Introduction Of Tyrosine Kinase Inhibitors Research Articles

Allogeneic haematopoietic cell transplantation for chronic myeloid leukaemia in Switzerland in the face of rapid development of effective drugs.

Until the year 2000, allogeneic haematopoietic cell transplantation (HCT) was the standard treatment for young and fit chronic myeloid leukaemia (CML) patients. CML was the main indication for allogeneic HCT. The introduction of tyrosine kinase inhibitors changed the treatment of CML patients dramatically. Allogeneic HCT was rapidly replaced by tyrosine kinase inhibitors as first-line treatment for CML, and the indication shifted to the treatment of non-responders, patients intolerant to tyrosine kinase inhibitors and patients whose CML is transforming to the accelerated phase and blast crisis. This paper describes changes in the use of transplantation technology for CML patients in the face of rapid drug development. All patients receiving a transplant for CML between 1997 and 2021 in Switzerland were included in the study. For the purpose of this analysis, time periods were analysed in quinquennia, 1997-2001 (Q1), 2002-2006 (Q2), 2007-2011 (Q3), 2012-2016 (Q4) and 2017-2021 (Q5), as the observation period spanned 25 years. Overall, 239 patients received a transplant. These included 96 in Q1, 56 in Q2, 25 in Q3, 34 in Q4 and 28 in Q5. Patient characteristics changed over time: recent patients were older and had a longer interval from diagnosis to transplantation because of tyrosine kinase inhibitor treatment. However, the proportions of patients receiving transplants during an early versus advanced disease stage differed little. Transplant technology changed, as well. Patients received intensive conditioning regimens less often due to higher age and more commonly had peripheral blood as opposed to bone marrow transplants. However, the type of stem cell donor selected did not differ. In a univariable analysis, there were no significant differences in survival, progression-free survival, non-relapse mortality, relapse incidence or incidences of acute and chronic graft-versus-host disease among the five quinquennia. In a multivariable analysis, older age, donors other than HLA-identical siblings and more advanced disease stage, but not the quinquennium, were associated with higher risk of death. Since the introduction of tyrosine kinase inhibitors haematopoietic cell transplantation has been used less frequently to treat CML. Patients in recent cohorts received transplants at an older age and later in the disease course; despite these higher risks, the outcome of allogeneic HCT has not worsened over time but has not improved, either. As the outcome is worse in advanced phases, it is important to conduct transplants before disease progression. Therefore, patients with advanced disease should be monitored closely and receive transplants in time.

Unveiling IL6R and MYC as Targeting Biomarkers in Imatinib-Resistant Chronic Myeloid Leukemia through Advanced Non-Invasive Apoptosis Detection Sensor Version 2 Detection.

The management of chronic myelogenous leukemia (CML) has seen significant progress with the introduction of tyrosine kinase inhibitors (TKIs), particularly Imatinib. However, a notable proportion of CML patients develop resistance to Imatinib, often due to the persistence of leukemia stem cells and resistance mechanisms independent of BCR::ABL1 This study investigates the roles of IL6R, IL7R, and MYC in Imatinib resistance by employing CRISPR/Cas9 for gene editing and the Non-Invasive Apoptosis Detection Sensor version 2 (NIADS v2) for apoptosis assessment. The results indicate that Imatinib-resistant K562 cells (K562-IR) predominantly express IL6R, IL7R, and MYC, with IL6R and MYC playing crucial roles in cell survival and sensitivity to Imatinib. Conversely, IL7R does not significantly impact cytotoxicity, either alone or in combination with Imatinib. Further genetic editing experiments confirm the protective functions of IL6R and MYC in K562-IR cells, suggesting their potential as therapeutic targets for overcoming Imatinib resistance in CML. This study contributes to understanding the mechanisms of Imatinib resistance in CML, proposing IL6R and MYC as pivotal targets for therapeutic strategies. Moreover, the utilization of NIADS v2 enhances our capability to analyze apoptosis and drug responses, contributing to a deeper understanding of CML pathogenesis and treatment options.

Late relapse of chronic myeloid leukemia after allogeneic bone marrow transplantation points to KANSARL (KANSL1::ARL17A) alteration: a case report with insights on the molecular landscape

Chronic myeloid leukemia is a myeloproliferative neoplasm characterized by the presence of the Philadelphia chromosome and the consequent BCR::ABL1 oncoprotein. In the era before the introduction of tyrosine kinase inhibitors (TKIs), the only potentially curative treatment was allogeneic hematopoietic stem cell transplantation (HSCT). Here, we present the case of a patient affected by CML who experienced a relapse 20 years after allogeneic HSCT. Following relapse, the patient was treated with imatinib and bosutinib, resulting in a deep molecular response and successfully discontinued treatment. Additional analysis including whole-exome sequencing and RNA sequencing provided some insights on the molecular mechanisms of the relapse: the identification of the fusion transcript KANSL1::ARL17A (KANSARL), a cancer predisposition fusion gene, could justify a condition of genomic instability which may be associated with the onset and/or probably the late relapse of his CML.

Comparison of long-term outcomes between imatinib and dasatinib prophylaxis after allogeneic stem cell transplantation in patients with Philadelphia-positive acute lymphoblastic leukemia: A multicenter retrospective study.

