Broad-spectrum Tyrosine Kinase Inhibitor Research Articles

Anlotinib potentiates anti-PD1 immunotherapy via transferrin receptor-dependent CD8+ T-cell infiltration in hepatocellular carcinoma.

The therapeutic potential of immune checkpoint blockade (ICB) extends across various cancers; however, its effectiveness in treating hepatocellular carcinoma (HCC) is frequently curtailed by both inherent and developed resistance. This research explored the effectiveness of integrating anlotinib (a broad-spectrum tyrosine kinase inhibitor) with programmed death-1 (PD-1) blockade and offers mechanistic insights into more effective strategies for treating HCC. Using patient-derived organotypic tissue spheroids and orthotopic HCC mouse models, we assessed the effectiveness of anlotinib combined with PD-1 blockade. The impact on the tumour immune microenvironment and underlying mechanisms were assessed using time-of-flight mass cytometry, RNA sequencing, and proteomics across cell lines, mouse models, and HCC patient samples. The combination of anlotinib with an anti-PD-1 antibody enhanced the immune response against HCC in preclinical models. Anlotinib remarkably suppressed the expression of transferrin receptor (TFRC) via the VEGFR2/AKT/HIF-1α signaling axis. CD8+ T-cell infiltration into the tumour microenvironment correlated with low expression of TFRC. Anlotinib additionally increased the levels of the chemokine CXCL14, crucial for attracting CD8+ T cells. CXCL14 emerged as a downstream effector of TFRC, exhibiting elevated expression following the silencing of TFRC. Importantly, low TFRC expression was also associated with a better prognosis, enhanced sensitivity to combination therapy, and a favourable response to anti-PD-1 therapy in patients with HCC. Our findings highlight anlotinib's potential to augment the efficacy of anti-PD-1 immunotherapy in HCC by targeting TFRC and enhancing CXCL14-mediated CD8+ T-cell infiltration. This study contributes to developing novel therapeutic strategies for HCC, emphasizing the role of precision medicine in oncology. Synergistic effects of anlotinib and anti-PD-1 immunotherapy demonstrated in HCC preclinical models. Anlotinib inhibits TFRC expression via the VEGFR2/AKT/HIF-1α pathway. CXCL14 upregulation via TFRC suppression boosts CD8+ T-cell recruitment. TFRC emerges as a potential biomarker for evaluating prognosis and predicting response to anti-PD-1-based therapies in advanced HCC patients.

Sorafenib inhibits ossification of the posterior longitudinal ligament by blocking LOXL2-mediated vascularization

Ossification of the Posterior Longitudinal Ligament (OPLL) is a degenerative hyperostosis disease characterized by the transformation of the soft and elastic vertebral ligament into bone, resulting in limited spinal mobility and nerve compression. Employing both bulk and single-cell RNA sequencing, we elucidate the molecular characteristics, cellular components, and their evolution during the OPLL process at a single-cell resolution, and validate these findings in clinical samples. This study also uncovers the capability of ligament stem cells to exhibit endothelial cell-like phenotypes in vitro and in vivo. Notably, our study identifies LOXL2 as a key regulator in this process. Through gain-and loss-of-function studies, we elucidate the role of LOXL2 in the endothelial-like differentiation of ligament cells. It acts via the HIF1A pathway, promoting the secretion of downstream VEGFA and PDGF-BB. This function is not related to the enzymatic activity of LOXL2. Furthermore, we identify sorafenib, a broad-spectrum tyrosine kinase inhibitor, as an effective suppressor of LOXL2-mediated vascular morphogenesis. By disrupting the coupling between vascularization and osteogenesis, sorafenib demonstrates significant inhibition of OPLL progression in both BMP-induced and enpp1 deficiency-induced animal models while having no discernible effect on normal bone mass. These findings underscore the potential of sorafenib as a therapeutic intervention for OPLL.

Sequential or up-front triple combination with durvalumab, tremelimumab, and bevacizumab for patients with unresectable hepatocellular carcinoma (HCC): MONTBLANC.

TPS574 Background: Escalation of treatment from one to two combined immune checkpoint inhibitors (CPI) has dramatically increased objective and clinical response in advanced hepatocellular carcinoma (HCC) patients. Establishing strategies with more than two CPI agents to further increase response while maintaining a manageable toxicity is therefore a top priority. The upfront simultaneous use of three or more CPI can yield a strong initial response to treatment, but it may also increase treatment-related toxicity. An alternative approach, which prioritizes safety over immediate response, involves utilizing different CPI doublets in a sequential manner. However, this design entails switching to a different combination only after radiological progression is observed, and recurrent progressions may lead to deteriorating liver function and treatment resistance. Trials of immunotherapy of HCC conducted in recent years showed that the efficacy of CPI, when used simultaneously, outweighs the drawbacks of their combined toxicity and that early radiological response to treatment, or the lack thereof, is a predictor of clinical outcome. In addition, failure of trials using broad-spectrum tyrosine kinase inhibitors (TKI) and CPI suggest that antibodies or narrow-spectrum TKI should be used for future CPI-based combinations in HCC studies. Based on these considerations, the MONTBLANC study is the first trial to assess the effectiveness of up-front triple treatment with a combination of the three currently approved immunological agents for HCC and to implement the concept of treatment escalation determined by lack of early radiological response (as opposed to treatment progression). Methods: The MONTBLANC study is a randomized, 2-arm phase II study on the efficacy of combinations of durvalumab, tremelimumab, and bevacizumab in patients with advanced HCC. Patients with preserved liver function (Child-Pugh A) with unresectable tumors or not amenable to local or locoregional treatment are randomized to an early escalation arm (A) or a triple treatment arm (B). Patients in arm A receive combined durvalumab and tremelimumab (STRIDE regimen). Treatment is escalated by the addition of bevacizumab upon detection of disease progression or in the absence of radiological response by the 4th month of treatment. Patients in arm B receive up-front STRIDE and bevacizumab. Treatment will continue until unacceptable toxicity or progression under the Bev-containing regimen. The primary endpoint is overall response rate (ORR). Clinical trial information: NCT05844046 .

