Remission In Chronic Myeloid Leukemia Research Articles

Treatment-Free Remission in Chronic Myeloid Leukemia

With the discovery of tyrosine kinase inhibitors (TKIs), overall survival in patients with chronic myeloid leukemia (CML) now approaches that of the general population. While these TKIs have proven to be lifesaving, remaining on them lifelong creates both physical and financial burdens for patients. Recently, multiple trials have begun looking into the efficacy of trialing patients off these TKIs to see if they can sustain treatment-free remission (TFR). TFR eligibility is currently limited to a small population of patients with both robust and sustained responses to TKIs. Currently, for those who attempt a trial of TFR, the average success rates are promising, with anywhere from 38 to 54% of patients experiencing sustained TFR. For those who fail to maintain sustained TFR, safety results to date are reassuring, with almost all patients successfully responding to the re-initiation of TKIs, with death and disease progression being very rare complications. Moving forward, research is being conducted to more accurately risk stratify patients at diagnosis and pair them with optimized upfront treatment regimens aimed at increasing candidacy for the trial of TFR.

CD302 predicts achievement of deep molecular response in chronic myeloid leukemia patients treated with imatinib

Achieving a deep molecular response (DMR) is a prerequisite for treatment-free remission in chronic myeloid leukemia (CML), and a key milestone for CML patients. This study identified patients unlikely to achieve a 5-year DMR through differential expression of cluster of differentiation (CD) genes, and clinical variables at diagnosis. Peripheral blood samples (n=131) from patients treated with imatinib or nilotinib underwent transcriptomic microarray profiling. The decision-tree analysis delineated two distinct poor-risk (PR) cohorts, distinguished by high 3-month BCR::ABL1% (PR-1), or high CD302 expression (PR-2). The 5-years DMR achievement rate was significantly lower in both PR groups compared to the good-risk (GR) group in patients treated frontline with imatinib (0% vs. 27% vs. 83%, p<0.0001), or nilotinib (PR-2 vs GR, 17% vs 83%, p=0.02). Gene-set enrichment analysis revealed reduced expression of cell cycle-related genes in PR-2, as well as increased metabolism and STAT3 pathway genes, which has previously been linked to leukemic cell persistence and resistance to tyrosine kinase inhibitors. Moreover, PR-2 had a higher frequency of CD34+CD302+ and CD14+CD302+ cells compared to GR samples. Strategies aimed at targeting STAT3, and/or metabolic pathways associated with high CD302 may provide novel therapeutic approaches that could help improve treatment outcomes and eradicate residual disease.

Abstract 187: Macrophage instead of leukemia cell expressed PD-L1 drives T cell exhaustion and immune evasion of BCRABL1 chronic myeloid leukemia

Abstract BCR-ABL1 fusion gene is the hall marker of chronic myeloid leukemia (CML). Currently, the immune microenvironment of BCRABL1 CML remains largely unexplored. Our recent investigation in a transgenic mouse model of BCRABL1 CML revealed a continuous increase in CD11b+Ly6Cint PMN-MDSC with the progression of the disease. Concurrently, there was an increase in CD11b+Ly6Chigh M-MDSC and F4/80+ macrophages. However, The levels of CD4+ T cells, CD8+ T cells, CD19+ B cells, and CD49b+ NK cells, which are essential for tumor-killing significantly decreased. This immune phenotype was consistently observed in both primary leukemia induction and following serial transplantation of cells from primary leukemic mice. Intriguingly, only recipient mice subjected to sublethal irradiation developed the disease, while mice with intact immune system remained disease-free, which underscores the vital role of the immune system in the development of CML. The predominant presence of CD11b+Ly6Cint PMN-MDSC in the peripheral blood, bone marrow and spleen implies these cells may be at least partially consisted of CML leukemia cells. To examine the hypothesis, qRT-PCR and immunofluorescence (IF) staining were conducted. In both assays, Ly6G+ cells from BCRABL1 mice coexpressed the BCRABL1 oncogene. Furthermore, when co-cultured with CD4 T cells, the division of T cells was significantly inhibited, implying immune suppression by the Ly6G+ PMN-MDSCs and/or CML leukemia cells. In addition, the immuosuppressive pathway genes including Arg1, Hif1a, Enptd1, TGFβ were significantly upregulated. To investigate the possible role of the PD1/PDL1 axis in the BCRABL1 model, flow cytometry analysis was conducted. Unexpectedly, PDL1 was barely expressed in CML leukemia cells, whereas the expression of PDL1 in M-MDSCs and macrophages significantly increased, accompanied by remarkable upregulation of PD1 expression on CD4 T cells and CD8 T cells during leukemia progression. In other words, PDL1 expression on macrophages, rather than leukemia cells, was found to induce T cell exhaustion. For translational purpose, mice transplanted with the primary CML leukemia cells were treated with chemotherapy drugs ponatinib alone or in combination with the anti-PD1 antibody. Compared with the chemotherapy alone group, the mice in the combinational therapy group exhibited rapid remission and better disease control. Most importantly, the disease relapse occurred at a slower rate after treatment discontinuation, suggesting the value of combinational therapy in achieving treatment free remission. In summary, our study not only revealed the dynamic changes of immune microenvironment in the BCRABL1 CML mouse model, but also revealed the different mechanisms underlying immune evasion of BCR-ABL1 CML leukemia cells, which sheds light on a combinational treatment for achieving the treatment free remission of CML. Citation Format: Xiaocui Lu, Hui Fang, Xuexiu Fang, Atsuko Matsunaga, Kebin Liu, Jorge Cortes, John K. Cowell, Tianxiang Hu. Macrophage instead of leukemia cell expressed PD-L1 drives T cell exhaustion and immune evasion of BCRABL1 chronic myeloid leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 187.

