Loss Of Major Molecular Response Research Articles

Kinetics of BCR::ABL1 transcript levels and molecular relapse after tyrosine kinase inhibitors discontinuation in chronic myeloid leukemia patients: preliminary results from the DES-CML study

Tyrosine kinase inhibitors (TKI) have revolutionized the treatment of patients with chronic myeloid leukemia. Patients who achieve sustained deep molecular response are eligible for treatment discontinuation. DES-CML is an ongoing, phase 2 multicentric discontinuation trial. Adult patients with CML in chronic phase with typical BCR::ABL1 transcripts, stable deep molecular response (MR4.5 IS) for two years, and no previous resistance were eligible. Patients underwent a phase of TKI dose de-escalation for six months before discontinuation. TKI was reintroduced at the previous dose if the patient lost major molecular response (MMR) at any time. This study aimed to assess the impact of BCR-ABL transcript kinetics during TKI de-escalation and discontinuation phases on treatment-free survival. So far, the study recruited 41 patients, and 38 patients discontinued therapy (4 were in the second discontinuation attempt). Eleven patients lost MMR, one during the de-escalation phase and ten after discontinuation. 24-month treatment-free survival was 66% (95% CI: 48-84%) in a median follow-up of 7 (1–30) months. No patient lost hematological response or had disease progression. A higher rate of molecular relapses occurred in patients with fluctuating BCR::ABL1 levels after the discontinuation phase (with loss of MR4.5, but no loss of MMR) (P=0.04, HR-4.86 (1.03-22.9) but not confirmed in the multivariate analysis. The longer duration of TKI treatment (P=0.03, HR-1.02, 95%CI - 1.00-1.04) and MMR (P=0.004, HR-0.95, 95%CI - 0.92-098) were independent factors of a lower relapse rate.

European Stop Tyrosine Kinase Inhibitor Trial (EURO-SKI) in Chronic Myeloid Leukemia: Final Analysis and Novel Prognostic Factors for Treatment-Free Remission.

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.The European Stop Kinase Inhibitors (EURO-SKI) study is the largest clinical trial for investigating the cessation of tyrosine kinase inhibitors (TKIs) in patients with chronic myeloid leukemia in stable deep molecular remission (DMR). Among 728 patients, 434 patients (61%; 95% CI, 57 to 64) remained in major molecular response (MMR) at 6 months and 309 patients of 678 (46%; 95% CI, 42 to 49) at 36 months. Duration of TKI treatment and DMR before TKI stop were confirmed as significant factors for the prediction of MMR loss at 6 months. In addition, the type of BCR::ABL1 transcript was identified as a prognostic factor. For late MMR losses after 6 months, TKI treatment duration, percentage of blasts in peripheral blood, and platelet count at diagnosis were significant factors in multivariate analysis. For the entire study period of 36 months, multiple logistic regression models confirmed duration of treatment, blasts, and transcript type as independent factors for MMR maintenance. In addition to the duration of treatment, transcript type as well as blasts in peripheral blood at diagnosis should be considered as important factors to predict treatment-free remission.

Biological Factors Associated with Treatment-Free Remission in Clinical Practice: Data from the Canarian Registry of CML

Introduction: The probability of maintaining treatment-free remission (TFR) after the discontinuation of tyrosine kinase inhibitors (TKI) is affected by clinical factors such as length of TKI treatment and the depth of molecular response. However, some individuals with similar treatment duration and response remain in TFR while others relapse. Thus, patient-specific factors must also play a role. Biological factors suggested to influence TFR include BCR::ABL1 transcript type, blasts at diagnosis, halving time (HT, first 3 months), BCR::ABL1 positivity at stop, and presence of somatic mutations. The aim of this study was to evaluate the biological factors associated with TFR in the clinical practice, using data from the Canarian CML Registry. Methods: The OMOP-standardized data of adult patients with chronic phase CML who discontinued TKI treatment included in the Canarian CML Registry (https://rclmc.es/rclmc/) were reviewed. Criteria to discontinue included TKI treatment ≥5 years and MR4.5 or better ≥3 years. TFR was defined as major molecular response (MMR), or deeper after stop. Molecular relapse was defined as loss of MMR in two consecutive tests. NGS was performed with the 30-gene panel Myeloid Solution (SOPHiA) on the MiSeq (Illumina) platform using 200 ng genomic DNA extracted from peripheral blood at diagnosis. Results: A total of 109 patients were included, with an average age of 50.5 years; 54 were male (49.5%). Median follow-up was 3.3 years. 86 patients discontinued from first-line, 21 from second- and 2 from third-line. 51% of patients (n=56) discontinued from imatinib, 31% from nilotinib (n=34), 16% from dasatinib (n=17), and 1% from bosutinib and ponatinib (1 patient each). The median TFR was 101 months ( Figure 1A; range 1.02-148.4 months). Thirty-two patients had molecular relapse and re-started TKI treatment: 36.7% with imatinib or dasatinib, 26.7% with nilotinib. Median time to regain MMR was 101 days (range 25-276). No difference was observed in the time to regain MMR for imatinib vs. 2G-TKI (106 vs. 144, p=0.419). No patients progressed to an accelerated phase. Differences were observed in duration of MR4 and MR4.5 prior to stop comparing the TFR vs. relapse groups (88.3 vs. 69.9 months, p=0.044; 74.2 vs. 58.6 months, p=0.079), but not total time on TKI (172.6 vs. 102.1, p=0.310), respectively. In terms of biological factors at diagnosis, 44 patients had blasts, 66.7% had a low Sokal risk. 23.9% expressed transcript e13a2 and 76.1% had e14a2. No differences in TFR were observed when blasts, Sokal or transcript were considered in chi-squared analyses. A long HT (>21.9 days, Shanmuganathan et al. Blood 2021;137) was of marginal significance for molecular relapse (p=0.076, OR 3.2) but no difference was found for short HT (<9.4 days). By Kaplan-Meier analysis, an MR3, 4, or 4.5 at stop was predictive of molecular relapse (n=42; Figure 1B) vs. an MR5 or undetectable (limit of detection 0.0001%). In multivariable analysis, only an MR5 or deeper at stop and withdrawal syndrome were predictive for TFR (p=0.003, HR 4.3; p=0.049, HR 0.20, respectively). NGS data was available for 47 patients. Myeloid mutations were detected in 21 patients (44.7%) at diagnosis, of these 11 had an epigenetic mutation (23.9%; in ASXL1, DNMT3A, TET2 or EZH2). 11 patients (23.9%) had a variant that was potentially germline (VAF 40-60%). By chi-squared and Kaplan-Meier analysis, no differences were observed between the median TFR for patients with or without a pathogenic somatic, epigenetic, ASXL1 or germline mutation. However, a greater separation of the curves was observed when considering TFR at 36 months for somatic (p=0.101) but not germline mutation. Conclusions: We confirmed previous observations that the biological factors BCR::ABL1 positivity at stop and longer HT were associated with molecular relapse although no difference was found for short HT. The impact of clinical factors on TFR, including duration of MR4 and MR4.5 prior to stop, were also confirmed in our real-life series with a long follow-up, while total TKI duration was not prognostic. Adnan Awad et al. associated the presence of epigenetic mutations at diagnosis with shorter TFR and higher relapse probability (Blood Cancer J. 2022;12). Here, a significant difference in TFR was not observed for epigenetic mutation at diagnosis; however, a tendency was observed between a pathogenic somatic but not a germline myeloid mutation and TFR at 36 months.

