FDA-approved Tyrosine Kinase Inhibitors Research Articles

A Tetravalent Bispecific Antibody Selectively Inhibits Diverse FGFR3 Oncogenic Variants

Abstract The receptor tyrosine kinase FGFR3 is frequently mutated in bladder cancer and is a validated therapeutic target. Although pan-FGFR tyrosine kinase inhibitors (TKI) have shown clinical efficacy, toxicity and acquired resistance limit the benefit of these agents. While antibody-based therapeutics can offer superior selectivity than TKIs, conventional ligand-blocking antibodies are usually ineffective inhibitors of constitutively active receptor tyrosine kinases. Furthermore, the existence of multiple oncogenic variants of FGFR3 presents an additional challenge for antibody-mediated blockade. Here, we developed a tetravalent FGFR3×FGFR3 bispecific antibody that inhibited FGFR3 point mutants and fusion proteins more effectively than any of the conventional FGFR3 antibodies that we produced. Each arm of the bispecific antibody contacted two distinct epitopes of FGFR3 through a cis mode of binding. The antibody blocked dimerization of the most common FGFR3 oncogenic variant (S249C extracellular domain mutation) and inhibited the function of FGFR3 variants that are resistant to pan-FGFR TKIs. The antibody was highly effective in suppressing growth of FGFR3-driven tumor models, providing efficacy comparable to that of the FDA-approved TKI erdafitinib. Thus, this bispecific antibody may provide an effective approach for broad and highly selective inhibition of oncogenic FGFR3 variants. Significance: Development of a bispecific antibody that broadly inhibits gain-of-function FGFR3 variants provides a therapeutic strategy to target tumors with oncogenic FGFR3 point mutations and fusions, a particularly difficult case for antibody blockade.

The role of next-generation sequencing in achieving diagnostic precision for dermatofibrosarcoma protuberans and its fibrosarcomatous variant.

e23531 Background: Dermatofibrosarcoma protuberans (DFSP) is a locally aggressive skin and subcutaneous fibroblastic neoplasm, characterized by COL1A1:: PDGFB fusions and, less frequently, PDGFD fusions. Approximately 10-15% of DFSP cases progress to distant metastases, yet the genetic mechanisms behind this transformation to fibrosarcomatous DFSP (FS-DFSP) or metastatic development remain unclear. Reports of DFSP in deeper tissues suggest a broader occurrence than previously recognized. We hypothesize that conventional histopathology may not adequately identify certain DFSP variants, especially those in deep tissues, potentially missing critical opportunities for targeted therapy with FDA-approved tyrosine kinase inhibitors. Methods: We searched Caris’s database to identify solid tumors with PDGFB or PDGFD fusions, markers of DFSP or FS-DFSP. We reviewed histologic features and clinical information, along with exome sequencing and copy number amplifications. Significance was tested using Mann Whitney U and Fisher’s exact tests as appropriate. Results: We identified 59 cases with PDGFB or PDGFD fusions: 55 COL1A1:: PDGFB, 3 EMILIN2:: PDGFD, and 1 COL1A2:: PDGFB cases. Of these, 51 were primary specimens and 8 metastatic. The patients included 31 males and 28 females, with a median age of 49 years (range: 14-93). Primary tumors occurred mainly in the skin/subcutis or deep soft tissues (35 trunk, 9 head and neck, 7 lower extremity, 2 upper extremity), but 6 were found in visceral organs (4 uterus, 1 cervix, 1 lung). Histologically, 20 cases were conventional DFSP and 32 were FS-DFSP. Notably, 21 tumors (36%) had been initially misclassified; most of which had metastatic presentation, unusual histology, or atypical location. Tumor sequencing revealed a higher incidence of genetic changes in addition to the PDGFB/ PDGFD fusions: concurrent mutations were detected in 66% of FS-DFSP cases versus 25% of DFSP cases (p = 0.009). Moreover, tumor mutational burden was significantly higher in FS-DFSP than DFSP (p = 0.006). The most prevalent mutations were in the TERT promoter and NF1, found exclusively in FS-DFSP cases. Conclusions: Conventional histology commonly fails to recognize FS-DFSP, leading to missed opportunities for targeted therapy. This highlights the essential role of next-generation sequencing in achieving greater diagnostic accuracy for DFSP and its fibrosarcomatous variant. While no single gene mutation consistently differentiates DFSP from FS-DFSP, the occurrence of additional genetic alterations is notably more common in FS-DFSP cases.

