, the successful TFR probability at 12 months after TKI withdrawal was computed with the Kaplan Meier method. Molecular relapse, defined as the loss of MMR or confirmed loss of MR3.0, progression, or death were considering as event in the event-free survival curve. Results. Of the 448 randomized patients, 289 had at least 48-month observation at the time of the present analysis and were evaluated for TFR eligibility, 141 in the IM arm and 148 in the NIL arm, respectively. Ninety-three patients (32%) showed a sustained MR4 in the fourth year and were deemed eligible for treatment discontinuation, 45 in the IM arm (32%) and 48 in the NIL arm (32%). Of the remaining 196 patients, 59 did not have the criteria to discontinue treatment and 137 previously went off study for failure, progression, toxicity, death, or other causes (66 in the IM arm and 71 in the NIL arm, respectively). We found that sustained MR4 achievement was significantly associated with low disease risk, according to both ELTS (81.7% vs 47.2% p<0.0001) and Sokal scores (50.5% vs 34.2%, p=0.008). There is a weak correlation to the age, being those eligible younger (median 52.5 vs 55 years, p=0.037), while no differences in gender and BCR::ABL1 isoform distributions were observed. Within the IM arm, patients who switched to NIL were 60/141 (43%), 44 within the first 12 months and 16 after the first year; those patients had a lower probability of starting the TFR phase compared to patients continuing IM (22% vs 40%, p=0.025). The median follow-up of the 93 patients who attempted treatment discontinuation at 48 months is 9.9 months (IQR: 5.3-12.1). The percentages of those patients in TFR were 82.9% (95% CI:74.8-91.8) at 6 months and 74.3% (95% CI:63.9-86.4) at 12 months. The analysis per random was considered premature given the short follow-up and the proportion of patients not yet evaluable for the discontinuation. Conclusions Although the results are still preliminary to draw definitive conclusions on the rate of sustained DMR and stable TFR , our data indicates that despite higher 24-month rates of MR4.5 in the NIL arm, the probability of reaching criteria for TFR attempt may be not different in the two study arms: one third of patients attempted discontinuation and the majority of them appear to be free of relapse after a median of 10 months from the therapy discontinuation. Among patients of the IM arm, patients switching to NIL due to absence of optimal response had a lower probability to attempt discontinuation. Noteworthy, as for the MR4.5 rate at 24 mo. of therapy, patients at low ELTS risk score are those with the highest probability to achieve sustained MR4 and being eligible for the treatment discontinuation.

Efficacy of Frontline Treatment with Initial Low-Dose Tyrosine-Kinase Inhibitors in Elderly Patients with Chronic Myeloid Leukemia: A “Campus CML” Study

Introduction Three TKIs, imatinib (IM), dasatinib (DAS) and nilotinib (NIL), are approved for frontline therapy in Italy. Choice of frontline TKI is based mainly on evaluation of patient's characteristics and clinical expectations. To avoid long term adverse events or potential drug interactions, elderly patients may start CML treatment with a frontline reduced dose of TKI (RD-TKI). Aim To analyse outcome of CP-CML patients aged over 65 years in a large and unselected cohort treated with RD-TKI. Methods We retrospectively evaluated 747 patients from 1/2012 to 12/2019 at 36 Hematology Centres participating at the “Campus CML” project. Results Clinical features for the whole cohort according to frontline TKI initial dose are reported in Table 1. Among all patients, 605 (81%) were treated with standard dose (SD) while the remaining 142 (19%) with reduced dose (RD). As to frontline TKI, 579 patients (77%) received IM and 158 (23%) a 2G-TKI (DAS n=78, 49%; NIL n=80, 51%). Of the 142 RD-TKI, 122 (85.9%) started with IM, 14 (9.9%) with DAS and 6 (4.2%) with NIL. Median RD was 100 mg for IM (range 100-300), 20 mg for DAS (range 20-50) and 250 mg for NIL (range 150-300). RD-TKI was mainly reported in IM treated patients (p=0.018), in elderly (p<0.001) and in patients with comorbidities, in particular diabetes (p=0.005) and ischemic heart disease (p=0.039). Number of concomitant drugs was also significantly associated with RD-TKI (p<0.001) probably to avoid drug interactions and subsequent toxicity. In detail, among RD-TKI, 41.1% of patients was treated with more than five concomitant drugs. Sokal score did not impact on TKI starting dose. No differences emerged between SD-TKI and RD-TKI in terms of haematological or extra-haematological toxicity. TKI frontline dose was not associated with difference in resistance, nor primary neither secondary resistance. Progression to blastic phase was reported in 1.2% of the whole population, none of which in RD-TKI. At 12 months no differences were noted in terms of achievement of major molecular response (MMR), obtained in 22.4% of SD-TKI treated patients and in 19% of RD-TKI treated patients. RD-TKI had inferior probability of deep molecular response (DMR) achievement (p=0.003), reported in 12.6% of patients. No differences were reported in 12-months cumulative rate of permanent discontinuation for any cause and for primary resistance between SD-TKI and RD-TKI as reported in Figure 1. Conclusions RD-TKI was a frontline treatment strategy used mainly in frail elderly patients, with more comorbidities and concomitant therapies. RD-TKI did not impact on primary resistance leading to TKI switch. While no differences were reported in the rate of MMR, the rate of 12-months DMR achievement was inferior in RD-TKI, but this result need to be confirmed with longer follow-up.