Although the prognosis of Philadelphia-positive acute lymphoblastic leukemia (Ph+ALL) has improved with the introduction of tyrosine kinase inhibitors (TKIs) and stem cell transplantation, prevention of relapse after transplantation remains a concern. The aim of this study was to compare the impact of TKI prophylaxis with imatinib and dasatinib on long-term outcomes after transplantation. Patients with Ph+ALL who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) at first complete remission (CR1) and received TKI prophylaxis after allo-HSCT were included in this retrospective analysis. Two cohorts were established based on the choice of TKI prophylaxis: the imatinib (Ima) and dasatinib (Das) cohorts. The survival and safety outcomes of these cohorts were compared. Ninety-one patients in the Ima cohort and 50 in the Das cohort were included. After a median follow-up of 50.6months, the 5-year cumulative incidence of relapse, nonrelapse mortality rate, and overall survival in the Ima and Das cohorts were 16.1% and 12.5%, 5.2% and 9.8%, and 86.5% and 77.6%, respectively, with no statistical differences. The cumulative incidence of mild chronic graft-versus-host disease was higher in the Das cohort. The most common adverse event was neutropenia (64.7% vs. 69.5%). The Das cohort had a higher incidence of gastrointestinal bleeding (25.5% vs. 2.3%) and gastrointestinal reaction (48.9% vs. 31.4%) than the Ima cohort. The proportion of patients treated on schedule was significantly lower in the Das cohort than in the Ima cohort, and drug intolerance was the main reason for protocol violation. For patients with Ph+ALL undergoing allo-HSCT in CR1, imatinib prophylaxis achieved long-term outcomes similar to those of dasatinib.

Chimeric antigen-receptor (CAR) engineered natural killer cells in a chronic myeloid leukemia (CML) blast crisis model.

During the last two decades, the introduction of tyrosine kinase inhibitors (TKIs) to the therapy has changed the natural history of CML but progression into accelerated and blast phase (AP/BP) occurs in 3-5% of cases, especially in patients resistant to several lines of TKIs. In TKI-refractory patients in advanced phases, the only curative option is hematopoietic stem cell transplantation. We and others have shown the relevance of the expression of the Interleukin-2-Receptor α subunit (IL2RA/CD25) as a biomarker of CML progression, suggesting its potential use as a therapeutic target for CAR-based therapies. Here we show the development of a CAR-NK therapy model able to target efficiently a blast crisis cell line (K562). The design of the CAR was based on the scFv of the clinically approved anti-CD25 monoclonal antibody (Basiliximab). The CAR construct was integrated into NK92 cells resulting in the generation of CD25 CAR-NK92 cells. Target K562 cells were engineered by lentiviral gene transfer of CD25. In vitro functionality experiments and in vivo leukemogenicity experiments in NSG mice transplanted by K562-CD25 cells showed the efficacy and specificity of this strategy. These proof-of-concept studies could represent a first step for further development of this technology in refractory/relapsed (R/R) CML patients in BP as well as in R/R acute myeloblastic leukemias (AML).

The Impact of Pretransplant Use of Tyrosine Kinase Inhibitors on Allogeneic Stem Cell Transplantation in Patients with Chronic Myeloid Leukemia-A Single-institution Retrospective Study.

Objective Chronic myeloid leukemia (CML) is a malignant hematological disorder, and allogeneic stem cell transplantation (allo-SCT) was its only curative treatment until the introduction of tyrosine kinase inhibitors (TKIs). Allo-SCT is still considered for CML patients who are resistant to TKIs and in an advanced phase. Currently, second- and third-generation (2/3 G) TKIs are typically incorporated into the first-line treatment of CML. However, the impact of 2/3 G TKIs on subsequent allo-SCT remains unclear. We therefore evaluated the effect of 2/3 G TKIs on allo-SCT. Methods We retrospectively evaluated the effect of pretransplant therapy with TKIs on the outcome of allo-SCT for CML using clinical data at our institution. Patients or Materials Thirty-two CML patients who received their first allo-SCT procedure at our institute from 2001 to 2020 were included. We divided the patients into three subgroups based on TKI treatment before allo-SCT. Patients receiving no TKIs, only imatinib (IM), and 2/3 G TKIs were classified into the Non-TKI, IM, and 2/3 G TKI groups, respectively. Results In a univariate analysis, the pretransplant use of 2/3 G TKIs was significantly associated with a higher 5-year overall survival (91.7%) and relapse-free survival (75.0%) than the use of IM (37.5% and 12.5%) in patients presenting with or progressing to the advanced phase. In addition, pretransplant use of 2/3 G TKIs did not increase the incidence of graft-versus-host disease (GVHD). Conclusions We demonstrated that the pretransplant use of 2/3 G TKIs was safe and improved the outcome of CML patients who presented with or progressed to the advanced phase without increasing the frequency of GVHD.

Assessment of knowledge, attitudes, and practices of CML patients and their families toward TKI therapy in China.