Immunomodulatory Activity of the Tyrosine Kinase Inhibitor Dasatinib to Elicit NK Cytotoxicity against Cancer, HIV Infection and Aging.

Tyrosine kinase inhibitors (TKIs) have been extensively used as a treatment for chronic myeloid leukemia (CML). Dasatinib is a broad-spectrum TKI with off-target effects that give it an immunomodulatory capacity resulting in increased innate immune responses against cancerous cells and viral infected cells. Several studies reported that dasatinib expanded memory-like natural killer (NK) cells and γδ T cells that have been related with increased control of CML after treatment withdrawal. In the HIV infection setting, these innate cells are associated with virus control and protection, suggesting that dasatinib could have a potential role in improving both the CML and HIV outcomes. Moreover, dasatinib could also directly induce apoptosis of senescence cells, being a new potential senolytic drug. Here, we review in depth the current knowledge of virological and immunogenetic factors associated with the development of powerful cytotoxic responses associated with this drug. Besides, we will discuss the potential therapeutic role against CML, HIV infection and aging.

Two-in-One Nanoparticle Formulation to Deliver a Tyrosine Kinase Inhibitor and microRNA for Targeting Metabolic Reprogramming and Mitochondrial Dysfunction in Gastric Cancer.

Dysregulational EGFR, KRAS, and mTOR pathways cause metabolic reprogramming, leading to progression of gastric cancer. Afatinib (Afa) is a broad-spectrum tyrosine kinase inhibitor that reduces cancer growth by blocking the EGFR family. MicroRNA 125 (miR-125) reportedly diminishes EGFRs, glycolysis, and anti-apoptosis. Here, a one-shot formulation of miR-125 and Afa was presented for the first time. The formulation comprised solid lipid nanoparticles modified with mitochondrial targeting peptide and EGFR-directed ligand to suppress pan-ErbB-facilitated epithelial–mesenchymal transition and mTOR-mediated metabolism discoordination of glycolysis–glutaminolysis–lipids. Results showed that this cotreatment modulated numerous critical proteins, such as EGFR/HER2/HER3, Kras/ERK/Vimentin, and mTOR/HIF1-α/HK2/LDHA pathways of gastric adenocarcinoma AGS cells. The combinatorial therapy suppressed glutaminolysis, glycolysis, mitochondrial oxidative phosphorylation, and fatty acid synthesis. The cotreatment also notably decreased the levels of lactate, acetyl-CoA, and ATP. The active involvement of mitophagy supported the direction of promoting the apoptosis of AGS cells, which subsequently caused the breakdown of tumor-cell homeostasis and death. In vivo findings in AGS-bearing mice confirmed the superiority of the anti-tumor efficacy and safety of this combination nanomedicine over other formulations. This one-shot formulation disturbed the metabolic reprogramming; alleviated the “Warburg effect” of tumors; interrupted the supply of fatty acid, cholesterol, and triglyceride; and exacerbated the energy depletion in the tumor microenvironment, thereby inhibiting tumor proliferation and aggressiveness. Collectively, the results showed that the two-in-one nanoparticle formulation of miR-125 and Afa was a breakthrough in simplifying drug preparation and administration, as well as effectively inhibiting tumor progression through the versatile targeting of pan-ErbB- and mTOR-mediated mitochondrial dysfunction and dysregulated metabolism.

Second-line therapy for advanced hepatocellular carcinoma with regorafenib or cabozantinib: Multicenter French clinical experience in real-life after matching.

