Multitargeted Kinase Inhibitor Research Articles

Multitargeted kinase inhibitors imatinib, sorafenib and sunitinib perturb energy metabolism and cause cytotoxicity to cultured C2C12 skeletal muscle derived myotubes

Tyrosine kinase inhibitors (TKIs) have advanced cancer treatment and prognosis but have also resulted in adverse effects such as fatigue, diarrhea, hypothyroidism, and other toxicities. We investigated TKI effects on skeletal muscle as a possible explanation of TKI induced fatigue. Changes in mitochondrial function due to inhibition of oxidative phosphorylation complexes, generation of superoxides, and inhibition of key transporters involved in uptake of glucose and/or nucleosides may result in alteration of energy metabolism and/or mitochondrial function. We investigated effects of imatinib, sorafenib and sunitinib on these processes in cultured C2C12 murine skeletal muscle cells. Imatinib, sorafenib and sunitinib were cytotoxic to C2C12 cells with IC50 values of 20, 8 and 8 µM, respectively. Imatinib stimulated glucose uptake and inhibited complex V activity by 35% at 50 µM. Sorafenib inhibited complex II/III and V with IC50 values of 32 and 28 µM, respectively. Sorafenib caused activation of caspase 3/7 and depolarization of mitochondrial membranes occurred very rapidly with complete loss at 5–10 µM. Sunitinib inhibited Complex I with an IC50 value of 38 µM and caused ATP depletion, caspase 3/7 activation, an increase in reactive oxygen species (ROS), and decreased nucleoside and glucose uptake. In conclusion, imatinib, sunitinib and sorafenib caused changes in mitochondrial complex activities, glucose and nucleoside uptake leading to decreased energy production and mitochondrial function in a skeletal muscle cell model, suggesting that these changes may play a role in fatigue, one of the most common adverse effects of TKIs.

A dual-targeting reconstituted high density lipoprotein leveraging the synergy of sorafenib and antimiRNA21 for enhanced hepatocellular carcinoma therapy

Sorafenib (So) is a multi-target kinase inhibitor extensively used in clinic for hepatocellular carcinoma therapy. It demonstrated strong inhibition both in tumor proliferation and tumor angiogenesis, while hampered by associated cutaneous side-effect and drug resistance. The knockdown of miR-21 with antisense oligonucleotides (antimiRNA21) was regarded as an efficient strategy for increasing tumor sensibility to chemotherapy, which could be employed to appreciate the efficacy of So. Herein, we successfully formulated a dual-targeting delivery system for enhanced hepatocellular carcinoma therapy by encapsulating So and antimiRNA21 in RGD pentapeptide-modified reconstituted high-density lipoprotein (RGD-rHDL/So/antimiRNA21). The RGD and apolipoprotein A-I (ApoA-I) on nanoparticles (NPs) could drive the system simultaneously to tumor neovascular and parenchyma by binding to the overexpressed ανβ3-integrin and SR-B1 receptors, achieving precise delivery of therapeutics to maximize the efficacy. A series in vitro and in vivo experiments revealed that co-delivery of So and antimiRNA21 by RGD-rHDL significantly strengthened the anti-tumor and anti-angiogenic effect of So with negligible toxicity towards major organs, reversed drug-resistance and was capable of remodeling tumor environments. The constructed RGD-rHDL/So/antimiRNA21 with improved efficacy and excellent tumor targeting ability provided new idea for chemo-gene combined therapy in hepatocellular carcinoma. Statement of SignificanceSorafenib (So) is a multi-target kinase inhibitor which was approved by FDA as first-line drug for hepatocellular carcinoma (HCC) therapy. However, long term application of So in clinic was hampered by serious dermal toxicity and drug resistance. Although numerous researchers were devoted to finding alternatives or therapies as combination treatments with So to reach more desired therapeutic efficacy, the therapeutic options were still limited. The present study prepares RGD pentapeptide decorated biomimic reconstituted high-density lipoprotein (rHDL) loaded with So and antimiRNA21 (RGD-rHDL/So/antimiRNA21) for enhanced HCC therapy. The RGD-rHDL/So/antimiRNA21 NPs offer an effective platform for anti-tumor and anti-angiogenesis therapy in HCC and provide new approach to reverse drug-resistance of So for feasible clinical application.

