Combination Of Dasatinib Research Articles

Dasatinib reduces 5-Fu-triggered apoptosis in colon carcinoma by directly modulating Src-dependent caspase-9 phosphorylation

Preclinical data have revealed the inhibitory effect of dasatinib on colon cancer. However, a combination of dasatinib and conventional chemotherapy has failed to show any meaningful outcome in a series of clinical trials. We, therefore, wondered whether Src kinase inhibitors were suitable for treating colon cancer in combination with chemotherapy drugs. This study was designed to explore whether dasatinib disturbed 5-Fu-triggered apoptosis in colon carcinoma. As a result, we established that Src was able to directly phosphorylate caspase-9 at tyrosine 251, leading to elevated caspase-9 activity. Dasatinib dramatically decreased 5-Fu triggered apoptosis in colon carcinoma via suppression of Src activation. Our findings may have partially explained why dasatinib combined with FOLFOX failed to show a meaningful clinical response in mCRC.

Abstract B47: Modeling epithelial plasticity-induced erlotinib resistance in non-small cell lung cancer

Abstract Background: Advanced non-small lung cancer (NSCLC) patients with EGFR mutations initially respond to treatment with the EGFR-targeted tyrosine kinase inhibitors (TKIs) such as erlotinib, but will invariably acquire resistance with progression of disease within 10–16 months. Mechanisms of EGFR TKIs resistance include second-site EGFR mutations (>50%), MET amplfication (5–10%), and mutations in PIK3CA (<5%). A much less well-defined mechanism of TKIs resistance are lung cancer cells that have appeared to undergone a morphologic change to a more mesenchymal phenotype (~5-30% of cases) or epithelial-mesenchymal transition (EMT). Whether epithelial plasticity programs like EMT are directly causative for erlotinib-acquired resistance has not been shown definitively in vivo. Methods: To examine the relationship between epithelial plasticity and erlotinib resistance in EGFR mutant lung cancers, we created an inducible CCSP-rtTA/tetO-EgfrL858R/Twist1 (CET) transgenic mice (Twist1 is a key regulator of EMT). We utilized the tetracycline-inducible gene expression system to control EgfrL858R/Twist1 gene expression in the lung by providing or withdrawing doxycycline to the mice. The mice were treated for 3 weeks with erlotinib and scanned by CT each week, and survival of the mice was also recorded. The tumor tissues were collected 1 week and 3 weeks after the start of treatment and used for immunohistochemical staining for H&E, Ki67, and cleaved caspase 3 (CC3). To investigate the mechanisms of treatment resistance, mice lung tumor tissues were collected after 3 weeks' treatment with erlotinib, and tumor lysates were used for RTK signaling antibody array analysis. Results: The lung tumors in the CET mice were more anaplastic than those seen in CE (CCSP-rtTA/tetO-EgfrL858R) mice, with larger, more irregular nuclei. This is consistent with reports of cancers expressing Twist1 being more aggressive. Both genotypes display diffuse hyperplasia instead of discrete tumors, which is similar to the disease seen in EGFR mutant NSCLC in humans. After 3 weeks of erlotinib treatment, a majority of CE mice demonstrated complete and partial responses as well as stable disease. Conversely, over half of the CET mice had tumor progression over the three weeks of treatment. CET mice median overall survival time, from the beginning of treatment, was 6.8 weeks, while CE mice lived a median of 8.7 weeks (p<0.01, Mantel–Cox test). When erlotinib-treated tissue was stained for Ki-67, there was no significant difference between proliferation levels in CE and CET mice. Apoptosis assessed through staining for CC3 showed apoptosis levels were decreased in CET erlotinib-treated compared to the CE erlotinib-treated lung tumors. RTK signaling antibody array analysis showed several signaling pathways that were found to be dysregulated between CE and CET lung tumors, with the highest signal observed from the Src kinase pathway. Targeting the Src pathway with 30 mg/kg of dasatinib in combination with erlotinib in CET mice demonstrated significant reduction in tumor burden and increased survival in comparison to the other single-drug groups (p<0.05, Mantel–Cox test). Conclusions: Expression of Twist1 induces resistance to erlotinib in EGFR mutant NSCLC, partially through activation of the Src signaling pathway. Combining erlotinib treatment with the Src inhibitor, dasatinib, in the CET mice leads to tumor regression, prolonged overall survival, as well as decreased proliferation and downstream signaling. Therefore, this combined treatment can potentially overcome Twist1-induced erlotinib resistance in NSCLC. Citation Format: Hailun Wang, Jessica Cades, Zachary Yochum, Katriana Nugent, Charles Rudin, Timothy Burns, Phuoc Tran. Modeling epithelial plasticity-induced erlotinib resistance in non-small cell lung cancer [abstract]. In: Proceedings of the AACR Special Conference: Advances in Modeling Cancer in Mice: Technology, Biology, and Beyond; 2017 Sep 24-27; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(10 Suppl):Abstract nr B47.