The introduction of tyrosine kinase inhibitors (TKIs) has revolutionized chronic myeloid leukemia (CML) treatment. The knowledge, attitude, and practice (KAP) of patients and their families play a significant role in treatment adherence and effectiveness. This study aimed to investigate the KAP of CML patients and their families regarding TKI therapy in China. From November 1 to December 31, 2022, a cross-sectional study was conducted at the Affiliated Huai'an No. 1 People's Hospital in China. A total of 313 CML patients and 268 family caregivers were selected using convenience sampling. Participants answered a self-designed questionnaire. The questionnaire contained demographic/clinical data and assessed KAP toward CML and TKI therapy. Participants exhibited mean KAP scores of 8.91 (55.7%), 33.10 (73.6%), and 2.20 (73.3%), respectively. Family members had higher knowledge and practice scores than patients (both P < .05), with factors such as younger age, urban residency, higher education, employment, higher income, and interaction with peers correlating with better knowledge scores (P < .001). Although participants were well-informed about their diagnosis and medication (>80%), understanding of disease causes (<30%) and treatment prognosis and side effects (<50%) was limited, and cost concerns affected 80.55%. Anxiety and depression were reported more among caregivers (46.64% and 13.8%) than patients (29.71% and 11.51%). While 84.85% adhered to the doctor's instructions, only 68.50% actively sought more CML information. Positive correlations were observed among KAP scores, indicating their interdependence (knowledge-attitude: R = 0.397; knowledge-practice: R = 0.598; attitude-practice: R = 0.353; all P < .001). The findings underscore the importance of tailored education to fill knowledge gaps about CML and the need to address financial concerns and provide psychological support. The positive correlations among knowledge, attitudes, and practices emphasize the need for comprehensive interventions. In conclusion, this study highlights the importance of tailored education, addresses financial concerns, and provides emotional support for CML patients and caregivers in China, despite limitations such as convenience sampling and questionnaire design. Future research should evaluate the effectiveness of educational interventions and long-term outcomes to further enhance the overall well-being of this population.

Flumatinib for the Treatment of Adult Patients with Resistant or Intolerant Chronic-Phase Chronic Myeloid Leukemia: Results from Real-World Data

Introduction Over the past decades, BCR-ABL1 tyrosine kinase inhibitors (TKIs) as the initial treatment for chronic phase Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia (CML-CP) have dramatically turned CML-CP into a manageable and potentially curable chronic disease. Nonetheless, in spite of the massive improvement in CML treatment over the last years with the introduction of TKIs, some patients (20%-30%) display intrinsic or acquired resistance to treatment during the disease course. Flumatinib Mesylate is a newer and orally available TKI with higher selectivity and potency against BCR-ABL1 kinase versus imatinib. According to the previous data，flumatinib can be an effective first-line treatment for CML-CP. Patients and Methods This study was initiated mainly to observe the safety and efficacy of flumatinib in the treatment of adult patients with resistant or intolerant Chronic-Phase Chronic Myeloid Leukemia, especially in second-line or above treatment in the real world. Efficacy and safety assessments were collected for the intent-to-treat population. Major molecular response (MMR) was defined as BCR-ABL1 transcript level ≤ 0.1% on the International Scale (IS), molecular response (MR4) was defined as BCR-ABL1 transcript level (IS) ≤ 0.01%; MR4.5 was defined as a BCR-ABL1 (IS) transcript level ≤ 0.0032%. DMR was defined as MR 4.0 or MR 4.5. Results Among the 58 evaluable patients with CML-CP, 54% were male, 47% were female. The median age of these patients is 45Y. During the observation period, there were 28 second-line conversion patients (48%), 19 third-line conversion patients (33%), and 11 fourth-line and above patients (19%). Prior therapies included imatinib, dasatinib, nilotinib, olverembatinib, radotinib and ponatinib. All patients converted to treatment of 600mg flumatinib daily. Among the 58 evaluable patients, 20 patients who had been treated with imatinib alone were converted to flumatinib, including 9 cases of IM resistance, 8 cases of IM intolerance and 2 case of personal reasons. During the 1-year follow-up, 52% of patients (n=30) were evaluable for the achievement of MMR. The patients with BCR-ABL1 (IS) &amp;gt; 10% at baseline, 3, 6 and 12 months were 48%, 17%, 23% and 26%, respectively; for patients with BCR-ABL1 (IS) &amp;lt; 0.1% were 26%, 40%, 49% and 52%, respectively; for patients with DMR were 26%, 40%, 49% and 52%, respectively. For imatinib-intolerant or -resistant patients, MMR was 44%. Subgroup analyses showed that the imatinib-intolerant or -resistant patients with BCR-ABL1 (IS) &amp;gt;10% at baseline, 3, 6 and 12 months were 65%, 0%, 10% and 0%, respectively; for patients with BCR-ABL1 (IS) &amp;lt; 0.1% were 10%, 33%, 80% and 44%, respectively; for patients with DMR were 5%, 11%, 30% and 11%, respectively. Meanwhile, 11% of patients could not be detected at molecular level (0.000%). Of the 58 patients, only Grade 1 AEs were reported, including diarrhea, rash and eye edema. Conclusion Flumatinib has good efficacy and safety in the treatment of adult patients with resistant or intolerant Chronic-Phase Chronic Myeloid Leukemia, it will be a good choice for second-line or above treatment for CML-CP In clinical practice.