ASC2ESCALATE: A US Phase 2, Open-Label, Single-Arm, Dose-Escalation Study of Asciminib (ASC) Monotherapy in Patients (Pts) with Chronic Myeloid Leukemia in Chronic Phase (CML-CP) As Second-Line (2L) and First-Line (1L) Treatment

CONCLUSIONS Adenosine triphosphate (ATP)-competitive tyrosine kinase inhibitors (TKIs) have increased survival in CML, although resistance and intolerance remain challenges, which often necessitate switch to another TKI. Many pts discontinue 1L treatment due to resistance/intolerance and switch to 2L therapy, to which resistance is typically higher. A need exists for effective, safe treatment options for pts in 1L and 2L. ASC is thefirst approved BCR::ABL1 inhibitor that Specifically Targets the ABL Myristoyl Pocket (STAMP), with activity against most BCR::ABL1 kinase domain mutations conferring resistance to ATP-competitive TKIs, potentially providing a new early-line treatment option. ASC was first approved in the United States for pts with CML-CP after ≥2 TKIs at 80 mg once daily (QD) or 40 mg twice daily (BID) and for pts with CML-CP with the T315I mutation at 200 mg BID. A large, phase 1, dose-escalation trial (NCT02081378) demonstrated efficacy and tolerability of ASC across a broad range of dosages. Also, with >2 years of follow-up, ASC demonstrated superior efficacy and better safety and tolerability compared with bosutinib in pts with CML-CP without the T315I mutation after ≥2 prior TKIs in the phase 3 ASCEMBL study (NCT03106779). We describe the phase 2 ASC2ESCALATE trial investigating efficacy and safety of ASC with dose escalation in pts with CML-CP receiving ASC as their 2L or 1L therapy. This is a phase 2, open-label, multicenter, single-arm, dose-escalation study with sites in the United States (NCT05384587) (Figure). Pts receiving ASC as their 2L TKI must be adults with non-T315I CML-CP who discontinued their first ATP-competitive TKI for warning response ( BCR::ABL1IS >1%-10% after 6 months or >0.1%-1% after 12 months of 1L treatment), resistance ( BCR::ABL1IS >10% after 6-12 months or >1% or loss of major molecular response [MMR] after >12 months of 1L treatment), or intolerance (with BCR::ABL1IS >0.1% at screening). In addition to pts receiving ASC as their 2L TKI, a separate cohort of newly diagnosed pts will be included, and these pts may receive up to 4 weeks of prior treatment with imatinib or an approved second-generation TKI (Table). All pts will start treatment with ASC 80 mg QD. Pts achieving BCR::ABL1IS ≤1% at 6 months will continue at the same dose; pts not achieving BCR::ABL1IS ≤1% at 6 months will have their dose escalated to 200 mg QD. In pts not achieving MMR at 12 months, dose escalation from 80 to 200 mg QD or from 200 mg QD to 200 mg BID will occur or the pt will be taken off the study. If pts have grade ≥3 or persistent grade 2 toxicity refractory to optimal management, no dose escalation will occur, and pts will remain on ASC at their most current dose. This dose-escalation strategy applies to both the 2L and 1L cohorts. The primary endpoint is MMR rate at 12 months in pts using ASC as their 2L TKI. As all primary and secondary endpoints for the 2L cohort will be measured for the 1L cohort as secondary endpoints, the MMR rate at 12 months in pts receiving ASC as their 1L TKI is a secondary endpoint. Additional secondary endpoints are the same for both 2L and 1L cohorts and include MMR rates at 3, 6, 18, and 24 months; MMR rates by all scheduled time points; MR 2 ( BCR::ABL1IS ≤1%), MR 4 ( BCR::ABL1IS ≤0.01%), and MR 4.5 ( BCR::ABL1IS ≤0.0032%) at and by scheduled time points; time to and duration of MMR; time to treatment failure; progression-free survival; overall survival; and safety/tolerability. Exploratory endpoints include assessment of BCR::ABL1 mutations. ASC2ESCALATE is the first clinical trial designed to assess pts with CML-CP using ASC as their 2L TKI and will provide critical information on efficacy and safety of dose escalation in pts for whom certain response milestones are not met in 2L and 1L. Dose escalation of ASC in 2L and 1L is another treatment strategy and results from ASC2ESCALATE will add to the growing body of evidence for using ASC to treat pts with CML-CP. Recruitment for pts using ASC as their 2L TKI began November 2022, and as of July 10, 2023, 5 pts have been enrolled in this cohort; Up to 92 and 90 pts are estimated to enroll in the 2L and 1L cohorts, respectively, across 90 sites.

Improvement of Treatment-Free Remission Rate Following Discontinuation of BCR::ABL1 Tyrosine Kinase Inhibitors in Chronic Phase, Chronic Myeloid Leukemia

Backgrounds: Several studies have shown that approximately one-half of patients with chronic phase chronic myeloid leukemia (CP-CML) who receive sufficient tyrosine kinase inhibitors (TKIs) and achieve and maintain a deep molecular response (DMR) are able to successfully discontinue therapy. The main factors affecting Treatment free remission (TFR) are the duration of TKIs treatment and the duration of DMR maintenance during TKI treatment. Aims: To investigate impact of longer duration of DMR, we analyzed the outcome of patients with CP-CML who maintained DMR for more than 6 years during TKIs treatment and discontinued TKIs. The clinical and molecular immunological application criteria were also investigated for safer and more successful TFR. Methods: Among patients newly diagnosed with CP-CML and treated at least one of TKIs (Imatinib, Nilotinib, Dasatinib, Bosutinib, and Radotinib) as the first treatment, patients who maintained MR4.5 (BCR::ABL1 IS ≤0.0032%) continuously for at least 6 years through qRT-PCR tests were enrolled in this study. After discontinuation, molecular responses were monitored for up to six months per month, up to 12 months every two months, and every three months thereafter using the qRT-PCR method. In the case of relapse, defined as loss of major molecular response (MMR), the last TKI therapy was reintroduced and molecular responses after resumption were monitored monthly until achievement of MMR using qRT-PCR. Results: Altogether 116 patients (50 males and 66 females) discontinued TKI. Median age at diagnosis was 43.0 years (range, 40.8-45.3) and the percentages of patients with low, intermediate and high Sokal risk scores ware 58 (50.0%), 35 (30.2%) and 18 (15.5%) patients, respectively with unknown Sokal risk scores in 5 (4.3%) patients. Prior to discontinuation, all patients received TKIs for a median of 120.6 months (range, 113.9-127.3), and the duration of sustained MR4.5 was 75.0 months (range, 70.7-79.3). At the time of discontinuation, 93 patients (80.2%) were receiving their first TKI (70 imatinib, 13 nilotinib, 6 radotinib, and 4 dasatinib) while 13 (11.2 %) and 10 (8.6%) patients were receiving their second and more than three TKIs respectively. All patients who received more than one TKI had changed to adverse events. After a median follow-up from treatment discontinuation of 42.2 months (range, 35.3-49.1), 28 (24.1%) patients have lost their response at a median of 8.4 months (range, 4.9-11.9) after discontinuation; 18 (64.3%) patients had molecular relapse within 6 months of TKI discontinuation and 7 (25.0%) patients lost MMR after 12 months from discontinuation. TFR rates at 12, 24, and 48 months were 81.9%, 76.0%, and 71.0%, respectively. No progression toward advanced-phase CML occurred, and when 28 patients who lost MMR were retreated with same TKI, 26 patients (92.9%) re-achieved MMR with a median of 5.6 months (range, 4.0-7.2). By univariate analysis, a TKI treatment duration of 10 years or more was the only significant predictor for maintained response (P<0.048). Conclusion: Our result demonstrates that TFR rate can be improved in patients who received TKI treatment for approximately 10 years and maintained DMR for more than 6 years regardless of the type of TKI. Based on results, we can confirm one of important factors for safer TFR in CP-CML patients.