E14a2 Transcript Favors Treatment-Free Remission in Chronic Myeloid Leukemia When Associated with Longer Treatment with Tyrosine Kinase Inhibitors and Sustained Deep Molecular Response

e14a2 Transcript Favors Treatment-Free Remission in Chronic Myeloid Leukemia When Associated with Longer Treatment with Tyrosine Kinase Inhibitors and Sustained Deep Molecular Response

The Role of G0S2 in Lipid Metabolism Regulation in Chronic Myeloid Leukemia

Introduction: Chronic myeloid leukemia (CML) can be effectively treated with tyrosine kinase inhibitors (TKIs) targeting BCR::ABL1, but resistance remains a clinical problem. TKIs do not target the quiescent CML leukemic stem cell (LSC), and many patients are treated for life at a high economic burden and sometimes with significant side effects. We recently published a tumor suppressor role for G0/G1 switch gene 2 (G0S2) in CML. Our data showed that loss of G0S2 expression in CML promoted disease progression and drug resistance by disrupting glycerophospholipid metabolism (Gonzalezet al. Clin Transl Med, 2022). Interestingly, G0S2 is an estrogen-response gene that demonstrated anti-estrogenic and pro-migratory effects in ER+ versus ER- breast cancer. Additionally, deletion of G0S2 prevented obesity and insulin resistance in mouse models. Since sex-based differences in lipid metabolism and obesity are well documented, we hypothesized that the tumor suppressor role of G0S2 in CML would differ based on sex. Methods: We used peripheral blood from wild-type and G0s2 knockout ( G0s2 -/-) mice (both male and female) who were fed with a normal versus a high-fat diet. Resulting lineage-negative (Lin-) cells were cultured in recombinant murine cytokines ± granulocyte-colony stimulating factor (mG-CSF, 25 ng/ml, 7-10 days) in in vitro differentiation assays. Flow cytometry analysis was performed to measure CD11b+ neutrophils. Additionally, we transduced Lin- cells from wild-type or G0s2 knockout mice with BCR::ABL1, and assessed their ability to form a leukemia-like disease process in male versus female recipient mice. We also performed G0S2 ectopic expression and knockdown experiments in the K562 CML cell line and assessed the resulting cells by liquid chromatography (LC)/mass spectrometry (MS)-based lipidomics and proteomics analyses. Immunoblots were performed to assess the resulting cells for changes in the autophagy markers, LC3A/B I-II. Results: For the experiments conducted with mouse peripheral blood, RT-qPCR data showed high G0S2 mRNA expression upon neutrophil differentiation in wild-type male mice (n=5), but not in the wild-type female mice (n=5). Flow cytometry measuring CD11b markers showed that a high-fat diet-induced neutrophil production in wild-type male mice, but not in wild-type female mice or G0s2 -/- mice, suggesting hormonal regulation involving G0S2 and female mice. Consistent with this observation, forced BCR::ABL1 expression in G0s2 -/- bone marrow reduced overall survival in female (n=4/group) but not male (n=5/group) mice compared with wild-type controls. In mass spectrometry-based lipidomics analyses, G0S2 knockdown resulted in a substantial decrease of di- and triglycerides. G0S2 knockdown also resulted in substantial changes in phosphatidylethanolamine and phosphatidylcholine expression, implicating G0S2 in the production of lipid bilayer components. Conversely, ectopic G0S2 expression promoted the accumulation of long- and very long-chain triglycerides and species of phosphatidylcholine and phosphatidylethanolamine in K562 cells. Proteomics analyses showed autophagy as one of the top pathways affected by altered G0S2 expression. When we measured LC3A/B I-II by immunoblot, we observed opposing effects comparing G0S2 ectopic expression versus knockdown. Conclusion: Altogether, these findings suggest sex-based differences in the role of G0S2 and lipid metabolism in CML stem and progenitor cell differentiation, survival, and autophagy, both in vitro and in vivo. Restoring G0S2 expression combined with BCR::ABL1 inhibition may be a novel clinical strategy to induce treatment-free remission in CML. However, further studies should assess whether this strategy will have similar effects in male versus female patients.