CO-RELATION OF P-GLYCOPROTEIN AND PLASMA IMATINIB IN IMATINIB RESPONDERS AND NON-RESPONDERS PATIENTS WITH CHRONIC MYELOID LEUKAEMIA

Objective: To measure and compare P-glycoprotein (P-gp) expressions in imatinib responders and non-responders with chronic myeloid leukemia-chronic phase (CML-CP) and correlate with plasma imatinib levels. Methods: Patients were classified into two groups based on their haematological and cytogenetic responses to imatinib: responders and non-responders. Liquid chromatography-mass spectrometry was used to measure plasma imatinib levels, while flow cytometry was used to evaluate leucocyte P-gp expression. Results: The median plasma imatinib trough levels in non-responders were 496 (217-3150) ng/ml compared to 2245 (454-4270) ng/ml in the responders, which was statistically significant (p=0.0003). The proportion of patients expressing P-gp in granulocytes was higher in the non-responder group than in the responder group (75% vs. 62.5%). The ratio of mean fluorescence intensity (RFI) revealed that non-responders had higher median P-gp expression than did respondents MFI (1.16(1.06-1.50) and 1.12(1.01-1.38), respectively; p = 0. 2307). In both groups, there was a negative correlation between P-gp expression and plasma imatinib trough levels (-0.4384 vs.-0.2848). Conclusion: Imatinib median plasma trough levels in non-responders were considerably lower. This was highly supported by P-gp expression in granulocytes, which is inversely related to imatinib plasma trough levels; however, the difference was not statistically significant, which could be attributed to the small number of patients. This could be the cause of imatinib resistance in non-responder CML-CP patients, and P-gp levels should be evaluated to optimize treatment in patients who do not achieve hematologic or cytogenetic response.

Somatic Mutations in Cancer-Related Genes Were Observed More Frequently in AYA CML Patients Compared to Elderly at Diagnosis, Whereas the Frequency Was Markedly Higher in Elderly Patients during TKI Treatment

CONCLUSIONS Several works showed that patients with chronic myeloid leukemia (CML) diagnosed at the age of 18 to 39 years (adolescent and young adults, AYAs), had a worse outcome of tyrosine kinase inhibitors (TKI) therapy compared to elderly patients. Only limited data on the molecular background differing AYA from the other age groups are available. To characterize the somatic mutation landscape of AYA CML patients in chronic phase at the time of diagnosis and follow-up in comparison to pediatric and elderly patients, and to follow their clonal evolution. Ph-positive acute lymphoblastic leukemia (Ph+ ALL) patients were included for comparison. Samples from the time of diagnosis (CML children N=18; AYA N=69; elderly N=70; Ph+ ALL children N=32, AYA N=13, elderly N=39) and TKI treatment follow-up (CML AYA N=69, elderly N=70) were analyzed with custom panel (22 whole genes, 40 selected exons). To follow the clonal evolution vital cells available from 10 CML patients were FACS sorted into populations of neutrophils, monocytes, T- and B-lymphocytes. Genomic BCR::ABL1 (g BCR::ABL1) and mutations were quantified using ddPCR in the sorted cells. At the time of diagnosis, a slightly higher frequency of somatic mutations was detected in AYA CML patients (28%, 19/69) compared to elderly (20%, 14/70) and children (11%, 2/18). The similar trend with markedly higher differences was observed in Ph+ ALL patients (62% 8/13 of AYA, 31% 12/39 of elderly, 22% 7/32 of pediatric). The most frequently mutated genes in AYA and elderly CML patients were identically ASXL1, DNMT3A, and TET2. Other mutated genes in AYA were FBXW7, IDH2, IKZF1 PHF6 and KDM6A, SETD2, SF3B1 in elderly. Considering the treatment response, a higher number of mutations at diagnosis were found in the AYA patients that responded optimally in follow-up (21%, 7/33) than in elderly 4% (1/26) and a slightly higher frequency of mutations in AYA patients who later failed on TKI (35%, 8/23) than in elderly 30% (13/43). In contrary, the frequency of acquired mutations or persisted mutations from diagnosis detected during TKI therapy was higher in elderly that failed on TKI therapy (67%, 29/43) than in AYA (52%, 12/23). The treatment failure was associated with de novo mutations in ABL1, RUNX1, TET2, ASXL1 in AYA and elderly CML patients, and in addition in IKZF1, and in DNMT3A, WT1, JAK2, respectively. Sorted cells were analyzed from the time of optimal response in 7 CML patients (+ diagnostic sample of 2 patients) with mutated ASXL1 in 6 patients, FBXW7 in 1 patient, DNMT3A in 1 patient and IDH2 in 1 patient. Samples from the time of therapy failure were available for sorting of 3 patients (+ diagnostic sample of 1 patient). All mutations were detected in g BCR::ABL1 positive neutrophiles and monocytes. The g BCR::ABL1 levels matched exactly with the levels of mutations except for 1 patient with ASXL1-mutated subclone (VAF 5%), which was found in g BCR::ABL1 positive cells. Similar data were found in patients with therapy failure. However, in one patient with secondary failure, the ASXL1 mutation detected at diagnosis disappeared. In all 10 CML patients, g BCR::ABL1 and mutations were not detected in T- and B- lymphocytes under the therapy. In diagnostic samples some g BCR::ABL1 and mutations positive T- and B- lymphocytes were found, but the levels were 3-4 log lower compared to levels in neutrophils and monocytes, which likely correspond to the contamination (purity check was done after sorting) than to the presence of a very small subset of physiological lymphoid cells. Of all age groups, AYAs had the highest number of mutations detected at the time of diagnosis with differences in the spectrum between CML and Ph+ ALL. A markedly higher de novo acquisition of mutations was observed in elderly CML patients during TKI treatment. Moreover, therapy failures were observed more frequently in elderly than in AYA CML patients. Clonal analysis of 10 CML patients outlined that myeloid, but not lymphoid stem/progenitor cells were mutated. Supported by MZCR NU21-07-00225