Retronectin and anti-CD3 monoclonal antibody actived T cell combined anti-PD-1 therapy in heavy-treated renal cell cancer.

e15053Background: Metastatic renal cell carcinoma (MRCC) has a poor prognosis after failure of multitargeted kinase inhibitors. New immunomodulators, such as anti-programmed death (PD)-1 antibody, ...

Successful treatment switch from lenvatinib to sorafenib in a patient with radioactive iodine-refractory differentiated thyroid cancer intolerant to lenvatinib due to severe proteinuria

Sorafenib and lenvatinib showed efficacy for patients with radioactive iodine (RAI)-refractory differentiated thyroid cancer (DTC) in pivotal phase 3 clinical trials. Although the efficacy of lenvatinib in patients who received previous treatment with multi-target kinase inhibitors (m-TKIs), including sorafenib, was reported, the efficacy of sorafenib in patients who previously received lenvatinib remains unknown. A 75-year-old woman diagnosed as RAI-refractory poorly differentiated carcinoma with multiple lung metastases and started treatment with lenvatinib. She continued to receive lenvatinib but with repeated dose interruptions and reductions due to continuous proteinuria. Because of severe and persistent proteinuria as well as newly developed renal impairment, lenvatinib was suspended after two years of treatment. After the 7-month suspension, her proteinuria and renal impairment were partially improved, but her lung metastases progressed. Because she was unable to tolerate previous treatment with lenvatinib, sorafenib was started. At 7 months of treatment with sorafenib, her lung metastases shrank and she could continue sorafenib without exacerbation of proteinuria or renal impairment. This case may suggest that sorafenib does not exacerbate the proteinuria or renal impairment induced by lenvatinib, and may be an effective treatment option for RAI-refractory DTC patients who are unable to tolerate lenvatinib.

PDGFRB mutation and tyrosine kinase inhibitor resistance in Ph-like acute lymphoblastic leukemia

AbstractPhiladelphia chromosome (Ph)-like acute lymphoblastic leukemia (ALL) comprises ∼10% to 15% of childhood ALL cases, many of which respond exquisitely to tyrosine kinase inhibitors (TKIs), for example, imatinib in PDGFRB-rearranged ALL. However, some cases developed drug resistance to TKIs and the mechanisms are poorly understood. In this study, we identified a novel PDGFRB fusion gene, namely AGGF1-PDGFRB, and functionally characterized its oncogenic potential in vitro. Further genomic profiling of longitudinally collected samples during treatment revealed the emergence of a mutation, PDGFRBC843G, which directly conferred resistance to all generations of ABL TKIs, including imatinib, dasatinib, nilotinib, and ponatinib. PDGFRB-mutant leukemia cells are highly sensitive to multitarget kinase inhibitor CHZ868, suggesting potential therapeutic options for some patients resistant to ABL TKIs. In summary, we describe a complex clonal evolution pattern in Ph-like ALL and identified a novel PDGFRB point mutation that drives leukemia relapse after ABL TKI treatment.

Sorafenib induced pustular psoriasis in a patient of hepatocellular carcinoma: a rare case report

<p class="abstract">Pustular psoriasis is the least common form of psoriasis characterized by the formation of psoriatic plaques studded with pustules. Sorafenib is an oral multi-targeted kinase inhibitor approved for the management of hepatocellular carcinoma. We report a biopsy proven case of pustular psoriasis induced by Sorafenib in a patient of hepatocelluar carcinoma. Cutaneous adverse effects with Sorafenib are rare but are not life threatening. We are reporting this case because of the rarity of association and for highlighting the need for early detection and management.</p>

Amplification of Oncolytic Vaccinia Virus Widespread Tumor Cell Killing by Sunitinib through Multiple Mechanisms.