CYP3A Mediates an Unusual C(sp2)-C(sp3) Bond Cleavage via Ipso-Addition of Oxygen in Drug Metabolism.

Mammalian cytochrome P450 drug-metabolizing enzymes rarely cleave carbon-carbon (C-C) bonds and the mechanisms of such cleavages are largely unknown. We identified two unusual cleavages of non-polar, unstrained C(sp2)-C(sp3) bonds in the FDA-approved tyrosine kinase inhibitor pexidartinib that are mediated by CYP3A4/5, the major human phase I drug metabolizing enzymes. Using a synthetic ketone, we rule out the Baeyer-Villiger oxidation mechanism that is commonly invoked to address P450-mediated C-C bond cleavages. Our studies in 18O2 and H2 18O enriched systems reveal two unusual distinct mechanisms of C-C bond cleavage: one bond is cleaved by CYP3A-mediated ipso-addition of oxygen to a C(sp2) site of N-protected pyridin-2-amines, and the other occurs by a pseudo-retro-aldol reaction after hydroxylation of a C(sp3) site. This is the first report of CYP3A-mediated C-C bond cleavage in drug metabolism via ipso-addition of oxygen mediated mechanism. CYP3A-mediated ipso-addition is also implicated in the regioselective C-C cleavages of several pexidartinib analogs. The regiospecificity of CYP3A-catalyzed oxygen ipso-addition under environmentally friendly conditions may be attractive and inspire biomimetic or P450-engineering methods to address the challenging task of C-C bond cleavages.

PDGFRA K385 mutants in myxoid glioneuronal tumors promote receptor dimerization and oncogenic signaling

Myxoid glioneuronal tumors (MGNT) are low-grade glioneuronal neoplasms composed of oligodendrocyte-like cells in a mucin-rich stroma. These tumors feature a unique dinucleotide change at codon 385 in the platelet-derived growth factor receptor α (encoded by the PDGFRA gene), resulting in the substitution of lysine 385 into leucine or isoleucine. The functional consequences of these mutations remain largely unexplored. Here, we demonstrated their oncogenic potential in fibroblast and Ba/F3 transformation assays. We showed that the K385I and K385L mutants activate STAT and AKT signaling in the absence of ligand. Co-immunoprecipitations and BRET experiments suggested that the mutations stabilized the active dimeric conformation of the receptor, pointing to a new mechanism of oncogenic PDGF receptor activation. Furthermore, we evaluated the sensitivity of these mutants to three FDA-approved tyrosine kinase inhibitors: imatinib, dasatinib, and avapritinib, which effectively suppressed the constitutive activity of the mutant receptors. Finally, K385 substitution into another hydrophobic amino acid also activated the receptor. Interestingly, K385M was reported in a few cases of brain tumors but not in MGNT. Our results provide valuable insights into the molecular mechanism underlying the activation of PDGFRα by the K385I/L mutations, highlighting their potential as actionable targets in the treatment of myxoid glioneuronal tumors.

Current Progress on the Influence Human Genetics Has on the Efficacy of Tyrosine Kinase Inhibitors Used to Treat Chronic Myeloid Leukemia.

The use of tyrosine kinase inhibitors (TKIs) has become the mainstay of treatment in patients suffering from chronic myeloid leukemia (CML), an adult leukemia caused by a reciprocal translocation between chromosomes 9 and 22, which createsan oncogene resulting in a myeloproliferative neoplasm. These drugs function by inhibiting the ATP-binding site on the fusion oncoprotein andsubsequently halting proliferative activity. The goal of this work is to investigate the current state of research into genetic factors that influence the efficacy of four FDA-approved TKIs used to treat CML. This overview attempts to identify genetic criteria that could be considered when choosing one drug over the others and to identify where more research is needed. Our results suggest thatthe usual liver enzymes impacting patient response may not be a major factor affecting the efficacy of imatinib, nilotinib, and bosutinib, and yet, that is where most of the past research has focused. More research is warranted on the impact that human polymorphisms of the CYP enzymes have on dasatinib. The impact of polymorphisms in UGT1A1 should be investigated thoroughly in other TKIs, not only nilotinib.The role of influx and efflux transporters has been inconsistent thus far, possibly due to failures to account for the multiple proteins that can transport TKIs and the impact that tumors have on transporter expression. Because physicians cannot currently use a patient's genetic profile to better target their treatment withTKIs, it is critical that more research be conducted on auxiliary pathways or off-target binding effects to generate new leads for further study. Hopefully, new avenues of research will help explain treatment failures and improve patient outcomes.