Identification of Individual Risk Factors for Treatment Free Remission (TFR) Failure in Chronic Phase Chronic Myeloid Leukemia (CP-CML) Patients: Predictive Models Developed on a Nationwide Clinical and Claim Database

Introduction Over the past decade, the landscape of CML has been radically improved by the introduction of Tyrosine Kinase Inhibitors (TKI). However, since prolonged TKI treatment would reduce compliance, with associated risk of relapse and progression, and increased toxicities, patients (pts) who achieve and maintain a deep molecular response can now attempt TKI treatment discontinuation to achieve TFR. As TFR attempts may fail due to loss of major molecular response and imply restart of TKI therapy, it is essential to study individual factors associated with TFR outcome and to develop predictive models to provide TFR outcome likelihood with respect to pts' characteristics. Methods Predictive models of TFR failure at 6, 12, 24 and 36 months after TFR attempts were developed on 2 populations: (i) on CP- CML pts managed in a reference center for CML who attempted TFR between January 2003 and January 2023, named CML-pts and (ii) on those CML-pts for which an individual indirect linkage to nationwide claim database succeeded, named CML-linked-pts. The model was thus developed based (i) on clinical data exclusively (demographics, CML characteristics, TKI lines, molecular response), and (ii) on clinical data combined with claim data, which provided information on comorbidities, other treatments than TKI and any healthcare resource use (HCRU) of interest. Correlation and features' predictive power was assessed through Pearson's correlation and predictive power scores (PPS). Logistic regression model and machine learning algorithms (k-nearest neighbor, support vector machine, single decision tree, random forest, multilayer perceptron, and gradient boosting machine) were used. Nested k-fold cross-validation (CV) was used to assess the robustness of the algorithms over all data and hyperparameter optimization was performed. Features' contribution to predict TFR outcomes were assessed using SHAP (“SHapley Additive exPlanations”) values. Results Analysis on (i) 208 CML-pts, who attempted 250 TFR - 208 first attempts (TFR 1), 42 second attempts (TFR 2). Median age was 59.6 (IQR:20.6) and 60.6 (IQR:18.2) years at TFR 1 and TFR 2, respectively, and M/F sex ratio was 1.17 and 1.1. The overall proportion of TFR failure was 35.6%, 43.6%, 46.8% and 48.8% at 6, 12, 24, and 36 months, respectively. Analysis on (ii) 118 CML-linked-ptss, who attempted 134 TFRs (110 TFR 1 24 TFR 2). Median age was 61.5 (IQR: 21.1) and 61.4 (IQR: 12.0) years at TFR 1 and TFR 2, respectively, and M/F sex ratio was 1.04 and 1.18. The proportion of TFR failure was 35.0%, 43.2%, 46.2% and 49.3% at 6, 12, 24 and 36 months, respectively. Studied predictive variables, in both populations (i) and (ii), had little correlation with TFR outcomes, ranging respectively from (i) -0.2 to 0.2 and (ii) -0.16 to +0.31, with poor predictive power (PPS from (i) 0 to 0.19, (ii) 0 to 0.25). Overall, predictive models hardly correctly predicted TFR failure - with sensitivity below 50% and were stronger at rather predicting absence of TFR failure - with specificity above 80%. Best performances were obtained with logistic regression model for both populations, for predicting at 6 and 12 months for population (i) and 6 months for population (ii). Accuracies were 72% for population (i) - with F1-score (i.e., model's ability to predict failure) of 50.0% at 6 months and 69.6% at 24 months -, and 77.8% for population (ii) - with F1-score 66.7% at 6 months. SHAP values showed that attempting a second TFR was the most predictive factor of TFR failure for both populations (i) and (ii) (see Figure 1). Sensitivity analyses considering only TFR 1 in the models showed no improvement in performance. Conclusion Although this study was conducted on one of the largest TFR cohorts ever studied, prediction abilities of the models for TFR failure at the different time points were not sufficient to be proposed as a decision support tool, when developed with either clinical data or with both clinical and claim data. The models were indeed able to predict success but did not manage to find patterns to predict failure; only TFR number had predictive power of TFR outcome. Besides, claim data did not provide HCRU-related predictive factors. Among study limits, this monocentric cohort would reflect homogeneous practices in a same center. Analysis on larger cohorts of patients from different centers would potentially allow the capture of more variability in clinical practices.

Long-Term Follow-up of the AST Trial of Treatment-Free Remission in Chronic Myeloid Leukemia Patients