Molecular mechanism of action and potential biomarkers of growth inhibition of synergistic combination of afatinib and dasatinib against gefitinib-resistant non-small cell lung cancer cells.

Epidermal growth factor receptor - tyrosine kinase inhibitor (EGFR-TKI) is the first choice of treatment for advanced non-small cell lung cancer (NSCLC) patients harbouring activating EGFR mutations. However, single agent usually has limited efficacy due to heterogeneous resistant mechanisms of cancer cells. Thus drug combination therapy would offer more benefits by synergistic interactions and avoidance of resistance emergence. In this study, we selected 8 NSCLC cell lines with different genetic characteristics as research models to investigate the efficacy of 4 agents (gefitinib, cetuximab, afatinib and dasatinib) and their combinations. As a single agent, both afatinib and dasatinib showed more inhibition against cell proliferation than gefitinib and cetuximab. Afatinib combined with dasatinib demonstrated significantly high efficacy against 7 gefitinib-resistant NSCLC cell lines. Moreover, it reversed the resistance to the 4 studied single agents in PTEN mutated NSCLC cells. By studying the activity of EGFR, Src and their downstream signalling pathways including PI3K/PTEN/Akt, Ras/Raf/MEK/ERK, Src/FAK and JAK/Stat, we demonstrated the synergistic interaction between afatinib and dasatinib was not only due to their blockage of different signalling pathways but also the complemental inhibition of the related signalling molecules such as Stat3. We also found that the level of Src, Stat3, and MAPK may be useful biomarkers predicating synergism between afatinib and dasatinib for the treatment of gefitinib-resistant NSCLC cells.

Abstract P4-03-15: Targeting Src kinase blocks development of afatinib resistance in HER2-positive breast cancer

Abstract Background: Afatinib is an irreversible pan-HER inhibitor approved for non-small cell lung cancer. We have previously shown that afatinib inhibits growth of HER2-positive breast cancer cells and enhances response to trastuzumab. However, we have also shown that long-term exposure to tyrosine kinase inhibitors leads to the development of acquired resistance. To determine if acquired afatinib resistance develops in HER2-positive breast cancer cells, we exposed a HER2-positive breast cancer cell line to afatinib for 6 months and investigated alterations in the cells following long-term exposure. Methods: SKBR3 cells were treated with 150 nM afatinib twice-weekly for 6 months. Growth response to drug inhibitors was assessed by acid phosphatase assay. Drug sensitivity was examined in four HER2-positive cell lines (SKBR3, EFM192A, BT474 and HCC1954) and three acquired trastuzumab resistant cell lines (SKBR3-T, BT474-T and EFM192A-T). Reverse phase protein array (RPPA) was used to determine alterations in key signaling pathways. Src, p-Src, EGFR, p-EGFR, ERK1/2, p-ERK 1/2 levels were examined by Western blotting. To examine the prevention of the development of afatinib resistance, cells were treated twice weekly with afatinib, dasatinib, or the combination and stained with crystal violet when confluent. Results: Following 6 months of afatinib treatment, the SKBR3-A cells were more resistant to afatinib compared to parental cells (IC50 SKBR3-A 284 ± 28.2 nM vs SKBR3-Par 10.9 ± 3.4 nM). Furthermore, the resistant cells were cross-resistant to lapatinib, neratinib and trastuzumab. RPPA interrogation of the SKBR3-A cells showed alterations in several pathways, including significantly increased levels of p-Src (Y416). SKBR3-A cells were more sensitive to Src inhibition with dasatinib compared to SKBR3-Par cells and the combination of afatinib and dasatinib was highly synergistic in SKBR3-A cells (CI value = 0.09 ± 0.06). The combination of afatinib and dasatinib was also synergistic in the trastuzumab resistant SKBR3-T cells (Table). Afatinib and dasatinib inhibited EGFR and Src activation and ERK 1/2 signalling in SKBR3-A cells. Short-term resistance assays showed that the addition of dasatinib to afatinib blocks the emergence of resistant cells in three of four HER2 positive cell lines tested and two of the three acquired trastuzumab resistant cell lines tetsed. Conclusion: HER2-positive breast cancer cells that are highly sensitive to afatinib can develop acquired resistance to afatinib within six months. Src is a potential target to prevent the development of afatinib resistance and thus combined treatment with afatinib and dasatinib may be beneficial in patients with HER2-positive breast cancer. Percentage growth in HER2-positive cells treated with afatinib and/or dasatinib for 5 days. 20 nM Afatinib40 nM Dasatinib20 nM Afatinib + 40 nM DasatinibSKBR325.2 ± 6.1109.9 ± 6.222.6 ± 6.2SKBR3-A62.1 ± 0.787.3 ± 11.036.3 ± 0.3*SKBR3-T42.6 ± 4.9107.4 ± 9.729.3 ± 3.5*BT47418.2 ± 3.079.5 ± 5.213.3 ± 1.1BT474-T6.9 ± 2.795.3 ± 2.06.2 ± 2.3EFM192A39.1 ± 4.7105.7 ± 3.135.3 ± 2.7EFM192A-T30.4 ± 5.299.8 ± 2.528.5 ± 4.4HCC195461.8 ± 8.180.5 ± 8.219.4 ± 3.6** indicates enhanced anti-proliferative response for the combination compared to the single agents. Citation Format: Conlon N, Canonici A, Morgan C, Cremona M, Hennessey BT, Eustace A, O'Brien N, Slamon D, Crown J, O'Donovan N. Targeting Src kinase blocks development of afatinib resistance in HER2-positive breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-03-15.