Oncolytic viruses pose many questions in their use in cancer therapy. In this study, we assessed the potential of mpJX-594 (mouse-prototype JX-594), a replication-competent vaccinia virus administered by intravenous injection, to target the tumor vasculature, produce immune activation and tumor cell killing more widespread than the infection, and suppress invasion and metastasis. These actions were examined in RIP-Tag2 transgenic mice with pancreatic neuroendocrine tumors that developed spontaneously and progressed as in humans. mpJX-594 initially infected tumor vascular endothelial cells, leading to vascular pruning and prolonged leakage in tumors but not in normal organs; parallel effects were observed in U87 gliomas. Viral infection spread to tumor cells, where tumor cell killing was much more widespread than the infection. Widespread tumor cell killing at 5 days was prevented by depletion of CD8+ T lymphocytes and did not require GM-CSF, as mpJX-594 variants that expressed human, mouse, or no GM-CSF produced equivalent amounts of killing. The antivascular, antitumor, and antimetastatic effects of mpJX-594 were amplified by concurrent or sequential administration of sunitinib, a multitargeted receptor tyrosine kinase inhibitor. These effects were not mimicked by selective inhibition of VEGFR2 despite equivalent vascular pruning, but were accompanied by suppression of regulatory T cells and greater influx of activated CD8+ T cells. Together, our results showed that mpJX-594 targets tumor blood vessels, spreads secondarily to tumor cells, and produces widespread CD8+ T-cell-dependent tumor cell killing in primary tumors and metastases, and that these effects can be amplified by coadministration of sunitinib.Significance: These findings reveal multiple unrecognized features of the antitumor properties of oncolytic vaccinia viruses, all of which can be amplified by the multitargeted kinase inhibitor sunitinib. Cancer Res; 78(4); 922-37. ©2017 AACR.

Pharmacokinetic Assessment of Cooperative Efflux of the Multitargeted Kinase Inhibitor Ponatinib Across the Blood-Brain Barrier.

A compartmental blood-brain barrier (BBB) model describing drug transport across the BBB was implemented to evaluate the influence of efflux transporters on the rate and extent of the multikinase inhibitor ponatinib penetration across the BBB. In vivo pharmacokinetic studies in wild-type and transporter knockout mice showed that two major BBB efflux transporters, P-glycoprotein (P-gp) and breast cancer resistance protein (Bcrp), cooperate to modulate the brain exposure of ponatinib. The total and unbound (free) brain-to-plasma ratios were approximately 15-fold higher in the triple knockout mice lacking both P-gp and Bcrp [Mdr1a/b(-/-)Bcrp1(-/-)] compared with the wild-type mice. The triple knockout mice had a greater than an additive increase in the brain exposure of ponatinib when compared with single knockout mice [Bcrp1(-/-) or Mdr1a/b(-/-)], suggesting functional compensation of transporter-mediated drug efflux. Based on the BBB model characterizing the observed brain and plasma concentration-time profiles, the brain exit rate constant and clearance out of the brain were approximately 15-fold higher in the wild-type compared with Mdr1a/b(-/-)Bcrp1(-/-) mice, resulting in a significant increase in the mean transit time (the average time spent by ponatinib in the brain in a single passage) in the absence of efflux transporters (P-gp and Bcrp). This study characterized transporter-mediated drug efflux from the brain, a process that reduces the duration and extent of ponatinib exposure in the brain and has critical implications for the use of targeted drug delivery for brain tumors.

Lenvatinib plus checkpoint inhibitors in patients (pts) with advanced intrahepatic cholangiocarcinoma (ICC): Preliminary data and correlation with next-generation sequencing.