Abstract C148: Type II ROS1 inhibitors and their liability on ROS1 rearranged non-small cell lung cancer with L2086F mutation

Abstract Introduction: Fusion oncoproteins involving the ROS1 receptor tyrosine kinase have been established as validated therapeutic targets in non-small cell lung cancer. FDA-approved ROS1 tyrosine kinase inhibitors (TKIs) such as crizotinib and entrectinib have shown substantial response rates in these patients, leading to improved outcomes. Historically, the solvent-front ROS1 kinase mutation, G2032R, was a recurrent resistance liability to first generation ROS1 TKI. Next-generation TKIs, including NVL-520, repotrectinib, and taletrectinib are active against the ROS1 G2032R and shown activity in both treatment-naïve and ROS1 G2032R acquired resistance setting. We and others showed that ROS1 L2086F a mutation in catalytic-spine 6 within the kinase domain confers resistance to all first and next-generation type I binding mode TKIs. Cabozantinib, a type II ROS1 inhibitor, is the only FDA-approved TKI that has showed clinical activity against ROS1 L2086F. Recent reports indicated that gilteritinib, an FLT3 TKI, exhibits activity against ALK L1256 (homologous to ROS1 L2086F). In this study, we investigated the efficacy of gilteritinib compared to cabozantinib in ROS1 L2086F resistance model systems. Methods: We tested the effectiveness of ROS1 TKI compared to gilteritinib in Ba/F3 cell lines expressing CD74-ROS1 and EZR-ROS1 resistant mutations. Additionally, we quantified the efficacy of cabozantinib and gilteritinib in ROS1 L2086F using soft agar assays. We engineered CRISPR-Cas9 genome-edited CUTO-28 cells expressing endogenous L2086F mutation, and to validate the activity of gilteritinib and cabozantinib against ROS1 L2086F. Results: The ROS1 kinase mutations F2004C, G2032R and L2086F are resistant to entrectinib inhibition. Cabozantinib, consistent with our previous published data, retains inhibitory activity against ROS1 G2032R and ROS1 L2086F, however the ROS1 F2004C mutation imposes cabozantinib-resistance. Gilteritinib, intriguingly, is active with IC50 ≤ 25 nM against ROS1 F2004C and ROS1 L2086F but not ROS1 G2032R. Immunoblotting studies showed on-target inhibition of ROS1 auto-phosphorylation and effector ERK1/2 activation in the case of ROS1 L2086F mutant cells treated with cabozantinib and gilteritinib. Conclusion: Gilteritinib demonstrates inhibitory activity against ROS1 L2086F mutation. Currently, patients with ROS1 L2086F resistance can be treated with cabozantinib as a second-line treatment option. The preclinical data presented herein suggest that gilteritinib could be an additional, potentially viable alternative to target the highly resistant ROS1 L2086F mutation. Additional studies are needed to explore the use of gilteritinib for ROS1 rearranged NSCLC. Citation Format: Rajat Thawani, Clare Keddy, Matteo Repetto, Kristen Jones, Katelyn Nicholson, Zoe Beach, Alexander Drilon, Monika Davare. Type II ROS1 inhibitors and their liability on ROS1 rearranged non-small cell lung cancer with L2086F mutation [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr C148.

Abstract B129: A bispecific antibody inhibits FGFR3 dimerization and is highly effective in FGFR3-driven tumor models