Complete response in advanced breast cancer patient treated with a combination of capecitabine, oral vinorelbine and dasatinib

BackgroundCurrently, there are no data available on the best choice of treatment in heavily pretreated patients with advanced breast cancer. However, the combination of oral vinorelbine and capecitabine has been demonstrated to be effective and safe in patients with advanced breast cancer pretreated with anthracycline. Furthermore, some studies assessed the activity of dasatinib, an oral tyrosine kinase inhibitor that inhibits five oncogenic tyrosine kinase families, alone or in combination with different chemotherapy in patients affected with advanced breast cancer.Case presentationA patient with metastatic breast cancer, hormone receptor positive and human epidermal grow factor receptor 2 negative, pretreated with epirubicine, taxanes and nab-paclitaxel, was submitted to third line chemotherapy with vinorelbine 60 mg/m2 on day 1, 8 plus capecitabine 1000 mg/m2 twice daily from day 1 to day 14 every 21 days. The patient was taking also dasatinib 100 mg once daily for chronic myeloid leukemia. The treatment was well tolerated and, after 15 months, computed tomography scan showed a complete response of liver metastases and bone stable disease. After another 28 months, a 18-fluorodeoxyglucose positron emission tomography scan showed a metabolic response of bone metastases without other site of disease.ConclusionsThis is the first case in literature about activity of dasatinib in combination with a chemotherapy schedule of oral vinorelbine and capecitabine in advanced breast cancer. This treatment showed both good tolerability and great activity with a long progression free survival of 54 months.

Potential Synergism of Caffeic Acid Phenethyl Ester and Dasatinib in C6 Glioma Cell Model: Adumbrating the Molecular Mechanism

1.1 Background: Gliomas are one of the most invasive, highly recurrent, heterogeneous cancers resistant to most of the current treatment regimes and hence almost incurable. CAPE and Dasatinib when used in a congruous combination and durations, present an antitumor potential for glioma. 1.2 Objective: CAPE and Dasatinib in combination have been shown to inhibit proliferation and induce apoptosis in C6 glioma cells. However, the signaling pathway of their antiproliferative and apoptotic effects remains unknown. In this study, the antiproliferative effects of combination treatment on C6 glioma cells were investigated. 1.3 Methods: Expression analysis of proteins thought to be mediating proliferation, cell motility, angiogenesis, and invasion was carried out to delineate the molecular mechanism entailing antineoplastic action of CAPE and Dasatinib. 1.4 Results: Co-treatment induces a change in cellular and nuclear morphology followed by apoptosis and a significant decrease in the activity of catalase and MMP-2, Pro-MMP 2, MMP-9 and Pro-MMP 9 in C6 glioma cells. Moreover, CAPE and Dasatinib modulate the expression of proteins having potential interactive crosstalk with major oncogenic pathways involved in glioma progression. Our results showed that combination treatment modulates the expression of p53, ERK1/2, and AKT in C6 glioma cells. p53, EGFR and PCNA transcript expressions were attuned in co-treated C6 cells. 1.5 Conclusion: Importantly, antineoplastic effects of CAPE and Dasatinib were far greater than those afforded by treatment with a single drug. Together these drugs reduce glioma proliferation and invasion felicitously implying that combination treatment could be a useful therapy for treatment of glioma.

Micellar formulations of Crizotinib and Dasatinib in the management of glioblastoma multiforme

Glioblastoma multiforme (GBM) defies the currently practiced management of radiotherapy, chemotherapy and surgery and hence, it is associated with a high fatality rate with a median survival of 14.6 months. In our previous work investigating different tyrosine kinase inhibitors (TKIs), we established that a combination of Crizotinib and Dasatinib exerted the most potent effect on different GBM cell lines. In this work, to improve targeted therapy at the site of the tumour and avoid systemic toxicity, we exploited the enhanced permeability and retention effect by designing micellar formulations of these two TKIs. Crizotinib and Dasatinib were successfully encapsulated in poly(styrene-co-maleic acid) (SMA) micelles which were then evaluated for their physicochemical characteristics, anti-proliferative effect, mode of cell death, efficacy in spheroid models, effect on cell signalling, antiangiogenic potential and in vivo anticancer activity. Our results showed that this combination had induced a potent anti-proliferative effect in four GBM cell lines grown as a monolayer and as a spheroid. The combination was also efficacious in in vitro models of angiogenesis and vascular mimicry. In vivo data showed the enhanced activity of the micellar TKIs compared to free drugs. In conclusion, we proved that micellar formulations of Crizotinib and Dasatinib carry promising in vitro and in vivo efficacy that warrant further investigation.

