Combination Index Values Research Articles

Phytochemical profiles, antioxidant activities, and synergistic antiproliferative effects of blueberry and apple peel extracts.

Blueberries and apples exhibit favorable bioactivity and health benefits due to their rich phytochemicals. Natural phytochemicals exist in complex forms, but there are few reports on whether have additive, synergistic or antagonistic effects between different phytochemicals. The aim of the present investigation was to elucidate the synergistic effects of blueberry extract (BE) and apple peel extract (APE) together in inhibiting the proliferation of HepG2 liver cancer cells. Meanwhile, phytochemical characterization of BE and APE were detected by HPLC, and total antioxidant activity was determined via cellular antioxidant activity (CAA) assay, oxygen radical absorption capacity (ORAC) assay and peroxy radical scavenging capacity (PSC) assay. The results showed that BE and APE were rich in phytochemicals and had potent antioxidant activities, which synergistically inhibited cell proliferation. In the bilateral combination, the dose reduction index (DRI) value increased 2-fold, and the combination index (CI) value at 95% inhibition was less than 1. Additionally, BE+APE supplementation could promote the expression levels of p53 and c-myc genes. In conclusion, the BE and APE had strong antioxidant activity and exhibited synergistic inhibition against HepG2 cells proliferation. This can provide a theoretical basis for the synergistic effect of different phytochemicals in health care. This article is protected by copyright. All rights reserved.

Synergistic effect of Hsp90 inhibitor ginkgolic acids C15꞉1 combined with paclitaxel on nasopharyngeal carcinoma.

Nasopharyngeal cracinoma is a kind of head and neck malignant tumor with high incidence and high mortality. Due to the characteristics of local recurrence, distant metastasis, and drug resistance, the survival rate of patients after treatment is not high. Paclitaxel (PTX) is used as a chemotherapy drug in treating nasopharyngeal carcinoma, but nasopharyngeal carcinoma cells are easy to develop resistance to PTX. Inhibition of heat shock protein 90 (Hsp90) can overcome common signal redundancy and resistance in many cancers. This study aims to investigate the anti-tumor effect of ginkgolic acids C15꞉1 (C15:1) combined with PTX on nasopharyngeal carcinoma CNE-2Z cells and the mechanisms. This experiment was divided into a control group (without drug), a C15:1 group (10, 30, 50, 70 μmol/L), a PTX group (5, 10, 20, 40 nmol/L), and a combination group. CNE-2Z cells were treated with the corresponding drugs in each group. The proliferation of CNE-2Z cells was evaluated by methyl thiazolyl tetrazolium (MTT). Wound-healing assay and transwell chamber assay were used to determine the migration of CNE-2Z cells. Transwell chamber was applied to the impact of CNE-2Z cell invasion. Annexin V-FITC/PI staining was used to observe the effect on apoptosis of CNE-2Z cells. The changes of proteins involved in cell invasion, migration, and apoptosis after the combination of C15꞉1 and PTX treatment were analyzed by Western blotting. Compared with the control group, the C15꞉1 group and the PTX group could inhibit the proliferation of CNE-2Z cells (all P<0.05). The cell survival rates of the C15꞉1 50 μmol/L combined with 5, 10, 20, or 40 nmol/L PTX group were lower than those of the single PTX group (all P<0.05), the combination index (CI) value was less than 1, suggesting that the combined treatment group had a synergistic effect. Compared with the 50 μmol/L C15꞉1 group and the 10 nmol/L PTX group, the combination group significantly inhibited the invasion and migration of CNE-2Z cells (all P<0.05). The results of Western blotting demonstrated that the combination group could significantly down-regulate Hsp90 client protein matrix metalloproteinase (MMP)-2 and MMP-9. The results of double staining showed that compared with the 50 μmol/L C15꞉1 group and the 10 nmol/L PTX group, the apoptosis ratio of CNE-2Z cells in the combination group was higher (both P<0.05). The results of Western blotting suggested that the combination group could decrease the Hsp90 client proteins [Akt and B-cell lymphoma-2 (Bcl-2)] and increase the Bcl-2-associated X protein (Bax). The combination of C15꞉1 and PTX has a synergistic effect which can inhibit cell proliferation, invasion, and migration, and induce cell apoptosis. This effect may be related to the inhibition of Hsp90 activity by C15꞉1.

Carvacrol-Fabricated Chitosan Nanoparticle Synergistic Potential with Topoisomerase Inhibitors on Breast and Cervical Cancer Cells.