Abstract Background: The receptor tyrosine kinase (RTK) FGFR3 is frequently mutated in bladder cancer (~15-20% in muscle invasive bladder cancer, MIBC) and is a validated therapeutic target. Oncogenic alterations in FGFR3 include point mutations in the extracellular domain (S249C, R248C, G372C, Y375C) and gene fusions that place an oligomerization domain from a fusion partner at the FGFR3 C-terminus (e.g., FGFR3-TACC3). Although pan-FGFR tyrosine kinase inhibitors (TKI) have demonstrated clinical efficacy, toxicity and acquired resistance limit the benefit of these agents. While antibody-based therapy can offer superior selectivity compared to TKIs, conventional ligand-blocking antibodies are usually ineffective inhibitors of constitutively active RTKs. Further, the existence of multiple oncogenic variants of FGFR3 presents an additional challenge for antibody-mediated blockade. Results: We generated a tetravalent bispecific FGFR3xFGFR3 antibody that potently inhibits both FGFR3 point mutants and fusions with better efficacy than the conventional antibodies that we produced and a clinical-stage comparator antibody. Mechanistically, our bispecific antibody binds FGFR3 through two different epitopes located in immunoglobulin-like domains D1 and D2/3 respectively. It potently blocks the dimerization of FGFR3 S249C, the most common oncogenic variant, inhibiting receptor phosphorylation and downstream signaling. Additionally, our bispecific antibody inhibits the function of FGFR3 gatekeeper mutations (V557M/L) that are resistant to TKIs. In FGFR3-driven tumor models, our antibody is highly effective, providing efficacy similar to that of the FDA-approved TKI erdafitinib. Conclusion: We have characterized the properties of a tetravalent bispecific FGFR3xFGFR3 antibody that shows strong anti-tumor activity in models driven by FGFR3 S249C as well as by FGFR3-TACC3 fusion, outperforming a conventional antibody that was previously in clinical development. The activity of the bispecific antibody is superior to the mixture of the two parental antibodies and results from strong inhibition of FGFR3 dimerization. Our bispecific antibody provides a novel approach to achieve selective and potent inhibition of multiple oncogenic variants of FGFR3 in bladder cancer, including FGFR3 variants that are resistant to FGFR TKIs. Citation Format: Yan Yang, Naga Suhasini Avvaru, Zaoli Jiang, Nina Liu, Michael Rosconi, Bojie Zhang, Yinyin Li, Erica Ullman, John Chia-Yang Lin, Yang Shen, Christopher Daly. A bispecific antibody inhibits FGFR3 dimerization and is highly effective in FGFR3-driven tumor models [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2023 Oct 11-15; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2023;22(12 Suppl):Abstract nr B129.

Disparities in dosing, drug reduction, and drug discontinuation among US FDA approved tyrosine kinase inhibitors

Background: Tyrosine kinase inhibitors (TKIs) have altered the therapeutic landscape of multiple hematological and solid malignancies. FDA approved starting doses of TKIs are based on the recommended phase 2 dose (RP2D) in clinical trials. However, patients are started on lower doses in practice. We assessed the dosing, drug reduction rates, and drug discontinuation rates among FDA approved TKIs and observed the disparity among study populations to understand if there was adequate representation of diversity in race. Methods: We established a database of all FDA approved TKIs from the FDA online label repository. We extracted descriptive data for indications and usage, type of approval, approval dosage, dose reduction recommendation, median age, race, dose reduction rates, drug discontinuation rates, dose modification, warnings, adverse reactions, clinical trial experience, and geriatric use above 65 yrs and 75 yrs. Results: Among all TKIs, median dose was 200 mg and average dose was 307.7 mg; 36 (24%) were approved bid vs 107 (72%) qd. Among approved indications, median rates of dose reduction rate (DRR), drug interruption rate (DIR), drug discontinuations rate (DDR) were 31%, 52%, and 10% respectively. Reasons for DRR, DIR, and DDR were diarrhea, fatigue, nausea, vomiting, hepatotoxicity, rash, and hypertension. Black and Hispanic races are consistently underrepresented among the TKI studies. Conclusions: TKIs have a variable dose reduction and drug discontinuation rate but these studies were done mostly in White individuals. Clinical trials should evaluate multiple dosing regimens and schedules to lessen the toxicity burden and improve QOL in patients while broadening the study population so that the studies will be generalizable to patients in clinical practice. Future studies are warranted to increase representation in the studies to address the disparities.

Axitinib targets cardiac fibrosis in pressure overload-induced heart failure through VEGFA-KDR pathway.

There are no specific clinical medications that target cardiac fibrosis in heart failure (HF). Recent studies have shown that tyrosine kinase inhibitors (TKIs) may benefit fibrosis in various organs. However, there is limited research on their application in cardiac fibrosis. Axitinib, an FDA-approved tyrosine kinase inhibitor, was used to evaluate its effects on cardiac fibrosis and function in pressure overload-induced heart failure. To build a pharmacological network, the pharmacological targets of axitinib were first retrieved from databases and coupled with key heart failure gene molecules for analysis and prediction. To validate the results outlined above, 8-week-old male C57BL/6 J mice were orally administrated of axitinib (30 mg/kg) daily for 8 weeks after Transverse Aortic Constriction (TAC) surgery. Mouse cardiomyocytes and cardiac fibroblasts were used as cell lines to test the function and mechanism of axitinib. We found that the pharmacological targets of axitinib could form a pharmacological network with key genes involved in heart failure. The VEGFA-KDR pathway was found to be closely related to the differential gene expression of human heart-derived primary cardiomyocyte cell lines treated with axitinib, based on analysis of the publicly available dataset. The outcomes of animal experiments demonstrated that axitinib therapy greatly reduced cardiac fibrosis and improved TAC-induced cardiac dysfunction. Further research has shown that the expression of transforming growth factor-β(TGF-β) and other fibrosis genes was significantly reduced in vivo and in vitro. Our study provides evidence for the repurposing of axitinib to combat cardiac fibrosis, and offers new insights into the treatment of patients with HF.