Combination of arsenic trioxide and Dasatinib: a new strategy to treat Philadelphia chromosome-positive acute lymphoblastic leukaemia.

Tyrosine kinase inhibitors (TKIs) have significantly improved the prognosis of Philadelphia chromosome‐positive acute lymphoblastic leukaemia (Ph+ ALL), one of the most common and aggressive forms of haematological malignancies. However, TKI resistance has remained an unsolved issue. In this study, we investigate the impact of adding arsenic trioxide (ATO) on the action of Dasatinib, a second‐generation TKI, in Ph+ ALL. We show that ATO cooperates with Dasatinib in both TKI‐sensitive and resistant Ph+ ALL cell lines to increase apoptosis and we unravel the underlying mechanisms. Indeed, combining ATO and Dasatinib leads to severe cell apoptosis by activating the UPR apoptotic IRE1/JNK/PUMA axis, while neutralizing the UPR ATF4‐dependent anti‐apoptotic axis, activated by ATO alone. Additionally, ATO and Dasatinib in combination repress the expression of several genes, which we previously showed to be associated with shorter survival probability in ALL patients. Overall these data support the use of ATO in combination with Dasatinib as a novel therapeutic regimen for Ph+ ALL patients.

Efficacy and safety of autologous peripheral blood stem cell transplantation for Philadelphia chromosome-positive acute lymphoblastic leukemia: A study protocol for a multicenter exploratory prospective study (Auto-Ph17 study).

Introduction:The prognosis of Philadelphia chromosome positive acute lymphoblastic leukemia (Ph + ALL) has been dramatically improved since the introduction of tyrosine kinase inhibitors (TKIs). Although allogeneic hematopoietic cell transplantation (allo-HCT) is a major treatment option, the role of autologous peripheral blood stem cell transplantation (auto-PBSCT) has been reconsidered, especially in patients who achieved early molecular remission.Methods and analysis:This is a multicenter exploratory study for Ph + ALL patients aged between 55 and 70 years who achieved complete molecular remission within 3 cycles of chemotherapy. The target sample size is 5, and the registration period is 2 years. The primary endpoint is Day100- mortality after transplantation, and the secondary endpoints are survival, relapse rate, nonrelapse mortality, and adverse events.This study is divided into 3 phases: peripheral blood stem cell harvest, transplantation, and maintenance. Chemomobilization is performed using a combination of cyclophosphamide (CPM), doxorubicin, vincristine (VCR), and prednisolone (PSL). As a preparative regimen, the LEED regimen is used, which consists of melphalan, CPM, etoposide, and dexamethasone. Twelve cycles of maintenance therapy using a combination of VCR, PSL, and dasatinib are performed.In association with relapse, the minimal residual disease (MRD) of BCR-ABL chimeric gene and T-cell subsets are analyzed both before and after auto-PBSCT.Ethics and dissemination:The protocol was approved by the institutional review board of Nagoya University Hospital and all the participating hospitals. Written informed consent was obtained from all patients before registration, in accordance with the Declaration of Helsinki. Results of the study will be disseminated via publications in peer-reviewed journals.Trial registration:Trial registration number UMIN000026445.

Dasatinib synergizes with ATRA to trigger granulocytic differentiation in ATRA resistant acute promyelocytic leukemia cell lines via Lyn inhibition-mediated activation of RAF-1/MEK/ERK

All-trans retinoic acid (ATRA) resistance has been a critical problem in acute promyelocytic leukemia (APL) relapsed patients. In this study, dasatinib synergized with ATRA to trigger differentiation in ATRA-resistant APL cell lines. The combined treatment activated RAF-1, MEK and ERK as well as enhanced ATRA-promoted up-regulation of the protein level of PU.1, C/EBPβ and C/EBPε. U0126 (MEK specific inhibitor) and sorafenib tosylate (RAF-1 specific inhibitor) suppressed the combined treatment-induced differentiation, ERK phosphorylation and the up-regulation of C/EBPs and PU.1. Sorafenib tosylate also attenuated the MEK activity. However, the combined treatment did not enhance Ras activity and Ras inhibitor neither blocked MEK activation nor inhibited differentiation. Therefore, the combined treatment induced differentiation via Ras independent RAF-1/MEK/ERK. Earlier than RAF-1 activation, dasatinib suppressed Lyn activity, the predominant activated Src family kinase (SFK) and dephosphorylated RAF-1 at S259. Furthermore, SFK inhibitor, PP2 did suppress Lyn activity and mimicked the effect of dasatinib on ATRA-induced differentiation as well as decreased phosphorylation of RAF-1 at S259. Thus, it was suggested that Lyn inhibition might activate RAF-1 by the dephosphorylation of RAF at S259 and lead to differentiation. In conclusion, the combination of dasatinib and ATRA could overcome ATRA resistance through Lyn inhibition-mediated activation of RAF-1/MEK/ERK.