500 Background: Lenvatinib (Len) is a multikinase inhibitor targeting VEGFR 1-3, FGFR 1-4 and other kinases. Pembrolizumab (Pem) and nivolumab (Nivo) are antibodies inhibiting programmed cell death 1 (PD-1) and reactivate T-cell cytotoxic effect. Len plus PD-1 inhibitors have shown promising results in treating various solid tumors. The role of this combination in ICC is undefined. Methods: 14 ICC pts (median age 49 years, range 34-68; 7 males and 7 females) with treatment of enrolled in a single center, observational study of Len plus Pem/Nivo. Objective response rate (ORR), disease control rate (DCR) and progression-free survival (PFS) were measured according to RECIST 1.1. Next generation sequencing (NGS) with deep coverage on 450 cancer genes and whole exome sequencing were performed in 7 pts to detect all classes of genomic alterations, tumor mutational burden (TMB) and microsatellite instability (MSI) status. Results: All 14 pts had > = 2 prior anticancer therapy with clinical stage IV. ORR was 21.4% with 3 pts achieved partial response (PR), DCR was 92.9% and clinical benefit rate (ORR + durable stable disease > = 5 months) was 64.3%. Median PFS was 5.9 months (95% CI: 4.2-6.2). The most common adverse events (AEs) included hypertension, aminotransferase elevation and fatigue. The grade-3 AEs were occurred at 14% while no grade-4 AE was observed. The most altered genes in the 7 sequenced tumors were IDH1 (3 pts), ARID1A (3 pts), PIK3CA (3 pts), TP53 (2 pts) and BAP1 (2 pts). 4 out of the 7 pts had high TMB ( > 12 mut/Mb) and all responded to Len plus Pem/Nivo with 2 PR. One pt with low TMB and FGFR2 mutation had a response of 27% decreased target lesion. Two low TMB pts were progressed, including one with FGFR2 rearrangement. A responder harbored a 399 bp deletion on MLH1, and was identified as MSI-H. More data will be presented. Conclusions: Our study preliminarily indicates that combining Len with PD-1 inhibitors results in promising efficacy in advanced ICC. High TMB from 450-gene NGS panel was strongly associated with a better therapeutic response.

Anticancer evaluation and molecular modeling of multi-targeted kinase inhibitors based pyrido[2,3-d]pyrimidine scaffold

An efficient synthesis of substituted pyrido[2,3-d]pyrimidines was carried out and evaluated for in vitro anticancer activity against five cancer cell lines, namely hepatic cancer (HepG-2), prostate cancer (PC-3), colon cancer (HCT-116), breast cancer (MCF-7), and lung cancer (A-549) cell lines. Regarding HepG-2, PC-3, HCT-116 cancer cell lines, 7-(4-chlorophenyl)-2-(3-methyl-5-oxo-2,3-dihydro-1H-pyrazol-1-yl)-5-(p-tolyl)- pyrido[2,3-d]pyrimidin-4(3H)-one (5a) exhibited strong, more potent anticancer (IC50: 0.3, 6.6 and 7 µM) relative to the standard doxorubicin (IC50: 0.6, 6.8 and 12.8 µM), respectively. Kinase inhibitory assessment of 5a showed promising inhibitory activity against three kinases namely PDGFR β, EGFR, and CDK4/cyclin D1 at two concentrations 50 and 100 µM in single measurements. Further, a molecular docking study for compound 5a was performed to verify the binding mode towards the EGFR and CDK4/cyclin D1 kinases.