Imatinib and M351-0056 enhance the function of VISTA and ameliorate the development of SLE via IFN-I and noncanonical NF-κB pathway.

V-domain immunoglobulin suppressor of T-cell activation (VISTA), an important negative checkpoint protein, participates in immunoregulation. Systemic lupus erythematosus (SLE) is an autoimmune disease in which patients exhibit high levels of autoantibodies and multi-organ tissue injury, primarily involving the kidney and skin. In wild-type (WT) mice and Vsir-/- mice with pristane-induced lupus-like disease, we found that VISTA deficiency exacerbated the lupus-like disease in mice, possibly through aberrant activation of type I interferon (IFN-I) signaling, CD4+ T cell, and noncanonical nuclear factor-κB (NF-κB) pathway. Surface plasmon resonance results showed that imatinib, an FDA-approved tyrosine kinase inhibitor, may have a high affinity for human VISTA-ECD with a KD value of 0.2009 μM. The biological activities of imatinib and VISTA agonist M351-0056 were studied in monocytes and T cells and in lupus-like disease murine model of chronic graft-versus-host disease (cGVHD) and lupus-prone MRL/lpr mice. VISTA small-molecule agonist reduced the cytokine production of peripheral blood mononuclear cells (PBMCs) and Jurkat cells and inhibited PBMCs proliferation. Moreover, they attenuated the levels of autoantibodies, renal injury, inflammatory cytokines, chemokines, and immune cell expansion in the cGVHD mouse model and MRL/lpr mice. Our findings also demonstrated that VISTA small-molecule agonist ameliorated the development of SLE through improving aberrantly activated IFN-I signaling and noncanonical NF-κB pathway. In conclusion, VISTA has a protective effect on the development and progression of SLE. VISTA agonist M351-0056 and imatinib have been firstly demonstrated to attenuate SLE, suggesting interventions to enhance VISTA function may be effective in treating SLE. VISTA deficiency exacerbates pristane-induced lupus-like disease in mice by promoting activation of the IFN-I and noncanonical NF-κB pathway. Imatinib was screened as a small-molecule VISTA agonist by molecular docking, SPR, and cellular level experiments. VISTA agonists (M351-0056 and imatinib) alleviated lupus-like disease progression in the cGVHD mouse model and MRL/lpr mice by inhibiting activation of IFN-I and noncanonical NF-κB pathway.

Combining the Tyrosine Kinase Inhibitor Cabozantinib and the mTORC1/2 Inhibitor Sapanisertib Blocks ERK Pathway Activity and Suppresses Tumor Growth in Renal Cell Carcinoma.

The molecular-guided therapeutic strategy of combining cabozantinib and sapanisertib restrains ERK activity to effectively suppress growth of renal cell carcinomas, including those unresponsive to immune checkpoint inhibitors.

Long-circulating thiolated chitosan nanoparticles of nintedanib with N-acetyl cysteine for treating idiopathic pulmonary fibrosis: In vitro assessment of cytotoxicity, antioxidant, and antifibrotic potential

Nintedanib (NIN) is one of the FDA-approved tyrosine kinase inhibitor drugs used to treat idiopathic pulmonary fibrosis (IPF). This study aimed to formulate a long-circulating injection of Nintedanib to treat bedridden patients with IPF. Nintedanib was incorporated into chitosan nanoparticles (NIN-NP) via the ionic gelation method, and N-acetyl cysteine (NAC), a known antioxidant and mucolytic agent, was added to the NIN-NP (NAC-NIN-NP). The lyophilized formulation had a particle size of 174 nm, a polydispersity index of 0.511, and a zeta potential of 18.6 mV. The spherical nanoparticles were observed in transmission electron microscopy, whereas field emission scanning electron microscopy showed irregular clusters of NP. The thiolation of the chitosan in NAC-NIN-NP was confirmed by ATR-FTIR and NMR, which improved drug release profiles showing >90 % drug release that was 2.42-folds greater than NIN-NP lasting for five days. The DPPH assay showed that adding NAC increased the % inhibition of oxidation in blank-NP (from 54.59 % to 87.17 %) and NIN-NP (58.65 %–89.19 %). The MTT assay on A549 cells showed 67.57 % cell viability by NAC-NIN-NP with an IC50 value of 28 μg/mL. The NAC formulation reduced hydroxyproline content (56.77 μg/mL) compared to NIN-NP (69.48 μg/mL) in WI-38 cell lines. Meanwhile, the healthy cells count with NAC-NIN-NP was higher (5.104 × 103) than with NIN-NP (4.878 × 103). In Hoechst staining, no significant damage to DNA was observed by the drug or formulation. Therefore, NAC-NIN-NP could be a promising treatment option for IPF patients and can be studied further clinically.