Propofol enhances BCR-ABL TKIs\u2019 inhibitory effects in chronic myeloid leukemia through Akt/mTOR suppression

BackgroundThe anti-cancer activities of intravenous anesthetic drug propofol have been demonstrated in various types of cancers but not in chronic myeloid leukemia (CML).MethodsWe systematically examined the effect of propofol and its combination with BCR-ABL tyrosine kinase inhibitors (TKIs) in CML cell lines, patient progenitor cells and mouse xenograft model. We analyzed propofol’s underlying mechanism focusing on survival pathway in CML cells.ResultsWe show that propofol alone is active in inhibiting proliferation and inducing apoptosis in KBM-7, KU812 and K562 cells, and acts synergistically with imatinib or dasatinib, in in vitro cell culture system and in vivo xenograft model. In addition, propofol is more effective in inducing apoptosis and inhibiting colony formation in CML CD34 progenitor cells than normal bone marrow (NBM) counterparts. Combination of propofol and dasatinib significantly eliminates CML CD34 without affecting NBM CD34 cells. We further demonstrate that propofol suppresses phosphorylation of Akt, mTOR, S6 and 4EBP1 in K562. Overexpression of constitutively active Akt significantly reverses the inhibitory effects of propofol in K562, confirm that propofol acts on CML cells via inhibition of Akt/mTOR. Interestingly, the levels of p-Akt, p-mTOR and p-S6 are lower in cells treated with combination of propofol and imatinib than cells treated with propofol or imatinib alone, suggesting that propofol augments BCR-ABL TKI’s inhibitory effect via suppressing Akt/mTOR pathway.ConclusionOur work shows that propofol can be repurposed to for CML treatment. Our findings highlight the therapeutic value of Akt/mTOR in overcoming resistance to BCR-ABL TKI treatment in CML.

239PD - A phase II trial of dasatinib (D) in combination with trastuzumab (T) and paclitaxel (P) in the first line treatment of HER2 positive metastatic breast cancer (MBC) patients (pts): GEICAM/2010-04

239PD - A phase II trial of dasatinib (D) in combination with trastuzumab (T) and paclitaxel (P) in the first line treatment of HER2 positive metastatic breast cancer (MBC) patients (pts): GEICAM/2010-04

Growth inhibitory effect of the Src inhibitor dasatinib in combination with anticancer agents on uterine cervical adenocarcinoma cells.

Uterine cervical adenocarcinoma has a poor clinical prognosis when compared with squamous cell carcinoma. Therefore, the development of new treatment strategies for uterine cervical adenocarcinoma is necessary. Src is a proto-oncogene that is important in cancer progression. Dasatinib is a Src inhibitor that has been reported to be effective when used in combination with anticancer drugs. The present study aimed to confirm Src expression in human cervical adenocarcinoma cell lines and to determine the mechanism underlying the inhibitory effect of dasatinib on Src signaling in vitro. Western blot analysis was performed to investigate Src expression in cervical adenocarcinoma cell lines (HeLa and TCO-2 cells). The cells were cultured for 48 h with the addition of different concentrations of anticancer drugs (paclitaxel or oxaliplatin). Viable cell count was measured using a colorimetric (WST-1) assay. The concentrations of anticancer agents were fixed according to the results obtained, and the same experiments were performed using the drugs in combination with dasatinib at various concentrations to determine the concentrations that significantly affected the number of viable cells. The presence or absence of apoptosis was investigated using a caspase-3/7 assay. Signal transduction in each cell line was examined using western blotting. Src was activated in the two cell lines, and cell proliferation was significantly suppressed by each anticancer drug in combination with 10 µM dasatinib. Caspase-3/7 activity was also increased and Src signaling was suppressed by each anticancer drug in combination with dasatinib. In conclusion, Src is overexpressed in cervical adenocarcinoma cell lines, and dasatinib inhibits intracellular Src signaling and causes apoptosis. The results of the present study suggest that Src may be targeted in novel therapeutic strategies for cervical adenocarcinoma.