Paclitaxel With and Without Pazopanib for Persistent or Recurrent Ovarian Cancer

Ovarian cancer is the leading cause of gynecologic cancer deaths in the United States. Pazopanib is an oral, multitarget kinase inhibitor of vascular endothelial growth factor receptors 1, 2, and 3; platelet-derived growth factor receptors α and β; and proto-oncogene receptor tyrosine kinase (c-KIT). To estimate the progression-free survival (PFS) hazard ratio (HR) of weekly paclitaxel and pazopanib compared with weekly paclitaxel and placebo in women with recurrent ovarian cancer. Secondary objectives included frequency and severity of adverse events, proportion responding, and overall survival (OS) in each arm. Translational research objectives included exploring the association between possible biomarkers and single-nucleotide polymorphisms in vascular endothelial growth factor A, interleukin 8, and hypoxia-inducible factor 1α; and PFS, OS, and proportion responding. A randomized, placebo-controlled, double-blind phase 2 study was conducted at 26 participating institutions. Patients were enrolled between December 12, 2011, and April 22, 2013. Data were frozen on August 11, 2014. Participants were patients with persistent or recurrent epithelial ovarian, fallopian tube, or primary peritoneal carcinoma with 1 to 3 prior regimens and performance status of 0 to 2. One hundred six patients enrolled; 100 were evaluable for toxic effects. All patients received paclitaxel 80 mg/m2 intravenously on days 1, 8, and 15 every 28 days and were randomized 1:1 to pazopanib 800 mg orally daily or placebo. The primary end point was PFS. The study was designed to detect a 37.5% reduction in the hazard with 80% power (α = 10%). A total of 106 women (median age [range], 61 [35-87] years; 88 [83%] white) were enrolled. Study arms were well balanced for age, performance status, measurable disease, and prior bevacizumab. Proportion responding was 14 of 44 (31.8%) vs 10 of 44 (22.7%) for pazopanib plus paclitaxel vs paclitaxel alone. Median PFS was 7.5 vs 6.2 months for pazopanib plus paclitaxel vs paclitaxel alone, respectively (HR, 0.84; 90% CI, 0.57-1.22; P = .20). Median OS was 20.7 vs 23.3 months for pazopanib plus paclitaxel vs paclitaxel alone (HR, 1.04; 90% CI, 0.60-1.79; P = .90). Severe hypertension was more common on the pazopanib plus paclitaxel arm (relative risk, 12.0; 95% CI, 1.62-88.84). More patients discontinued treatment on the paclitaxel arm for disease progression (34 of 52 [65.4%] vs 17 of 54 [31.5%]), and more on the pazopanib plus paclitaxel arm for adverse events (20 of 54 [37%] vs 5 of 52 [9.6%]). No association was found between single-nucleotide polymorphisms (interleukin 8 and hypoxia-inducible factor 1α) and OS and proportion responding. Patients with VEGFA CC genotype may be more resistant to weekly paclitaxel than those with the AC or AA genotype, with 1 of 14 (7%), 3 of 15 (20%), and 4 of 8 (50%) responding, respectively. The combination of pazopanib plus paclitaxel is not superior to paclitaxel in women with recurrent ovarian cancer. clinicaltrials.gov Identifier: NCT01468909.

Midostaurin inhibits hormone-refractory prostate cancer PC-3 cells by modulating nPKCs and AP-1 transcription factors and their target genes involved in cell cycle

The development of prostate cancer from a clinically localized, hormone-naive state to a hormonerefractory phenotype involves a complex interplay of protein kinase C (PKC) and activator protein-1 (AP-1). Therefore, the present study aimed to uncover the roles of PKC and AP-1 through midostaurin-mediated regulation—a multi-target protein kinase inhibitor. Androgen Receptor-negative, hormone-refractory prostate cancer cells (PC-3) were used as an in-vitro model system. The effect of midostaurin on cell viability was assessed by an MTT assay. Expression studies on PKC-α, PKC-d, different AP-1 transcription factors, and AP-1 regulating genes were analyzed by semiquantitative RT-PCR, and protein levels of Bcl-2 were evaluated by western blotting. Midostaurin decreased the viability of hormone-refractory PC-3 cells. Furthermore, midostaurin significantly induced the transcripts of apoptotic-mediated PKC-d, tumor suppressor p53, cell cycle inhibitor p21cip1/waf1, death receptor TNF-α, pro-apoptotic Bax, and Caspase-8, and eventually inhibited the expression of pro-survival PKC-e, pro-oncogene c-Jun, c-Fos, Fra-1, positive growth regulator cyclin D1, and anti-apoptotic Bcl-2. In addition, midostaurin also decreased the protein expression of anti-apoptotic Bcl-2. The present study provided evidence that midostaurin suppresses tumor growth and induces apoptosis in hormone-refractory PC-3 cells via modulation of PKC-d and PKC-e expression, and regulation of PMA-altered c-Jun, c-Fos, and Fra-1 AP-1 transcription factors and their target genes involved in cell cycle regulation (cyclin D1, p53, p21, Bcl-2, and TNF-α). Thus, pharmacological targeting of PKC and AP-1 factors may have therapeutic potential against hormone-refractory prostate cancer.