The role of cytochrome P450 3A4-mediated metabolism in sorafenib and lapatinib hepatotoxicity.

Tyrosine kinase inhibitors (TKIs) are increasingly popular drugs used to treat more than a dozen different diseases, including some forms of cancer. Despite having fewer adverse effects than traditional chemotherapies, they are not without risks. Liver injury is a particular concern. Of the FDA-approved TKIs, approximately 40% cause hepatotoxicity. However, little is known about the underlying pathophysiology. The leading hypothesis is that TKIs are converted by cytochrome P450 3A4 (CYP3A4) to reactive metabolites that damage proteins. Indeed, there is strong evidence for this bioactivation of TKIs in in vitro reactions. However, the actual toxic effects are underexplored. Here, we measured the cytotoxicity of several TKIs in primary mouse hepatocytes, HepaRG cells, and HepG2 cells with and without CYP3A4 modulation. To our surprise, the data indicate that CYP3A4 increases resistance to sorafenib and lapatinib hepatotoxicity. The results have implications for the mechanism of toxicity of these drugs in patients and underline the importance of selecting an appropriate experimental model.

Evaluating patient adherence and persistence to first-line tyrosine-kinase inhibitors for metastatic renal cell carcinoma.

e18856 Background: Tyrosine kinase inhibitors (TKIs) have been approved in treating advanced renal cell carcinoma (RCC) since 2005. More recently, combination therapy with an immune checkpoint inhibitor (ICI) and a kinase inhibitor (TKI) is considered standard of care in the first-line setting of metastatic RCC. While oral neoplastic therapies such as TKIs promote patient autonomy, these therapies pose unique challenges including ensuring patients take medications as indicated (i.e., adherence) and for the recommended duration (i.e., persistence). Persistence and adherence data from prescription dispensing and refill patterns are important to health care providers, systems, and payers in order to assess and/or optimize the therapeutic goal(s) of anticancer treatment. Therefore, we sought to explore adherence and persistence of first-line TKIs when used in combination with ICIs for treating metastatic RCC. Methods: Adults with metastatic RCC who received at least two prescriptions for FDA-approved TKIs used in combination with ICIs between April 29, 2019 and August 29,2022 were identified at University of California Irvine Medical Center. Adherence was determined by calculating the Medication Possession Ratio (MPR) and the Proportion of Days Covered (PDC). TKI persistence was evaluated using the Kaplan-Meier method. Also evaluated was the average length of therapy. We examined additional dispensing and refill pattern indicators, including the monthly total number of prescriptions filled. Results: A total of 66 individuals and 849 prescriptions were discovered. The mean duration of treatment for all patients was 237 days, and the median duration was 201 days (Table 1). The mean persistence was 303 days, whereas the median persistence was 233 days. Over 180 days, the median MPR was 83%, whereas the median PDC was 72%. The median variable PDC was 86%, while the median variable MPR was 105%. September was historically the month with the lowest prescription counts (16 +/- 2). Conclusions: We observed a significantly longer median duration of oral TKIs therapy (201 days) in an academic medical center than the national average ( < 100 days). This analysis of real-world data reveals that lengthier treatment durations for TKI+ICI combinations are feasible. Further research is warranted to identify possible factors such as clinical monitoring or adverse effect management that may prolong adherence and persistence. [Table: see text]

Functional consequence and therapeutic targeting of cryptic ALK fusions in monosomy 7 acute myeloid leukemia.

Acute myeloid leukemia (AML) patients have a wide array of cytogenetic and molecular aberrations, which can influence response to therapy. Monosomy 7 is a rare subset within pediatric AML (prevalence of <2%) that is highly associated with poor outcomes. Fusions involving the anaplastic tyrosine kinase (ALK) gene were exclusively identified in 14.3% of this high-risk cohort, while absent across all other AML. Given the dismal outcomes of monosomy 7, we evaluated the use of crizotinib, an FDA-approved tyrosine kinase inhibitor, used to treat patients with ALK fusions. Our findings suggest that crizotinib may serve as a novel therapy for these patients.

Evaluation of Free Online ADMET Tools for Academic or Small Biotech Environments.

For a new molecular entity (NME) to become a drug, it is not only essential to have the right biological activity also be safe and efficient, but it is also required to have a favorable pharmacokinetic profile including toxicity (ADMET). Consequently, there is a need to predict, during the early stages of development, the ADMET properties to increase the success rate of compounds reaching the lead optimization process. Since Lipinski's rule of five, the prediction of pharmacokinetic parameters has evolved towards the current in silico tools based on empirical approaches or molecular modeling. The commercial specialized software for performing such predictions, which is usually costly, is, in many cases, not among the possibilities for research laboratories in academia or at small biotech companies. Nevertheless, in recent years, many free online tools have become available, allowing, more or less accurately, for the prediction of the most relevant pharmacokinetic parameters. This paper studies 18 free web servers capable of predicting ADMET properties and analyzed their advantages and disadvantages, their model-based calculations, and their degree of accuracy by considering the experimental data reported for a set of 24 FDA-approved tyrosine kinase inhibitors (TKIs) as a model of a research project.

Computational Investigation of 1, 3, 4 Oxadiazole Derivatives as Lead Inhibitors of VEGFR 2 in Comparison with EGFR: Density Functional Theory, Molecular Docking and Molecular Dynamics Simulation Studies

Vascular endothelial growth factor (VEGF) is an angiogenic factor involved in tumor growth and metastasis. Gremlin has been proposed as a novel therapeutic pathway for the treatment of renal inflammatory diseases, acting via VEGFR 2 receptor. To date, most FDA-approved tyrosine kinase (TK) inhibitors have been reported as dual inhibitors of EGFR and VEGFR 2. The aim of the present study was to find the potent and selective inhibitor of VEGFR 2 specifically for the treatment of renal cancer. Fourteen previously identified anti-inflammatory compounds i.e., 1, 3, 4 oxadiazoles derivatives by our own group were selected for their anti-cancer potential, targeting the tyrosine kinase (TK) domain of VEGFR2 and EGFR. A detailed virtual screening-based study was designed viz density functional theory (DFT) study to find the compounds' stability and reactivity, molecular docking for estimating binding affinity, SeeSAR analysis and molecular dynamic simulations to confirm protein ligand complex stability and ADMET properties to find the pharmacokinetic profile of all compounds. The DFT results suggested that among all the derivatives, the 7g, 7j, and 7l were chemically reactive and stable derivatives. The optimized structures obtained from the DFTs were further selected for molecular docking, and the results suggested that 7g, 7j and 7l derivatives as the best inhibitors of VEGFR 2 with binding energy values -46.32, -48.89 and -45.01 kJ/mol. The Estimated inhibition constant (IC50) of hit compound 7j (0.009 µM) and simulation studies of its complexes confirms its high potency and best inhibitor of VEGFR2. All the derivatives were also docked with EGFR, where they showed weak binding energies and poor interactions, important compound 7g, 7j and 7i exhibited binding energy of -31.01, -33.23 and -34.19 kJ/mol respectively. Furthermore, the anticancer potential of the derivatives was confirmed by cell viability (MTT) assay using breast cancer and cervical cancer cell lines. At the end, the results of ADMET studies confirmed these derivatives as drug like candidates. Conclusively, the current study suggested substituted oxadiazoles as the potential anticancer compounds which exhibited more selectivity towards VEGFR2 in comparison to EGFR. Therefore, the identified lead molecules can be used for the synthesis of more potent derivatives of VEGFR2, along with extensive in vitro and in vivo experiments, that can be used to treat various cancers, especially renal cancers, and to prevent angiogenesis due to aberrant expression of VEGFR2.

Itraconazole-Induced Increases in Gilteritinib Exposure Are Mediated by CYP3A and OATP1B.

Gilteritinib, an FDA-approved tyrosine kinase inhibitor approved for the treatment of relapsed/refractory FLT3-mutated acute myeloid leukemia, is primarily eliminated via CYP3A4-mediated metabolism, a pathway that is sensitive to the co-administration of known CYP3A4 inhibitors, such as itraconazole. However, the precise mechanism by which itraconazole and other CYP3A-modulating drugs affect the absorption and disposition of gilteritinib remains unclear. In the present investigation, we demonstrate that pretreatment with itraconazole is associated with a significant increase in the systemic exposure to gilteritinib in mice, recapitulating the observed clinical drug–drug interaction. However, the plasma levels of gilteritinib were only modestly increased in CYP3A-deficient mice and not further influenced by itraconazole. Ensuing in vitro and in vivo studies revealed that gilteritinib is a transported substrate of OATP1B-type transporters, that gilteritinib exposure is increased in mice with OATP1B2 deficiency, and that the ability of itraconazole to inhibit OATP1B-type transport in vivo is contingent on its metabolism by CYP3A isoforms. These findings provide new insight into the pharmacokinetic properties of gilteritinib and into the molecular mechanisms underlying drug–drug interactions with itraconazole.