Background: Treatment-free remission (TFR) is a new goal for chronic myeloid leukemia (CML) patients who achieved a long deep molecular response (DMR) with better quality of life, reduced adverse events and high economic impact. The primary objective of the AST trial was to estimate molecular relapse rate at 24 month in CP-CML patients who discontinued TKI. Secondary objective to explore predictive markers for sustained TFR through clinical and immunological analysis ( innate inmune response). This update provides longer follow-up data and includes a new cohort of patients. Patients and Methods: AST-Argentina Stop Trial (NCT05926128) is a multicenter prospective study that included patients from 15 centers. Recruited patients ≥ 18 years, treated with TKI for at least 4 years, sustained MR 4.0 for ≥ 2 years and confirmed typical BCR-ABL1 b3a2 and/or b2a2 transcripts. Molecular studies were centralized in 2 internationally standardized laboratories and were performed monthly during the first 6 months, every 2 months until the first year, and every 3 months during the second year. TKI was restarted due to loss of major molecular response (MMR). Expression of multiple NK cell immunophenotypic markers(CD3-CD56+) was analyzed by flow cytometry at discontinuation time and 3 months later. The nonparametric Mann-Whitney test was used to compare the differences between relapsed and responding patients. Molecular relapse-free survival was estimated using the Kaplan-Meier method and optimal cut-off points were obtained using ROC curves. Comparisons between survival curves were made using the Log rank test method. The differences were considered statistically significant with p-values less than 0.05. Multivariate analysis was performed using the COX regression model. Results: A total of 81 patients divided into 2 cohorts were evaluated: 46 patients recruited between February 2018 and July 2020 (1st cohort) and 35 patients recruited between July 2022 and April 2023. Between these two periods, recruitment was stopped due to the COVID19 pandemic. This analysis focuses on the 1st cohort that has completed 24 months in the study. The median age was 57.5 years (24-86), median duration of treatment before discontinuation was 10.5 years (4.2-20). TKI treatment prior to discontinuation was as follows: Imatinib in 34 (73%) patients, Dasatinib 8 (17%), and Nilotinib 4 (9%). According to Sokal risk score: 22 (48%) were low risk, 14 (30%) intermediate, and 10 (22%) high risk. Seventeen patients (37%) lost MMR, leading to a 63% molecular relapse-free survival rate with a median follow-up of 47 months (41-52). All patients who lost MMR recovered it after restarting the same TKI, with a median time to response of 2.8 months (1-7). With a prolonged follow-up, 2 late relapses were observed (18 and 42 months) (Fig 1). For a univariate analysis, the continuous variables were dichotomized seeking to maximize the difference between the different cohorts. The differences were significant in the variables time in DMR (cut-off point: 51 months, p=0.0166)(HR=0.97 (0.94 - 0.99); p=0.013). Two of the NK cell markers showed significant differences between groups at month 3 after starting treatment, PD1 (Mann-Whitney p=0.035; Log-Rank test p=0.033) and NK-p44 (Mann-Whitney p=0.015; Log -Rank test p=0.020). Multivariate analysis using the Cox model that included variables as gender, age at diagnosis, time in DMR, time in TKI prior to discontinuation, Sokal score, and type of inhibitor, the clinical predictor of time in DMR was the only predictor, significantly associated with a higher rate of TFR, (HR = 0.97 (0.95 - 0.99); p=0.020). No patient experienced disease progression to advanced stages or death for any reason. Conclusion:This is the first multicenter study of TKI discontinuation in CML patients in Argentina showing that TKI can be safely discontinued in those who achieve and maintain a DMR before discontinuation. Molecular relapse-free survival rate was slightly higher than that reported in the international literature, and longer follow-up confirmed the sustained response. DMR before discontinuation showed to be a robust predictor of TFR. Although the sample size was increased, longer follow-up is needed to validate these findings in the second cohort. Potential advantages of TFR will not only impact in patients' quality of life but also show considerable reduction in the use of economic resources.

Final Report: Somatic Mutations and HMGCLL1 Haplotype Are Not Associated with Molecular Relapse-Free Survival in Patients with Chronic Myeloid Leukemia Who Attempt Treatment-Free Remission

Background Chronic myeloid leukemia (CML) is a clonal hematopoietic stem cell disorder resulting from the BCR::ABL1 rearrangement. Patients with CML have a comparable life expectancy to that of age-matched individuals in the general population when they achieve an optimal response with tyrosine kinase inhibitor (TKI) therapy. With the aim of improving the quality of life of patients who are significantly affected by drug-related adverse events and financial burden, the practical goal of CML treatment has shifted to treatment-free remission (TFR), defined as the successful discontinuation (DISC) of TKI therapy without losing leukemia control. TKI treatment DISC is a safe procedure but requires appropriate candidate selection and frequent molecular monitoring. Several biomarkers were investigated, but no definite biomarker has yet been successfully identified and validated. We have investigated somatic mutations before TKI discontinuation and HMGCLL1 haplotype as a potential biomarker for TFR, given that they were previously described as predictors of CML outcomes. Patients and methods A total of 155 patients who attempted TKI discontinuation for TFR from 5 countries were included: Canada (n=71), Brazil (n=30), Argentina (n=28), Italy (n=23), and the Czech Republic (n=3). We applied our in-house single molecule-molecular inversion probe (smMIP) panel which is a barcoded error-corrected DNA-based sequencing with a limit of detection up to 0.2%. The panel encompasses 40 genes with 332 amplicon probes: epigenetic modifiers (n=7), activation signaling (n=12), myeloid transcription factor (TF; n=5), spliceosome (n=3), tumor suppressor (n=3), cohesion (n=4), miscellaneous (n=3) and 8 HMGCLL1 single nucleotide polymorphisms (SNPs). Two groups were constructed based on these eight SNPs: group 1: CTCAGGCA (C- haplotype) or group 2: ACGTAATG (A-haplotype). Samples were collected prior to TKI DISC when patients met the criteria for TFR attempt. Molecular relapse-free survival (mRFS) was calculated from the date of TKI DISC to the date of confirmed loss of deep molecular response (DMR). Loss of DMR includes single-time loss of major molecular response (MMR) or two consecutive episodes of loss of molecular response 4 log or deeper response (MR4). Kaplan-Meier survival estimate was used to evaluate mRFS and Cox's proportional hazard regression model was applied. Results The median MR4 duration prior to TKI DISC was 7.2 years (range 4.7-9.3), while overall TKI treatment duration was 8.5 years (range 6.0-11.6). With a median follow-up of 831 days (range: 460-1,415), out of the 155 patients, 68 (43.9%) lost response, among whom 6 lost MMR only, 12 lost MR4 only, and 50 lost MMR and MR4, both. Median time to MMR loss was 95 days (range 83.5-137). A total of 71 mutations were detected in 51 patients (32.9%). TET2 mutation was the most frequent mutation, detected in 17 cases (24%) followed by ASXL1 (n=14; 20%) and DNMT3A (n=12; 17%). When grouped by relevant biological pathways involved, mutations in epigenetic genes (n=42, 61%) were the most frequently involved. mRFS rate was 64% (95% CI [55.8-71.1%]) and 56% [48.2-64.0%] at 6 and 12 months, respectively. During the univariate analysis, no significant difference was observed in mRFS according to the presence, number, or type of somatic mutations, or the HMGCLL1 haplotype. Additionally, there were no significant differences in mRFS based on age, sex, Sokal risk group, line of TKI therapy, or TKI drug type prior to TKI DISC. However, MR4 duration prior to TKI DISC was associated with mRFS rate: patients with≥7.3 years (n=71) showed higher mRFS: 74.09% [62.05-82.82%] compared to those <7.3 years (n=74) with mRFS rate of 44.36% [32.54 -55.51] (p <0.01, HR 0.36 [0.21-0.63]). In addition, a longer duration of TKI treatment before TKI DISC was associated with higher mRFS: patients with ≥ 8.3 years of treatment (n=85) showed 71.8% mRFS [60.4-80.4], compared to 42.5% mRFS [30.5-54.0%] in those with <8.3 years (n=71) (p<0.01, HR 0.48 [0.31-0.74]). Multivariate analyses for mRFS confirmed that MR4 duration and the total duration of TKI treatment before TKI DISC were associated with TFR outcomes, but not the presence of epigenetic mutations, any mutation, or HMGCLL1 haplotype (Table1). Conclusion In CML, somatic mutations before attempting TFR are frequently observed. However, our current study does not support their prognostic significance as TFR-predictive biomarkers.

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.