The Outcomes of Pregnancies in Japanese Patients with CML in the TKI Era; A Result of Nationwide Survey

Background The introduction of tyrosine kinase inhibitors (TKIs) has dramatically improved the survival of patients with chronic myeloid leukemia (CML). Although the median age at diagnosis of CML is around 55 years, CML affects all generations, rendering a substantial population of women of childbearing potential. Therefore, issues related to conception and pregnancy are becoming increasingly important, because TKIs have the potential risk of fetal abnormalities and spontaneous abortion. Planned pregnancy during treatment-free remission (TFR) is an ideal way to avoid exposure of the embryo and fetus to a TKI. However, in real-life situations, not all conceptions are planned, not all patients fulfill the eligibility criteria for TFR, and some cases develop CML during pregnancy. Information about pregnancy in patients with CML is still limited in the TKI era. Study Design and Methods We designed a retrospective observational study of female patients with CML in the chronic phase who experienced pregnancy. We conducted a nationwide survey to collect data associated with CML treatment, conception, and pregnancy outcomes. This study was approved by the institutional review boards of Aiiku Hospital and each hospital participating in the survey. This study is registered in the University Medical Information Network (UMIN000042762). Results We sent questionnaires to 463 hematological centers to ask whether they made a diagnosis of CML in female patients of childbearing age and we received replies from 206 centers (recovery rate: 44.5%). A total 853 female patients aged 45 years or younger were diagnosed as having CML between 2002 and 2020, and 78 patients became pregnant by December 2020. Information of 70 pregnancies in 49 patients was obatained for analysis. The median age at CML diagnosis was 26 (range, 9-40) years and the median age at pregnancy was 33 (range, 21-42) years. Times of pregnancy varied from once to five times, and times of childbirth ranged from zero to three times. There were three types of pregnancies: CML onset during pregnancy (n=9), unplanned pregnancy during treatment or stopping treatment with TKI (n=25), and planned pregnancy during TFR or treatment with interferon (IFN)-α (n=36). The median durations from CML diagnosis to first pregnancy were 4.1 years in patients with unplanned pregnancies and 9.1 years in patients with planned pregnancies. Nine pregnancies in patients with CML onset during pregnancy resulted in seven births and two elective abortions. Twenty-five unplanned pregnancies led to 14 births, eight elective abortions and three spontaneous abortions. In 36 planned pregnancies, there were 27 births, one stillbirth and seven spontaneous abortions, and one case was during pregnancy at the time of the search. Elective abortions were chosen in 10 pregnancies, possibly due to exposure of the embryo to a TKI (n=9) or due to not achieving MMR at the time of a positive pregnancy test (n=6). TFR was chosen in 31 pregnancies, resulting in 26 births and five spontaneous abortions. MMR or deeper response was sustained in 18 of 26 (69%) pregnancies with childbirth and 15 of 18 (83%) pregnancies with DMR at the time of a positive pregnancy test. Treatment with IFN-α was chosen in 23 pregnancies and resulted in 20 births and three spontaneous abortions. Among the 13 patients with MMR or a deeper response at the time of pregnancy, only one patient (7.7%) lost MMR during pregnancy. Treatment with IFN-α was commenced after loss of MMR was experienced during pregnancy with TFR in four cases, with MMR being regained in two cases and CCyR being sustained in the other two cases until delivery. Conclusions Although our analysis was based on a limited number of patients, TFR could be a reasonable option for patients who achieve DMR and desire childbearing. Treatment with IFN-α might be another option for pregnancy in patients who achieved MMR or a deeper response.

Comparison of Long-Term Outcome between Imatinib and Dasatinib Prophylaxis after Allogeneic Stem Cell Transplantation in Patients with Philadelphia-Positive Acute Lymphoblastic Leukemia-a Multi-Center Retrospective Study

Background: Though the prognosis of Philadelphia-positive (Ph-positive) acute lymphoblastic leukemia (ALL) has been improved since the introduction of tyrosine kinase inhibitors (TKIs) and combined with allogeneic stem cell transplantation (allo-HSCT), relapse after HSCT remains a concern. Prophylactic TKIs after allo-HSCT seemed a promising strategy to prevent relapse. But the optimal choice of the agent is still obscure.Methods: We retrospectively analyzed the clinical data of Ph-positive ALL patients who underwent allo-HSCT in CR1 from 6 medical centers in China between September 2010 and October 2021. Patients were divided into two cohorts according to different choice of TKI after allo-HSCT, namely Ima cohort with imatinib prophylaxis and Das cohort with dasatinib prophylaxis. Survival and safety outcomes of two cohorts were compared, and prognostic factors were determined by univariate and multivariate analyses.Results: One hundred and forty-one patients, with median age of 37 years (range, 14-61 years), were included, of whom 91 were in Ima cohort and 50 were in Das cohort. After median follow-up of 50.6 months, 5-year cumulative relapse rate (CIR), non-relapse mortality rate (NMR), leukemia-free time (LFS) and overall survival (OS) in Ima and Das cohort were 16.1% and 12.5%; 5.2% and 9.8%; 78.8% and 77.6%; 86.5% and 77.6%, respectively, with no significant difference. Mild cGVHD was higher in Das cohort compared to Ima cohort, while the total, moderate or severe cGVHD were similar. The most common adverse event was neutropenia (66.4%). Das cohort owned higher incidence of gastrointestinal bleeding and gastrointestinal reaction than Ima cohort. The proportion of patients treated on schedule was 30% in Das cohort, lower than that of in Ima cohort (p&amp;lt;0.001). Drug intolerance was the main reason for not completed treatment as intended.Conclusions: For patients with Ph-positive ALL receiving allo-HSCT in CR1, imatinib prophylaxis after transplantation could obtain the same long-term outcome compared to dasatinib, showing better tolerance.

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.