Treatment-Free Remission after Ponatinib Cessation in Chronic Phase (CP) Chronic Myeloid Leukemia (CML) Patients. the Ponastop Observational Study

Introduction: Ponatinib has proven its efficacy as salvage therapy for patients intolerant, or resistant (and ABL1T315I+ mutation) to at least 2 tyrosine kinase inhibitors (TKI) in CP-CML. Despite the unfavourable profile of such patients, some durable deep molecular response (DMR, i. e. MR 4 and MR4.5) might be observed, and it is arguable to propose a treatment-free remission (TFR) strategy to these patients, despite the fact that this is not currently recommended. The aim of this study is to analyse the results of TFR in CP-CML patients that have received ponatinib as last line of therapy for any reason. Methods: This a retrospective multicentric European analysis of CP-CML patients undergoing ponatinib at any dose for prior TKI-intolerance or -resistance and obtaining at least 2 years of MR4.5, assessed on at least 4 successive samples, and undergoing a treatment-free remission (TFR) procedure and follow-up. All BCR::ABL1 assessments have been performed in ELN reference laboratories and expressed in % on the international scale (IS). Loss of major molecular response (MMR i. e. BCR::ABL1 transcript ≥0.1% IS) on one datapoint was sufficient to consider relapse. Clinical information were extracted from individual patients' files. All patients have given their written agreement in participating to this observational study. Results: Fifteen cases could be collected and analysed with 27% males, 73% females of a median age of 43 (24-79) years at CML diagnosis and of 56 (30-83) at ponatinib cessation. All patients were in CP at diagnosis and at ponatinib cessation. None of these patients were harbouring additional chromosomal abnormalities at diagnosis or beyond. Sokal scores were low in 50%, intermediate in 25% and high in 25% of patients, ELTS scores were low in 64% and intermediate in 36% of patients. None of these patients has undergone allogeneic stem cell transplant. Three patients were ABL1T315I mutated. The median time between CP-CML diagnosis and ponatinib initiation was 52 (1.5-145) months, the median initial dose of ponatinib was 45 mg QD for 12 patients, 30 mg QD for 2 patients and 15 mg QD for 1 patient. One patient had 4 previous lines of TKI prior to ponatinib, 4 patients 3 prior lines, 5 patients 2 prior lines, 4 patients 1 prior line and 1 patient was in ponatinib first-line (EPIC trial). Thirteen arterial events occurred on ponatinib in these 15 patients, all prior to ponatinib cessation. At cessation, the median dose of ponatinib was 30 mg QD for 1 patient, 15 mg QD for 7 patients, 7.5 mg QD for 2 patients, and ≤ 6.4 mg QD for 4 patients. Ten (67%) patients were resistant to prior TKI before ponatinib, 3 were intolerant, 1 intolerant and resistant and 1 was in first-line ponatinib. The median ponatinib treatment duration prior to cessation was 71 (21- 124) months and the time from ponatinib initiation to sustained DMR was 14 (2-112) months. The median follow-up after cessation was 11 (2-55) months. One patient died in TFR of severe SARS-CoV2 lung infection 23 months after cessation. The median survival without MMR loss after ponatinib cessation was 69.26% at 12-months, 24-months and 54-months. Time to MMR-loss KM curve is presented in Figure 1. The four patients loosing MMR after ponatinib cessation resumed low dose ponatinib (≤ 15 mg QD) for 2 and asciminib (80 mg BID) for 2, three patients regained MMR (one non evaluable with too short follow-up). Conclusions: TFR attempt represents a strategy that can be applied to ponatinib patients in the setting of heavily pretreated CP-CML in a similar way as of less advanced CP-CML patients, with high success rates and no disease progression. If those data are confirmed by further studies and longer follow-up, TFR strategies might have to be considered also in previously heavily pre-treated patients.

Excellent Early and Major Molecular Responses Observed with Asciminib Treatment for CP-CML: Results from the ALLG CML13 Ascend-CML Study