Abstract 1933: Discovery of first-in-class small molecule CD99 inhibitors for targeted therapy of Ewing sarcoma

Abstract Ewing sarcoma (ES) is an aggressive bone and soft tissue malignancy that affects predominantly children and adolescents with a high propensity to metastasize and poor prognosis. CD99 is a transmembrane cell surface protein that is highly expressed on ES cells, and routinely used as a marker for histological diagnosis of ES. We screened small molecule libraries for their binding to recombinant CD99 protein and subsequent selective inhibition of ES cell growth. We identified two structurally similar FDA-approved nucleoside analogues, clofarabine and cladribine that selectively inhibited the growth of ES cells in a panel of 14 ES vs. 28 non-ES cell lines. A significant negative correlation was found in human cell lines between CD99 expression and IC50 values for clofarabine and cladribine. Both drugs inhibited CD99 dimerization and its interaction with downstream signaling components cyclophilin A and PKA-RIIα as well as led to reduced ROCK2 protein expression and migration in ES cells. A membrane-impermeable analog of clofarabine showed similar cytotoxicity in ES cells, suggesting that it can function through inhibiting CD99 alone without any effect on DNA metabolism. Clofarabine and cladribine led to a significant increase in hypodiploid DNA content of ES cells, which was diminished by suppression of CD99 expression. Both drugs drastically inhibited anchorage-independent growth of ES cells, but clofarabine was more effective in inhibiting ES xenografts. Finally, the screening of a set of chemotherapy drugs revealed a synergy for the combination of anti-CD99 drugs and dasatinib in ES cells, which may translate into increased survival and reduced toxicity. Overall, our findings suggest that clofarabine is a good candidate for early phase clinical trials in children with ES. Citation Format: Haydar Celik, Marika Sciandra, Bess Flashner, Elif Gelmez, Neslihan Kayraklıoğlu, David V. Allegakoen, Jeff R. Petro, Erin J. Conn, Sarah Hour, Jenny Han, Lalehan Oktay, Purushottam B. Tiwari, Mutlu Hayran, Maria Cristina Manara, Jeffrey A. Toretsky, Katia Scotlandi, Aykut Uren. Discovery of first-in-class small molecule CD99 inhibitors for targeted therapy of Ewing sarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1933. doi:10.1158/1538-7445.AM2017-1933

Abstract 1090: Preclinical evaluation of combination therapy with dasatinib and sorafenib for the treatment of brain metastases

Abstract Brain metastases, the most common type of intracranial tumors in adults, carry a dismal prognosis with a median survival of less than 18 months regardless of primary status or treatment given. As part of an ongoing project, this study is concerned with the preclinical evaluation of targeted combination therapy for the treatment of brain metastases. The cell line used in this study was the H1915 (ATCC® CRL-5904TM) human lung cancer cell line, which was originally derived from a brain metastasis from primary lung adenocarcinoma. The cell line was stably transfected with a plasmid that allows expression of firefly luciferase (i.e., H1915-luc) so that the tumor growth in a mouse orthotopic model of brain metastases can be assessed in real time using the Xenogen in vivo bioluminescence imaging (BLI). Our previous study has demonstrated that the synergistic effect of combined dasatinib and sorafenib treatment was cell-line dependent. In this study, the cytotoxicity of dasatinib and sorafenib, when used alone or in combination at the fixed molar ratios of 3:1, 1:1 and 1:3 (dasatinib:sorafenib), was further examined in H1915-luc cells using the MTT assay. The results demonstrated that simultaneous and continuous exposure of H1915-luc cells to dasatinib and sorafenib at the fixed concentration ratio of 1:1 and 1:3 for 72 h showed synergism (the combination index value between 0.7 and 0.8) at effect levels of 40 and 80% inhibition of cell viability. For the in vivo study, an orthotopic mouse model of brain metastases was established by injecting H1915-luc cells into the right general carotid artery of individual athymic nude mice followed by permanent ligation. The preliminary study showed that following the intracarotid injection of H1915-luc cells, brain metastases were formed and readily to be detected by BLI. The obtained whole brain samples were fixed in OCT and stored at -80oC. The brain sections are to be subjected to the immunofluorescence double staining of CD31 and firefly luciferase to assess the potential effect of the dasatinib-sorafenib combination on microscopic brain metastasis formation and progression and vessel co-option. Given the fact that brain metastases usually have a poor response to chemotherapeutic agents in part due to the presence of blood-brain barrier, a pharmacokinetic study is underway to characterize the distribution of sorafenib and dasatinib in normal brain tissues and brain metastases using the serial blood sampling and brain microdialysis technique. Overall, results from the in vitro cytotoxicity study demonstrated the synergistic effect of dasatinib and sorafenib on H1915-luc human lung cancer cells, providing a rationale for the in vivo evaluation the potential of this combination for the treatment of brain metastases from lung carcinomas. Citation Format: Qingyu Stephanie Zhou, Xiaofang Guo. Preclinical evaluation of combination therapy with dasatinib and sorafenib for the treatment of brain metastases [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1090. doi:10.1158/1538-7445.AM2017-1090