Inhibition of autophagy enhances the targeted therapeutic effect of sorafenib in thyroid cancer.

The multi-target kinase inhibitor sorafenib has been approved for the treatment of patients with advanced differentiated thyroid cancer. However, different sensitivities to sorafenib have been observed, and few patients have benefited from sorafenib treatment in the long term. In the event of acquired resistance to sorafenib it is not beneficial to continue treatment in most patients. Autophagy can be induced in a variety of cancer treatments and plays an important role in cancer treatment. The role of autophagy in sorafenib treatment of thyroid cancer has not been fully demonstrated. The present study investigated whether autophagy is activated by sorafenib during the treatment of thyroid cancer, examined the underlying mechanisms, and explored potential strategies to enhance the therapeutic sensitivity of sorafenib. Chloroquine(CQ) is an autophagy inhibitor that has been reported to increase sensitivity to various cancer treatments. Thyroid cancer xenograft model mice were treated with sorafenib, CQ, or a combination of sorafenib and CQ. We observed that CQ or sorafenib treatment suppressed tumor growth, while mice treated with the combination of sorafenib and CQ displayed significantly reduced tumor growth compared with those treated with sorafenib or CQ alone. Western blotting results indicated that sorafenib concurrently inhibited the activities of the MAPK and AKT/mTOR pathways in thyroid cancer. Autophagy was activated by sorafenib in thyroid cancer, both invitro and invivo, which was at least in part due to suppression of the AKT/mTOR pathway. Combination treatment including CQ could inhibit the autophagic flux induced by sorafenib. Silencing the key autophagy gene ATG5 using small interfering RNA also increased the anticancer effect of sorafenib. In summary, the present study revealed that inhibition of autophagy enhances the anticancer effect of sorafenib, and the combination of CQ with sorafenib treatment represents a potential therapeutic strategy for treating advanced differentiated thyroid cancer.

Clinical guidance for radioiodine refractory differentiated thyroid cancer.

Prognosis from differentiated thyroid cancer is worse when the disease becomes refractory to radioiodine. Until recently, treatment options have been limited to local therapies such as surgery and radiotherapy, but the recent availability of systemic therapies now provides some potential for disease control. Multitargeted kinase inhibitors (TKIs) including lenvatinib and sorafenib have been shown to improve progression-free survival in phase III clinical trials, but are also associated with a spectrum of adverse effects. Other TKIs have been utilized as "redifferentiation" agents, increasing sodium iodide symporter expression in metastases and thus restoring radioiodine avidity. Some patients whose disease progresses on initial TKI therapy will still respond to a different TKI and clinical trials currently in progress will clarify the best options for such patients. As these drugs are not inexpensive, care needs to be taken to minimize not only biological but also financial toxicity. In this review, we examine the basic biology of radioiodine refractory disease and discuss optimal treatment approaches, with specific focus on choice and timing of TKI treatment. This clinical field remains fluid, and directions for future research include exploring biomarkers and considering adjuvant TKI use in certain patient groups.

Management of Adverse Events Associated with Cabozantinib Therapy in Renal Cell Carcinoma.

Cabozantinib leads to improved survival outcomes in renal cell carcinoma patients compared with everolimus. However, management of the adverse event profile is crucial to achieve optimum adherence and outcomes with the use of cabozantinib. This review aims to provide appropriate guidance that will minimize the impact of adverse events and help to maximize the utility of this agent in patients with advanced renal cell carcinoma.

Optimal therapy for patients with hepatocellular carcinoma and resistance or intolerance to sorafenib: challenges and solutions.