BACKGROUNDStarting a second-line systemic treatment for hepatocellular carcinoma (HCC) is a common situation. The only therapeutic options in France are two broad-spectrum tyrosine kinase inhibitors (TKIs), regorafenib (REG) and cabozantinib (CBZ), but no comparative real-life studies are available.AIMTo evaluate the progression-free survival (PFS) of patients treated with REG or CBZ, we investigated the disease control rate (DCR), overall survival (OS), and safety of both drugs. To identify the variables associated with disease progression over time.METHODSA retrospective multicenter study was performed on the clinical data of patients attending one of three referral centers (Avignon, Marseille, and Nice) between January 2017 and March 2021 using propensity score matching. PFS and OS were assessed using the Kaplan-Meier method. Multivariate analysis (MA) of progression risk factors over time was performed in matched-pair groups.RESULTSFifty-eight patients 68 (62-74) years old with HCC, Barcelona clinic liver cancer (BCLC) B/C (86%), Child-Pugh (CP)-A/B (24%) received REG for 3.4 (1.4-10.5) mo as second-line therapy. Twenty-eight patients 68 (60-73) years, BCLC B/C (75%), CP-A/B (25%) received CBZ for 3.7 (1.8-4.9) mo after first-line treatment with sorafenib [3 (2-4) (CBZ) vs 4 (2.9-11.8) mo (REG), P = 0.0226]. Twenty percent of patients received third-line therapy. After matching, PFS and DCR were not significantly different after a median follow-up of 6.2 (2.7-11.7) mo (REG) vs 5.2 (4-7.2) mo (CBZ), P = 0.6925. There was no difference in grade 3/4 toxicities, dose reductions, or interruptions. The OS of CP-A patients was 8.3 (5.2-24.8) vs 4.9 (1.6-11.7) mo (CP-B), P = 0.0468. The MA of risk factors for progression over time identified C-reactive protein (CRP) > 10 mg/L, neutrophil-to-lymphocyte ratio (NLR) > 3, and aspartate aminotransferase (AST) > 45 IU as predictive factors.CONCLUSIONThis multicenter indirect comparative study found no significant difference in PFS between REG and CBZ as second-line therapy for advanced HCC. Elevated levels of inflammatory markers (CRP and NLR) and AST were associated with non-control of TKIs over time. A 2-mo online progression risk calculation is proposed.

Abstract 3346: BBT-207, a novel, 4th generation, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) with broad-spectrum activity to both treatment-emergent and drug-naïve mutants for the treatment of NSCLC

Abstract Background: Activating mutations in EGFR, e.g., L858R (L) and Del19 (D), are observed in 14.1-32.3% of NSCLC worldwide and defines a druggable entity. Single agent EGFR TKI treatment was established in clinical trials. However, a treatment-emergent mutation of T790M (T) was identified as a major source of drug resistance. Irreversible 2nd and 3rd generation EGFR TKIs were shown effective. Mutant-specific inhibition by 3rd generation EGFR TKIs reduced adverse events such as skin toxicities. The emergence of a missense mutation at C797 (C), to which irreversible TKIs covalently bind, limited their efficacy. Patients harboring treatment-emergent C mutations are left with few therapeutic options. Despite anecdotal reports of efficacy from 1st generation TKIs, these complex molecular variants involving C797 are an increasing clinical concern. To prevent the emergence of drug-resistant subclones, a broad-spectrum EGFR TKI against both treatment-emergent and drug-naïve mutants is required. Such a 4th generation EGFR TKI must also enable monotherapy, allowing precise dose adjustment in case of toxicity. Method: Derived from BBT-176 which is under clinical evaluation (NCT04820023), we synthesized BBT-207 and other related molecules. Using Promega ADP-Glo™ kinase assay, we tested compounds against wild-type (WT) and mutated EGFR proteins. Ba/F3 cells harboring WT and mutated EGFR genes were created and cell viability was measured by CellTiter-Glo® and SpectraMax iD3®. In vivo anti-tumor activity was evaluated in Ba/F3 cell-derived xenograft models and an Osimertinib-resistant patient-derived xenograft model. Single dose pharmacokinetic (PK) study was performed in animals. Results: BBT-207 showed IC50 values < 10 nM against EGFR triple mutants (DTC and LTC) and comparable IC50 values against double mutants (DC and LC), while Osimertinib was ineffective in both groups. BBT-207 was also as active as Gefitinib to single mutants (D and L). Double mutants containing T790M (DT and LT) were inhibited effectively by BBT-207 and Osimertinib at similar concentrations, while not by Gefitinib. In in vivo models to which Osimertinib was inactive (LC and DTC), significant tumor growth inhibition was observed from BBT-207 alone, which was enhanced by the addition of Osimertinib. PK studies in mouse, rat, dog and monkey were consistent with high exposure and sustained drug concentrations above the IC50 values, with evidence of penetration into the central nervous system. Conclusion: BBT-207 is a reversible, mutant-specific, broad-spectrum TKI, active to clinically observed mutations of EGFR and is expected to be compatible with monotherapy of QD schedule in humans. BBT-207 is well-positioned to augment the treatment of EGFR mutated NSCLC, either for acquired drug resistance or in earlier line. Citation Format: Taiguang Jimmy Jin, Sang-Uk Kang, Chulwon Kim, Jehrod Brenneman, Mihee Song, Pavel Printsev, Bo-Bae Seo, Yong-Hee Lee, Sang-Yoon Lee. BBT-207, a novel, 4th generation, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) with broad-spectrum activity to both treatment-emergent and drug-naïve mutants for the treatment of NSCLC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3346.

Sunitinib-Induced Elevation of Mean Corpuscular Volume (MCV)-Exploring Its Possible Clinical Relevance in Cancer Patients.