Augmentation of the anticancer activity of CYT997 in human prostate cancer by inhibiting Src activity

BackgroundAbnormalities of tubulin polymerization and microtubule assembly are often seen in cancer, which make them very suitable targets for the development of therapeutic approach against rapidly dividing and aggressive cancer cells. CYT997 is a novel microtubule-disrupting agent with anticancer activity in multiple cancer types including prostate cancer. However, the molecular mechanisms of action of CYT997 in prostate cancer have not been well characterized.MethodsSrc knockdown cells were achieved by lentiviral-mediated interference. The drug effects on cell proliferation were measured by MTS. The drug effects on cell viability and death were determined by Cell Titer-Glo® Luminescent cell viability kit and flow cytometry with Zombie Aqua™ staining. The drug effects on apoptosis were assessed by Cell Death Detection Elisa kit and Western blot with a cleaved PARP antibody. The drug effects on cell invasion were examined by Matrigel-coated Boyden chambers. Oxidative stress was detected by DCFH-DA staining and electrochemical biosensor. Mouse models generated by subcutaneous or intracardiac injection were used to investigate the in vivo drug efficacy in tumor growth and metastasis.ResultsCYT997 effectively inhibited proliferation, survival, and invasion of prostate cancer cells via blocking multiple oncogenic signaling cascades but not the Src pathway. Inhibition of Src expression by small hairpin RNA or inactivation of Src by dasatinib increased the CYT997-induced cytotoxicity of in vitro. Moreover, the combination of dasatinib and CYT997 exhibited a superior inhibitory effect on tumor growth and metastasis compared with either of the drugs alone.ConclusionOur findings demonstrate that blockage of Src augments the anticancer effect of CYT997 on prostate cancer and suggest that co-treatment of dasatinib and CYT997 may represent an effective therapeutic regimen for limiting prostate cancer.

Combination of PP242 and dasatinib suppresses the progression of acute myeloid leukemia in a mouse model

Objective: To establish the acute myeloid leukemia (AML) mouse model, and to preliminarily investigate the efficiency of dasatinib, a tryosine kinase inhibitor, and PP242, an inhibitor of PI3K/Akt/mTOR signaling pathway in the development of AML. Methods: The lineage(-) (Lin(-)) cells of C57BL/6J were transduced with retrovirus carrying MSCV-MLL-AF9-IRES-GFP fusion gene. The transduced cells were transplanted into lethally irradiated recipient mice to induce AML, and then the AML mouse model were established. The leukemia mice were treated with vehicle, dasatinib, PP242, dasatinib+ PP242, separately. The survival of the recipient mice was observed and the percentage of leukemia cells in peripheral blood (PB) and bone marrow (BM) was examined every four days. The apoptosis rates and cell cycle status of leukemia cells were also examined by FLOW. The leukemia cells in different group were sorted, the mRNA of these leukemia were extracted and reverse transcripted for related gene expression by qRT-PCR. The molecular mechanism of supression of leukemia cells growth was studied via RNA-Seq experiments. Results: Compared with control group, either PP242 or dasatinib could prolong the survival rate of recipient mice, however, the combination treatment AML mice with PP242 and dasatinib prolonged the life span of AML mice more significantly. The combination of PP242 and dasatinib could decrease the percentage of leukemia cells in PB and BM more significantly, arresting more leukemia cells in G0 phase, inducing more apoptosis of leukemia cells. Conclusion: Combination of tryosine kinase inhibitor-dasatinib and PI3K/Akt/mTOR signaling pathway inhibitor- PP242 could delay the progression of AML by inducing more leukemia to apoptosis and arrest more leukemia cells in the cell cycle G0 phase, it may be provied a new method for clinical therapy.

A phase I dose expansion cohort study of dasatinib in combination with bevacizumab in advanced solid tumors (NCT01445509).

2585 Background: Dasatinib is a known inhibitor of the SRC family kinases and is approved for use in chronic myelogenous leukemia. Bevacizumab inhibits angiogenesis, binding to human vascular endothelial growth factor (VEGF, or VEGF-A) with high affinity. VEGF receptor signals intracellularly via a cascade regulated by SRC. Given the presence of this signaling pathway in both tumor cells and endothelial cells, we hypothesized that attenuation of both SRC and VEGF simultaneously would have synergistic antitumor activity. We previously reported the maximum tolerated dose (MTD) of dasatinib 100mg daily with bevacizumab 10mg/kg q2wk in patients with advanced solid tumors. We now report clinical activity of the combination, and translational endpoints of an expansion cohort. Methods: This is a phase 1 dose escalation with non-randomized expansion cohort. We monitored safety, and response was assessed every 8 weeks using RECIST criteria. Correlative endpoints include blood flow by dynamic MR imaging, endothelial cell density by CD31 immunohistochemistry, functional angiogenic potential by plasma cytokines and rat aortic ring assay, and tumor cell activation state by phosphoprotein analysis. Results: We enrolled 39 patients at the MTD for a total of 50 patients on study, including both the dose escalation and dose expansion phases. No patient experienced dose limiting toxicities during dose escalation. The most common adverse events were grade 2 hypertension and proteinuria. By RECIST, 5 (10%) patients had a partial response, and stable disease was seen in 29 (58%) of patients with a range from 12-145+ weeks on study. We had two exceptional responders with endometrial carcinoma who continue on study to date (112 weeks and 145 weeks). Translational endpoints were correlated with clinical outcome. Conclusions: Bevacizumab and dasatinib are safe in combination, with potential clinical activity. This combination warrants further investigation in solid tumors. Ongoing translational research using specimens from exceptional responders will suggest potential biomarkers of clinical benefit, to be tested in future prospective clinical trials. Clinical trial information: NCT01445509.