The only US Food and Drug Administration (FDA)-approved first-line systemic therapy for hepatocellular carcinoma (HCC) is sorafenib; however, resistance or intolerance to sorafenib is unfortunately common. In this review, we briefly describe systemic therapies that can be considered for patients with HCC who show resistance or intolerance to sorafenib. For all patients with HCC who need systemic therapy, we strongly advocate for participation in clinical trials. Cytotoxic chemotherapy plays a minor role in the treatment of advanced HCC, with some data supporting the use of FOLFOX (infusional fluorouracil, leucovorin, and oxaliplatin) and GEMOX (gemcitabine-oxaliplatin). Multi-target kinase inhibitors such as lenvantinib and regorafenib have recently met their primary endpoints as first- and second-line therapy, respectively, with regorafenib now representing the only FDA-approved drug for second-line treatment of HCC. Other targeted therapies remain under investigation, but results so far have not significantly changed clinical practice. Immunotherapy is an interesting area of research in the treatment of HCC with preclinical and early clinical data demonstrating exciting results; thus numerous investigational studies are currently focusing on immunotherapy in the treatment of HCC. While systemic treatment options in HCC remain a challenge for providers, in this review, we summarize the current literature and highlight areas of progress with respect to the treatment of patients with HCC and resistance or intolerance to sorafenib.

Rhabdomyosarcoma cells are susceptible to cell death by LDK378 alone or in combination with sorafenib independently of anaplastic lymphoma kinase status.

Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase that is often overexpressed in rhabdomyosarcoma (RMS). However, its oncogenic and functional role in RMS remains unclear. Therefore, we investigated the antitumor activity of LDK378 (ceritinib), a new second-generation ALK inhibitor approved for patients with ALK-positive non-small-cell lung cancers. Here, we report that LDK378 reduces cell viability and induces cell death in RMS cell lines at low micromolar IC50 concentrations irrespective of ALK expression levels or phosphorylation status. Compared with Karpas 299 non-Hodgkin's lymphoma cells carrying the NPM-ALK fusion gene, RMS cell lines proved to be far less sensitive to LDK378. The broad-range caspase inhibitor zVAD.fmk significantly protects RMS cells from LDK378-mediated cell death, indicating that LDK378 induces caspase-dependent apoptotic cell death. Before the onset of apoptosis, LDK378 reduces phosphorylation of AKT, S6 ribosomal protein, STAT3 and - to a lesser extent - phosphorylation of ERK, showing that it suppresses key survival pathways. Importantly, we identify a synergistic induction of cell death by combining subtoxic concentrations of LDK378 with the multitargeting kinase inhibitor sorafenib. Calculation of the combination index confirmed that this interaction is synergistic. Also, LDK378 cooperates with sorafenib to significantly reduce colony formation of RMS cells, showing that this combination affects long-term clonogenic growth. In conclusion, LDK378 induces caspase-dependent apoptotic cell death in RMS cells independent of their ALK status and synergizes at subtoxic concentrations with sorafenib to induce cell death. These findings have important implications for the use of LDK378 in RMS.

Crizotinib, a MET inhibitor, inhibits growth, migration, and invasion of breast cancer cells in vitro and synergizes with chemotherapeutic agents.

MET is a receptor tyrosine kinase known for its pleiotropic effects in tumorigenesis. Dysregulations of MET expression and/or signaling have been reported and determined to be associated with inferior outcomes in breast cancer patients rendering MET a versatile candidate for targeted therapeutic intervention. Crizotinib is a multi-targeted small-molecule kinase inhibitor for MET, ALK, and ROS1 kinases. This study evaluated the anti-proliferative, cytotoxic, anti-migratory, and anti-invasive effects of crizotinib in breast cancer cells in vitro. Cell viability was assessed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) colorimetric assay. In vitro wound-healing assay was used to examine the effect of crizotinib on breast cancer cell migration. The expressions of Ki-67, MET, and phospho-MET receptors were characterized using immunofluorescence staining. Results showed that crizotinib has significant anti-proliferative activity on all mammary tumor cells with IC50 values of 5.16, 1.5, and 3.85 µM in MDA-MB-231, MCF-7, and SK-BR-3 cells, respectively. Crizotinib induced cytotoxic effects in all breast cancer cells examined. Combined treatment of small dose of crizotinib with paclitaxel or doxorubicin exhibited a highly synergistic inhibition of growth of MDA-MB-231 and MCF-7 cells with combination index values <1 while no significant effect was observed in SK-BR-3 cells compared with individual compounds. Treatment with crizotinib demonstrated a remarkable reduction in the expression of Ki-67 protein in all 3 tested cell lines. Crizotinib inhibited migration and invasion of MDA-MB-231 cells in a dose-dependent fashion. Crizotinib reduced MET receptor activation in MDA-MB-231 cells when treated at effective concentrations. In conclusion, crizotinib suppressed proliferation, migration, and invasion of breast cancer cells in vitro. The results of this study demonstrated that combined treatment of crizotinib with chemotherapeutic agents resulted in a synergistic growth inhibition of specific breast cancer cell lines.