Outcomes of Adolescents and Young Adult Patients with Chronic Myeloid Leukemia in the Era of Second-Generation TKIs and Treatment-Free Remission

Background: While chronic myeloid leukemia (CML) is most often diagnosed in older adults, it is frequently diagnosed in adolescents and young adults (AYA). Defined by the NCI as individuals between the ages of 15-39 years old, AYA CML patients have been understudied by comparison to their older counterparts, with little known about their outcomes in the United States (US) in the era of second-generation tyrosine kinase inhibitors (TKIs) and treatment-free remission (TFR). We sought to determine the clinical outcomes of AYA patients with CML at our institution, a CML specialty center. Methods: We performed a single-center, retrospective cohort study of patients with CML who were diagnosed between the ages of 15-39 years old and seen in our adult hematology clinic between January 2012 and December 2022. Patients were identified by ICD-9 and ICD-10 codes from the electronic medical record and chart review. Descriptive statistics were used to summarize the data. Outcomes evaluating second-generation TKIs (2G-TKIs) started with patients diagnosed in June 2010. Outcomes evaluating molecular response included BCR-ABL1 PCR testing conducted after implementation of the International Scale (IS) in 2012. Molecular treatment milestones were defined per the 2023 NCCN guidelines for CML. Results: Of 396 CML patients evaluated at our institution, 136 (34.3%) were diagnosed as AYA at a median age of 31 years (range 15-39). The majority were male (62.5%; n=85/136) and English speaking (94.1%; n=128/136). The most frequently cited race/ethnicities were Caucasian (40.4%; n=55/136), Asian (20.6%; n=28/136), and Hispanic (19.1%; n=26/136). At time of diagnosis, 91.2% (n=124/136) were in chronic phase (CP), followed by 4.4% (n=6/136) in accelerated phase (AP) and 4.4% (n=6/136) in blast phase (BP). Of those diagnosed in advanced phase, 91.7% (n=11/12) were male and 66.7% (n=8/12) were Asian or Hispanic. Of CP patients evaluated, 75.8% (n=94/124) started treatment in the 2G-TKI era. Most CP patients were first prescribed dasatinib (61.7%; n=58/94), followed by imatinib (28.7%; n=27/94), and nilotinib (8.5%; n=8/94). Of 62 patients in CP with available molecular data after 2012, 64.5% (n=40/62) met a transcript level <10% at 3-months and 80.6% (n=50/62) met a transcript level <1% at 12-months. Major molecular response (MMR) was achieved and maintained in 59.7% (n=37/62) of these patients, with 25.8% (n=16/62) losing MMR and 14.5% (n=9/62) never achieving MMR. Reasons for loss of MMR included TFR attempts (31.3%; n=5/16), non-adherence from side effects (25%; n=4/16), lack of health insurance/inability to afford medication (18.8%; n=3/16), lack of response (18.8%; n=3/16), and pregnancy attempts (6.3%; n=1/16). Fertility was a notable issue for AYA patients, with 16 females (31.4%; n=16/51) and 18 patients overall (13.2%; n=18/136) interrupting or delaying start of TKI because of pregnancy/fertility. For patients who attempted TFR, 48.1% (n=13/27) remained off TKI in MMR at time of last follow-up. Of 130 AYA patients with CP or AP CML at diagnosis, 7.7% (n=10/130) experienced disease transformation, including 3.2% (n=3/94) of CP patients in the 2G-TKI era. Of 14 patients who presented or transformed into BP, 42.8% (n=6/14) underwent allogeneic stem cell transplantation and 64.3% (n=9/14) died. Of the entire cohort, 9.56% (n=13/136) patients died at a median age of 35 years old, including 5.4% who presented in CP (n=7/124) and 50% (n=6/12) of those who presented in AP/BP. Of the 13 who died, 11 (84.6%) died from CML-related complications. Conclusions: This represents the largest analysis of NCI-defined AYA CML patients in the US in the 2G-TKI era. Molecular response, progression and successful TFR rates in AYA CP CML patients appear to approximate those reported in prior large clinical trials that compared 2G-TKIs with imatinib. AYA patients can experience unique challenges that impact their management, including pregnancy/fertility and adherence, which can affect clinical outcomes. Patients may also present with aggressive advanced phase disease leading to mortality despite transplantation. Further study is warranted to better support the needs of this patient population. Evaluation of CML patients ≥ 40 years old at diagnosis at our institution is ongoing. A formal comparison between these groups will be presented.

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.

Patient-guided dose reduction of tyrosine kinase inhibitors in chronic myeloid leukaemia (RODEO study): study protocol for a prospective, multicentre, single-arm trial

BackgroundDose reduction of tyrosine kinase inhibitors (TKI) in patients with chronic myeloid leukaemia (CML) with an optimal response to TKIs may support cost-effective medication use by maintaining therapeutic effectiveness while reducing adverse events and medication costs. As the choice for dose reduction depends on patients’ individual needs and preferences, a patient-centred approach is warranted. Therefore, a study to evaluate the effectiveness of patient-guided dose reduction in patients with CML who are in a major or deep molecular response is designed.MethodsThis study is a prospective, multicentre, single-arm study. 147 patients with CML (aged ≥ 18 years) in chronic phase, who are treated with imatinib, bosutinib, dasatinib, nilotinib or ponatinib, and have reached at least major molecular response (defined as having BCR-ABL levels < 0.1% for an uninterrupted period of 6 months) are eligible. Patients will use an online patient decision aid and a shared decision making consultation will be held, after which patients who choose to will receive a personalised, lower TKI dose. Primary outcome is the proportion of patients with intervention failure at 12 months after dose reduction, defined as patients who have restarted their initial dose due to (expected) loss of major molecular response. For this, BCR-ABL1 levels will be analysed from blood samples drawn at baseline, 6 weeks after dose reduction and 3-monthly thereafter. Secondary outcomes include the proportion of patients with intervention failure at 6 and 18 months after dose reduction. Other outcomes include differences before and after dose reduction regarding the number and severity of patient-reported side effects; quality of life; beliefs about medicines; and medication adherence. Patients’ level of decisional conflict and regret after choosing dose reduction will be assessed, as will the decisional process experienced by patients and healthcare providers.DiscussionOutcomes of this trial using a personalised approach will provide clinical and patient-reported data to guide future dose reduction of TKIs in CML. If the strategy appears to be effective, it may be implemented as another valid option to offer next to standard of care to prevent potential unnecessary exposure to higher TKI doses in this selected group of patients.Trial registrationEudraCT number 2021-006581-20.

Importance of TKI treatment duration in treatment-free remission of chronic myeloid leukemia: results of the D-FREE study

Treatment-free remission (TFR) is a new goal for patients with chronic myeloid leukemia in chronic phase (CML-CP) with a sustained deep molecular response (DMR) to treatment with tyrosine kinase inhibitors (TKIs). However, optimal conditions for successful TFR in patients treated with second-generation (2G)-TKIs are not fully defined. In this D-FREE study, treatment discontinuation was attempted in newly diagnosed CML-CP patients treated with the 2G-TKI dasatinib who achieved BCR-ABL1 levels of ≤ 0.0032% (MR4.5) on the international scale (BCR-ABL1IS) and maintained these levels for exactly 1 year. Of the 173 patients who received dasatinib induction therapy for up to 2 years, 123 completed and 60 (48.8%) reached MR 4.5. Among the first 21 patients who maintained MR4.5 for 1 year and discontinued dasatinib, 17 experienced molecular relapse defined as loss of major molecular response (BCR-ABL1IS > 0.1%) confirmed once, or loss of MR4 (BCR-ABL1IS > 0.01%) confirmed on 2 consecutive assessments. The estimated molecular relapse-free survival rate was 16.7% at 12 months. This study was prematurely terminated according to the protocol’s safety monitoring criteria. The conclusion was that sustained DMR for just 1 year is insufficient for TFR in CML-CP patients receiving dasatinib for less than a total of 3 years of treatment.