ATP-competitive BCR::ABL1 inhibitors are effective in many patients with CP-CML patients. However, a significant minority experience treatment failure with currently available drugs due to resistance or toxicity. Asciminib, a first-in-class myristoyl site BCR::ABL1 inhibitor, is now indicated in many jurisdictions for CP-CML after ≥2 prior lines of treatment. The Australasian Leukaemia and Lymphoma Group (ALLG) CML13 ASCEND-CML trial assessed its tolerability and efficacy in the frontline setting, where data are scarce. ALLG CML13 is a prospective open-label phase II study that completed enrolment in Dec 2022 at 14 sites. Patients commenced asciminib 40mg twice a day (BID) at time of diagnosis, and were assessed according to optimal 2020 ELN targets ( BCR::ABL1 ≤10%, ≤1% & ≤0.1% at 3, 6, 12 months respectively); and ≤0.01% at 18 months. Patients in Major Molecular Response (MMR; BCR::ABL1 ≤0.1%) at 12 months were switched to 80mg QD for ease of administration. Patients with treatment failure ( BCR::ABL1 >10% at 3 or 6 months; BCR::ABL1 >1% at 12 or 18 months) continued asciminib, with additional imatinib or dasatinib or nilotinib, according to physician preference. Patients with a suboptimal response at 6, 12, or 18 months, but without treatment failure, continued asciminib but with the dose doubled to 80mg BID. This is a pre-specified analysis of the co-primary end points: i) final analysis of Early Molecular Response (EMR, BCR::ABL1 ≤10% at 3 months) and ii) interim analysis of MMR by 12 months. By data cut-off in May 2023, 101 patients had median follow-up of 20 (0-29) months (including 1 patient who enrolled but never started therapy due to elevated lipase at baseline). Grade 3/4 adverse events (AEs) included neutropenia and thrombocytopenia, (reported in 6% and 5% of patients, respectively); increased lipase/amylase reported in 8% (clinical pancreatitis reported in 2%), anaemia (2%), infection (2%) and 1% each of increased AST/ALT, back, abdominal and chest pain from pulmonary embolism. The only treatment emergent vascular event was a stroke, reported in a male patient aged 73 with pre-existing diabetes and hypertension, after 20 months of asciminib. Fifteen patients discontinued asciminib: 6 due to AEs (2 with persistent cytopenia requiring an allograft, 3 with recurrent asymptomatic lipase elevation, 1 with pancreatitis); 3 lost to follow-up; and 6 due to resistant disease (1 confirmed loss of MMR at 9 months, without ABL1 mutation; 1 transformed to lymphoid blast crisis at 6 months with myristoyl site mutations A337T/V and P465S; 1 loss of MMR at 6 months with A337T mutation; 1 loss of MR2 with V506L; and 2 with failure to achieve EMR - below). No other transformation occurred. During the first 3 months of treatment, 85% of patients had an assigned dose density of >90%; 9% of patients dose reduced to <66%. EMR was achieved by 94/101 patients (93.1%; 96% CI 86-97%): 1 patient never started treatment, 1 patient missed this assessment, 3 patients had withdrawn by this timepoint, and 2 had BCR::ABL1 of 24% and 210%, respectively. Neither of the EMR failure patients had myristoyl site mutations; both were subsequently intolerant of combination TKI/asciminib therapy because of cytopenia and headaches, respectively and are now on dasatinib monotherapy. Six patients dose escalated and remain on asciminib 80mg BID: 3 after failing to achieve MMR by 12 months, & 3 failing to achieve MR4 after 18 months; 2 have since achieved their targets. By 3 months, 48/101 (48%) patients achieved MMR and 12 (11.9%) achieved MR4. Considering only patients with >12 months of follow up, the interim rate of MMR by 12 months is 62/75 patients (82.7%; 98% CI 70-92%). With “off-protocol for any reason” as the competing risk, the cumulative incidences of MMR & MR4.5 by 12 months were 81.1% & 32.3% respectively (Figure). ASCEND is one of the first studies using frontline asciminib, with excellent achievement of EMR and MMR, and low transformation rate. Rates of MMR at 12 months are comparable to those reported with second generation TKIs, though achievement of deeper responses appears more rapid with asciminib. Treatment was well tolerated in general: majority of AEs were grade I/II events that did not result in treatment discontinuation, and only one vascular event was observed. Early achievement of MMR and MR4 may accelerate eligibility for, & increased success of, treatment-free remission attempts.

Loss of Function of SETD2 Tumor Suppressor in Chronic Myeloid Leukemia (CML) Progenitors Fosters Genomic Instability and Enhances Clonogenic Potential

BACKGROUND AND AIMS - Genomic instability is a hallmark of chronic myeloid leukemia (CML) cells since the chronic phase (CP) of the disease, and results in BCR::ABL1 mutations and/or additional genetic and genomic aberrations that may drive resistance to tyrosine kinase inhibitors (TKIs) and progression to blast crisis (BC). Genomic instability is also a feature of CML stem and progenitor cells and may contribute to their persistence. The SETD2 tumor suppressor codes for a protein that trimethylates histone H3 at lysine 36 (H3K36me3). In solid tumors, SETD2 loss of function has been shown to impair H3K36me3-mediated recruitment of DNA damage response components. We have recently reported that non genomic loss of function of SETD2 is a feature of BC CML and results from premature proteasome-mediated degradation of the SETD2 protein triggered by Aurora kinase A phosphorylation and MDM2 ubiquitination. In the present study, we aimed to assess SETD2/H3K36me3 status in CD34+ progenitors of CP CML patients (pts) and whether SETD2/H3K36me3 deficiency may play a role in genomic instability in CML models. METHODS - Western blotting (WB) was used to assess SETD2 protein expression and H3K36me3 as a surrogate marker of SETD2 function in the CD34+ cell fraction isolated from the bone marrow of 20 newly diagnosed CP CML pts and from a pool of healthy donors (HD). SETD2 forced expression in CD34+ progenitors from newly diagnosed CP CML pts and in the SETD2-deficient KCL22 cell line was performed by nucleofection. SETD2 knock-down in the SETD2-proficient LAMA84 cell line was performed by RNAi. Clonogenic capacity was evaluated by clonogenic assays. Chromatin immunoprecipitation sequencing (ChIP-seq) for H3K36me3 was performed on an Illumina HiSeq2000 with a min 50 million 150-bp single-end reads per replicate. High resolution karyotyping wias perfomed with Cytoscan HD arrays. DNA damage and DNA repair activation were assessed in primary samples and cell lines by WB and immunofluorescence (IF) using antibodies specific for phospho-H2AX, mismatch repair (MMR) and homologous recombination repair (HR) proteins. RESULTS - WB demonstrated a marked down-modulation of SETD2 expression, paralleled by H3K36me3 deficiency, in the CD34+ cells of all newly diagnosed CP CML pts as compared to the total mononuclear fraction and to CD34+ cells from HDs. To investigate whether SETD2 loss affects the activation and proficiency of HR and MMR, we used chronic exposure to UV rays or a single exposure to hydrogen peroxide (1mM for 30 and 60 min). Both induced DNA damage in SETD2 siRNA-depleted LAMA84 cells. Compared to parental cells, cells silenced for SETD2 failed to activate the ATM-dependent repair pathway. Moreover, we found that ATM inactivation prevents H2AX foci formation, associated with a loss of RAD51 and RAD54 (HR) and MSH6 (MMR) repair foci. To confirm the hypothesis that SETD2 is a tumor suppressor implicated in maintaining genomic stability in CML, we transfected SETD2-deficient KCL22 cells with an ectopic SETD2 plasmid. SETD2 forced expression was able to restore DNA damage response, as demonstrated by WB and IF detection of ATM, p95 and H2AX phosphorylation, BRCA1, BRCA2 and CtIP expression and finally RAD51 and RAD54 localization on HR repair foci observed after UV or hydrogen peroxide exposure. High-resolution karyotyping after DNA damage showed increased rate of DNA breakpoints in SETD2-deficient cells, preferentially occuring at loci where H3K36me3 marks were lost as assessed by ChiP-seq. In line with the effects observed in cell line models, forced expression of SETD2 in CD34+ cells from 5 CP CML pts was found to restore proliferation control, since a >50% reduction in clonogenic potential was observed after nucleofection. CONCLUSIONS - Our findings demonstrate that SETD2 is a bona fide tumor suppressor in CML progenitors and establish a functional link between SETD2 loss of function and genomic instability. SETD2 inactivation may thus play a pivotal role in the harmful cascade of events that may foster drug resistance and ultimately lead to disease progression. Since SETD2 loss of function in CML is mediated by post-translation mechanisms, hence is reversible, therapeutic strategies aimed at interfering with these mechanisms may restore proliferation control and interrupt this cascade. Supported by AIRC IG 2019 (23001) and by Italian Ministry of Health, “Bando Ricerca Finalizzata 2016”, project GR-2016-02364880.