Real-World Evidence of Treatment-Free Remission in Chronic Myeloid Leukemia at an Academic Center in the Deep South

Background: Treatment-free remission (TFR) is increasingly becoming a treatment goal for patients with chronic myeloid leukemia (CML) in chronic phase (CP). Although strict criteria guide tyrosine kinase inhibitor (TKI) discontinuation, there exists a knowledge gap in understanding patient and provider experience regarding TFR in real-world clinical practice. Here, we report our TFR experience in patients with CML-CP, treated at an academic center in the Deep South. Methods: A retrospective chart review was performed to evaluate outcomes of patients with CML-CP at the University of Alabama at Birmingham. The NCCN Version 2.2023 criteria for TKI discontinuation was utilized. Institutional review board approval was obtained. Results: We identified 204 patients with CML-CP through electronic medical records (EMR) . The median follow-up for the entire population was 95m (range 2-246m). The median age was 54y (range 21-75y) and majority of the patients were females (62%) and non-Hispanic whites (NHWs) (70%). A diagnostic bone marrow biopsy was performed on 59% of the patients. Most of the patients had p210 breakpoint (93%). Frontline therapy mainly consisted of imatinib (42%), dasatinib (32%) and nilotinib (16%). Out of the 204 patients, 44 (22%) met all the criteria for TKI discontinuation (Table 1). The median age for these patients was 53y (range 20-75y) and majority of the patients were females (68%) and NHWs (68%). Frontline therapy consisted of imatinib (59%), dasatinib (23%) and nilotinib (18%). Out of the 44 patients eligible for TFR attempt, 35 (80%) were offered TKI discontinuation by their provider whereas 9 (20%) were not. Reasons for not offering TKI discontinuation were not documented in the EMR. Twenty-four out of 35 patients attempted TKI discontinuation. The median time to TKI discontinuation for these patients was 114m (range 45-246m). Frontline therapy consisted of imatinib (n=13), dasatinib (n=7) and nilotinib (n=4) for those that attempted TFR. Ten patients had to resume TKI (imatinib=5, dasatinib=1, nilotinib=4) due to an increasing transcript after a median of 8m (range 2-29m). The remaining 14 patients (58%) remain in TFR to date with a median follow-up of 29m (6-51m). Eleven patients, eligible for TKI discontinuation, were offered a trial of TFR but did not attempt it. Three patients were satisfied with ongoing therapy and did not want to attempt TKI discontinuation or dose-reduction. Eight patients were hesitant to discontinue therapy and agreed to reduce the dose of the current therapy after discussing with their provider. Seven of those eight patients remain on a reduced TKI dose and 1 had to increase the dose due to an increase in transcript. Conclusion: In our single-center experience, we report that although most of the patients eligible for TKI discontinuation were offered a TFR attempt by their provider, there remains room for improvement. More than half the patients that attempted TKI discontinuation remain off therapy. Patient preference was the main reason for not attempting TKI discontinuation but there was willingness to attempt dose-reduction. Further studies are needed to understand both patient and provider perspectives regarding TFR to identify opportunities for improvement.