Sunitinib is a broad-spectrum multitargeted tyrosine kinase inhibitor mainly used as second-line therapy for non-resectable gastrointestinal stromal or first-line treatment option of metastatic renal cell carcinoma (mRCC), and as an “off-label” option in pediatric oncology. It has been previously reported that sunitinib elevates the mean corpuscular volume of erythrocytes (MCV) in treated subjects. The aim of this study was to assess time-dependent changes of this effect and evaluate its possible clinical relevance. In this study, 179 adult and 21 pediatric patients with solid tumors treated with sunitinib were retrospectively analyzed. The laboratory and treatment-related data were collected for each treatment period. The regression model with a broken-line relationship was used to fit time dependence of the MCV. In the adult group, the MCV was increasing during the first 21.6 weeks (median) of treatment in a median level of 99.8 fL, where it stabilized. MCV increase was faster in the patients who suffered from treatment-related adverse events (21.3 vs. 24.6 weeks, p = 0.010). In the pediatric cohort, the MCV dynamics were similar to adults. In conclusion, MCV changes during sunitinib treatment in pediatric and adult patients may be of clinical utility in monitoring sunitinib treatment course.

Emerging Therapies for Hepatocellular Carcinoma (HCC).

Simple SummaryPrimary liver cancer, also known as Hepatocellular carcinoma (HCC), is considered to be a major global health challenge. Due to delays in diagnosis at early asymptomatic stages, HCC reaches a severe aggressive stage, thereby having a significant negative impact on patient survival. In addition, HCC shows marked resistance to conventional cancer treatments such as chemo- and radiotherapy. A variety of new and advanced therapies are continuously being evaluated to acquire a breakthrough in HCC treatment to enhance overall and recurrence-free survival. Appropriate identification and selection of target genes and utilization of safe and effective therapeutic approaches, such as gene therapy or immunotherapy, are key strategies for the effective treatment for HCC. This review paper intends to provide a perspective on emerging approaches as avenues towards more effective and safer therapies for HCC.Hepatocellular carcinoma (HCC) arises from hepatocytes and accounts for 90% of primary liver cancer. According to Global Cancer Incidence, Mortality and Prevalence (GLOBOCAN) 2020, globally HCC is the sixth most common cancer and the third most common cause of cancer-related deaths. Reasons for HCC prognosis remaining dismal are that HCC is asymptomatic in its early stages, leading to late diagnosis, and it is markedly resistant to conventional chemo- and radiotherapy. Liver transplantation is the treatment of choice in early stages, while surgical resection, radiofrequency ablation (RFA) and trans arterial chemoembolization (TACE) are Food and Drug Administration (FDA)-approved treatments for advanced HCC. Additional first line therapy for advanced HCC includes broad-spectrum tyrosine kinase inhibitors (TKIs), such as sorafenib and lenvatinib, as well as a combination of immunotherapy and anti-angiogenesis therapy, namely atezolizumab and bevacizumab. However, these strategies provide nominal extension in the survival curve, cause broad spectrum toxic side effects, and patients eventually develop therapy resistance. Some common mutations in HCC, such as in telomerase reverse transcriptase (TERT), catenin beta 1 (CTNNB1) and tumor protein p53 (TP53) genes, are still considered to be undruggable. In this context, identification of appropriate gene targets and specific gene delivery approaches create the potential of gene- and immune-based therapies for the safe and effective treatment of HCC. This review elaborates on the current status of HCC treatment by focusing on potential gene targets and advanced techniques, such as oncolytic viral vectors, nanoparticles, chimeric antigen receptor (CAR)-T cells, immunotherapy, and clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9), and describes future prospects in HCC treatment.

INTRIGUE: A phase III, randomized, open-label study to evaluate the efficacy and safety of ripretinib versus sunitinib in patients with advanced gastrointestinal stromal tumor previously treated with imatinib

359881 Background: Sunitinib is approved for advanced gastrointestinal stromal tumor (GIST) after imatinib failure. Ripretinib, a broad-spectrum KIT and PDGFRA switch-control tyrosine kinase inhibitor (TKI), is indicated for the treatment of adult patients (pts) with GIST who received prior treatment with 3 or more TKIs, including imatinib. We compared the efficacy and safety of ripretinib vs sunitinib in pts with advanced GIST who progressed on or were intolerant to imatinib. Methods: This multicenter, global, randomized, open-label phase 3 study (NCT03673501) enrolled adult pts with GIST who progressed on or had intolerance to imatinib. Pts were randomized 1:1 to ripretinib 150 mg once daily (QD) or sunitinib 50 mg QD (4 wks on/2 wks off). Randomization was stratified by KIT mutational status and imatinib intolerance. The primary endpoint was progression-free survival (PFS) by independent radiologic review (IRR) using modified RECIST version 1.1. Key secondary endpoints were objective response rate (ORR) by IRR and overall survival (OS). Hierarchical testing was performed for primary and key secondary endpoints in a prespecified sequence; testing pts with a KIT exon 11 primary mutation (Ex11 intention-to-treat [ITT] population) preceded the all-patient (AP) ITT population. Data cutoff was 1 Sep 2021; final analyses of PFS and ORR and the first interim analysis of OS were conducted. Results: A total of 453 pts were randomized to ripretinib (n = 226; Ex11 ITT, n = 163) or sunitinib (n = 227; Ex11 ITT, n = 164). Median age was 60 yrs (range 18–88) and most pts were white (66.2%) males (62.0%). PFS was not statistically different between ripretinib and sunitinib in the Ex11 ITT (hazard ratio [HR] 0.88, 95% CI 0.66, 1.16; P = 0.36; median 8.3 vs 7.0 mos) or in the AP populations (HR 1.05, 95% CI 0.82, 1.33; P = 0.72; median 8.0 vs 8.3 mos). ORR was numerically higher for ripretinib vs sunitinib in the Ex11 ITT (23.9% vs 14.6%; difference 9.3%, 95% CI 0.7, 17.8; nominal P = 0.03) and AP ITT populations (21.7% vs 17.6%; difference 4.2%, 95% CI −3.2, 11.5; nominal P = 0.27). OS data was highly immature; median OS was not reached in either arm. Fewer pts in the ripretinib arm experienced Grade 3-4 (G3-4) treatment-emergent adverse events (TEAEs) vs sunitinib (41.3% vs 65.6%). Among G3-4 TEAEs with a difference ≥5% between arms, ripretinib had fewer events vs sunitinib (hypertension [8.5% vs 26.7%], palmar-plantar erythrodysesthesia [1.3% vs 10.0%], neutropenia [0% vs 6.3%], and neutrophil count decreased [0% vs 7.2%]). Conclusions: The PFS in both arms was longer than PFS achieved by sunitinib in its pivotal phase 3 trial. While the PFS for ripretinib did not meet the primary endpoint of superiority vs sunitinib, meaningful clinical activity and fewer G3-4 TEAEs were observed in pts with advanced GIST treated with ripretinib after imatinib failure. Clinical trial information: NCT03673501.

