Number Of Tyrosine Kinase Inhibitors Research Articles

Evaluation of Synergistic Anti-Leukemic Efficacy of PHI-101 in Preclinical Model of FLT3-ITD Acute Myeloid Leukemia

Background: AML is a heterogeneous disease with an overall cure rate of 40-50%. Some types of AML have even poorer prognosis with FLT3 mutant AML patients having only a 20-25% cure rate with chemotherapy alone. In order to improve the outcome for this high-risk AML, a number of tyrosine kinase inhibitors (TKI) have been developed and to date. Given the difficulty of identifying appropriate targets and treatment options for AML, combining drug options for AML treatment may produce clinical benefits. PHI-101 is a selective next-generation type I FLT3 inhibitor that shows potent anti-leukemic activity against AML samples harboring FLT3-ITD and/or TKD mutations. In a clinical trial, PHI-101 demonstrates significant clinical responses and tolerability in refractory or relapsed AML patients as monotherapy. To investigate the optimal way to combine PHI-101 with other therapies, a number of other drugs utilized in treating AML were tested both, in vitro and in vivo to determine synergistic or additive effects that might improve efficacy for relapsed/refractory/elderly FLT3 mutant AML patients. Study Design and Methods: Combination effects of simultaneous versus sequential treatment of PHI-101 with other agents, including daunorubicin, cytarabine, venetoclax (Ven), and azacytidine (Aza) were tested using human leukemia cell lines harboring FLT3-ITD mutations (MV4-11, Molm13, Molm14) or FLT3-wild type as controls. The cell growth inhibition was assessed by CCK-8, MTT and/or CellTiter-Glo assays as well as annexin V-binding by flow cytometry and the Chou-Talalay method was used to calculate the combination index (CI. using Compusyn software. The potential mechanisms of effect on combination therapy were explored by Western blotting of a variety of signal transduction pathways including FLT3 phosphorylation and downstream pathways BCL-2 family expression, and DNA damage. The MV4-11 xenograft mouse model was used to assess in vivo efficacy of PHI-101 combination therapy. Results: Among the substances tested for combination therapy with PHI-101 in FLT3-ITD cell lines MV4-11 and Molm14 cell lines, Aza and Ven treatment both showed synergy with both simultaneous and sequential treatment. Ven was highly synergistic when used simultaneously with PHI-101 in MV4-11 cells. Cell growth inhibition effect (GI 50) of PHI-101, Aza, and Ven used alone was measured first to calculate the CI in combination with increasing concentrations of each drug together of treatment for 72hrs. The GI 50 of PHI-101 in FLT3-mutant cell lines (MV4-11, Molm13, Molm14) were 7.0, 3.8, and 3.4 nM, respectively. The GI 50 of the gilteritinib was 5.7, 10.2, and 10.8 nM, respectively. On the other hand, the GI 50 of Aza were 198.9, 140.4, and 85.4 nM, that of Ven were 38.2, 8.4, and 56.5 nM. PHI-101 was the most efficient antitumor agent compared to other drugs tested in this study. The CI of Aza and PHI-101 was 0.01216 (EC 50), 0.05981 (EC 75), 0.29468 (EC 90) in MV4-11 cells. The observed synergistic effects were confirmed in the other FLT3-ITD cell lines as well. PHI-101 and venetoclax combined therapy in MV4-11 showed synergism (CI<0.1), and the CI was 0.00002 (EC 50), 0.00104 (EC 75), 0.01243 (EC 90). By Western blotting, the combination of Aza or Ven with PHI-101 resulted in a significant induction of p-H2AX and PARP cleavage in the FLT3-ITD cell lines (MV4-11), but not in FLT3-WT cell lines (THP-1). To further validate the synergistic anti-leukemic activity of PHI-101 with these agents, MV4-11-derived mouse xenograft models were generated and treated at various doses. In the MV4-11-xenograft model, PHI-101 alone or combined with Ven or Aza significantly decreased tumor volume. In line with the cell viability data, Ven and Aza combined with PHI-101 induced significant cell-killing in vivo. Conclusion: Treatment of AML cells with the combination of Ven or Aza with PHI-101 in vitro induced rapid induction of apoptosis and inhibition of cell growth that showed significant synergy. In vivo data showed improved efficacy for the combination treatment with these agents. In vitro and in vivo data from the preclinical AML models provides a rationale to evaluate the activity of PHI-101 in combination for patients who are ineligible for more intensive chemotherapeutic induction therapy. Improved anti-leukemic efficacy by combined therapy with PHI-101 represent a promising therapeutic strategy for newly diagnosed or R/R FLT3-mutant AML patients

Real-World Evaluation of Treatment Patterns and Clinical Outcomes Among Patients with Chronic Myeloid Leukemia in Chronic Phase (CML-CP) Treated with Asciminib in US Clinical Practice

Introduction: Tyrosine kinase inhibitors (TKIs) are the mainstay of treatment for CML-CP. Asciminib, a first-in-class inhibitor to Specifically Target the ABL Myristoyl Pocket (STAMP), was FDA-approved on 10/29/2021 for the treatment of adult patients with Philadelphia chromosome-positive (Ph+) CML-CP, previously treated with two or more TKIs or Ph+ CML-CP with the T315I mutation. This study described treatment patterns and real-world clinical outcomes of asciminib in the US. Methods: Data through 11/30/2022 from adult patients with Ph+ CML-CP who initiated asciminib were obtained from the Flatiron Health oncology electronic health record (EHR)-derived de-identified database. Patients who initiated asciminib after ≥2 previous TKIs, without a stem-cell transplant prior to asciminib, and without the T315I mutation, were included in the overall cohort. Time-to-treatment discontinuation and molecular response (MR; time-to-BCR::ABL1 ≤0.1% and time-to-BCR::ABL1 ≤1%, separately) were evaluated from asciminib initiation (index date) using Kaplan-Meier analyses overall, and by the number of TKIs used pre-index (2 previous TKIs, and ≥3 previous TKIs). Patients were required to have ≥1 MR test post-index to be included in the MR assessment; a sensitivity analysis was conducted excluding patients with BCR::ABL1 ≤0.1% or better (≤1% or better) for time-to-BCR::ABL1 ≤0.1% (time-to-BCR:ABL1 ≤1%), as evaluated in the ASCEMBL trial. Results: Overall,97 patients with Ph+ CML-CP initiated asciminib (median age: 63 years, 50.5% female, 64.9% White, 84.8% ECOG 0-1, 61.9% from community-based practices, median follow-up of 6 months post-index). Other malignancies (19.6%), chronic pulmonary disease (18.6%), renal disease (18.6%), and congestive heart failure (16.5%) were the most prevalent pre-index comorbidities. The distribution of last MR in the 3 months pre-index was: 24.7% BCR::ABL1 >10%, 18.6% BCR::ABL1 ≤10% and >1%, 12.4% BCR::ABL1 ≤1% and >0.1%, 12.4% BCR::ABL1 ≤0.1% and >0.01%, and 8.2% BCR::ABL1 ≤0.01% (23.7% not tested/documented). Forty-six patients (47.4%) initiated asciminib after 2 previous TKIs, 24 (24.7%) after 3 TKIs, and the remainder after ≥4 previous TKIs (27.8%). Most patients (78.4%) were prescribed 80 mg (40.2% once daily, 38.1% 40 mg twice a day) at treatment initiation. Use of TKIs prior to asciminib included dasatinib (85.6%), imatinib (63.9%), bosutinib (61.9%), nilotinib (53.6%), and ponatinib (15.5%). Treatment sequences among patients who initiated asciminib after 2 previous TKIs (n=46) are presented in Figure 1. Overall (n=97), persistence rates were 85.7% by 12-weeks (2 previous TKIs: 89.8%; ≥3 previous TKIs: 82.5%) and 78.1% by 24-weeks (2 previous TKIs: 81.8%; ≥3 previous TKIs: 75.3%) post-index. Among patients with ≥1 MR test post-index (n=70), 31.3% (2 previous TKIs: 43.3%; ≥3 previous TKIs: 21.6%) and 49.7% (2 previous TKIs: 71.5%; ≥3 previous TKIs: 33.4%) achieved or maintained BCR::ABL1 ≤0.1% by 12- and 24-weeks, respectively. In addition, 51.3% (2 previous TKIs: 68.7%; ≥3 previous TKIs: 37.2%) and 64.2% (2 previous TKIs: 79.7%; ≥3 previous TKIs: 51.4%) achieved or maintained BCR::ABL1 ≤1% by 12- and 24-weeks, respectively. For patients without BCR::ABL1 ≤0.1% prior to asciminib (n=52; Figure 2), 14.6% (2 previous TKIs: 20.6%; ≥3 previous TKIs: 10.4%) and 32.9% (2 previous TKIs: 56.7%; ≥3 previous TKIs: 17.9%) achieved BCR::ABL1 ≤0.1% by 12- and 24-weeks, respectively, with a median time of 30.7 weeks (2 previous TKIs: 23.0 weeks; ≥3 previous TKIs: 38.1 weeks). For patients without BCR::ABL1 ≤1% prior to asciminib (n=43), 35.6% (2 previous TKIs: 61.9%; ≥3 previous TKIs: 21.9%) and 46.3% (2 previous TKIs: 61.9%; ≥3 previous TKIs: 37.2%) achieved BCR::ABL1 ≤1% by 12- and 24-weeks, respectively, with a median time of 24.6 weeks (2 previous TKIs: 11.3 weeks; ≥3 previous TKIs: 26.9 weeks). Conclusion: This is the first real-world study describing treatment patterns and clinical outcomes among patients with Ph+ CML-CP treated with asciminib in the US. The findings of real-world treatment efficacy based on achieving BCR::ABL1 ≤0.1% were consistent with the ASCEMBL trial. Patients who initiated asciminib after 2 previous TKIs had higher persistence and treatment response rates than those initiated on asciminib after ≥3 previous TKIs. Further studies are warranted to continuously demonstrate the effectiveness of asciminib in a real-world setting.

Systematic screening identifies ABCG2 as critical factor underlying synergy of kinase inhibitors with transcriptional CDK inhibitors

BackgroundTriple-negative breast cancer (TNBC) is a subtype of breast cancer with limited treatment options and poor clinical prognosis. Inhibitors of transcriptional CDKs are currently under thorough investigation for application in the treatment of multiple cancer types, including breast cancer. These studies have raised interest in combining these inhibitors, including CDK12/13 inhibitor THZ531, with a variety of other anti-cancer agents. However, the full scope of these potential synergistic interactions of transcriptional CDK inhibitors with kinase inhibitors has not been systematically investigated. Moreover, the mechanisms behind these previously described synergistic interactions remain largely elusive.MethodsKinase inhibitor combination screenings were performed to identify kinase inhibitors that synergize with CDK7 inhibitor THZ1 and CDK12/13 inhibitor THZ531 in TNBC cell lines. CRISPR-Cas9 knockout screening and transcriptomic evaluation of resistant versus sensitive cell lines were performed to identify genes critical for THZ531 resistance. RNA sequencing analysis after treatment with individual and combined synergistic treatments was performed to gain further insights into the mechanism of this synergy. Kinase inhibitor screening in combination with visualization of ABCG2-substrate pheophorbide A was used to identify kinase inhibitors that inhibit ABCG2. Multiple transcriptional CDK inhibitors were evaluated to extend the significance of the found mechanism to other transcriptional CDK inhibitors.ResultsWe show that a very high number of tyrosine kinase inhibitors synergize with the CDK12/13 inhibitor THZ531. Yet, we identified the multidrug transporter ABCG2 as key determinant of THZ531 resistance in TNBC cells. Mechanistically, we demonstrate that most synergistic kinase inhibitors block ABCG2 function, thereby sensitizing cells to transcriptional CDK inhibitors, including THZ531. Accordingly, these kinase inhibitors potentiate the effects of THZ531, disrupting gene expression and increasing intronic polyadenylation.ConclusionOverall, this study demonstrates the critical role of ABCG2 in limiting the efficacy of transcriptional CDK inhibitors and identifies multiple kinase inhibitors that disrupt ABCG2 transporter function and thereby synergize with these CDK inhibitors. These findings therefore further facilitate the development of new (combination) therapies targeting transcriptional CDKs and highlight the importance of evaluating the role of ABC transporters in synergistic drug–drug interactions in general.

Landscape of potentially targetable receptor tyrosine kinase fusions in diverse cancers by DNA-based profiling

Recurrent fusions of receptor tyrosine kinases (RTKs) are often driving events in tumorigenesis that carry important diagnostic value and are potentially targetable by the increasing number of tyrosine kinase inhibitors (TKIs). Here, we characterized the spectrum of 1324 RTK fusions with intact kinase domains in solid tumors by DNA-based high-throughput sequencing. Overall, the prevalence of RTK fusions were 4.7%, with variable frequencies and diverse genomic structures and fusion partners across cancer types. Cancer types, such as thyroid cancers, urological cancers and neuroendocrine tumors are selective in the RTK fusions they carry, while others exhibit highly complex spectra of fusion events. Notably, most RTKs were promiscuous in terms of the partner genes they recombine with. A large proportion of RTK fusions had one of the breakpoints localized to intergenic regions. Comprehensive genomic profiling revealed differences in co-mutational patterns pre- and post-TKI treatments across various RTK fusions. At baseline, multiple cases were detected with co-occurring RTK fusions or concomitant oncogenic mutations in driver genes, such as KRAS and EGFR. Following TKI resistance, we observed differences in potential on- and off-target resistance mutations among fusion variants. For example, the EML4-ALK v3 variant displayed more complex on-target resistance mechanisms, which might explain the reduced survival outcome compared with the v1 variant. Finally, we identified two lung cancer patients with MET+ and NTRK1+ tumors, respectively, who responded well to crizotinib treatment. Taken together, our findings demonstrate the diagnostic and prognostic values of screening for RTK fusions using DNA-based sequencing in solid tumors.

Systemic Therapy for Lung Cancer Brain Metastases.

Systemic therapy for brain metastases (BM) is quickly moving from conventional cytotoxic chemotherapy toward targeted therapies, that allow a disruption of driver molecular pathways. The discovery of actionable driver mutations has led to the development of an impressive number of tyrosine kinase inhibitors (TKIs), that target the epidermal growth factor receptor (EGFR) mutations, anaplastic-lymphoma-kinase (ALK) rearrangements, and other rare molecular alterations in patients bearing metastatic non-small cell lung cancer (NSCLC) in the brain, with remarkable results in terms of intracranial disease control and overall survival. Moreover, these drugs may delay the use of local therapies, such as stereotactic radiosurgery (SRS) or whole-brain radiotherapy (WBRT). New drugs with higher molecular specificity and ability to cross the CNS barriers (BBB, BTB and blood-CSF) are being developed. Two major issues are related to targeted therapies. First, the emergence of a resistance is a common event, and a deeper understanding of molecular pathways that are involved is critical for the successful development of effective new targeted agents. Second, an early detection of tumor progression is of utmost importance to avoid the prolongation of an ineffective therapy while changing to another drug. In order to monitor over time the treatment to targeted therapies, liquid biopsy, that allows the detection in biofluids of either circulating tumor cells (CTCs) or circulating tumor DNA (ctDNA) or exosomes, is increasingly employed in clinical trials: with respect to BM the monitoring of both blood and CSF is necessary. Also, radiomics is being developed to predict the mutational status of the BM on MRI.For patients without druggable mutations or who do not respond to targeted agents, immunotherapy with checkpoint inhibitors is increasingly employed, alone or in combination with radiotherapy. Pseudoprogression after immunotherapy alone maybe a challenge for several months after the start of treatment, and the same is true for radionecrosis after the combination of immunotherapy and SRS. In this regard, the value of advanced MRI techniques and PET imaging for a better distinction of pseudoprogression/radionecrosis and true tumor progression is promising, but needs validation in large prospective datasets. Last, a new frontier in the near future will be chemoprevention (primary and secondary), but we need to identify among solid tumors those subgroups of patients with a higher risk of relapsing into the brain and novel drugs, active on either neoplastic or normal cells of the microenvironment, that are cooperating in the invasion of brain tissue.

MET-Pyk2 Axis Mediates Acquired Resistance to FGFR Inhibition in Cancer Cells.

Deregulation of fibroblast growth factor receptors (FGFRs) signaling, as a result of FGFR amplification, chromosomal translocation, or mutations, is involved in both initiation and progression of a wide range of human cancers. Clinical data demonstrating the dependence of cancer cells on FGFRs signaling clearly indicate these receptors as the molecular targets of anti-cancer therapies. Despite the increasing number of tyrosine kinase inhibitors (TKIs) being investigated in clinical trials, acquired resistance to these drugs poses a serious therapeutic problem. In this study, we focused on a novel pan-FGFR inhibitor—CPL304110, currently being investigated in phase I clinical trials in adults with advanced solid malignancies. We analyzed the sensitivity of 17 cell lines derived from cancers with aberrant FGFR signaling, i.e. non-small cell lung cancer, gastric and bladder cancer to CPL304110. In order to explore the mechanism of acquired resistance to this FGFR inhibitor, we developed from sensitive cell lines their variants resistant to CPL304110. Herein, for the first time we revealed that the process of acquired resistance to the novel FGFR inhibitor was associated with increased expression of MET in lung, gastric, and bladder cancer cells. Overexpression of MET in NCI-H1703, SNU-16, RT-112 cells as well as treatment with HGF resulted in the impaired response to inhibition of FGFR activity. Moreover, we demonstrated that cells with acquired resistance to FGFR inhibitor as well as cells overexpressing MET displayed enhanced migratory abilities what was accompanied with increased levels of Pyk2 expression. Importantly, inhibition of both MET and Pyk2 activity restored sensitivity to FGFR inhibition in these cells. Our results demonstrate that the HGF/MET-Pyk2 signaling axis confers resistance to the novel FGFR inhibitor, and this mechanism is common for lung, gastric, and bladder cancer cells. Our study suggests that targeting of MET/Pyk2 could be an approach to overcome resistance to FGFR inhibition.

Nilotinib and Imatinib Utilization in Iran over 14 years

Background: Tyrosine Kinase Inhibitors (TKIs) are drugs of choice for Chronic Myeloid Leukemia (CML) treatment. CML healthcare costs greatly exceed of other haematological malignancies treatment mostly due to TKIs. There are several generic and brand preparations of imatinib and nilotinib, the only available TKIs, in Iran with different prices and varied insurance coverage. We have studied TKIs utilization and also investigate the effect of different insurance coverage on TKIs utilization in Iran. Methods: This was drug utilization study about Imatinib and Nilotinib over 14 years. It was conducted in two phases; data extraction from pharmaceutical wholesale data (2003-2017) for utilization trend assessment and registered data of prescriptions from Sizdah-Aban Pharmacy (2011-2014) for utilization trend and insurance coverage assessment such as; prescriptions frequency, number of TKIs, insurance companies and their cost coverage in each prescription. Results: Imatinib consumption increased significantly from 2003 to 2013. This trend stopped afterward. Nilotinib consumption had ascending trend. The trend line of years 2014 to 2017 was steeper and statistically significant (β=0.0014, p-value=0.02). The amount of nilotinib cost coverage by insurance companies increased significantly from 2011 to 2014 (p-value=0.04). The coverage of imatinib costs by insurance companies changed slightly during the study period that was not statistically significant. Frequency of prescriptions with full cost coverage doubled for nilotinib, while did not change remarkably for imatinib, from 2011 to 2014. Mean (SD) of imatinib and nilotinib counts per prescription was significantly higher in prescriptions for which 100% of the cost was covered. Conclusion: We found increasing trend in nilotinib utilization and observed some effects from nilotinib cost coverage by insurance on its consumption. This study made a clear picture for policy makers to monitor imatinib and nilotinib use appropriateness and design the proper cost-effective studies to make evidence-based decisions.

Prolonged survival and response to tepotinib in a non-small-cell lung cancer patient with brain metastases harboring MET exon 14 mutation: a research report.

Tyrosine kinase inhibitors (TKIs) have transformed the standard of care in lung cancer. A number of TKIs have been discovered that specifically target oncogenes, including MET receptor tyrosine kinase. Second-generation MET TKIs are showing improved efficacy over first-generation TKIs. Herein, we report a case of a patient with metastatic lung adenocarcinoma harboring a MET exon 14 splice site mutation who has had prolonged disease control by a second-generation MET-TKI tepotinib. A 66-yr-old man was diagnosed with stage IV lung adenocarcinoma. He was started on carboplatin, paclitaxel, and bevacizumab, but had severe toxicity. He was switched to pembrolizumab as his tumor was PD-L1 70%, and molecular testing was not yet performed because of insufficient tissue. A bronchoscopy with endobronchial ultrasound was performed and a MET exon 14 splice site mutation was detected by next-generation sequencing. Upon progression, he was then enrolled in a clinical trial of tepotinib and continues with stable disease for more than 45 cycles and 31 mo. The MET receptor tyrosine kinase and the ligand hepatocyte growth factor (HGF) have been implicated as oncogenes and drivers of non-small-cell lung cancer (NSCLC). Newer MET TKIs including capmatinib and tepotinib more recently showed not only improved localized control and response, but early data suggests intracranial activity as compared to first-generation MET TKIs, both in the front-line and the refractory setting. This is a case report demonstrating an effective duration of response in a patient with widely metastatic lung adenocarcinoma harboring a MET exon 14 mutation.

Dose adjustment for tyrosine kinase inhibitors in non‑small cell lung cancer patients with hepatic or renal function impairment (Review).

In recent years, a number of tyrosine kinase inhibitors (TKIs) have been approved for the treatment of non-small cell lung cancer. These novel treatments exhibit improved efficacy and toxicity when compared to conventional chemotherapy agents. TKIs are administered orally, which has the advantages of improved flexibility and convenience for the patients. However, challenges have arisen in the use of these novel agents. Prescribing drugs for patients with hepatic or renal function impairment poses a challenge for clinicians due to the large pharmacokinetic variability in each individual patient. Moreover, several TKIs have been shown to cause laboratory test abnormalities normally associated with hepatic or renal injury. The aim of the present review was to discuss the effects of hepatic and renal function impairment on the pharmacokinetic variability of 17 TKIs and their potential hepatotoxicity and nephrotoxicity, and to recommend dose adjustment for patients with hepatic or renal impairment.

Assessment of tumor enhancement by contrast-enhanced CT in solid tumor-bearing dogs treated with toceranib phosphate.

In humans, contrast-enhanced CT (CECT) has been used to indirectly assess the antiangiogenic effects demonstrated by a number of tyrosine kinase inhibitors. This retrospective, cross-sectional study aimed to quantitatively evaluate changes in tumor contrast-enhancement (CE) using CECT in solid tumor-bearing dogs treated with toceranib phosphate (TOC). The changes in tumor size and CE were measured using the Hounsfield unit (HU) scale in CECT images before TOC treatment and between 30 and 90 days after initiating the treatment. Among the 36 dogs treated with TOC, eight (22.2%) showed a partial response, 22 (61.1%) showed stable disease, and six (16.7%) showed progressive disease. Thirty (83.3%) of 36 dogs showed a decrease in tumor CE (median: -20%, range: -1% to -48%) after initiating the treatment. The results indicated that tumor CE and size changes were observed in tumor-bearing dogs that were treated with TOC; however, tumor CE was not significantly correlated with tumor regression. We suggest that these results could serve as pilot data to evaluate the antiangiogenic effects associated with TOC.

Management of Brain Metastases in Non-Small-Cell Lung Cancer.

Lung cancer is the leading cause of cancer-related death in the United States. Approximately 20% of these patients present with brain metastases (BMs). Surgical resection, stereotactic radiosurgery, and whole-brain radiation therapy have historically been the primary treatment modalities for patients with non-small-cell lung cancer (NSCLC) and BMs. The treatments for BMs have become complex with the discovery of targetable molecular drivers and the development of an astonishing number of tyrosine kinase inhibitors. Many of these tyrosine kinase inhibitors have robust and durable efficacy against CNS metastases. In many circumstances, these drugs can defer local therapy and even reduce the risk of CNS progression. More recently, immune checkpoint inhibitors have changed the treatment landscape for many patients with NSCLC; however, the role of immunotherapy in patients with BMs is the subject of ongoing investigations. This article will review the current data and our approach to patients with NSCLC and BMs.

1550P - Preferential expression of the affected MET allele in lung carcinomas with heterozygous MET exon 14 skipping mutations: Implications for clinical testing

BackgroundLung carcinomas (LCs) carrying MET exon 14 skipping (exon 14Δ) mutations are responsive to a number of tyrosine kinase inhibitors. There is a need to incorporate MET analysis in the diagnostic pipeline for LC patients. MethodsNucleic acids were extracted from formalin-fixed paraffin-embedded archival LC samples and subjected to cDNA synthesis. This pool of genomic DNA and cDNA was sequentially tested for EGFR, ALK and MET mutations by PCR-based assays. ResultsAllele-specific PCR detected MET exon 14 skipping in 35/1415 (2.5%) EGFR mutation–negative LCs. There was a highly pronounced association with the elderly age of the patients (median age 69 years as compared to 62 years in EGFR/ALK/MET mutation-negative cases; p=1.821e-06). 34/35 (97%) LCs with MET exon 14 skipping mutations showed preferential expression of the affected MET allele, while the wild-type transcript was almost undetectable in these tumors. In addition, we identified a subset of MET wild-type LCs, which produced normal MET transcript but also expressed residual amounts of MET exon 14Δ RNA message, probably due to alternative splicing. ConclusionsThe mere detection of MET exon 14Δ signal by allele-specific PCR does not warrant the presence of corresponding clonal MET mutation. Comparison of expression of MET exon 14Δ and wild-type alleles is essential for reliable identification of tumors carrying drug-sensitizing MET lesions. Legal entity responsible for the studyThe authors. FundingRussian Science Foundation (grant 17-75-30027). DisclosureAll authors have declared no conflicts of interest.

Comparative analysis of expression of mutant and wild-type alleles is essential for reliable PCR-based detection of MET exon 14 skipping

MET exon 14 skipping (exon 14Δ) mutations are associated with tumor sensitivity to a number of tyrosine kinase inhibitors, however clinical testing for MET gene status remains complicated. We developed a simple allele-specific PCR cDNA-based test, which allowed for the identification of MET exon 14Δ allele in 35 (2.5%) out of 1415 EGFR mutation–negative lung carcinomas (LCs). MET exon 14Δ was significantly associated with elderly age and non-smoking status of the patients. A total of 34 (97%) out of 35 tumors carrying MET exon 14Δ showed preferential expression of the mutated allele; this imbalance was attributed to the down-regulation of the expression of the wild-type gene copy. Sanger sequencing confirmed the presence of genomic exon 14 splice site mutations in 24/35 (68.6%) cases, which showed MET exon 14 skipping by PCR. In addition to LCs described above, some carcinomas demonstrated low-abundance MET exon 14Δ-specific signal. Low-level expression of MET exon 14Δ allele may potentially compromise the results of allele-specific PCR-based tests, therefore comparison of the level of expression of mutated and normal alleles is essential for the reliability of MET gene testing.

The role of metastasectomy in the treatment of metastatic renal cell carcinoma

The role of metastasectomy in metastatic renal cell carcinoma (mRCC) has been widely debated. Most clinical information regarding metastasectomy has been obtained from small retrospective studies that include heterogenous patient populations. It is unclear in what setting patients may confer the most clinical benefit. Moreover, a significant portion of clinical evidence suggesting additional benefit of metastasectomy is derived from a non-contemporary era, when interleukin-2, interferon-alpha, and limited number of tyrosine kinase inhibitors were the only available treatment options in addition to surgery. In efforts to answer these questions, we peruse the current literature of metastasectomy in mRCC by specific anatomical location, analyze the clinicopathological factors associated with metastasectomy outcomes, and discuss the potential role of metastasectomy as an adjunct to targeted therapy and immunotherapy.

Targeting ALK in Cancer: Therapeutic Potential of Proapoptotic Peptides.

ALK is a receptor tyrosine kinase, associated with many tumor types as diverse as anaplastic large cell lymphomas, inflammatory myofibroblastic tumors, breast and renal cell carcinomas, non-small cell lung cancer, neuroblastomas, and more. This makes ALK an attractive target for cancer therapy. Since ALK–driven tumors are dependent for their proliferation on the constitutively activated ALK kinase, a number of tyrosine kinase inhibitors have been developed to block tumor growth. While some inhibitors are under investigation in clinical trials, others are now approved for treatment, notably in ALK-positive lung cancer. Their efficacy is remarkable, however limited in time, as the tumors escape and become resistant to the treatment through different mechanisms. Hence, there is a pressing need to target ALK-dependent tumors by other therapeutic strategies, and possibly use them in combination with kinase inhibitors. In this review we will focus on the therapeutic potential of proapoptotic ALK-derived peptides based on the dependence receptor properties of ALK. We will also try to make a non-exhaustive list of several alternative treatments targeting ALK-dependent and independent signaling pathways.

Prognostic Model of Successful Tyrosine Kinase Inhibitors Discontinuation Based on the Russian RU-SKI Multicenter Prospective Study

Background: A large number of tyrosine kinase inhibitors (TKI) discontinuation studies has shown that about 50% of chronic myeloid leukemia (CML) patients (pts) after TKI cessation lose a major molecular response (MMR) and should return to therapy. Despite the fact that, after TKI resumption, almost all patients re-achieve deep molecular remission, facilitating a more accurate selection process for therapy cessation remains topical.Aim: Develop a prognostic model for the better selection of CML patients for TKI discontinuation.Methods: The base for the training set was the Russian multicenter prospective study RU-SKI on the discontinuation of TKI in pts with CML and deep molecular response (DMR). Ninety-eight CML pts with chronic phase (CP), TKI therapy for at least three years and a stable DMR (BCR-ABL<0.01%) for at least two years were enrolled. Seven Pts with a previous history of unsuccessful treatment-free remission (TFR) were excluded from the analysis. The BCR-ABL level was evaluated by RQ-PCR according to the international scale (IS). The schedule of molecular tests was as follows: monthly during the first six months (mo) after TKI cessation, every two mo from six to 12 mo and every three mo thereafter. Treatment by the same TKI was resumed in case of MMR loss (BCR-ABL>0.1%). We used the Kaplan-Meier method for calculating the probability of TFR. Univariate analyses were performed using the log-rank test to identify prognostic factors for TFR. Variables found to be significant at the p<0.10 level were entered into a proportional hazards regression analysis. We categorized each independently significant factor into two groups, depending on the optimal cutoff level obtained by ROC analysis and the minimum P-value approach. The next step was a second multivariate analysis including categorized variables. A favorable factor from each variable was scored as 1, while the adverse factor was scored proportionally to the level of hazard ratio. The cumulative score for each patient was calculated. Patients were allocated to either a high or a low risk group concerning MMR loss after the cutoff level was determined by ROC analysis. The validation set included a series of 48 retrospective cases of discontinued patients selected according to RU-SKI inclusion criteria.Results: Baseline characteristics of the training set (n=91): male: 48%; median (Mе) age at TKI cessation 46 years (range 22 to 80); Me duration of TKI therapy 8.3 years (range three to 16.2); Me duration of DMR 3.2 years (range two to 10.7). Therapy before treatment cessation: imatinib in 63 (69%) pts, second-generation (2G) TKI in 28 (31%) pts. Me follow-up time after TKI cessation was 14 mo (range three to 36). Probability of TFR was 55% after 12 mo of follow-up. We analyzed the following factors: age, gender, history of previous resistance to imatinib, type and line of TKI, duration of therapy, length of DMR, depth of molecular response before cancellation, Sokal risk group. Age, Sokal risk group, duration of therapy and depth of molecular response were found to be independently significant factors and included in the survival prognostic model (Table 1). 73% (n=66) of pts scored 5.5 points or less and were assigned to the low risk group. The probability of TFR was 64% and 33% for the low risk and high risk groups, respectively (p=0.001) (Figure 1). Baseline characteristics of validation set (n=48): male: 36%; Ме age at TKI cessation 46 years (range 22 to 76); Me duration of TKI therapy six years (range 3.5 to 13.2); Me duration of DMR 2.8 years (range two to 10). Therapy before treatment stopped: imatinib in 31 (65%) pts, 2G TKI in 17 (35%) pts. Me follow-up time after TKI cessation was 36 mo (range six to 116). Probability of TFR was 47% after 30 mo of follow-up. In the validation set, 77% (n=37) of pts were assigned to the low risk group. The probability of TFR was 56% and 18% for the low risk and high risk groups, respectively (p=0.007) (Figure 2).Conclusion: RU-SKI prognostic model is effective in prediction of successful TFR and can be used for better selection of CML pts for TKI discontinuation. [Display omitted] DisclosuresShukhov:Novartis: Other: provided consultations and performed lectures ; Bristol Myers Squibb: Other: provided consultations and performed lectures . Chelysheva:Novartis: Other: provided consultations and performed lectures; Fusion Pharma: Other: provided consultations ; Bristol Myers Squibb: Other: provided consultations and performed lectures. Turkina:Novartis: Other: provided consultations; Bristol Myers Squibb: Other: provided consultations; Phizer: Other: provided consultations; Fusion Pharma: Other: provided consultations.

Current perspective: Osimertinib-induced QT prolongation: new drugs with new side-effects need careful patient monitoring

An increasing number of tyrosine kinase inhibitors (TKIs) are available for the treatment of non–small cell lung cancer (NSCLC). QT prolongation is one of the known, but relatively rare, adverse events of several TKIs (e.g. osimertinib, crizotinib, ceritinib). Screening for QT prolongation in (high risk) patients is advised for these TKIs. When a QT prolongation develops, the physician is challenged with the question whether to (permanently) discontinue the TKI. In this perspective, we report on a patient who developed a grade III QT prolongation during osimertinib (a third-generation epidermal growth factor receptor [EGFR]-TKI) treatment. On discontinuation of osimertinib, she developed a symptomatic disease flare, not responding to subsequent systemic treatment. The main aim of this perspective is to describe the management of QT prolongation in stage IV EGFR driver mutation NSCLC patients. We also discuss the ethical question of how to weigh the risk of a disease flare due to therapy cessation against the risk of sudden cardiac death. A family history of sudden death and a prolonged QT interval might indicate a familiar long QT syndrome. We have summarised the current monitoring advice for TKIs used in the treatment of lung cancer and the most common drug–TKI interactions to consider and to optimise TKI treatment in lung cancer patients.

FIKK Kinase, a Ser/Thr Kinase Important to Malaria Parasites, Is Inhibited by Tyrosine Kinase Inhibitors.

A relatively high-affinity inhibitor of FIKK kinase from the malaria parasite Plasmodium vivax was identified by in vitro assay of recombinant kinase. The FIKK kinase family is unique to parasitic organisms of the Apicomplexan order and has been shown to be critical in malaria parasites. The recombinant kinase domain was expressed and screened against a small molecule library, revealing a number of tyrosine kinase inhibitors that block FIKK kinase activity. A family of tyrphostins was further investigated, to begin exploring the FIKK kinase pharmacophore. Finally, emodin was identified as a relatively high-affinity FIKK kinase inhibitor, identifying this family of anthraquinones as potential lead compounds for the development of antimalarials targeting the FIKK kinase.

Midostaurin treatment in FLT3-mutated acute myeloid leukemia and systemic mastocytosis

ABSTRACTIntroduction: A number of tyrosine kinase inhibitors (TKIs) have been developed that inhibit the constitutively activated kinase activity caused by activating tyrosine kinase mutations, such as FLT3 or KIT, thus interrupting signaling pathways. Currently, midostaurin is the only approved TKI as monotherapy for aggressive systemic mastocytosis (SM), SM with associated hematological neoplasm, or mast cell leukemia displaying a KIT mutation as well as in combination with standard intensive chemotherapy for adult patients with newly diagnosed FLT3-mutated acute myeloid leukemia (AML).Areas covered: We provide a concise review of the pharmacology, tolerability and clinical efficacy of midostaurin and emerging new treatment options for ASM and FLT3-mutated AML.Expert commentary: Currently, midostaurin is the only approved TKI in aggressive SM, SM with associated hematological neoplasm, or mast cell leukemia inducing responses including complete remissions. With regard to AML, midostaurin is the first drug to receive regulatory approval in this indication in the molecularly defined subgroup of AML with FLT3 mutations. By introduction of this new standard in AML with FLT3 mutations, the bare has been raised for future approvals of next generation FLT3 inhibitors which will be based increasingly on head to head comparisons with midostaurin.

Therapeutic immune monitoring of CD4+CD25+ T cells in chronic myeloid leukemia patients treated with tyrosine kinase inhibitors.

Tyrosine kinase inhibitors (TKIs), including imatinib, dasatinib and nilotinib, are effective forms of therapy for various types of solid cancers and Philadelphia chromosome-positive (Ph+) chronic myeloid leukemia. A number of TKIs have been known to have strong effects on T cells, particularly cluster of differentiation (CD) 4+CD25+ T cells, also known as regulatory T cells (Tregs). There is currently a deficit in the available clinical data regarding this area of study. In the present study, a total of 108 peripheral blood samples were collected from patients with chronic myeloid leukemia (CML) at diagnosis (n=31), and at 3 and 6 months following treatment with TKI [imatinib (n=12), dasatinib (n=11) and nilotinib groups (n=8)] and healthy controls (n=15). Peripheral blood mononuclear cells were collected from the patients prior to and following TKI treatment. The subtype and number of T lymphocytes in patients and healthy donors were analyzed using flow cytometry. Additionally, flow cytometry and ELISA were used to detect the proliferation and suppression of Tregs. Expression of cytokines and other molecules [forkhead box P3 (FOXP3), glucocorticoid-induced tumor necrosis factor receptor (GITR) and cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4)] were also analyzed at 3 and 6 months following treatment with TKIs. It was indicated that, at diagnosis, a similar number of lymphocytes were detected in patients and control. However, following treatment with a TKI, the number of total T cells, Tregs, CD4+ T and CD8+ T cells decreased to various degrees in patients. Furthermore, the decrease in the number of Tregs was more significant with time. Although treatment with imatinib, dasatinib and nilotinib demonstrated similar inhibitory effects on the quantity of Tregs in vivo, the TKIs exhibited differential effects on the function of Tregs in vitro. Proliferation, suppression and expression of cytokines [interleukin (IL)-4, IL-10 and transforming growth factor (TGF)-β] and molecules (FOXP3, GITR and CTLA-4) decreased significantly in treatment groups with imatinib and dasatinib. The decrease was not significant in the nilotinib treatment group. Imatinib and dasatinib may exert more marked inhibitory roles compared with nilotinib on regulating the number and function of Tregs. These results suggest that personalized treatment and follow-up of CML patients during TKI treatment, particularly for those who received post-transplant TKI treatment may be beneficial.