Cytogenetic and Molecular Remission in Chronic Myeloid Leukemia in Togo

The availability of tyrosine kinase inhibitors (TKIs) in Togo through the GIPAP program has revolutionized the management of chronic myeloid leukemia and increased patient life expectancy. However, diagnosis and molecular monitoring of therapeutic efficacy remain a real challenge due to the inaccessibility of cytogenetic and molecular biology tools. We’ve conducted, a cross-sectional, descriptive study that ran from December 21, 2022, to January 20, 2023, with the aim to evaluate the cytogenetic and molecular remission in CML patients followed at the CHU Campus de Lomé in Togo. Patients diagnosed with chronic-phase CML who had been treated for at least three months with imatinib or dasatinib and had achieved complete hematological remission were included. Dosage of BCR-ABL transcript levels was performed by RQ-PCR in Seattle, USA, using Dried Blood Spot. The transcript detection limit was 0.003% i.e., MR4. A total of 38 patients were included, 68.4% of them were treated with imatinib and 31.6% with dasatinib. In terms of remission, 28.9% had not achieve a partial cytogenetic remission while 15.8% of patients had achieved a MR4 remission and 7.9% a major molecular remission. Major molecular remission was achieved at a mean follow-up time of 95 months for patients taking imatinib and 22 months for those taking dasatinib. Patients in MR4 were on imatinib after a mean of 68 months. All in one, our study showed a high rate of treatment failure. Better access to cytogenetic and molecular biology tools is needed to improve management.

The Success of Treatment Free Remission in Chronic Myeloid Leukaemia in Clinical Practice: A Single-Centre Retrospective Experience from South Africa.

Chronic myeloid leukaemia (CML) management has evolved from a disease once considered to be incurable just over 2 decades ago to that of one of a "functional cure" as defined by the sustained molecular response on stopping tyrosine kinase inhibitor(TKI) therapy. The next goal of CML management has been treatment-free remission (TFR). The past 4 years have seen much international data on TFR attempts in CML in clinical practice. However, Africa as a continent has lagged behind the rest of the world, in keeping up with the latest trends in CML management, and so this study aims to address this gap by assessing the outcome of TFR in CML in a single centre in South Africa (SA). We conducted a retrospective cohort study in 12 CML patients in the chronic phase to assess the success of TKI discontinuation. The patients were treated in King Edward VIII Hospital (KEH), a tertiary, academic hospital in KwaZulu-Natal, South Africa, and the study period was from June 2020 to May 2022. Patients included had to have been on TKI therapy for a minimum of 5 years and achieved a deep molecular response (DMR) for a minimum period of 3 years. The overall TFR cohort showed a success rate of 75% at a median follow-up of 12 months. All patients who failed TFR, defined as a loss of major molecular remission (MMR), failed within 6 months of stopping TKI therapy. All patients who failed TFR regained DMR after retreatment with TKI, with no disease progression reported. The only factor influencing the success of TFR was the total period of TKI therapy. Despite our study having a small cohort of patients, this study demonstrated that TFR in CML is an attainable goal, even in a resource-limited setting.

Association of TIM-3 checkpoint receptor expression on T cells with treatment-free remission in chronic myeloid leukemia.

Dysregulation of immune-checkpoint receptors has been reported at diagnosis of chronic myeloid leukemia (CML), however, their role in the maintenance of remission after tyrosine kinase inhibitor (TKI) cessation is unclear. We assessed programmed cell death-1 (PD-1), T-cell immunoglobulin, and mucin-domain containing protein-3 (TIM-3), cytotoxic T-lymphocyte-associated protein-4 (CTLA-4), lymphocyte-activation gene-3 (LAG-3), andT-cell immunoreceptor with immunoglobulin and immunoreceptor tyrosine-based inhibitory motif (ITIM) domains (TIGIT) expression on T-cell subsets, regulatory T cells (T-regs), and natural killer (NK) cells at the time of TKI cessation in 44 patients (22 patients sustained treatment-free remission [TFR] and 22 experienced molecular relapse [MolR]). We confirmed our previous finding that absolute numbers of T-regs are increased in patients who experienced MolR compared with those who sustained TFR. The immune-checkpoint receptors PD-1, CTLA-4, LAG-3, and TIGIT on Tor NK cells were not differentially expressed between the MolR and TFR groups. However, TIM-3 was consistently upregulated on bulk T cells (CD3+) and T-cell subsets including, CD4+ T cells, CD8+ T cells, and T-regs, in patients who relapsed in comparison with those who maintained TFR after discontinuation. Furthermore, gene expression analysis from publicly available data sets showed increased TIM-3 expression on CML stem cells compared with normal hematopoietic stem cells. These findings suggest that among the targetable immune-checkpoint molecules, TIM-3 blockade may potentially improve effector immune response in patients with CML stopping TKI, while concomitantly targeting leukemic stem cells and could be a promising therapeutic strategy for preventing relapse after cessation of TKI in patients with CML.