P-107 Dermatopathological review of cutaneous squamous cell carcinoma events in patients with gastrointestinal stromal tumors treated with ripretinib

Ripretinib, a broad-spectrum KIT and PDGFRA switch-control tyrosine kinase inhibitor (TKI), is indicated for patients with advanced gastrointestinal stromal tumor (GIST) who have received prior treatment with 3 or more kinase inhibitors, including imatinib. Ripretinib also inhibits BRAF in vitro. The incidence of all-grade cutaneous squamous cell carcinoma (cuSCC) with BRAF inhibitors, vemurafenib and dabrafenib, was 12.5% in a meta-analysis of 6,445 patients from 21 studies. cuSCC occurred in 7% of 351 patients with advanced GIST enrolled in either the phase 1 (NCT02571036) or phase 3 INVICTUS study (NCT03353753) receiving at least 1 dose of ripretinib.

Gastrointestinal stromal tumours.

Gastrointestinal stromal tumours (GIST) have an incidence of ~1.2 per 105 individuals per year in most countries. Around 80% of GIST have varying molecular changes, predominantly mutually exclusive activating KIT or PDGFRA mutations, but other, rare subtypes also exist. Localized GIST are curable, and surgery is their standard treatment. Risk factors for relapse are tumour size, mitotic index, non-gastric site and tumour rupture. Patients with GIST with KIT or PDGFRA mutations sensitive to the tyrosine kinase inhibitor (TKI) imatinib that are at high risk of relapse have improved survival with adjuvant imatinib treatment. In advanced disease, median overall survival has improved from 18 months to >70 months since the introduction of TKIs. The role of surgery in the advanced setting remains unclear. Resistance to TKIs arise mainly from subclonal selection of cells with resistance mutations in KIT or PDGFRA when they are the primary drivers. Advanced resistant GIST respond to second-line sunitinib and third-line regorafenib, as well as to the new broad-spectrum TKI ripretinib. Rare molecular forms of GIST with alterations involving NF1, SDH genes, BRAF or NTRK genes generally show primary resistance to standard TKIs, but some respond to specific inhibitors of the activated genes. Despite major advances, many questions in both advanced and localized disease remain unanswered.

Evaluation of ponatinib in vitro effect in three canine mast cell tumor cell lines expressing FGFR-1, PDGFR-α, and VEGFR-2

Ponatinib is a broad-spectrum tyrosine kinase inhibitor that targets numerous receptor tyrosine kinases (RTKs), including but not limited to fibroblast growth factor receptor (FGFR)-1, platelet derived growth factor receptor (PDGFR)-α, and vascular endothelial growth factor receptor (VEGFR)-2. This study evaluated the expression of FGFR-1, PDGFR-α, and VEGFR-2 in three canine mast cell tumor (MCT) cell lines (CM-MC1, VI-MC1, CoMS) and the effects of ponatinib on these MCT cell lines.Quantitative RT-PCR confirmed the expression of FGFR-1, PDGFR-α, and VEGFR-2 in the three MCT cell lines. Ponatinib exhibited dose- and time-dependent cytotoxicity in MCT cell lines via MTT assay. The IC50 for 24, 48, and 72 h across the three cell lines ranged from 38.47 nM to 103.3 nM, which is clinically comparable to dose ranges established for humans. Significantly increased apoptosis in each cell line was seen between 12 and 18 h after treatment with IC50 of ponatinib via Annexin-V and Caspase-3/7 assays. These data suggest that ponatinib could be a possible therapeutic agent for canine MCTs. Further studies are needed to investigate the prognostic value of FGFR-1, PDGFR-α, and VEGFR-2 in canine MCTs.