Effect of BCR::ABL1 transcript type and droplet digital polymerase chain reaction on successful treatment-free remission in chronic myeloid leukemia patients who discontinued tyrosine kinase inhibitor.

Droplet digital polymerase chain reaction (ddPCR) is an exact method of measurement. We conducted this study to identify the prognostic factors for successful treatment-free remission in patients with chronic-phase chronic myeloid leukemia who discontinued tyrosine kinase inhibitors (TKIs). We also aimed to validate ddPCR for predicting molecular relapse. This is a prospective, multicenter study. We enrolled patients treated with TKIs for at least 3 years with a confirmed sustained deep molecular response (DMR) for at least 1 year. TKI was re-administered in patients who experienced the loss of major molecular response (MMR). A total of 66 patients from five institutions in South Korea were enrolled. During a median follow-up period of 16.5 months, 29/66 (43.9%) patients experienced molecular relapse; the probability of molecular relapse-free survival (RFS) at 6 or 12 months after TKI discontinuation was 65.6% or 57.8%, respectively, with most molecular relapses occurring within the first 7 months. All patients who lost MMR were re-treated with TKI, and all re-achieved MMR at a median of 2.8 months. E14a2 transcript type (p = 0.005) and longer DMR duration (⩾48 months) prior to TKI discontinuation (p = 0.002) were associated with prolonged molecular RFS and with sustained DMR. Patients with both e13a2 transcript type and detectable BCR::ABL1 (⩾MR5.0) by ddPCR at the time of TKI discontinuation showed shorter duration of molecular RFS (p = 0.015). Our data suggest that transcript type and BCR::ABL1 transcript levels on ddPCR should be taken into consideration when deciding whether to discontinue TKI therapy.

Feasibility of treatment-free remission with generic imatinib: Results of generic imatinib-free trial-in-chronic myeloid leukaemia-chronic phase study.

Both innovator and generic imatinib are approved for the treatment of Chronic Myeloid Leukaemia-Chronic phase (CML-CP). Currently, there are no studies on the feasibility of treatment-free remission (TFR) with generic imatinib. This study attempted to determine the feasibility and efficacy of TFR in patients on generic Imatinib. In this single-centre prospective Generic Imatinib-Free Trial-in-CML-CP study, twenty six patients on generic imatinib for ≥3 yr and in sustained deep molecular response (BCR ABLIS ≤0.01% for more than two years) were included. After treatment discontinuation, patients were monitored with complete blood count and BCR ABLIS by real-time quantitative PCR monthly for one year and three monthly thereafter. Generic imatinib was restarted at single documented loss of major molecular response (BCR ABLIS>0.1%). At a median follow up of 33 months (interquartile range 18.7-35), 42.3 per cent patients (n=11) continued to be in TFR. Estimated TFR at one year was 44 per cent. All patients restarted on generic imatinib regained major molecular response. On multivariate analysis, attainment of molecularly undetectable leukaemia (>MR5) prior to TFR was predictive of TFR [P=0.022, HR 0.284 (0.096-0.837)]. The study adds to the growing literature that generic imatinib is effective and can be safely discontinued in CML-CP patients who are in deep molecular remission.

A Phase II, Single-Arm Study of De-Escalation and Treatment-Free Remission in Patients with Chronic Myeloid Leukemia Treated with Nilotinib in First-Line Therapy Followed By a Second Attempt after Nilotinib and Asciminib Combination: Dante Study

Introduction: Treatment-free remission (TFR) is considered one of the main goals of therapy in patients with chronic myeloid leukemia (CML). Several studies have shown that treatment discontinuation can be successfully achieved in roughly 50% of patients with a sustained deep molecular response (sDMR). However, the remaining 50% require reintroduction of tyrosine kinase inhibitor (TKI) therapy. Although about 90% of patients who experience molecular relapse regain a major molecular response (MMR) after restarting TKI therapy, due to poorly understood mechanism(s), the probability for those patients of failing a second attempt to discontinue TKI (TFR2) is higher compared to the first attempt. The above-mentioned data implies that, to aim to a second TFR, a different therapeutic strategy might be needed. Asciminib (ASC), unlike all approved TKIs that bind to the ATP site of the BCR-ABL1 oncoprotein, is an allosteric, first-in-class STAMP (Specifically Targeting the ABL Myristoyl Pocket) inhibitor with a new mechanism of action that has shown efficacy in heavily pre-treated patients after two or more TKIs (Rea et al. 2021). An ongoing phase I dose-finding study (NCT02081378) has shown that ASC combined with TKI is both effective and well tolerated in heavily pretreated CML patients, suggesting that combination treatment between an allosteric and an ATP-competitive TKI may deepen clinical responses without serious safety concerns (Mauro et al. 2019). The changes introduced in the DANTE study (NCT03874858) by the amendment 4 aim to assess whether ASC in combination with nilotinib (NIL) can lead to higher and more durable TFR2 rates than those reported in other studies. Methods: After providing written informed consent, the TFR2 phase will enroll - from 29 Italian centers, approximately 60-70 adult CML patients in chronic phase, who have been (i) treated for at least 3 calendar years with NIL, (ii) failed a first TFR attempt, (iii) restarted NIL for at least 1 year and (iv) fulfill all inclusion/exclusion criteria. The study consists of 4 phases: screening, re-induction (week 0-96), TFR2 (week 96-144) and follow up phase. In the re-induction phase, patients will be treated with ASC 40 mg BID and NIL 300 mg BID for 96 weeks and will have scheduled biweekly/monthly visits until week 12, and then every 12 weeks. NIL dose may be less than 300 mg BID if appropriate by clinical judgement but must be at least 300 mg daily. During re-induction, sDMR is defined as no loss of MR4.0 (BCR-ABL level ≤ 0.01% IS) in any BCR-ABL RQ-PCR assessment. Patients with sDMR at the end of re-induction will enter in TFR2 and ASC plus NIL will be discontinued. If two or more consecutive quarterly BCR-ABL RQ-PCR assessments are not performed during re-induction or results are not available, the patient will not be eligible for TFR2 and will be treated with NIL 300 mg BID until the end of the TFR2 stage (week 144). Patients not eligible for TFR2 but with a response more than an MMR will continue treatment with ASC and NIL until the end of re-induction (week 96) and then continue NIL monotherapy at 300 mg BID until the end of the TFR2 stage (week 144). Patients with loss of MMR at any time during re-induction or during NIL monotherapy will be discontinued from the study. If MMR loss occurs during TFR2, NIL 300 mg BID will be restarted and administered until end of study (Fig1). Endpoints: The primary endpoint is the percentage of patients in TFR 48 weeks after stopping NIL and ASC combination. Key secondary endpoints are: (i) percentage of patients eligible for TFR2, (ii) the number of patients with loss of MMR in TFR2 and regain MMR/DMR by the end of the TFR2 stage (iii) BCR-ABL kinetics in the different study phases (iv), OS, TFS and PFS and (v) the safety of the combination. The TFR2 stage is descriptive and no formal statistical testing is necessary or applicable. Conclusions: The expected results from this phase II interventional study, will potentially represent a milestone in treatment strategy for those patients who aim to discontinue NIL for the second time by providing them with several benefits including an improved quality of life.