Breast and cervical cancers are the most common heterogeneous malignancies in women. Chemotherapy with conventional drug delivery systems having several limitations along with development of multidrug resistance compelled us to seek out targeted therapeutics. Nanoparticles are suitable substitutes to circumvent multidrug resistance for the targeted treatment of cancer. The current study was aimed to investigate the anticancer effect of carvacrol-loaded chitosan nanoparticles with topoisomerase inhibitors. The average size of carvacrol-loaded chitosan nanoparticles was found to be 80 nm with 24.7 mV ζ-potential, and maximum absorbance was observed at 275 nm. Among all drug combinations, the carvacrol nanoparticles with the doxorubicin combination group exerted greater dose-dependent growth inhibition of both MCF-7 and HeLa cells as compared to single carvacrol nanoparticles and doxorubicin. Combination index values of carvacrol nanoparticles and the doxorubicin combination group showed a strong synergistic effect as they were found to be between 0.2 and 0.4, 0.31 for MCF-7 and 0.34 for HeLa cells. The carvacrol nanoparticles in combination with doxorubicin on MCF-7 cells reduced the dose 16.32-fold for carvacrol nanoparticles and 4.09-fold for doxorubicin at 6.23 μg/mL IC50, while on HeLa cells, this combination reduced the dose 13.18-fold for carvacrol nanoparticles and 3.83-fold for doxorubicin at 9.33 μg/mL IC50. As the dose reduction values were greater than 1, they indicated favorable dose reduction. It was concluded that the combination of carvacrol-loaded chitosan nanoparticles with topoisomerase inhibitors may represent an innovative and promising strategy to improve the efficacy, resistance, and targeted delivery of chemotherapeutics in cancer.

Effect of capecitabine and melatonin on HER2+ (SK-BR-3) and HER2- (MCF7) human breast cancer cell lines

Purpose: To determine the effect of melatonin in combination with capecitabine on the proliferation and induction of apoptosis in MCF-7 and SK-BR-3 breast cancer cell lines.Methods: The MTT assay (3- (4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide) was performed to investigate the effect of capecitabine and in combination with melatonin on cell lines and to determine the half-maximal concentration (IC50) and combination index. Expression of apoptotic markers, Bax, Bcl-2, and caspase-3 were measured by polymerase chain reaction (PCR) after treatment.Results: The IC50 of melatonin and capecitabine in MCF-7 and SK-BR-3 cell lines were 4.52 mM and 619.36 μg/mL, and 5.1 mM and 679.51 μg/mL, respectively. The combined use of melatonin and capecitabine significantly reduced IC50. Also, combination index (CI) values were &lt; 1, indicating that the combination of capecitabine and melatonin has a synergistic effect. The results of gene expression also showed enhancement in the Bax/Bcl-2 ratio in melatonin-capecitabine combination compared with capecitabine alone in both cell lines.Conclusion: Melatonin-capecitabine-induced cell death is controlled by caspase-3 and Bax/Bcl-2-dependent apoptosis. The combination of melatonin and capecitabine has a synergistic effect on both HER2+ and HER2- cells.

Synergistic effects of trastuzumab and gambogic acid on MDA-MB-453 breast cancer cell line

Trastuzumab is one of the most commonly used monoclonal antibodies in the treatment of breast cancer. It is effective because it binds to the HER2 receptor and inhibits the signaling pathways for proliferation and metastasis. However, intrinsic or acquired resistance resulting from the various signaling pathways of heterogeneous breast cancer reduces its efficacy. To increase its efficacy, it is combined with different agents in the treatment. In this study, the synergistic effect of the combination of trastuzumab and gambogic acid on the breast cell line MDA-MB -453 was investigated in vitro. At the end of 12-, 24-, 48-, and 72-hour incubation, their antiproliferative effects were determined by XTT method. Combination Index (CI) values of the study were calculated using CompuSyn.exe software. The highest synergistic effect was obtained with 12.5 µg/mL trastuzumab + 1.25 µM gambogic acid (CI-4) at the 72nd hour. The activity of the antioxidant enzyme catalase (CAT) was also measured for the applications. We observed that combination of trastuzumab and gambogic acid decreased CAT activity at 24, 48 and 72nd hours. It was concluded that gambogic acid may be a good candidate for combination with other agents in targeted drug design.

Characterization of the Synergistic Antioxidant Activity of Epigallocatechin Gallate (EGCG) and Kaempferol.