Flumatinib Versus Imatinib As a Frontline Therapy for Patients with Chronic Myeloid Leukemia in Chronic Phase: A Propensity Score Matching Study from Real-World Data

Background: Flumatinib mesylate, as a novel oral BCR-ABL1 tyrosine kinase inhibitor, is approved as a frontline therapy for chronic myeloid leukemia in chronic phase (CML-CP) in China since 2019. Mechanistically, with its structure of trifluoromethyl and pyridine flumatinib blocked BCR-ABL1 kinase autophosphorylation with much more potent activity than did imatinib and even showed higher efficacy than nilotinib against wild-type BCR-ABL1 kinase. Currently, there is still lacking the real-world effectiveness and safety of flumatinib in patients with CML. Methods: We retrospectively analyzed efficacy and safety of CML-CP patients (≥16 years) used flumatinib (600mg daily) or imatinib (400mg daily) as first-line treatment from 2020 to 2023, presenting a real-world comparison study. A propensity score (PS) matching was performed to adjust for Sokal risk score to compare the treatment efficacy, survival outcomes and safety of flumatinib and imatinib in a clinically well matched cohort. Results: PS matching resulted in 20 patients from each cohort being matched for Sokal risk scores. The median follow-up of the flumatinib-treated and imatinib-treated cohorts was 441 days and 487 days, respectively. In the intention-to-treat (ITT) population analysis, there is no differences between flumatinib and imatinib groups in 3-month early molecular response rate (85% vs. 80%, p = 0.677), 6-month major molecular response rate (MMR) (50% vs. 40%, p = 0.525) and 12-month MMR (55% vs. 50%, p = 0.752). In term of deep molecular response, more patients receiving flumatinib achieved molecular remission 4.5 (MR4.5) and molecular remission 4 (MR4.0) at 6 months (35% vs.0%, p = 0.004; and 45% vs. 5.0%, p = 0.003, respectively) and appeared to have higher 12-month MR4.5 and 12-month MR4.0 (45% vs.10%, p = 0.013; and 45% vs. 20%, p = 0.091, respectively; Table). During the follow-up period, treatment discontinuation occurred in 6 and 9 patients in flumatinib-treated and imatinib-treated cohorts respectively, including 2 and 3 patients due to drug resistance and 3 and 4 patients due to toxicity. The 2-year probability of event-free survival was 70% among the patients who received flumatinib and 47% among those who received imatinib ( p = 0.85), and the corresponding 2-year failure-free survival probabilities were 85% and 76%, respectively ( p = 0.77). Adverse events of edema, rash were more frequent in imatinib arm (any grade; 0% vs. 25%, p = 0.017; and 0% vs. 25%, p = 0.035, respectively), whereas alanine transaminase elevation appeared to be more frequent in flumatinib arm (any grade, 15% vs. 0%, p = 0.072). Of note, one patient receiving flumatinib had grade 3 QT prolongation and ventricular premature beat and was discontinued. Conclusions: The real-world data demonstrated that as a first-line treatment setting, flumatinib can bring patients with chronic phase CML higher rates of responses, and faster and deeper responses, indicating that flumatinib could be an alternative effective first-line treatment for CML-CP. The adverse events of flumatinib, such as cardiovascular events, abnormal liver function, and diarrhea, need to be given continuous concern in future studies.

Long-term Results of Imatinib Discontinuation in Patients with Chronic Phase Chronic Myeloid Leukemia: National Multicenter Prospective Study.

The discovery of imatinib is a milestone for chronic myeloid leukemia (CML) (1). As life expectancy in CML patients has approached that of the general population (2), research has shifted towards improving quality of life and economic considerations. After 2010, it has been shown that some patients could maintain molecular response even after discontinuing imatinib (3). This national multicenter prospective cohort study aimed to observe the long-term consequences of discontinuing imatinib therapy in adult chronic phase CML patients. A total of 41 patients were included. The median follow-up time after imatinib discontinuation was 48 months (minimum-maximum 6-81 months). The rate of molecular relapse-free survival (MRFS) at 48 months was 33,2% (CI:48.2-18.2). Twenty-seven of 41 patients lost their major molecular response MMR, treatment was started again, and the molecular response was re-achieved with imatinib in all patients. There was no significant relationship between molecular relapse and clinical factors like duration of treatment or molecular response status. Discontinuing imatinib resulted in approximately 4,392,000 Turkish Liras (TRY) or 245,150 US dollars (USD) in savings. In conclusion, imatinib discontinuation with close molecular monitoring is a safe option and provides important national economic benefits and enhanced quality of life. This approach should be considered for all eligible patients. This is the first tyrosine kinase inhibitor discontinuation study from Turkey.