Real-Life Experience of Sorafenib Maintenance after Allogeneic Hematopoietic Stem Cell Transplantation for FLT3-ITD AML Reveals High Rates of Toxicity-Related Treatment Interruption

Introduction: FLT3-Internal Tandem Duplication (FLT3-ITD) mutations of the gene encoding the FLT3 tyrosine kinase receptor are found in 25-30% of AML patients and are associated with a poor prognosis despite intensive chemotherapy and allogeneic hematopoietic stem cell transplantation (HSCT). FLT3 tyrosine kinase inhibitors (TKI) significantly improve survival of FLT3 mutated AML patients in large prospective trials (Stone, NEJM 2017; doi:10.1056/NEJMoa1614359). Post-HSCT maintenance with sorafenib - a broad-spectrum TKI with strong activity against FLT3 - was recently shown to reduce the risk of relapse and improve survival in the phase II SORMAIN trial (Burchert, JCO 2020; doi: 10.1200/JCO.19.03345). Importantly, clinical trials reported a low rate of toxicities requiring sorafenib discontinuation (Chen et al, BBMT 2014;doi: 10.1016/j.bbmt.2014.09.007; Burchert et al., J Clin Oncol. 2020; doi: 10.1200/JCO.19.03345). The aim of our single-center retrospective analysis was to evaluate the real-life experience in patients treated with post-allogeneic HSCT sorafenib maintenance therapy for FLT3-ITD AML with a particular focus on tolerability and toxicity-related treatment interruption. Methods: We conducted a single-center retrospective study on 33 FLT3-ITD AML patients undergoing allogeneic HSCT in complete remission between 2013 and 2020, including 20 patients who received sorafenib maintenance and 13 who did not. Sorafenib was started at hematologic reconstitution at 200 mg BID and increased at 400 mg BID after a week in case of good tolerance. Treatment was maintained until two years if tolerated. In case of toxicity, the drug was either reduced to 200mg BID, or stopped. Among the 13 patients in the untreated group, 8 were transplanted between 2013 and 2016 before we started to routinely use sorafenib maintenance, and 5 were transplanted in 2017 or later. Among the latter, sorafenib maintenance was not started because of aGVHD and insufficient hematologic reconstitution (n=3), low-allelic ratio of FLT3-ITD (n=1), early death due to PTLD (n=1). Results: In the sorafenib group (n=20), median time from transplant to sorafenib initiation was 68 days (range 40-213). Overall, 16 patients (80%) experienced toxicities leading to dose reduction (4 patients, 20%) or interruption (12 patients, 60%). In these patients, the average time on sorafenib before toxicity occurrence was 98 days (range 1-717; only one patient stopped treatment after 1 day because of severe diarrhea). Most common toxicities were skin (7, grade II), gastrointestinal (5, grade II), and hematologic (5, grade II and III). One patient experienced uveitis (grade III) and pneumonia (grade IV), both resolutive after sorafenib interruption. One patient experienced severe hypertension (grade III), 1 had hepatitis (grade III) and another one a PRESS syndrome (grade IV) possibly related to sorafenib. Other causes of sorafenib interruption included FLT3-ITD negative relapse in 1 patient, relapse in 1 patient, and end of scheduled maintenance in 1 patient. Among the 12 patients who interrupted sorafenib because of toxicities, 3 patients were re-challenged with good tolerance in 2 cases, while 7 were switched to midostaurine. Among these 7, 4 completed the 2-y treatment and 3 interrupted midostaurine because of toxicities (2 patients experienced digestive intolerance and 1 pneumonia). The average time of sorafenib exposure in the whole sorafenib group was 180 days (range 1-765). Importantly, the analysis of patients' outcome confirmed the previously reported positive impact of sorafenib maintenance on overall survival (Figure 1B) despite high rates of treatment interruption. Conclusion: Our real-life analysis reveals higher rates of toxicity-related interruption of sorafenib maintenance after allogeneic HSCT than previously reported in clinical trials. Interestingly, our results confirm the favorable impact of sorafenib maintenance on clinical outcome despite a high rate of toxicity-related treatment interruption, suggesting the feasibility of switching to other maintenance approaches in case of low tolerability. Disclosures No relevant conflicts of interest to declare. OffLabel Disclosure: sorafenib as a maintenance treatment to prevent FLT3-ITD mutated AML reccurence after allogeneic transplantation

LENVAGIST - A multicenter, comparative, placebo-controlled, double-blinded, phase II study of the efficacy of lenvatinib in patients with locally advanced or metastatic GIST after failure of imatinib and sunitinib.