Novel Insights in TKI Resistance in BCR:: ABL1-Positive B-Cell Acute Lymphoblastic Leukemia Beyond Kinase Domain Mutations

Background and Aim Despite the introduction of tyrosine kinase inhibitors (TKIs), approximately 30% of newly diagnosed pediatric and adult BCR:: ABL1-positive B-cell acute lymphoblastic leukemia (B-ALL) patients experience relapsed or refractory disease (Biondi et al, Lancet Haematology 2018; Bassan et al, Journal of Clinical Oncology 2010). ABL1 kinase domain mutations, hindering TKI binding, explain part of the relapses and are acquired during TKI therapy but are rarely detected in newly diagnosed BCR:: ABL1-positive B-ALL patients (Baer et al, Haematologica 2022). Intrinsic TKI resistance mechanisms in BCR:: ABL1-positive B-ALL present prior to TKI treatment are less well documented. Therefore, we aimed to identify potential biomarkers for TKI sensitivity at diagnosis using primary patient samples and newly generated cell lines made from patient-derived xenografts (PDX cell lines). Patients and Methods Leukemic cells from diagnosis of BCR:: ABL1-positive B-ALL patients without ABL1-kinase domain mutations were used to measure cell survival in an ex vivo co-culture assay after imatinib (1.95-125 μM), dasatinib (1.95-125 nM), or bosutinib (0.016-2 μM) exposure. TKI sensitivity was assessed using the area under the dose-response curve (AUC), with &amp;lt;80 arbitrary units (AU) classified as imatinib-sensitive, 80-120 AU as intermediate, and &amp;gt;120 AU as resistant. Multiplex ligation-dependent probe amplification, whole exome sequencing, and RNA sequencing were performed on diagnostic material if available. ABL1 phosphorylation and expression levels were measured using (phospho)flow cytometry in patient-derived xenografts from diagnostic samples and (PDX) cell lines. Results We determined ex vivo sensitivity to imatinib, dasatinib, and bosutinib in 32 pediatric and 19 adult BCR:: ABL1-positive B-ALL patient samples. We observed a substantial variability in ex vivo imatinib response in pediatric and adult patient samples (median AUC: 98 AU; range: 16 to 281 AU). The sensitivity towards imatinib strongly correlated with the sensitivity towards second-generation TKIs dasatinib and bosutinib (rho = 0.84; p &amp;lt; 0.001 and rho= 0.89; p &amp;lt;0.001). Moreover, imatinib's AUC of samples derived from newly diagnosed patients who relapsed after TKI treatment was higher compared with those derived from patients who did not suffer from a relapse (median AUC 123 vs 84 AU; p = 0.03). We observed that an increase in ex vivo imatinib resistance was correlated with a decreased amount of phosphorylated ABL1 protein (rho=-0.92; p=0.0013) and total ABL1 protein (rho=-0.82; p=0.01) in untreated, newly diagnosed samples. Ex vivo exposure to imatinib reduced the ABL1 phosphorylation levels in both sensitive and resistant samples but resistant cells exhibited lower levels of (p)ABL1 protein, indicating reduced dependence on BCR-ABL1 signaling. The ex vivo imatinib resistance in samples carrying deletions in B-cell development genes IKZF1 and/or PAX5 was higher than in samples without these deletions (median AUC: 122 versus 80 AU; p=0.01). In addition, one imatinib-resistant patient had a p.His1038Arg mutation in ZEB2, which is recurrent in B-ALL and this gene has also been described as B-cell development gene (Studd et al, Blood Cancer Journal 2021). Interestingly, another resistant patient had a mutation in SETD2,a gene previously associated with ex vivo TKI resistance in chronic myeloid leukemia cell lines (Sheng et al, Cell Proliferation 2019). Other secondary lesions included SH2B3 inactivation lesions and CRLF2 rearrangements. These lesions were present in intermediately sensitive and resistant BCR:: ABL1-positive samples and are expected to lead to increased JAK/STAT signaling, potentially serving as a resistance mechanism for TKI. Conclusion Our study revealed that the amount of total and phosphorylated ABL1 protein was correlated with ex vivo TKI sensitivity. Newly diagnosed TKI-resistant BCR:: ABL1 samples were further characterized by somatic lesions in B-cell development genes including IKZF1. These results link the known poor prognostic value of IKZF1 deletions in BCR:: ABL1-positive B-ALL patients (van der Veer et al. Blood 2014; Fedullo et al, Haematologica 2019) with intrinsic mechanisms of TKI resistance other than tyrosine kinase domain mutations.

Combinatorial Treatment Options for Highly Resistant Compound Mutations in the Kinase Domain of the BCR::ABL1 Fusion Gene

The introduction of tyrosine kinase inhibitor (TKI)-based therapies has dramatically changed the outcome in patients with chronic myeloid leukemia (CML) and Ph-positive acute lymphoblastic leukemia (Ph+ALL). However, the occurrence of point mutations in the kinase domain (KD) of the BCR::ABL1 fusion gene can impair or inhibit the efficacy of individual TKIs. In advanced phases of CML and in Ph +ALL, patients frequently develop compound mutations (CMs), defined as the presence of more than one mutation on the same BCR::ABL1 molecule in a leukemic cell, which are often highly or even completely resistant to any individual TKI. Some CMs respond to high doses of the currently most potent available TKI, ponatinib, but the dose-related toxicity is an important impediment. The most frequently occurring CMs, which include the gatekeeper mutation T315I, are often resistant to any currently available TKI. We performed in vitro analyses using a common cell line model based on Ba/F3 cells expressing a panel of 12 different CMs (V299L/G250E, V299L/E255V, V299L/F359V, F317L/Y253H, F317L/E255V, F317L/F359V, F359V/Y253H, T315I/M244V, T315I/G250E, T315I/E255K, T315I/E255V, T315I/F359V) in BCR::ABL1 constructs introduced into the cells by a transposon-mediated approach. The presence of single insertion copies of the mutant constructs was verified by FACS analysis to preclude skewed test results potentially caused by multiple copies of the mutant construct. The cells pre-tested in this way were exposed in vitro to different concentrations of various drugs including ponatinib combined with a number of other agents such as asciminib, hydroxyurea, palbociclib, venetoclax, ibrutinib, vodobatinib, and crizotinib. The drug concentrations tested corresponded to the spectrum of the respective dosing regimens used in the clinical setting. The cell viability assays performed indicated that CMs responding only to elevated concentrations of ponatinib could be suppressed by combinatorial treatment with lower concentrations of ponatinib and different other agents tested. Moreover, CMs displaying high levels of resistance to TKIs applied as single agents mostly revealed adequate in vitro responses to individual drug combinations with ponatinib, most commonly including asciminib, hydroxyurea or crizotinib. Only the most resistant CM constellation tested, T315I/F359V, failed to respond to the compounds investigated and showed a limited response to the combination of high concentrations of ponatinib with hydroxyurea. A good response of this CM in vitro was only achieved by a combination of ponatinib with a very high concentration of crizotinib indicating the need for further testing of additional candidate drugs for this constellation. Overall, combinatorial treatment of BCR::ABL1 CMs indicated that relatively low concentrations of the drugs used are capable of effectively inhibiting in vitro survival of mutant cells in most instances, which is important with regard to the expected toxicity of combinatorial treatment approaches. Since our earlier data indicated a good correlation between in vitro test results and clinical responses, our observations may serve as a basis for novel treatment options in patients with Ph +leukemias displaying challenging BCR::ABL1 KD-mutations. [This project was supported by an educational grant from Incyte Biosciences International Sàrl]

Tyrosine Kinase Inhibitor (TKI) Treatment Patterns in 5,261 Chronic Phase (CP) Chronic Myeloid Leukemia (CML) Patients in “Real-Life” Settings: A Population-Based Study Using a Nationwide Claim Database

Introduction The introduction of TKI in CP-CML enabled responders to reach a similar survival to that of the general population. However, recent small-sized real-life studies showed that 1 in 5 CP-CML patients (pts) received at least 3 lines of TKI, mainly due to resistance or the onset of adverse events (AE). The objective of this study is to document real-life TKI treatment patterns nationwide in CML pts with a long-term follow-up, with a focus on pts who initiated at least a 3 rd line and associated disease burden. Methods This real-life non-interventional study was conducted using the French nationwide claim database (SNDS, Système National des Données de Santé), covering over 99% of French beneficiaries. Pts who initiated their first TKI with an indication for CML (imatinib, dasatinib, nilotinib, bosutinib, ponatinib) between January 2010 and December 2018, aged 18 years old or older at TKI initiation (index date T 0), and with healthcare resource use (HCRU) markers of CML - i.e., reasons for hospitalization and reported Long-Term Disease - without markers of confounding disease for the use of TKIs, were included. Treatment patterns were assessed from T 0 to December 2020 or death, through the description of TKI treatment sequences (TKI lines), adherence - discontinuations (≥ 3 months) during a TKI line and Medication Possession Ratio (MPR) -, and line duration (Time to Next Treatment (TTNT) estimates). TTNT was calculated as cumulative incidence of TKI switches, with death as competing risk; switches were defined as discontinuation of a TKI followed by the start of a different TKI. Results A total of 5,261 CML pts initiated their 1 st line TKI, with a median age at T 0 of 59.5 years (IQR: 23.2) and a M/F ratio of 1.2. The median follow-up from T 0 was 5.6 years (IQR: 4.6). Respectively 2,299, 1,017 and 426 pts initiated 2 nd, 3 rd and 4 th TKI line. Most frequent TKIs used as 1 st and 2 nd lines were imatinib (73.1%), and dasatinib (60.4%; Figure 1), respectively. From the 3 rd line, TKI patterns changed following the reimbursement of bosutinib in 2015 and ponatinib in 2016, and subsequently stabilized; shares in pts treated in 3 rd line and more at the beginning of 2020 were roughly equally distributed between marketed TKIs. TKI discontinuations rates during a line varied from 76.2% for 1 st line to 56.2% for 4 th lines. The median cumulative duration of discontinuations tended to decrease across lines (2.9, 2.5, 2.3 and 2.1 months for 1 st, 2 nd, 3 rd, and 4 th line, respectively); IQRs across lines were similar. The proportion of pts with a good medication adherence (MPR ≥ 80%) was around 80% for all TKI lines. TTNT was similar across all TKIs and all lines; 10-year TTNT rates were 48% (95CI: [47%; 50%]), 56% [53%; 59%], 56% [51%; 61%], 48% [42%; 54%] for 1 st, 2 nd, 3 rd, and 4 th lines. For pts who switched, most of switches occurred during the first year following line initiation (51% of switches observed in the first year for both 1 st, 2 nd, 3 rd, and 4 th lines), 24% occurred during the second year, and 10% during the third year. The 10-year cumulative incidences of death were 12% (95CI: [11%; 14%]), 9% [8%; 11%], 12% [9%; 16%], 14% [6%; 25%] for 1 st, 2 nd, 3 rd, and 4 th lines, respectively. The proportion of CML pts who initiated at least 3 lines of TKIs was 19.3% from raw estimates (n=1,017/5,261) and would be 27% based on TTNT estimates. Their characteristics were similar to pts who initiated 1 st line TKI (sociodemographic, comorbidities). Regarding HCRU, respectively 37.2% and 29.8% of pts had at least one hospitalization during 1 st and 6 th semesters following 3 rd line initiation; 7.9% to 5.8% visited emergency room, and around 10% had at least one sick leave per semester. Conclusion Using one of the largest cohorts of CML pts ever studied, with a follow-up period up to 10 years (median 5.6 years), this real-life study confirmed that multiple TKI switches are now common. We confirmed that at least 1 out of 5 CML patient fails at least two TKI lines. From TTNT estimates, surrogate marker for the duration of clinical benefit, lines of TKI would be effective over the long-term for around half of pts, and half of the switches occur within the first two years, regardless of line position. Finally, this real-world study illustrates the need for permanent care of these pts and alternative treatment options to avoid resistance or intolerance and induce a similar survival as the general population of the same age.

Liver resection for metastatic GIST tumor improves survival in the era of tyrosine kinase inhibitors: a systematic review and meta-analysis.

Survival for gastrointestinal stromal tumor (GIST) has been increasing over the years after the introduction of tyrosine kinase inhibitors. However, the role of metastasectomy for GIST is still controversial. Patients are currently treated with imatinib or sunitinib in case of imatinib failures as optimal medical therapy for metastatic GIST. The Pubmed, EMBASE, and Cochrane Library were systematically searched. Overall survival following liver resection ± tyrosine kinase inhibitor treatment for metastatic GIST was compared to treatment with tyrosine kinase inhibitors alone. Eleven studies including both randomized control trials and retrospective cohort studies were included in the final analysis with a total of 988 patients. Seven studies encompassed data on 556 patients with isolated liver metastases (219 surgery ± drug groups and 337 drug-only groups) were included. Overall survival was significantly improved in patients undergoing liver resection ± drug therapy in comparison to drug therapy alone. [HR (95%CI) = 2.10 (1.58, 2.79); p<0.00001]. Subgroup analysis showed that patients also had improved progression free survival based on 4 studies. [HR (95%CI) = 1.92 (1.43, 2.56); p<0.00001]. In case of concurrent liver and peritoneal metastases, patients showed improved overall survival with aggressive surgical approaches based on 10 studies. [HR (95%CI) = 1.90 (1.56, 2.31); p<0.00001]. This meta-analysis found that liver resection for patients with metastatic GIST regardless of peritoneal metastases improved progression free and overall survival in conjunction with tyrosine kinase inhibitors as compared with medical therapy alone. Furthermore, liver resections did not have any immediate detrimental impact on survival in the group of patients selected.

Assessments of therapeutic effects according to timings for combined therapy with axitinib and immune check point inhibitor in a mouse renal cell carcinoma model

Recently, several types of systemic therapy using tyrosine kinase inhibitor (TKI) and immune checkpoint inhibitor (ICI) have been performed for advanced renal cell carcinoma (aRCC) patients; however, the optimal strategy of sequential treatment with these agents has not been well established. The objective of this study was to determine the differences of therapeutic effects according to timing for the introduction of TKI and ICI using a mouse RCC, RenCa model. The effects of combined treatment of TKI and/or ICI with axitinib, anti-mouse programmed death (PD)-1, or PD-ligand 1 (PD-L1) antibody on tumor growth and survival after subcutaneous and intravenous injection of RenCa cells, respectively, were compared according to three different treatment schedules: simultaneous administration, initial axitinib administration, and initial ICI administration. Infiltrating patterns of lymphocytes into tumors after combined treatments were evaluated by immunohistochemical staining. In mice treated with anti-PD-1 and anti-PD-L1 antibodies, significantly marked inhibitory effects on subcutaneous growth of tumors were observed in the simultaneous and initial ICI treatment groups, but not the group with the initial axitinib administration, compared to controls without treatment. Survival intervals of mice after intravenous injection of RenCa cells were significantly longer in the simultaneous and initial ICI administration, but not the initial axitinib administration, compared to the control. Furthermore, both CD8+ to CD3+ and CD8+ to CD11b+ T-lymphocyte ratios in subcutaneous RenCa tumors were significantly higher in the simultaneous and initial ICI administration, but not the initial axitinib administration, compared to the control. Favorable control against aRCC progression may be achieved by administering TKI and ICI simultaneously or ICI followed by TKI.

Myelofibrosis at diagnosis is associated with the failure of treatment-free remission in CML patients.