Cytotoxic effects of 15-deoxy-Δ12,14-prostaglandin J2 alone and in combination with dasatinib against uterine sarcoma in vitro.

Effective chemotherapeutic strategies for uterine sarcoma are lacking; existing therapies achieve poor response rates. Previous studies have identified the prostaglandin 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) as a potential anticancer treatment; however, its effectiveness in uterine sarcoma has not been examined. Furthermore, the molecular mechanisms underlying the cytotoxic mechanism of 15d-PGJ2 remain unclear. Here, we evaluated the effects of 15d-PGJ2 alone and in combination with the tyrosine kinas inhibitor (TKI) dasatinib in uterine sarcoma cell lines (MES-SA, MES-SA/DX5 and SKN). 15d-PGJ2 inhibited cell growth and increased apoptosis. Western blotting demonstrated that 15d-PGJ2 treatment increased MEK and ERK phosphorylation, and decreased levels of phosphorylated AKT. Dasatinib in combination with 15d-PGJ2 significantly reduced cell proliferation compared with 15d-PGJ2 alone, and repressed both the AKT and MAPK pathways. The cell growth inhibition rate in the PGJ2 was 21.5±12.0, 35.3±5.4 and 28.3±4.2%, respectively (MES-SA, MES-SA/DX5 and SKN cell lines) and the cell growth inhibition rate in the combination therapy was significantly higher compared with 15d-PGJ2 alone (MES-SA; 64.2±0.8, MES-SA/DX5;23.9±8.2 and SKN; 41.4±17.6%). The PGJ2 IC50 determined by MTT assay was 27.41,10.46 and 17.38 µmol/l, respectively (MES-SA, MES-SA/DX5 and SKN cell lines) and the dasatinib IC50 was 6.68,17.30 and 6.25 µmol/l, respectively. Our findings demonstrate that 15d-PGJ2 suppresses proliferation by inactivating the AKT pathway in uterine sarcoma. Furthermore, combining 15d-PGJ2 with dasatinib produced a synergistic effect on cancer cell inhibition by repressing 15d-PGJ2-mediated activation of MAPK signaling, and further repressing AKT signaling. These results suggest that 15d-PGJ2 could be used in combination with dasatinib as a potential therapeutic approach for uterine sarcoma.

A phase I study of the SRC kinase inhibitor dasatinib with trastuzumab and paclitaxel as first line therapy for patients with HER2-overexpressing advanced breast cancer. GEICAM/2010-04 study.

The anti-HER2 antibody trastuzumab have shown clinical activity in combination with chemotherapy in different breast cancer settings. However, most of patients treated with this antibody progress after a period of treatment. Activation of the kinase SRC has been linked with resistance to trastuzumab in several preclinical studies. We designed a phase I clinical study to explore the activity of weekly trastuzumab (2 mg/kg) plus paclitaxel (80 mg/m2) in combination with the anti-SRC kinase inhibitor Dasatinib in the first line treatment of HER2 metastatic breast cancer. The primary objective was to determine the maximum tolerated dose (MTD) and recommended phase II dose (RP2D); secondary objectives included efficacy, objective response rate (ORR), pharmacokinetics and pharmacodynamics. A “3+3” design guided dose escalation with two oral dose levels of dasatinib: 100mg (DL1) and 140 mg (DL2). 10 patients were included in the phase I part. Dasatinib 100 mg q.d. was established as the recommended RP2D. The median number of administered cycles was 12 (range, 1 to 18). Grade 3 treatment-related AEs at DL1 were diarrhea (n = 2), hyponatremia (n = 1), fatigue (n = 1), and AST/ALT elevation (n = 1). A significant reduction in p-SRC expression on epidermal keratinocytes on sequential skin biopsies was observed. In conclusion, we describe the feasibility of the combination of dasatinib, trastuzumab and paclitaxel, and its effect on proteins involved in trastuzumab resistance. The phase II part of this study is currently evaluating efficacy.