Genetic Landscape of Chronic Myeloid Leukemia and a Novel Targeted Drug for Overcoming Resistance.

Tyrosine kinase inhibitors (TKIs) exemplify the success of molecular targeted therapy for chronic myeloid leukemia (CML). However, some patients do not respond to TKI therapy. Mutations in the kinase domain of BCR::ABL1 are the most extensively studied mechanism of TKI resistance in CML, but BCR::ABL1-independent mechanisms are involved in some cases. There are two known types of mechanisms that contribute to resistance: mutations in known cancer-related genes; and Philadelphia-associated rearrangements, a novel mechanism of genomic heterogeneity that occurs at the time of the Philadelphia chromosome formation. Most chronic-phase and accelerated-phase CML patients who were treated with the third-generation TKI for drug resistance harbored one or more cancer gene mutations. Cancer gene mutations and additional chromosomal abnormalities were found to be independently associated with progression-free survival. The novel agent asciminib specifically inhibits the ABL myristoyl pocket (STAMP) and shows better efficacy and less toxicity than other TKIs due to its high target specificity. In the future, pooled analyses of various studies should address whether additional genetic analyses could guide risk-adapted therapy and lead to a final cure for CML.

Acquired miR-142 deficit in leukemic stem cells suffices to drive chronic myeloid leukemia into blast crisis

The mechanisms underlying the transformation of chronic myeloid leukemia (CML) from chronic phase (CP) to blast crisis (BC) are not fully elucidated. Here, we show lower levels of miR-142 in CD34+CD38− blasts from BC CML patients than in those from CP CML patients, suggesting that miR-142 deficit is implicated in BC evolution. Thus, we create miR-142 knockout CML (i.e., miR-142−/−BCR-ABL) mice, which develop BC and die sooner than miR-142 wt CML (i.e., miR-142+/+BCR-ABL) mice, which instead remain in CP CML. Leukemic stem cells (LSCs) from miR-142−/−BCR-ABL mice recapitulate the BC phenotype in congenic recipients, supporting LSC transformation by miR-142 deficit. State-transition and mutual information analyses of “bulk” and single cell RNA-seq data, metabolomic profiling and functional metabolic assays identify enhanced fatty acid β-oxidation, oxidative phosphorylation and mitochondrial fusion in LSCs as key steps in miR-142-driven BC evolution. A synthetic CpG-miR-142 mimic oligodeoxynucleotide rescues the BC phenotype in miR-142−/−BCR-ABL mice and patient-derived xenografts.

CML-024 Patched Homolog (PTCH1) Gene as a Reliable Marker for Predicting Imatinib Response in Chronic Phase Chronic Myeloid Leukemia Patients in Correlation With Early Response to First-Line of Treatment Imatinib

CML-024 Patched Homolog (PTCH1) Gene as a Reliable Marker for Predicting Imatinib Response in Chronic Phase Chronic Myeloid Leukemia Patients in Correlation With Early Response to First-Line of Treatment Imatinib

POSTER: CML-024 Patched Homolog (PTCH1) Gene as a Reliable Marker for Predicting Imatinib Response in Chronic Phase Chronic Myeloid Leukemia Patients in Correlation With Early Response to First-Line of Treatment Imatinib

POSTER: CML-024 Patched Homolog (PTCH1) Gene as a Reliable Marker for Predicting Imatinib Response in Chronic Phase Chronic Myeloid Leukemia Patients in Correlation With Early Response to First-Line of Treatment Imatinib

Risk of progression in chronic phase-chronic myeloid leukemia patients eligible for tyrosine kinase inhibitor discontinuation: Final analysis of the TFR-PRO study.

Disease progression to accelerated/blast phase (AP/BP) in patients with chronic phase chronic myeloid leukemia (CP-CML) after treatment discontinuation (TD) has never been systematically reported in clinical trials. However, recent reports of several such cases has raised concern. To estimate the risk of AP/BP among TD-eligible patients, we conducted TFR-PRO, a cohort retro-prospective study: 870 CP-CML patients eligible for TD formed a discontinuation cohort (505 patients) and a reference one (365 patients). The primary objective was the time adjusted rate (TAR) of progression in relation to TD. Secondary endpoints included the TAR of molecular relapse, that is, loss of major molecular response (MMR). With a median follow up of 5.5 years and 5188.2 person-years available, no events occurred in the TD cohort. One event of progression was registered 55 months after the end of TD, when the patient was contributing to the reference cohort. The TAR of progression was 0.019/100 person-years (95% CI [0.003-0.138]) in the overall group; 0.0 (95% CI [0-0.163]) in the discontinuation cohort; and 0.030 (95% CI [0.004-0.215]) in the reference cohort. These differences are not statistically significant. Molecular relapses occurred in 172/505 (34.1%) patients after TD, and in 64/365 (17.5%) patients in the reference cohort, p < .0001. Similar rates were observed in TD patients in first, second or third line of treatment. CML progression in patients eligible for TD is rare and not related to TD. Fears about the risk of disease progression among patients attempting TD should be dissipated.