SOMCL-085, a novel multi-targeted FGFR inhibitor, displays potent anticancer activity in FGFR-addicted human cancer models.

Aberrant fibroblast growth factor receptor (FGFR) activation is found across a diverse spectrum of malignancies, especially those lacking effective treatments. SOMCL-085 is a novel FGFR-dominant multi-target kinase inhibitor. Here, we explored the FGFR-targeting anticancer activity of SOMCL-085 both in vitro and in vivo. Among a panel of 20 tyrosine kinases screened, SOMCL-085 potently inhibited FGFR1, FGFR2 and FGFR3 kinase activity, with IC50 values of 1.8, 1.9 and 6.9 nmol/L, respectively. This compound simultaneously inhibited the angiogenesis kinases VEGFR and PDGFR, but without obvious inhibitory effect on other 12 tyrosine kinases. In 3 representative human cancer cell lines with different mechanisms of FGFR activation tested, SOMCL-085 (20-500 nmol/L) dose-dependently inhibited FGFR1-3 phosphorylation and the phosphorylation of their key downstream effectors PLCγ and Erk. In 7 FGFR aberrant human cancer cell lines, regardless of the mechanistic complexity of FGFR over-activation, SOMCL-085 potently inhibited FGFR-driven cell proliferation by arresting cells at the G1/S phase. In the FGFR1-amplified lung cancer cell line H1581 xenograft mice and FGFR2-amplified gastric cancer cell line SNU16 xenograft mice, oral administration of SOMCL-085 (25, 50 mg·kg-1·d-1) for 21 days substantially suppressed tumor growth without affecting their body-weight. These results suggest that SOMCL-085 is a potent multi-target FGFR inhibitor that inhibits the FGFR-dependent neoplastic phenotypes of human cancer cells in vitro and in vivo.

How and When to Use FLT3 Inhibitors

Activating mutations of the receptor tyrosine kinase FLT3 are one of the most common genetic lesions found in acute myeloid leukemia.1 The internal tandem duplication mutations (FLT3-ITD mutations) are found in 20-25% of newly-diagnosed cases and point mutations in the tyrosine kinase domain (FLT3-TKD), primarily at residue aspartate 835, are found in roughly 7% of cases. Shortly after they were discovered, it was recognized that the FLT3-ITD mutations were associated with an increased tendency to relapse and a resultant decreased overall survival probability, at least in the setting of conventional induction and consolidation chemotherapy.2-7 The FLT3-TKD mutations probably also worsened outcomes compared to patients with wild type FLT3, although to a lesser degree than seen with FLT3-ITD mutations.8-11 However, the aggressive application of allogeneic transplant in remission has resulted in improved outcomes for FLT3-ITD-mutated AML, at least in comparison with historical controls,12-18 and the use of tyrosine kinase inhibitors (TKIs) is now also likely contributing to improved survival for these patients. Currently, the multi-targeted kinase inhibitor, midostaurin, has received regulatory approval for use in FLT3-mutated AML,19,20 and another multi-targeted inhibitor, sorafenib, is available for off-label use. There are several more FLT3 TKIs in development, and so these agents are likely to be an important part of the therapy of FLT3-mutated AML in the immediate future. Here I offer recommendations for current use and speculation on use in the near future.