Treatment- Free Remission in Chronic Myeloid Leukemia -Experience of a Single Brazilian Private Institution Using Imatinib Copies

Introduction: In addition to the best possible overall survival, discontinuation of the tyrosine kinase -inhibitor (TKI) treatment [treatment free response (TFR)] without observing a recurrence of the disease has become a standard part of chronic myeloid leukemia (CML) care. Evidence of several studies suggest that patients who have achieved a sustained stable deep molecular response (DMR) as MR4 and MR4.5 can be safely discontinued with close monitoring without relapse, despite BCR/ABL1 DNA remaining detectable. In Brazil, CML patients have received almost exclusively Imatinib as first-line treatment and since 2013, only generics and copies of imatinib mesylate have been used in first-line throughout the whole Public Health System and in several institutions within the private system. However, in both scenarios there is a limit coverage of PCR exams/ year which allows for adequate monitoring but it is not sufficient for the implementation of TFR safely in eligible patients Aims: To report a Brazilian single institution Imatinib discontinuation trial and to evaluate factors impacting treatment -free response (TFR) and treatment free survival (TFS) Methods: From 2020 -2021 , 26 eligible patients were invited to participate in a single arm trial of Imatinib discontinuation (DIP). Inclusion criteria: age > 18 years, chronic phase, minimum of 04 years of Imatinib therapy, deep molecular response sustained > or = 02 years (confirmed by 04 tests in the last two years, defined MR4.0 or MR 4.5 and a confirmatory exam at the moment of the screening). Atypical transcripts were excluded. After discontinuation, patients were monitored by RT- PCR monthly in the first year, every two months in the second year and every three months since the third year. Criteria for Imatinib re-initiation: loss of MMR confirmed by two exams, loss of cytogenetic response, loss of hematologic response, disease progression. TFR was calculated from the date of discontinuation until first event: loss of MMR, Imatinib reintroduction, death any cause or last follow up. TFS was calculated from the date of imatinib discontinuation until reintroduction or last follow- up (censoring deaths not related to CML). The costs of exams were provided by own founds of our institution. Results: From 26 patients, 20 patients agreed to consent inform to discontinuation of imatinib. 06 patients declined despite information because their insecurity about TFR. Twelve patients (60%) presented MR4 . Median age was 52.3 years old and 13 (65%) were female. Median time diagnosis to discontinuation of imatinib 8.04(4.6-15.5) years. Twelve (60%) patients sustained TFR. Seven patients of twelve had presented MR 4 and five had MR 4.5 in the screening, respectively . (p=0,85) .It means 58,3% of the total of patients with MR 4 and 62,5% with MR 4.5 . In this interim analysis the median time of follow up was 14.5 (2.7-18.8) months. One patient died due to COVID19 with major molecular response (MMR). Eight (40%) lost MMR and imatinib was restarted. In this group the median time until MMR loss was 7.24 (2.1-13.8) months. At this moment, 07 patients (87,5 %) recovered MMR . In addition , in this group 06 patients (75%) achieved the same level of MR with reintroduction of imatinib with median 5.2 (3.7-6.3) months. Regarding adherence, 4 (20%) had some absences in monthly medical consultations and 1(5%) missed follow-up. Fifteen tests (6.14%) were performed to confirm MR loss, however only in 8 tests (53.3%) were confirmed. In fact, 04 patients (33,33%) still in TFR because of the double confirmatory test. There was no transformation to advanced phases. Gender, age at de diagnosis , age at discontinuation, Sokal , BCR-ABL trasncripts type , duration of Imatinib therapy , duration of MR 4.0 or MR4.5 did not affect TFR. Withdrawal syndrome occurred in 05 patients (25%) ; 04 patients with grade 1 and 01 patient with grade 2, had been used corticosteroid for few days. Conclusions: Despite the small number of patients included and short time of follow-up, the preliminary results of this trial demonstrated the feasibility and safety of Imatinib discontinuation , even using Brazilian copies, and the results were similar of that presented in another trials . The confirmatory exam to establish the loss of TFR was useful and safe. Adhesion of a discontinuation is one of the most important keys of the success of TFR.

Clonal Hematopoiesis Detected at the Time of Tyrosine Kinase Inhibitor Cessation Is Associated with Delayed Molecular Recurrence after Treatment-Free Remission in Patients with CML

Background Treatment-free remission (TFR) is a goal of therapy. However, ~50% of patients who attempt TFR will relapse, which mostly occurs by 6 months. The acquisition of somatic mutations in hematopoietic cells is common with age (clonal hematopoiesis, CH). Through next-generation sequencing studies we identified CH in patients in deep molecular remission. CH variants provide a selective growth advantage to cells, driving their clonal expansion. The clones also give rise to mutated immune effector cells with a proinflammatory profile that exacerbate diseases with a chronic inflammatory component, such as atherosclerosis. CH variants could potentially influence TFR, either by outcompeting an emerging residual CML clone or by altering immune function, which is known to play an important role in TFR. Aim To determine whether CH variants present at the time of therapy cessation could influence TFR. Methods An RNA-based hybridization capture sequencing method targeting 17 of the most frequently mutated CH genes was developed and applied to samples of 138 patients who attempted TFR. CH variants met strict criteria for pathogenicity based on their potential to confer growth and survival advantages. The CH status was confirmed by repeat testing of samples of 28 patients. The method reproducibly detected variants with a variant allele frequency (VAF) of ≥0.4%. Results The median follow-up for the 138 patients was 66 months from the TFR attempt. Molecular recurrence was defined as loss of major molecular response (MMR, BCR::ABL1 ≤0.1%). The probability of TFR was 64.5% at 6 months, 59.4% at 12 months and 51.0% at 84 months. CH variants were detected in 61/138 patients (44%): 107 variants in 12 genes. Multiple variants, range 2 - 7, were detected in 26 patients (19%). The median VAF was 0.9%, range 0.4 - 44%. Variants most frequently occurred in TET2 (44% of variants), DNMT3A (25%), PPM1D (7.4%) and ASXL1 (6.5%). The average age at cessation was 59.6 years, range 33 - 85. The average age of patients with CH was higher than those without CH: 64.7 versus 55.5 years, P < .0001. Only 3/13 patients (15%) aged ≤40 had CH compared with 6/7 patients (86%) ≥80. CH was significantly associated with TFR to 36 months after cessation. The optimal criteria for TFR prediction were at least one CH variant of VAF >2% or >2 variants (CH >2%/>2). Thirty-one of 138 patients (22%) had CH of VAF >2% (n = 24) or >2 variants (n = 7). The probability of TFR for these 31 patients was significantly higher than for the remaining patients when assessed at 6, 12, 24 and 36 months after cessation, Figure. The probability of TFR at 6 months was 90.3% for patients with CH >2%/>2 versus 57.0% for the remaining patients, P = .001. The probability of TFR at 36 months was 65.9% versus 51.2%, P = .049. A landmark analysis was performed at 12 months for the 74 patients who maintained TFR at 12 months. MMR was subsequently lost in 8/74 patients and the probability of TFR at 84 months was 86.9%. CH >2%/>2 occurred for 23/74 patients (31%). The probability of late molecular recurrence was higher among the patients with CH >2%/>2: 27.3% versus 5.5% for the remaining patients, P = .009. Overall, molecular recurrence occurred for 12/31 patients (39%) with CH >2%/>2 and 53/107 of remaining patients (50%). Time to molecular recurrence after cessation was longer for patients with CH >2%/>2 than the remaining patients: median 12.5 months versus 3.5 months, P < .0001. The longer time to molecular recurrence was linked to a different pattern of loss of MMR. The median time between first loss of MR4 (BCR::ABL1 ≤0.01%) and loss of MMR was 145 days for patients with CH >2%/>2 and 28 days for remaining patients, P = .0007. BCR::ABL1 values more frequently fluctuated before loss of MMR in patients with CH >2%/>2: 8/12 patients (67%, fluctuation over 120-1335 days) versus 6/53 (11%, fluctuation over 85-715 days) in the remaining patients, P =.016. Conclusion CH may improve the probability and duration of TFR, delaying the time to molecular recurrence, which has implications for patient selection and monitoring. Patients with CH who are eligible for therapy cessation have an excellent prospect of remaining drug-free for 1-2 years but their long term prospects of sustained TFR may be less certain compared to other patients, given the slower dynamics of relapse. Delayed relapse could be due to competition for clonal dominance between residual leukemic cells and larger CH clones, or modulation of the immune microenvironment. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Economic Impact Analysis of Treatment-Free Remission in Chronic Myeloid Leukemia Patients with Sustained Deep Molecular Response in the AST-2018 Trial