Designing Novel BCR-ABL Inhibitors for Chronic Myeloid Leukemia with Improved Cardiac Safety.

Development of tyrosine kinase inhibitors (TKIs) targeting the BCR-ABL oncogene constitutes an effective approach for the treatment of chronic myeloid leukemia (CML) and/or acute lymphoblastic leukemia. However, currently available inhibitors are limited by drug resistance and toxicity. Ponatinib, a third-generation inhibitor, has demonstrated excellent efficacy against both wild type and mutant BCR-ABL kinase, including the “gatekeeper” T315I mutation that is resistant to all other currently available TKIs. However, it is one of the most cardiotoxic of the FDA-approved TKIs. Herein, we report the structure-guided design of a novel series of potent BCR-ABL inhibitors, particularly for the T315I mutation. Our drug design paradigm was coupled to iPSC–cardiomyocyte models. Systematic structure–activity relationship studies identified two compounds, 33a and 36a, that significantly inhibit the kinase activity of both native BCR-ABL and the T315I mutant. We have identified the most cardiac-safe TKIs reported to date, and they may be used to effectively treat CML patients with the T315I mutation.

Abstract GS109: Ponatinib-induced Cardiotoxicity Is Driven By S100A8/A9-NLRP3-IL1β Signaling Mediated Excessive Inflammation

Background: The tyrosine kinase inhibitor (TKI) ponatinib is the oral drug for the treatment of chronic myelogenous leukemia (CML) patients with T315I (gatekeeper) mutation. Pharmacovigilance analysis of FDA and WHO datasets have revealed that ponatinib is the most cardiotoxic agent among all FDA-approved TKIs in a real-world scenario. However, the mechanism of ponatinib-induced cardiotoxicity is unknown. The cardiotoxic effects of ponatinib remained hidden in preclinical studies and were only revealed in phase 2 clinical studies and by the subsequent meta-analysis. The lack of well-optimized mouse models has hampered the in vivo cardio-oncology studies. To this end, here we aimed to investigate the hidden cardiotoxic mechanism of ponatinib and strategies to prevent the cardiotoxic manifestations. Methods: We employed wild-type C57BL/6, cardiovascular (CV) comorbidity models e.g., transverse aortic constriction (TAC)-pressure overload (cardiac comorbidity) and high-fat diet-fed ApoE -/- (vascular comorbidity), to investigate the cardiotoxic mechanism of ponatinib. Echocardiography was performed to assess cardiac function. Comprehensive immune profiling was performed to identify ponatinib-induced immune activation using flow cytometry analysis and cytokine assay. Results: Echocardiographic assessment of ponatinib treated high-fat diet-fed ApoE -/- and pressure overload (PO) murine model showed a significant decline in cardiac function, suggesting the key role of CV-comorbidities in ponatinib-induced cardiomyopathy. A combination of multiple in vitro and in vivo models was employed to delineate the underlying molecular mechanisms. An unbiased RNA-Seq analysis identified the enrichment of dysregulated inflammatory genes, including a multi-fold upregulation of alarmins S100A8/A9 as a top hit in ponatinib-treated hearts. Mechanistically, we demonstrate that ponatinib activates the S100A8/9-TLR4-NLRP3-IL-1β signaling pathway in cardiac and systemic myeloid cells (monocytes and neutrophils), in vitro and in vivo , thereby leading to excessive myocardial and systemic inflammation. Excessive inflammation was central to the cardiac pathology because interventions with broad-spectrum immunosuppressive glucocorticoid dexamethasone or direct NLRP3 inhibitor Cy-09 nearly abolished the ponatinib-induced cardiac dysfunction. Taken together, these findings uncover a novel mechanism of ponatinib-induced cardiac inflammation leading to cardiac dysfunction. Conclusions: These findings uncover a novel mechanism of ponatinib-induced cardiac inflammation leading to cardiac dysfunction. Our results provide critical preclinical data and rationale for a clinical investigation into immunosuppressive interventions to mitigate ponatinib-induced cardiotoxicity.