Step-in dosing of bosutinib in pts with chronic phase chronic myeloid leukemia (CML) after second-generation tyrosine kinase inhibitor (TKI) therapy: results of the Bosutinib Dose Optimization (BODO) Study

The approved dose of bosutinib in chronic phase CML is 400 mg QD in first-line and 500 mg QD in later-line treatment. However, given that gastrointestinal (GI) toxicity typically occurs early after treatment initiation, physicians often tend to start therapy with lower doses although this has never been tested systematically in prospective trials in the Western world. The Bosutinib Dose Optimization (BODO) Study, a multicenter phase II study, investigated the tolerability and efficacy of a step-in dosing concept of bosutinib (starting at 300 mg QD) in chronic phase CML patients in 2nd or 3rd line who were intolerant and/or refractory to previous TKI treatment. Of 57 patients included until premature closure of the study due to slow recruitment, 34 (60%) reached the targeted dose level of 500 mg QD following the 2-weekly step-in dosing regimen. While the dosing-in concept failed to reduce GI toxicity (grade II–IV, primary study endpoint) to < 40% (overall rate of 60%; 95% CI: 45–74%), bosutinib treatment (mean dosage: 403 mg/day) showed remarkable efficacy with a cumulative major molecular remission (MMR) rate of 79% (95% CI: 66 to 88%) at month 24. Of thirty patients refractory to previous therapy and not in MMR at baseline, 19 (64%) achieved an MMR during treatment. GI toxicity did not significantly impact on patient-reported outcomes (PRO) and led to treatment discontinuation in only one patient. Overall, the results of our trial support the efficacy and safety of bosutinib after failure of second-generation TKI pre-treatment. Trial registration: NCT02577926.

Pregnancy and long-term outcomes of female patients with chronic myeloid leukemia on tyrosine kinase inhibitors who experienced unplanned pregnancies

PurposeDespite the general recommendation to avoid Tyrosine Kinase Inhibitors (TKIs) for Chronic Myeloid Leukemia (CML) during pregnancy, unplanned pregnancies still occur, particularly among female patients residing in low- and middle-income countries (LMICs). We aimed to investigate the outcomes of pregnancy, foetal development, and disease progression among female CML patients in chronic phase (CML-CP) undergoing TKI therapy who encountered unplanned pregnancies in a tertiary care hospital in northern India. MethodsWe conducted a retrospective analysis of all pregnancies in female CML-CP between January 2002 and December 2022 at our hospital. Patients were included if they had a confirmed diagnosis of CML-CP, were receiving TKI therapy during conception, and had available medical records. We analysed the data on pregnancy outcomes, foetal development, and disease progression through a review of medical records. ResultsWe identified 36 pregnancies in female CML-CP patients on TKI therapy during the study period, with 33 (91.7%) being unplanned. Sixteen pregnancies (48.5%) were conceived at less than major molecular remission (MMR) status. Twelve pregnancies (36.4%) were electively terminated, 4 (12.1%) had miscarriages, and, 17 (51.5%) pregnancies resulted in childbirth. Out of the 17 childbirths, 10 were full-term deliveries, and 7 were preterm deliveries. Twin pregnancies had a high incidence (18.2%). Among the 21 pregnancies that were not electively terminated, TKI was stopped at the first pregnancy detection in 14 pregnancies, while imatinib was continued throughout 7 pregnancies. Patients who discontinued TKI had a higher but statistically non-significant incidence of adverse pregnancy outcomes compared to those who continued imatinib throughout pregnancy (64.2% vs. 28.6%, p = 0.18). Additionally, the risk of long-term disease progression among patients who discontinued TKI during pregnancy and those who continued imatinib throughout pregnancy was 21.4% and 16.7% (p = 0.9), respectively. The risk of long-term disease progression was significantly increased in those persistently at less than MMR pre- and post-gestation (p = 0.0002). ConclusionOur findings suggest that continuing imatinib therapy during pregnancy, may be a reasonable option for CML patients residing in low- and middle-income countries to reduce the risk of disease progression and adverse pregnancy outcomes. Patients persistently at less than MMR levels pre- and post-gestation should be closely monitored for the risk of long-term disease progression. Further studies with larger sample sizes are needed to confirm these results.

Despite warnings, co-medication with proton pump inhibitors and dasatinib is common in chronic myeloid leukemia, but XS004, a novel oral dasatinib formulation, provides reduced pH-dependence, minimizing undesirable drug-drug interactions.

Dasatinib and other tyrosine kinase inhibitors (TKI) have revolutionized the treatment of chronic myeloid leukemia (CML). However, as a lipophilic weak base, crystalline monohydrate, dasatinib (Sprycel®) is poorly soluble, rendering a pH-dependent absorption and a highly variable bioavailability. Thus, co-medication with proton pump inhibitors (PPI) profoundly impairs dasatinib uptake and is clearly recommended against. XS004 is a novel oral immediate release and amorphous solid dispersion (ASD) formulation of dasatinib and is bioequivalent to the original crystalline dasatinib at 30% lower dosages. XS004 is designed to mitigate gastric pH dependency, thus optimizing absorption and bioavailability. We investigated the prevalence of dasatinib and PPI co-medication among chronic-phase CML patients in a real-world setting and assessed the plasma pharmacokinetics (PK) of XS004 with and without PPI co-medication (omeprazole) in healthy volunteers. Using the Swedish CML and Prescribed Drug Registers, we identified 676 TKI-treated CML patients; 320 (47%) had been prescribed PPI at some point after CML diagnosis. Among dasatinib-treated patients, the 2-year cumulative PPI co-medication was 24%. Interestingly, the 5-year overall survival was significantly lower for TKI-treated CML patients with versus without PPI co-medication (79% vs. 94%; hazard ratio 3.5; 95% confidence interval, 2.1-5.3; p < .0001). When assessing PK of XS004, neither Cmax nor area under the plasma concentration curve levels in plasma were significantly altered by the PPI co-medication. In conclusion, despite warnings, PPI co-medication is common among dasatinib-treated CML patients in a real-world setting. The new XS004 ASD formulation of dasatinib provided, in contrast to original crystalline dasatinib, superior pH independence with stable bioavailability, thereby minimizing drug-drug interactions. This may improve the long-term efficacy and tolerability of dasatinib in CML.