Inflammation perturbs NK cell phenotype and function in chronic myeloid leukemia (CML)

Abstract Natural killer (NK) cells have the capacity to recognize and clear cancer cells by releasing cytotoxic granules. In fact, NK cells’ mature phenotype and abundance are associated with prolonged treatment-free remission in chronic myeloid leukemia (CML). However, NK cell anti-leukemic activity is suppressed during the disease, and the environmental triggers of this impairment are not fully characterized. Given the role of inflammatory cytokines in the progression of myeloid malignancies, we define their impact on NK cell function in a BCR-ABL1 +CML chimeric mouse model. Consistent with clinical observations, NK cells are reduced in counts in leukemic mice, display immature phenotype, low degranulation rate, and altered expression of activating and inhibitory receptors. Single-cell RNAseq analysis confirmed these observations at the transcriptional level, and revealed enrichment in genes and pathways associated with inflammatory cytokine response (e.g., GM-CSF, LTα/β, XCL1, IL-6st, IL-2Ra, SOCS1/2/3, CIS; IL-6/STAT3 and TNFa/NF-kB pathways) in CML-exposed NK cells. To validate the clinical relevance of our findings, we characterized NK cells from CML patients. As expected, NK cell frequencies are reduced in our cohort and display diminished K562-targeted degranulation. Mirroring mouse scRNAseq data, patient NK cells possess a pro-inflammatory gene signature with the activation of JAK-STAT, TNFa/NF-kB, and PI3K-Akt signaling pathways. As this is likely triggered by leukemic cytokines, we found that leukemic serum dampens ex vivo NK cell degranulation capacity. Thus, we speculate that NK cells are sensitive to CML-associated cytokines and that inflammation represents an optimal target for NK-boosting immunotherapies.

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.

SOHO State of the Art Updates and Next Questions | Update on Treatment-Free Remission in Chronic Myeloid Leukemia (CML).

Tyrosine kinase inhibitor (TKI) discontinuation, also known as treatment-free remission (TFR) is currently one of the main goals of chronic myeloid leukemia (CML) therapy. TKI discontinuation should be considered in eligible patients for several reasons. Specifically, TKI therapy is associated with reduced quality of life, long-term side effects, and a heavy financial burden on both the patients and society. TKI discontinuation is a particularly important goal for younger patients diagnosed with CML because of the treatment's effects on their growth and development in addition to potential long-term side-effects. Numerous studies with thousands of patients have demonstrated the safety and feasibility of attempting TKI discontinuation in a select group of patients who have achieved a sustained deep molecular remission. With current TKIs, approximately 50% of patients will be eligible for attempting TFR of which only 50% will achieve a successful TFR. Therefore, in reality, only 20% of patients with newly diagnosed CML will achieve a successful TFR, and the majority of patients will need to continue TKI therapy indefinitely. However, several ongoing clinical trials are investigating treatment options for patients to achieve deeper remission with the ultimate goal of a cure, which is defined as being off drug with no evidence of disease.