TPS11568 Background: GastroIntestinal Stromal Tumors (GIST) are paradigmatic models of cancers with a driver mutation of an oncogene, in which imatinib is recommended as adjuvant therapy or treatment of locally advanced and metastatic forms. After failure of imatinib (either progression or toxicity), sunitinib and regorafenib are indicated as 2nd and 3rd lines, respectively. Beyond approved drugs, tyrosine kinase inhibitors (TKI) can bring clinical benefit because some clones remain sensitive to TKI. Lenvatinib is a broad spectrum TKI targeting KIT, RET, PDGFRA, VEGFR 1-3 and FGFR 1-4, that is approved in the treatment of differentiated thyroid carcinoma and metastatic renal cell carcinoma and hepatocellular carcinoma. Methods: This prospective, randomized, placebo-controlled, double-blinded, multicenter trial evaluates the efficacy and safety of Lenvatinib in adult GIST patients (pts) who failed at least to previous imatinib and sunitinib. Seventy-four pts will be randomly allocated in a 1:1 ratio to receive either oral lenvatinib, at a daily dose of 24mg, or its matching placebo, continuously, until progression of disease (PD) or unacceptable toxicity. Randomization will be stratified according to the number of different previous anticancer drugs (2 or > 2). The primary objective is to compare the Progression-free survival (PFS) between arms. The expected median PFS are 1.5 month in the control arm and 3.0 months in the experimental arm (HR = 0.5). Seventy one events will provide 90% power to show significant improvement in PFS, using a 2-sided log-rank test at a 10% level. Secondary endpoints include the overall survival, the objective response rate, the best overall response, the quality of life and the safety profile. Patients allocated in the placebo arm who experience PD (RECIST 1.1) may switch to active lenvatinib. Radiological endpoints will be evaluated using the RECIST 1.1. Translational objectives will be to identify blood and tumor parameters as predictive markers of lenvatinib efficacy. Recruitment has been activated in January 2020. Ten participating sites of the French Sarcoma Group will participate in the trial. Clinical trial information: NCT04193553 .

Sitravatinib, a Tyrosine Kinase Inhibitor, Inhibits the Transport Function of ABCG2 and Restores Sensitivity to Chemotherapy-Resistant Cancer Cells in vitro.

Sitravatinib, also called MGCD516 or MG-516, is a broad-spectrum tyrosine kinase inhibitor (TKI) under phase III clinical evaluation. Herein, we explored the activity of sitravatinib toward multidrug resistance (MDR) by emphasizing its inhibitory effect on ATP-binding cassette super-family G member 2 (ABCG2). ABCG2 is a member of ATP-binding cassette (ABC) transporter family and plays a critical role in mediating MDR. Sitravatinb received an outstanding docking score for binding to the human ABCG2 model (PDB code: 6ETI) among thirty screened TKIs. Also, an MTT assay indicated that sitravatinib at 3 μM had the ability to restore the antineoplastic effect of various ABCG2 substrates in both drug-selected and gene-transfected ABCG2-overexpressing cell lines. In further tritium-labeled mitoxantrone transportation study, sitravatinib at 3 μM blocked the efflux function mediated by ABCG2 and as a result, increased the intracellular concentration of anticancer drugs. Interestingly, sitravatinib at 3 μM altered neither protein expression nor subcellular localization of ABCG2. An ATPase assay demonstrated that ATPase activity of ABCG2 was inhibited in a concentration-dependent manner with sitravatinib; thus, the energy source to pump out compounds was interfered. Collectively, the results of this study open new avenues for sitravatinib working as an ABCG2 inhibitor which restores the antineoplastic activity of anticancer drugs known to be ABCG2 substrates.

YQFM Alleviates Side Effects Caused by Dasatinib through the ROCK/MLC Pathway in Mice.

Dasatinib, as a second-generation broad-spectrum tyrosine kinase inhibitor, presents an antitumor effect by inhibiting tyrosine kinases. However, dasatinib causes serious side effects, such as gastrointestinal bleeding and liver toxicity, possibly through the activation of ROCK kinase and MLC phosphorylation. At present, there is no effective prevention and treatment method. Previous research studies have shown that YQFM (YiQiFuMai powder injection) protects the blood-brain barrier by inhibiting the ROCK/MLC signaling pathway; whether YQFM can alleviate the side effects of dasatinib is unknown. In this study, dasatinib was injected (i.p. 70 mg/kg) and YQFM (i.p. 0.336 g/kg, 0.672 g/kg, 1.342 g/kg) was given in advance for 3 days to mice, to explore the effect of YQFM on side effects induced by Dasatinib. The results confirmed that YQFM significantly decreased Evans blue leakage in the small intestine and increased intestinal blood flow, increased the expression of ZO-1, Occludin, and VE-cadherin, and reduced the contents of D-lactic acid, s-VE-cadherin, Alanine aminotransferase (ALT), and Aspartate aminotransferase (AST) in serum. Finally, YQFM inhibited the expression of ROCK-1 and phosphorylation of MLC induced by Dasatinib. These findings suggested that YQFM could improve the side effects caused by Dasatinib linked with the ROCK/MLC signaling pathway, as shown in the graphical abstract.

Enhanced efficacy of sitravatinib in metastatic models of antiangiogenic therapy resistance.

Tyrosine kinase inhibitors (TKIs) that primarily target angiogenesis are approved to treat several cancers in the metastatic setting; however, resistance is common. Sequential treatment or ‘switching’ from one TKI to another following failure can be effective, but predicting which drugs will have cross-over sensitivity remains a challenge. Here we examined sitravatinib (MGCD516), a spectrum-selective TKI able to block MET, TAM (TYRO3, AXL, MerTK) and multiple receptor families (including PDGFRs, VEGFRs, and Ephs). Transcriptomic analysis of several mouse and human cell lines revealed diverse molecular changes after resistance to two TKIs (sunitinib and axitinib) with multiple sitravatinib targets found to be upregulated. Sitravatinib treatment in vitro resulted in enhanced anti-proliferative effects in resistant cells and was improved compared to TKIs with similar target profiles. In vivo, primary tumor growth inhibition after sitravatinib treatment in mice was enhanced in resistant tumors and metastasis suppression improved when tumors were surgically removed. Together, these results suggest that the diverse and often inconsistent compensatory signaling mechanisms found to contribute to TKI resistance may paradoxically improve the tumor-inhibiting effects of broad-spectrum TKIs such as sitravatinib that are able to block multiple signaling pathways. Sitravatinib in the second-line setting following antiangiogenic TKI treatment may have enhanced inhibitory effects in local and disseminated disease, and improve outcomes in patients with refractory disease.