Introduction: The introduction of tyrosine kinase inhibitors (TKIs) has revolutionized the treatment of chronic myeloid leukemia (CML), bringing the life expectancy of patients close to that of the general population. However, TKI treatment is associated with adverse events, some of them serious or affecting quality of life. In addition, drug costs have a high economic impact, especially in low-income countries. Treatment-free remission (TFR) is an emerging goal for CML patients and it has been associated with cost savings in different country analyses. Main Objective: Assess the economic impact of TKI discontinuation in patients included in the AST2018 Trial. Secondary objective: Estimate the long-term saving in patients included in the AST2018 Trial, considering Argentinian life expectancy. Methods: AST2018 is a multicentric, prospective trial that recruited aged >18 years CML chronic phase patients, with confirmed typical BCR-ABL1 transcripts b3a2 and/or b2a2, under TKI treatment for at least ≥ 4 years and sustained MR4.0 for ≥ 2 years. Molecular tests were centralized in 2 harmonized laboratories and performed monthly for the first 6 months, every 2 months until the 1st year, and every 3 months until month 24. TKI was restarted at confirmed loss of major molecular response (MMR). The economic impact was evaluated by an Excel-based budget impact model, in order to estimate the costs of the patients in first-line pharmacological treatment for CML. We considered the costs of TKI-treatment, PCRs performing and medical visits as money flow. We calculated the present value of savings, in US dollars, in patients who discontinued treatment during the trial. Results: Between February 2018 and March 2022, we evaluated 50 CML patients in the AST2018 trial, 46 were enrolled from 7 centers in Argentina, and were included in this economic analysis. The median patients’ age was 57.5 years (24-85). TKI treatment before discontinuation was Imatinib 34/46 (74%), Nilotinib 4/46 (9%) and Dasatinib 8/46 (17%). After 24 months since first patient was enrolled, 30/46 (65%) patients continued free from TKI, Imatinib 21/34, Nilotinib 2/4 and Dasatinib 7/8, with a median follow-up of 31.3 months (range 25.9 - 38.1). Treatment was restarted after losing MMR in 16/46 (35%) patients. We considered the costs of TKI treatment, PCR performing and physician visits, and we calculated the estimated cost saving per patient at 24 months on TFR: Imatinib US$ 78,433; Dasatinib US$ 102,817 and Nilotinib US $106,161. For the 30 patients who persisted in TFR for 24 months, total cost saving was US$ 2,579,137. For 17 patients who lost MMR, US$ 335,043 dollars were saved previously to TKI reinitiation. Adding up both amounts, the total economic saving in AST2018 was US$ 2,914,181. We performed an analysis of the potential cost savings of remaining in TFR beyond 24 months and according to life expectancy in Argentina (76 years), median age of patients in this trial and cost per patient/year on TKI treatment, the estimated cost saving per patient was US$ 714,512. Conclusions: This is the first economic analysis of the AST2018 trial on TKI discontinuation in CML patients with sustained deep molecular response in Argentina. Our analysis shows that, in spite of the PCR spending, there is a considerable saving in patients on TFR. A careful approach for patients participating in TFR trials or programs will decrease the risk of relapse and make TFR a reality in our region. Potential advantages of TFR will not only impact in patients’ quality of life but also show considerable reduction in the use of economic resources. In developing countries, where lack of molecular monitoring is still an issue outside academic centers, these savings could be redirected to this unmet need making TFR feasible and a goal for the patient and the healthcare system. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Treatment-Free Response in Chronic Myeloid Leukemia Using Brazilian Imatinib Copies As First Line - Results from Two Prospective Clinical Trials

Introduction: Several trials have demonstrated the feasibility of tyrosine kinase inhibitors (TKI) treatment in chronic myeloid leukemia (CML) patients with a deep molecular response, but little data is available about the results using imatinib copies. Brazil has been using imatinib copies as a first-line treatment since 2013. Aim: To report the results of two Brazilian imatinib copies trials and to evaluate factors impacting treatment-free remission (TFR) and treatment-free survival (TFS) after imatinib discontinuation. Methods: From Dec-2016 until Oct-2018 (USP trial, NCT03239886) and from Oct-2020 until Apr-2021(Hemomed Trial- DIP), 51 eligible patients were included to participate in two trials of imatinib discontinuation. Inclusion criteria: age > 18 years, chronic phase, minimum of three years (USP trial) and four years (DIP) of imatinib copies therapy, a deep molecular response, defined as MR4.0 or MR4.5 sustained for more than 2 years, and a confirmatory test at the moment of the screening. Atypical transcripts were excluded. After discontinuation, patients on the USP trial were monitored by Q-PCR monthly for the first 6 months and bimonthly after 6 months for the first year and quarterly afterwards. Patients in DIP monitoring were monthly for the first year and every 2 months in the second year. Minimal criteria for IM re-initiation was loss of major molecular response (MMR) confirmed by two exams. Results: Median age was 53 years at the time of discontinuation. 58% male (USP) and 65% female (DIP). Imatinib´s therapy was 9.9 years (3-15.5 y). 52.9% had MR4.5 at the screening. TFS at 6 months was 78% (95 Cl 67-90), 12 months 66% (95 Cl 54-80) and at 24 months 54% (95 Cl 42-71). TFS by center at 12 months were 64.5 % (USP) and 67% (DIP). TFS according to previous molecular response after 24 months of follow-up (MR4 vs. MR4.5) (p =0,086). MMR recovery was present in 100% with a median time of 3.5 months. Four patients are still on TFR because the double testing of MMR loss was not confirmed. Conclusion: These two trials demonstrated the feasibility and safety of imatinib discontinuation, even using Brazilian copies, and the results were similar to that presented in another trial. The confirmatory exam to establish the loss of TFR was useful and safe. However, the results no suggest a benefit on monthly Q-PCR after six months of follow-up. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal