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Although tyrosine kinase inhibitors (TKIs) determined an improvement of responses and overall survival (OS) in chronic phase chronic myeloid leukemia (CP-CML) patients, some patients still fail the achievement of important milestones.In this review, we focus on the need of appropriate molecular and mutational monitoring during TKI treatment with new laboratory tools and on new compounds developed to counteract the unmet clinical need in CP-CML.The appropriate identification of BCR::ABL1 dependent and independent mechanisms of resistance with Next Generation Sequencing (NGS) and digital droplet PCR (ddPCR) can allow to improve the therapeutic strategies and prevent the onset of a failure to treatment. New compounds have been recently approved or are still in investigational trials to improve the response in some critical forms of resistance and/or intolerance to available TKIs.

Background: The outcome of chronic myeloid leukemia (CML) patients in chronic phase has changed after the introduction of tyrosine kinase inhibitors (TKIs). The life expectancy is actually similar to that of the general population. Although outstanding results were achieved, about 20-30% of patients failed to achieve molecular milestones or experienced a severe toxicity and needed to switch to a second line. Objective: The aim of this review is to report on possible future management in CML, from dose optimization to avoid long-term off-target events to new agents for the treatment of resistant and/or intolerant patients. Methods: Broad research on Medline, Embase and archives from EHA and ASH congresses was performed. Results: New TKIs have been developed to counteract resistance and/or intolerance in the setting of T315I mutated patients. The benefits of ponatinib dose optimization have been recently reported in the OPTIC trial. New trials to test the dose optimization are ongoing. Conclusion: Reduction of the standard dose could be performed to reduce the specific TKI toxicity. Selective TKIs could be prescribed in the future as third line treatment.

JAK2 inhibitors have changed the therapeutic strategies for the management of primary and secondary myelofibrosis. Ruxolitinib, the first available agent, improved disease-related symptoms, spleen volume, and overall survival compared to conventional chemotherapy. It has been revealed that after 3 years of treatment, about 50% of patients discontinued ruxolitinib for resistance and/or intolerance and should be candidate to a second line of treatment.Second-generation tyrosine kinase inhibitors have been tested in this setting, but all these new drugs do not significantly impact on disease progression. Novel agents are in developments that target on different pathways, alone or in combination with JAK2 inhibitors.In this review, we summarize all the clinical efficacy and safety data of these drugs providing a vision of the possible future.

Ruxolitinib is approved for polycythemia vera (PV) patients after failure to previous cytoreductive therapy, based on durable results observed in phase 3 trials. We report a multicenter retrospective study demonstrating the efficacy and safety of ruxolitinib in real-life setting. Eighty-three patients were evaluated. Median follow-up was 24.5 months (IQR 14.0-29.3). At a 3-month response assessment, ruxolitinib provided significant benefit in reducing hematocrit (HCT) level (p 0.001), phlebotomy requirement (p 0.001), leucocytes (p = 0.044), and disease-related symptoms (p 0.001). The exposure-adjusted rates (per 100 patient-years) of infectious complications, thromboembolic events, and secondary malignancies were 6.9, 3, and 3.7, respectively. Non-melanoma skin cancers (NMSC) were the most frequent (40%) SM type. Lymphoproliferative disorders were not detected. Five (6%) patients permanently discontinued ruxolitinib treatment and four (5%) evolved in myelofibrosis (MF), but none in acute leukemia. The rate of MF evolution per 100 patient-years of exposure was 2.8. In our experience, ruxolitinib confirmed its efficacy and safety outside of clinical trials.

The clinical scenario for chronic myeloid leukemia patients rapidly changed after the introduction of tyrosine kinase inhibitors (TKIs). Second-generation TKIs as frontline treatment increased the rate of deep molecular responses without increasing the rate of overall survival. About 20% of patients experience resistance to these agents, needing alternative treatments. Here, we reviewed the possible mechanisms of resistance, available treatment, and new drugs developed to counteract and overcome resistance.Results of novel TKIs have been recently reported, especially for the setting of T315I mutated patients, such as olverembatinib and asciminib, or for patients who developed resistance due to other mutations, such as vodobatinib. Most of new TKIs are selected among compounds tested selective on ABL, therefore without possible off-target effects in the long term. New potential treatments are on the horizon in the field of CML, able to rescue patients treated firstly with one or more second-generation TKIs. Results of ongoing trials and real-world evidence dataset will help us to identify the appropriate timing of intervention and to select appropriate candidate to these drugs.

Unmet needs remain in the treatment of chronic phase chronic myeloid leukemia (CML) in later lines. Sequential use of tyrosine kinase inhibitors (TKIs) is associated with decreased overall survival and emergence of new mutations, particularly the T315I mutation. Among the new drugs developed to overcome resistance and intolerance, the STAMP inhibitor asciminib (which specifically targets the ABL myristoyl pocket) is the first example of a drug that works by allosteric inhibition. This review focuses on its mechanism of action, pharmacokinetic, efficacy, and toxicity, as well as how this drug will change the therapeutic approach for CML patients not eligible to receive other available drugs.

Despite the fact that, in the last years, life expectancy of chronic myeloid leukemia (CML) patients has reached that of the normal population, a significant proportion of CML patients is likely to fail treatment with first- or second-generation tyrosine kinase inhibitors (TKIs). Failure to first-line treatment is commonly due to molecular resistance or unbearable toxicity. New specific compounds are tested in this setting to fulfill this unmet clinical need in CML; of these, asciminib has shown efficacy based on allosteric inhibition which allows to overcome resistance and off-target toxicity. This review aims to cover how asciminib will change the therapeutic scenario of CML, highlighting its mechanism of action, pharmacokinetics, efficacy and toxicity. Asciminib will be a possible option as third-line therapy for patients carrying resistant mutations, such as T315I, and/or not eligible for treatment with other TKIs.

Background Tyrosine kinase inhibitors (TKIs) revolutionized treatment of chronic myeloid leukemia (CML). However, the first months of therapy are crucial, as optimal response is defined as the achievement of molecular milestones at 3, 6 and 12 months (mo.) and as many toxicities, also causing a TKI switch, are more frequent in the 1st year. Methods To evaluate achievement of early molecular response (MR) and incidence of events leading to a TKI change during the 1st year of therapy, we retrospectively studied 1650 CP-CML patients diagnosed from 2012 and 2019 at 31 Hematology Centres and treated with frontline imatinib (IM) or second-generation (2G) TKIs dasatinib or nilotinib. Optimal MR at 3, 6 and 12 mo. were assessed according to 2020 ELN recommendations. Results Frontline TKI was IM in 926 (56.1%) and 2G-TKIs in 724 (43.9%) cases: the main clinical features at diagnosis of the entire cohort and according to frontline treatment is reported in the Table 1. Commonest comorbidities were arterial hypertension (38.7%), previous neoplasm (13.6%), diabetes (11.3%), peripheral vascular diseases (7.8%), COPD (7.5%) and ischemic heart disease (6.8%). IM-treated patients were older (p Optimal MR was achieved at 3 mo. by 1186/1430 (82.9%), at 6 mo. by 1025/1352 (75.8%) and at 12 mo. by 826/1264 patients (65.3%), respectively. Total number of patients discontinuing TKI in the 1st year was 321/1650 (19.4%), being higher with IM (237/926, 25.5%) than 2G-TKIs (84/724, 11.6%) (p0.001), hematologic toxicity (1.7%, 2.0% IM vs 1.4% 2G-TKIs, p=0.25) and progression (1.0%, 1.2% IM vs 0.8% 2G-TKIs, p=0.56). Cumulative incidence of discontinuation at 3, 6 and 12 mo. were 5.6%, 10.7% and 19.3%, respectively; values for IM and 2G-TKIs at the three timepoints were 8.1%, 15.0%, 25.5% and 2.5%, 5.3%, 11.5% (p Conclusions This real-world study on over 1600 CML patients shows that almost 20% discontinue frontline TKI during the 1st year, mostly for primary resistance or toxicity. Discontinuation rates are higher with IM compared to 2G-TKIs, mostly at 3 mo. and are probably due to a lower attainment of early MR. The impact of older age, higher risks and heavier burden of comorbidities in IM patients should be considered and need deeper investigation. Figure 1 Figure 1. Disclosures Elena: GILEAD: Membership on an entity's Board of Directors or advisory committees; NOVARTIS: Membership on an entity's Board of Directors or advisory committees; PFIZER: Membership on an entity's Board of Directors or advisory committees; CELGENE: Other: funding for meeting participation. Sportoletti: AstraZeneca: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; AbbVie: Consultancy, Honoraria. Stagno: InCyte: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria, Other: Support for attending meetings and/or travel; Novartis: Consultancy, Honoraria, Other: Support for attending meetings and/or travel, Research Funding. Iurlo: Pfizer: Speakers Bureau; Incyte: Speakers Bureau; Novartis: Speakers Bureau; Bristol Myers Squibb: Speakers Bureau. Bonifacio: Novartis: Honoraria; Pfizer: Honoraria; Amgen: Honoraria; Bristol Myers Squibb: Honoraria. Breccia: Pfizer: Honoraria; Incyte: Honoraria; Abbvie: Honoraria; Bristol Myers Squibb/Celgene: Honoraria; Novartis: Honoraria. Latagliata: Novartis: Honoraria; Pfizer: Honoraria; BMS Cellgene: Honoraria.

Introduction Chronic Myeloid Leukemia (CML) has become highly curable after introduction of Tyrosine-Kinase Inhibitors (TKIs). However, several side-effects have been reported with the prolonged use of TKIs: in particular, severe cardiovascular and pulmonary toxicities were observed with 2 nd generation TKIs (2G-TKIs), nilotinib and dasatinib. Imatinib is generally considered safer, even if some concerns were recently raised on its renal toxicity and occurrence of late anemia. Aims To evaluate the impact of imatinib compared to 2G-TKIs on the hemoglobin (Hb) levels in the long-lasting frontline treatment of CML patients. Methods From 1/2002 to 12/2015, 365 CML patients were diagnosed and treated frontline with TKIs in 2 different Centres in Italy: of them, 123 permanently discontinued the treatment before the 5 th year from the start due to intolerance (31 cases, 25.2%), primary resistance (41, 33.3%), secondary resistance (16, 13.0%), blastic evolution (4, 3.2%), unrelated death (12, 9.8%) or were lost to follow-up (19, 15.5%). At 5 years, the remaining 242 patients were still receiving frontline TKI treatment and were considered for the present analysis. Hb levels were recorded at baseline and thereafter every 12 months up to the 5 th year of treatment. Results As to frontline treatment, 186 patients (76.8%) received imatinib and 56 (23.2%) 2G-TKIs (nilotinib in 44 cases and dasatinib in 12, respectively). The main clinical features at diagnosis of the entire cohort and according to frontline treatment are reported in the table: median Hb value at baseline was significantly lower in patients treated with 2G-TKIs. Median Hb values at different time-points according to frontline treatment are reported in the Figure. In patients treated with imatinib, median Hb levels at 12 th (12.5 g/dl, IQR 11.6-13.5) and 60 th month (12.4 g/dl, IQR 11.4-13.3) were stable compared to baseline (12.8 g/dl, IQR 11.3-13.8) (p=0.248 and p=0.075, respectively). On the contrary, median Hb levels at 12 th (13.4 g/dl, IQR 12.2-14.3) and 60 th month (13.6 g/dl, IQR 12.0-14.6) showed a significant increase compared to baseline (11.8 g/dl, IQR 10.6-13.7) in patients treated with 2G-TKIs (p Conclusions Present data highlight that long-lasting treatment with imatinib can have a negative late effect on erythropoiesis, with incomplete recovery of hemoglobin levels and occurrence of late anemia in about 15% of patients at the 60 th month of therapy.This possible adverse event, which is still unrecognized and seems very rare with 2G-TKIs, could affect quality of life and should be recognized in the long-term management of CML patients. Figure 1 Figure 1. Disclosures Latagliata: BMS Cellgene: Honoraria; Pfizer: Honoraria; Novartis: Honoraria. Martelli: Novartis: Other: advisory board; Gilead: Other: advisory board. Breccia: Pfizer: Honoraria; Novartis: Honoraria; Incyte: Honoraria; Bristol Myers Squibb/Celgene: Honoraria; Abbvie: Honoraria.