Abstract 3812: Overcoming de novo and acquired modes of cetuximab resistance by broad-spectrum receptor tyrosine kinase inhibitors

Abstract MEK inhibition has been shown to delay emergence of cetuximab resistance in colorectal cancer (CRC) (Nat Commun 22;6:8305, 2015). By exploiting a novel 3D culture system, we herein show that three broad-spectrum tyrosine kinase inhibitors overcome de novo and acquired resistance to cetuximab. By culturing a CRC cell line, HCA-7 in 3D in type I collagen, we previously identified two novel modes of cetuximab resistance. In 3D culture, HCA-7-derived CC are sensitive to cetuximab, while SC exhibit de novo cetuximab resistance (PNAS 114:E2852-E2861, 2017). Continuous exposure of CC to cetuximab resulted in colonies that acquired resistance to cetuximab, designated CC-CR, which was dependent in part on increased levels of lncRNA MIR100HG that leads to increased WNT signaling (Nat Med 23:1331-1341, 2017). We previously showed increased MET and RON tyrosine phosphorylation in SC cells and that MET/RON inhibitor, crizotinib overcomes SC cetuximab resistance. We now show that crizotinib also overcomes acquired cetuximab resistance in CC-CR. A phospho-RTK array showed increased phosphorylation of several RTKs, including MET and RON, in SC and CC-CR cells compared to cetuximab-sensitive CC counterparts. Furthermore, other multi-RTK inhibitors cabozantinib and BMS-777607 helped overcome cetuximab resistance, as measured by 3D colony growth and activation state of key signaling molecules. Conversely, addition of RTK ligands HGF and NRG1 induced cetuximab resistance in CC cells, which could be blocked by addition of crizotinib and this was associated with disorganized spindle positioning during cell division, leading to multi-layering of CC cultures. By FACS analysis, we observed increased cell cycle arrest in G1 phase in SC and CC-CR cultures treated with cetuximab and crizotinib. Furthermore, we show that crizotinib overcomes cetuximab resistance in vivo in SC nude mice xenografts. Finally, in a direct comparison between vertical suppression (EGFR/MEK inhibition) and parallel inhibition (EGFR/multi-RTK inhibition), we observed a higher degree of synergy with the latter strategy. The non-overlapping toxicities of cetuximab and crizotinib warrants consideration for its clinical deployment. Note: This abstract was not presented at the meeting. Citation Format: Bhuminder Singh, Ramona Graves-Deal, Galina Bogatcheva, Robert J. Coffey. Overcoming de novo and acquired modes of cetuximab resistance by broad-spectrum receptor tyrosine kinase inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3812.

Novel approaches to treating advanced systemic mastocytosis.

Mastocytosis is a myeloproliferative neoplasm characterized by expansion of abnormal mast cells (MCs) in various tissues, including skin, bone marrow, gastrointestinal tract, liver, spleen, or lymph nodes. Subtypes include indolent systemic mastocytosis, smoldering systemic mastocytosis and advanced systemic mastocytosis (AdvSM), a term collectively used for the three most aggressive forms of the disease: aggressive systemic mastocytosis, mast cell leukemia, and systemic mastocytosis with an associated clonal hematological non-mast cell disease (SM-AHNMD). MC activation and proliferation is physiologically controlled in part through stem cell factor (SCF) binding to its cognate receptor, KIT. Gain-of-function KIT mutations that lead to ligand-independent kinase activation are found in most SM subtypes, and the overwhelming majority of AdvSM patients harbor the KITD816V mutation. Several approved tyrosine kinase inhibitors (TKIs), such as imatinib and nilotinib, have activity against wild-type KIT but lack activity against KITD816V. Midostaurin, a broad spectrum TKI with activity against KITD816V, has a 60% clinical response rate, and is currently the only drug specifically approved for AdvSM. While this agent improves the prognosis of AdvSM patients and provides proof of principle for targeting KITD816V as a driver mutation, most responses are partial and/or not sustained, indicating that more potent and/or specific inhibitors are required. Avapritinib, a KIT and PDGFRα inhibitor, was specifically designed to inhibit KITD816V. Early results from a Phase 1 trial suggest that avapritinib has potent antineoplastic activity in AdvSM, extending to patients who failed midostaurin. Patients exhibited a rapid reduction in both symptoms as well as reductions of bone marrow MCs, serum tryptase, and KITD816V mutant allele burden. Adverse effects include expected toxicities such as myelosuppression and periorbital edema, but also cognitive impairment in some patients. Although considerable excitement about avapritinib exists, more data are needed to assess long-term responses and adverse effects of this novel TKI.