Development of acute monocytic leukemia (AMoL) during molecular remission of chronic myeloid leukemia treated with nilotinib

Development of acute monocytic leukemia (AMoL) during molecular remission of chronic myeloid leukemia treated with nilotinib

Assesment of Patient'S Perspective on Treatment Free Remission in CML: A Turkish Multicenter Cohort

Treatment free remission (TFR) is one of the main goals of therapy in Chronic Myeloid Leukemia (CML). Patient perspective and expectations have an indicative effect on discontinuation decisions. We analyzed 116 CML patients' perspective on TFR and factors that associated with willingness for tyrosine kinaz inhibitor (TKI) discontinuation from four different center in Turkey based on a national survey. Patients in our cohort had 7.8% awareness of TFR and after brief information willingness to attempt TFR has been reached to 58.9% in all population. Shorter disease duration was associated with enhanced willingness to attempt discontinuation in multivariate analyses (p=0.031). Most common patient related limitation for TKI discontinuation decision was anxiety about disease relaps and TKI resistance. Even disease relaps in TFR means molecular and detectable with close monitoring, patients still had considerable concerns about TKI discontinuation.

Management of Patients with Treatment-Free Remission in Chronic Myeloid Leukemia

Background: Chronic myeloid leukemia (CML) is a relatively common BCR-ABL-positive chronic myeloproliferative neoplasm within the structure of morbidity by hematological malignancies with primary bone marrow (BM) involvement, being characterized in the advanced phases by a relapsing evolution, sizable disease burden, unfavorable socio-economic impact and poor prognosis. Tyrosine kinase inhibitors (TKIs) have improved fundamentally the treatment outcomes in CML, bringing the patients' life expectancy closer to that of the general population. Nevertheless, TKI discontinuation studies indicate discordance in the incidence of hematological and molecular relapses. Objectives: The aim of the study was to evaluate the short- and long-term outcomes of treatment discontinuation in CML patients with complete molecular response (CMR). Material and methods: This prospective study included 22 patients with chronic phase of CML, treated and followed up at the Oncologic Institute from Moldova between 2017-2022. The age range was 29-73 years (average age - 45.8 years). The male/female ratio was 1:1.2. The quantitative reverse transcription polymerase chain reaction (PCR) was performed in order to determine the expression of the BCR-ABL p210 and p190 transcripts. Five transcription products (b2a2, b3a2, b2a3, b3a3 si e1a2) were analyzed by the usage of the PCR test. The real-time quantitative PCR revealed the wide range of BCR-ABL p210 transcript: 21.84-100% IS. In 7 (31.8%) cases the initial rate of BCR-ABL p210-positive cells was less than 50%. Only 2 (9.0%) patients also proved to be positive for BCR-ABL p190 transcript. Results: CMR was obtained in 15 (68.2%) patients after imatinib therapy and in 7 (31.8%) patients after therapy with 2nd TKIs generation. The therapy with TKIs was stopped due to the different reasons in all patients after the achievement of CMR. Two (9.1%) patients discontinued the TKIs treatment due to the pregnancy. The molecular relapse occurred in 6 (27.3%) pts, including one pregnant female. There were no subsequent hematological relapses. All patients with molecular relapse had the initial BCR-ABL p210 transcript expression > 50%. One (4.5%) of them was positive for BCR-ABL p190 transcript at diagnosis. The CMR span ranged between 2.5-26 months in relapsed patients. The range of BCR-ABL p210 transcript in the relapsed cases was 0.002-0.56%. These patients attained the 2nd CMR after resuming the treatment with the same or higher TKIs generation. In 2 (9.0%) pregnant females the pregnancy resulted in the healthy newborns. One (4.5%) female with a history of lymphoblastic type of acute phase experienced the minor molecular relapse (BCR-ABL p210 transcript - 0.56%), and reobtained the CMR after restarting imatinib mesylate. The relapsed patients did not develop the 2nd molecular relapse. All patients are alive, with the ECOG-WHO score of 0-1. Conclusions: TKIs stopping proved to be a reliable management option in CML patients with chronic phase, CMR and low BCR-ABL p210 transcript expression at diagnosis. The stable 2nd CMR may be achieved after resuming the TKIs treatment at a higher dosage or generation in patients with minor molecular relapse. Pregnancy may not influence the molecular relapse rate after TKIs discontinuation and its curability.

Efficacy of Ropeginterferon Alpha 2b in Inducing Treatment Free Remission in Chronic Myeloid Leukemia - an International, Randomized Phase III Trial (ENDURE, CML-IX) of the German CML-Study Group

Background: Only a minority of chronic myeloid leukemia (CML) patients can eventually successfully discontinue tyrosine kinase inhibitor (TKI) therapy after achieving a stable deep molecular remission. Mechanisms underlying a durable treatment free remission (TFR) are not well understood but supposedly involve restoration of anti-CML immunity. It was therefore hypothesized that interferon alpha (IFN) - a potent inducer of Th1-immunity and prior standard therapy in CML - might improve the TFR probability. Randomized trials to improve TFR rates in CML are currently lacking. ENDURE, CML-IX (NCT03117816) is a multicenter, international phase III trial evaluating the role of a novel form of pegylated proline interferon-alpha 2b (ropeg-interferon-alpha, ropeg-IFN) in inducing TFR. Patients and Methods: CML patients in stable deep molecular remission (MR4 or better for at least 12 months prior to screening) and with history of at least 3 years of TKI exposure were eligible to participate in this study. Patients in stable molecular remission could also be included if they had failed a former TKI discontinuation attempt (2nd stopper). Patients were randomized 1:1 to receive either ropeg-IFN 100μg s.c. every 2 weeks for 15 months (ropeg-IFN arm) or no further treatment after TKI stop treatment (no treatment arm). The primary efficacy endpoint of the trial was molecular relapse free survival (MRFS) with molecular relapse being defined as loss of major molecular remission (MMR), which is any increase of the BCR::ABL1 transcript level to >0.1% according to the international scale (IS). Time to relapse is defined as the time from randomization to relapse. Secondary endpoints were MRFS at month 6, 12 and 24 after TKI discontinuation. BCR::ABL1 measurable residual disease (MRD) was monitored from peripheral blood and centrally assessed for all centers in Germany and locally at the French centers. There was a post study follow up to collect clinical and molecular data. Results: Between May 2017 and June 2021, 203 evaluable patients (68 female, 135 male) with a median age of 55 years were randomized at 24 centers in Germany and 3 centers in France to receive ropeg-IFN (n=95) or no treatment (n=108) after TKI stop. For 77 patients in the ropeg-IFN arm (81%) and 86 patients in the no treatment arms (80%) it was their first TKI discontinuation attempt. At the time of data cut off in June 2022, the median observation time for all patients was 36 months. The hazard ratio (HR) of molecular relapse for the ropeg-IFN cohort versus the no treatment cohort was 1.03 (95% CI, 0.68 to 0.1.55; log-rank P=0.89). The Kaplan-Meier probabilities of molecular relapse free survival (MRFS) by 6, 12, and 24 months after TKI discontinuation were 73% (95%-CI: 62-81%), 64% (95-CI: 53-73%) and 56% (95%-CI: 45-66%) for the ropeg-IFN versus 67% (95-CI: 57-75%), 60% (95-CI: 50-69%) and 59% (95%-CI: 49-68%) for no treatment (Figure 1). The MRFS at months 6 and 12 after TKI stop (secondary endpoints) were 70% (95%-CI: 60-79%) and 64% (95%-CI: 53-73%) in 91 patients for ropeg-IFN group versus 65% (95-CI: 56-74%) and 59% (95-CI: 49-68%) in 107 and 104 patients for the no treatment group. Of 90 patients who were candidates for restarting TKI due to MMR loss, 82 patients were actually evaluable for TKI restart. Of those, 77 patients re-achieved at least MMR within 12 months (median time to reestablishing MMR was three months). Of the 5 patients who did not regain MMR, one patient withdrew consent and others were treated for only 1, 3, 4, and 11 months after TKI restart. Ropeg-IFN was well tolerated. Hematological and non-hematological WHO grade 3/4 toxicity occurred in 23 patients in the ropeg-IFN (31 adverse events) and in 20 patients in the no treatment arm (26 adverse events). Three deaths were reported on study which were unrelated to CML (cardiac arrest, fall from stairs, unknown). A detailed safety analysis will be presented at the meeting. Conclusion: Ropeg-IFN maintenance after discontinuing TKI-monotherapy does not increase the proportion of patients, who persistently maintain at least an MMR. The German CML-V (TIGER) trial currently explores the impact of IFN maintenance on TFR when patients receive a combination of TKI plus IFN before TKI stop. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

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.

Leukemia Stem Cells as a Potential Target to Achieve Therapy-Free Remission in Chronic Myeloid Leukemia.

Simple SummaryLeukemic stem cells represent a rare subpopulation of leukemic cells, which not only drive leukemia initiation and progression, but also contribute to drug resistance and/or disease relapse. To achieve permanent cures and prevent relapse, eradication of leukemia stem cells is essential. Chronic myeloid leukemia is a myeloproliferative disorder, and tyrosine kinase inhibitors have dramatically improved long-term outcomes and quality of life for patients. Point mutations of the kinase domain of BCR-ABL1 lead to drug resistance, and as a result, several new generations of tyrosine kinase inhibitor have been introduced to the clinic. Some patients develop drug resistance without known mutations, however, and the presence of leukemia stem cells is believed to be at least partially associated with resistance development and disease relapse. The identification of specific markers distinguishing leukemia stem cells from healthy hematopoietic stem cells, and the potential contributions of the bone marrow microenvironment to leukemia pathogenesis, have also been explored. In this review, we revisit the current knowledge regarding the roles of leukemia stem cells in response to pharmacological treatment and explore how durable treatment-free remission may be achieved after discontinuing tyrosine kinase inhibitor treatment.Leukemia stem cells (LSCs, also known as leukemia-initiating cells) not only drive leukemia initiation and progression, but also contribute to drug resistance and/or disease relapse. Therefore, eradication of every last LSC is critical for a patient’s long-term cure. Chronic myeloid leukemia (CML) is a myeloproliferative disorder that arises from multipotent hematopoietic stem and progenitor cells. Tyrosine kinase inhibitors (TKIs) have dramatically improved long-term outcomes and quality of life for patients with CML in the chronic phase. Point mutations of the kinase domain of BCR-ABL1 lead to TKI resistance through a reduction in drug binding, and as a result, several new generations of TKIs have been introduced to the clinic. Some patients develop TKI resistance without known mutations, however, and the presence of LSCs is believed to be at least partially associated with resistance development and CML relapse. We previously proposed targeting quiescent LSCs as a therapeutic approach to CML, and a number of potential strategies for targeting insensitive LSCs have been presented over the last decade. The identification of specific markers distinguishing CML-LSCs from healthy HSCs, and the potential contributions of the bone marrow microenvironment to CML pathogenesis, have also been explored. Nonetheless, 25% of CML patients are still expected to switch TKIs at least once, and various TKI discontinuation studies have shown a wide range in the incidence of molecular relapse (from 30% to 60%). In this review, we revisit the current knowledge regarding the role(s) of LSCs in CML leukemogenesis and response to pharmacological treatment and explore how durable treatment-free remission may be achieved and maintained after discontinuing TKI treatment.

Treatment-Free Remission in Chronic Myeloid Leukemia and New Approaches by Targeting Leukemia Stem Cells.

The therapeutic landscape for chronic myeloid leukemia (CML) has improved significantly with the approval of tyrosine kinase inhibitors (TKIs) for therapeutic use. Most patients with optimal responses to TKIs can have a normal life expectancy. Treatment-free remission (TFR) after discontinuing TKI has increasingly become a new goal for CML treatment. However, TKI only “control“ CML, and relapse after discontinuation has become a key factor hindering patient access to attempt TFR. In this study, we reviewed studies on TKI discontinuation, including both first and second-generation TKI. We also reviewed predictors of relapse, new monitoring methods, and strategies targeting leukemic stem cells.

Update on Treatment-Free Remission in CML

Introduction Treatment-free remission (TFR) is one of the main goals of chronic myeloid leukemia (CML) therapy. Tyrosine kinase inhibitor (TKI) discontinuation should be considered in eligible patients for several reasons. Patients with CML on TKI have a reduced quality of life.1 TKIs are associated with long-term side effects, such as cardiovascular and renal complications.2 TKIs are associated with a heavy financial burden, both to patients and society. Numerous studies with thousands of patients have demonstrated the safety and feasibility of attempting TKI discontinuation.3–7 Finally, TKI discontinuation is an important goal for children diagnosed with CML due to long-term side effects and effects on growth and development.8 With current TKIs, approximately 50% of patients will be eligible for attempting TFR. Of those, only 50% will achieve a successful TFR. So, in reality, only 20% of patients with newly diagnosed CML will achieve a successful TFR, and the majority of patients will need to continue TKI therapy indefinitely.