Immune modulation in chronic myeloid leukaemia patients treated with nilotinib and interferon-alpha.

The addition of interferon to tyrosine kinase inhibitors (TKIs), to improve deep molecular response (DMR) and potentially treatment-free remission (TFR) rates in chronic-phase chronic myeloid leukaemia (CP-CML) patients is under active investigation. However, the immunobiology of this combination is poorly understood. We performed a comprehensive longitudinal assessment of immunological changes in CML patients treated with nilotinib and interferon-alpha (IFN-α) within the ALLG CML11 trial (n = 12) or nilotinib alone (n = 17). We demonstrate that nilotinib+IFN transiently reduced absolute counts of natural killer (NK) cells, compared with nilotinib alone. Furthermore, CD16+ -cytolytic and CD57+ CD62L- -mature NK cells were transiently reduced during IFN therapy, without affecting NK-cell function. IFN transiently increased cytotoxic T-lymphocyte (CTL) responses to leukaemia-associated antigens (LAAs) proteinase-3, BMI-1 and PRAME; and had no effect on regulatory T cells, or myeloid-derived suppressor cells. Patients on nilotinib+IFN who achieved MR4.5 by 12 months had a significantly higher proportion of NK cells expressing NKp46, NKp30 and NKG2D compared with patients not achieving this milestone. This difference was not observed in the nilotinib-alone group. The addition of IFN to nilotinib drives an increase in NK-activating receptors, CTLs responding to LAAs and results in transient immune modulation, which may influence earlier DMR, and its effect on long-term outcomes warrants further investigation.

Myeloid Cell Leukemia-1 (MCL-1) and Its Correlation with the Prognostic Scoring System in Chronic Myeloid Leukemia

The prognostic scoring system is used to assess the prognosis of Chronic Myeloid Leukemia (CML) patients to get the right treatment strategy. Poor prognosis, treatment resistance, and tumorigenesis have been associated with the overexpression of Myeloid Cell Leukemia-1 (MCL-1), an anti-apoptotic protein in several hematologic malignancies, including CML. Research on the correlation between MCL-1 levels and the scoring system prognostic in patients with CML is still limited. This study aims to evaluate the correlation between MCL-1 levels and the prognostic scoring system in chronic phase CML patients. This research was conducted on chronic phase CML patients who came to the Division of Hematology and Medical Oncology, Department of Internal Medicine, Dr. Hasan Sadikin Hospital Bandung, Indonesia. Data is collected from medical records of patients examined for MCL-1 protein levels from previous studies and results of prognostic scoring systems (Sokal, Hasford, and EUTOS. Data were analyzed to evaluate the correlation between the MCL-1 level and the prognostic scoring system. Forty patients had a male-female ratio of 1.5. The average age is 40±11 years, with an age range of 19 to 61 years. The median MCL-1 protein level was 0.27 (min 0.02-max 4.1). Statistical analysis showed no significant correlation between MCL-1 levels and Sokal, Hasford, and EUTOS scores in chronic phase CML patients (p=0.285; p=0.923 and p=0.663, respectively).

Stopping study in chronic myeloid leukemia: Defining a new paradigm for Ontario CML1.

e19069 Background: The National Comprehensive Cancer Network (NCCN) guidelines state that in order to safely stop tyrosine kinase inhibitor (TKI) therapy in chronic myeloid leukemia (CML) patients, we need access to reliable polymerase chain reaction (PCR) tests on a monthly basis (4 weeks). However, Ontario, Canada can only provide a 6-week turnaround reliably. Therefore, we aimed to test a new paradigm for safely stopping TKI treatment by monitoring molecular response every 6 weeks for 6 months instead of the recommended 4-week intervals. Methods: A prospective pilot cohort study was conducted to assess the outcome of cessation of TKI treatment in chronic-phase CML patients. Eligibility criteria includes obtaining MMR4 (4-log reduction) for 2 years and had to have been on TKI therapy for 5 years. Patients' PCR for BCR-ABL, a driver of CML, was tested every 6 weeks for 30 weeks to ensure ongoing major molecular response (MMR). The primary endpoint was successful maintenance of MMR3 (3-log reduction) or greater at 36 weeks. Secondary endpoints include incidence of withdrawal syndrome, psychological effects, and quality of life (QoL) as per the EORTC Global Quality of Life scoring system were assessed during each visit every 6 weeks for 30 weeks. The secondary endpoint was assessing whether MMR was regained once lost. Results: 18 consenting patients were enrolled, 2 were censored from data analysis as additional time is required to assess whether they regained deep molecular response after stopping, 1 patient was deemed too early to analyze. 12 of the 17 enrolled participants were able to successfully stop TKI therapy and remain in remission at 30 weeks, yielding a 71% success rate. 5 patients had relapsed and 3 successfully regained MR 3.0 with resumption of TKI therapy. Conclusions: The findings demonstrated in a small pilot study that testing at 6-week intervals is safe and effective. Most Ontario CML patients treated in large community centers and have not stopped TKI therapy based on the NCNN guidelines that recommend a 4-week testing turnaround. We plan to expand this study to other sites in Ontario and if successful, this new paradigm may enable more CML patients to stop TKI therapy in a safe manner leading to significant financial and clinical impact. Data will be updated at the time of the conference. By determining that Q6 weekly is a safe paradigm, there is potential for increased comfort in patients unable to maintain Q4 weekly testing for various reasons such as compliance or patients in rural settings. Clinical trial information: OCT1250 , CML1 .