The management of patients with chronic myeloid leukemia (CML) has been revolutionized by the introduction of tyrosine kinase inhibitors (TKIs), which induce deep molecular responses so that treatment can eventually be discontinued, leading to treatment-free remission (TFR) in a subset of patients. Unfortunately, leukemic stem cells (LSCs) often persist and a fraction of these can again expand in about half of patients that attempt TKI discontinuation. In this study, we show that presence of myelofibrosis (MF) at the time of diagnosis is a factor associating with TFR failure. Fibrotic transformation is governed by the action of several cytokines, and interestingly, some of them have also been described to support LSC persistence. At the cellular level, these could be produced by both malignant cells and by components of the bone marrow (BM) niche, including megakaryocytes (MKs) and mesenchymal stromal cells (MSCs). In our cohort of 57 patients, around 40% presented with MF at diagnosis and the number of blasts in the peripheral blood and BM was significantly elevated in patients with higher grade of MF. Employing a CML transgenic mouse model, we could observe higher levels of alpha-smooth muscle actin (α-SMA) in the BM when compared to control mice. Short-term treatment with the TKI nilotinib, efficiently reduced spleen weight and BCR::ABL1 mRNA levels, while α-SMA expression was only partially reduced. Interestingly, the number of MKs was increased in the spleen of CML mice and elevated in both BM and spleen upon nilotinib treatment. Analysis of human CML-vs healthy donor (HD)-derived MSCs showed an altered expression of gene signatures reflecting fibrosis as well as hematopoietic support, thus suggesting MSCs as a potential player in these two processes. Finally, in our cohort, 12 patients qualified for TKI discontinuation, and here we observed that all patients who failed TFR had BM fibrosis at diagnosis, whereas this was only the case in 25% of patients with achieved TFR, further supporting the link between fibrosis and LSC persistence.

Prognosis in Chronic Myeloid Leukemia: Baseline Factors, Dynamic Risk Assessment and Novel Insights.

The introduction of tyrosine kinase inhibitors (TKIs) has changed the treatment paradigm of chronic myeloid leukemia (CML), leading to a dramatic improvement of the outcome of CML patients, who now have a nearly normal life expectancy and, in some selected cases, the possibility of aiming for the more ambitious goal of treatment-free remission (TFR). However, the minority of patients who fail treatment and progress from chronic phase (CP) to accelerated phase (AP) and blast phase (BP) still have a relatively poor prognosis. The identification of predictive elements enabling a prompt recognition of patients at higher risk of progression still remains among the priorities in the field of CML management. Currently, the baseline risk is assessed using simple clinical and hematologic parameters, other than evaluating the presence of additional chromosomal abnormalities (ACAs), especially those at "high-risk". Beyond the onset, a re-evaluation of the risk status is mandatory, monitoring the response to TKI treatment. Moreover, novel critical insights are emerging into the role of genomic factors, present at diagnosis or evolving on therapy. This review presents the current knowledge regarding prognostic factors in CML and their potential role for an improved risk classification and a subsequent enhancement of therapeutic decisions and disease management.

Gilteritinib: The Story of a Proceeding Success into Hard-to-Treat FLT3-Mutated AML Patients.

The traditionally dismal outcome of acute myeloid leukemia (AML) patients carrying the FMS-related tyrosine kinase 3 (FLT3) mutations has been mitigated by the recent introduction of tyrosine kinase inhibitors (TKI) into clinics, such as midostaurin and gilteritinib. The present work summarizes the clinical data that led to the use of gilteritinib in clinical practice. Gilteritinib is a second-generation TKI with deeper single-agent activity than first-generation drugs against both FLT3-ITD and TKD mutations in human studies. Moreover, the phase I/II dose-escalation, dose-expansion Chrysalis trial showed an acceptable safety profile of gilteritinib (diarrhea, elevated aspartate aminotransferase, febrile neutropenia, anemia, thrombocytopenia, sepsis, and pneumonia) and a 49% overall response rate (ORR) in 191 FLT3-mutated relapsed/refractory (R/R) AML patients. In 2019, the pivotal ADMIRAL trial showed that the median overall survival was significantly longer in patients treated with gilteritinib than among those receiving chemotherapy (9.3 vs. 5.6 months, respectively) and the ORR to gilteritinib was 67.6%, outperforming the 25.8% for chemotherapy arm and leading to the license for its clinical use by the US Food and Drug Administration. Since then, several real-world experiences have confirmed the positive results in the R/R AML setting. Finally, gilteritinib-based combinations currently under investigation, with several compounds (venetoclax, azacitidine, conventional chemotherapy, etc.) and some practical tips (maintenance after allogeneic transplantation, interaction with antifungal drugs, extramedullary disease, and onset of resistance), will be analyzed in detail in this review.

Telomere loss is accompanied by decreased pool of shelterin proteins TRF2 and RAP1, elevated levels of TERRA and enhanced glycolysis in imatinib-resistant CML cells

Telomere length may be maintained by telomerase nucleoprotein complex and shelterin complex, namely TRF1, TRF2, TIN2, TPP1, POT1 and RAP1 proteins and modulated by TERRA expression. Telomere loss is observed during progression of chronic myeloid leukemia (CML) from the chronic phase (CML-CP) to the blastic phase (CML-BP). The introduction of tyrosine kinase inhibitors (TKIs), such as imatinib (IM), has changed outcome for majority of patients, however, a number of patients treated with TKIs may develop drug resistance. The molecular mechanisms underlying this phenomenon are not fully understood and require further investigation. In the present study, we demonstrate that IM-resistant BCR::ABL1 gene-positive CML K-562 and MEG-A2 cells are characterized by decreased telomere length, lowered protein levels of TRF2 and RAP1 and increased expression of TERRA in comparison to corresponding IM-sensitive CML cells and BCR::ABL1 gene-negative HL-60 cells. Furthermore, enhanced activity of glycolytic pathway was observed in IM-resistant CML cells. A negative correlation between a telomere length and advanced glycation end products (AGE) was also revealed in CD34+ cells isolated from CML patients. In conclusion, we suggest that affected expression of shelterin complex proteins, namely TRF2 and RAP1, TERRA levels, and glucose consumption rate may promote telomere dysfunction in IM-resistant CML cells.