Epigallocatechin gallate (EGCG) and kaempferol exhibit cellular antioxidant activity; however, their interactive effects in terms of antioxidant actions and underlying mechanisms remain unclear. In this study, their cytoprotective effects were examined against 2,2-azobis (2-amidinopropane) dihydrochloride solution (ABAP)-induced oxidative stress in HepG2 cells. The results showed that the median effective dose (EC50) of the EGCG and kaempferol (6:1.5, c/c) combination was 3.4 ± 0.1 μg/mL, with a combination index (CIavg) value of 0.54, which represented a significant synergistic effect. Further experiments proved that the combined pretreatment with EGCG and kaempferol exerted protective effects by suppressing reactive oxygen species (ROS) generation, upregulating cellular antioxidant enzyme activities (superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px)) in a dose-dependent manner. The mechanism of synergistic antioxidant effects of EGCG combined with kaempferol may be due to the up-regulation of higher antioxidant enzyme activities that improve the antioxidant capacities and balance the cell oxidative stress. The synergistic antioxidant effect of EGCG and kaempferol can provide a theoretical basis for the development of formulas of functional food ingredients.

A comparative analysis of growth kinetics, image analysis, and biofuel potential of different algal strains

Due to the global population growth and economic development, energy demand has increased worldwide. Countries take steps to improve their alternative and renewable energy sources. Algae is one of the alternative energy sources and can be used to produce renewable biofuel. In this study, nondestructive, practical, and rapid image processing techniques were applied to determine the algal growth kinetics and biomass potential of four algal strains, including C. minutum, Chlorella sorokiniana, C. vulgaris, and S. obliquus. Laboratory experiments were conducted to determine different aspects of biomass and chlorophyll production of those algal strains. Suitable non-linear growth models, including Logistic, modified Logistic, Gompertz, and modified Gompertz models, were employed to determine the growth pattern of algae. Moreover, the methane potential of harvested biomass was calculated. The algal strains were incubated for 18 days, and the growth kinetics were determined. After the incubation, the biomass was harvested and assessed for its chemical oxygen demand content and biomethane potential. Among the tested strains, C. sorokiniana was the best in biomass productivity (111.97 ± 0.9 mg L−1d−1). The calculated vegetation indices, namely; colorimetric difference, color index vegetation, vegetative, excess green, excess green minus excess red, combination, and brown index values showed a significant correlation with biomass and chlorophyll content. Among the tested growth models, the modified Gompertz shows the best growth pattern. Further, the estimated theoretical CH4 yield was highest for C. minutum (0.98 mL g−1) compared to other tested strains. The present findings suggest that image analysis can be used as an alternative method to study the growth kinetics and biomass production potential of different algae during cultivation in wastewater.

DIPG-57. TESTING FOR SYNERGY AMONG RADIATION AND HIGHLY CLINICALLY RELEVANT CHEMOTHERAPEUTIC AGENTS IN PATIENT-DERIVED MODELS OF DIFFUSE MIDLINE GLIOMA

Abstract Diffuse midline gliomas (DMG) are aggressive pediatric brain tumors with minimal long-term survival. Radiation is currently the only standard-of-care treatment and is non-curative. Several chemotherapy agents have shown preclinical and/or early clinical promise, and we hypothesize that finding effective chemoradiotherapeutic combinations is likely to be necessary to achieve long-term survival, based on experience from other previously incurable childhood cancers. We treated 8 DMG/DIPG cell lines with one, two, or three treatments among the HDAC inhibitor panobinostat, the CDK4/6 inhibitor ribociclib, the DRD2 inhibitor ONC201, the XPO1 inhibitor selinexor, the PI3K inhibitor paxalisib, and radiation. We then measured the cell survival with MTS assays. Cells were treated with drug concentrations ranging from 1 nM to 100 uM. To assess for synergy among our combinations, we used the Combination Index (CI) model, in which a score of &amp;lt;1 implies synergy. Of the 15 2-treatment combinations, ONC201 + radiation, ONC201 + paxalisib, ribociclib + ONC201, selinexor + paxalisib, and ribociclib + paxalisib met our criteria as successful, synergistic combinations: at least three cell lines with at least 90% cell death achieved, a CI value of 0.5 or lower at doses with at least 50% cell death, and at least 66% of dose levels with a CI value of 0.5 or lower. Early analysis suggests that ribociclib + ONC201 + paxalisib, ONC201 + paxalisib + radiation, and ONC201 + selinexor + paxalisib are the most effective three-treatment combinations. Patient-derived cell culture data in a heterogeneous pool of DMG/DIPG cell lines demonstrate synergy using several combinations of clinically relevant treatments, especially those including paxalisib. We are now optimizing treatment sequencing in synergistic combinations and testing in orthotopic xenograft models. Our goal is to find combinations that can become cycles of therapy in a multimodality clinical trial.

Zhuidu Formula suppresses the migratory and invasive properties of triple-negative breast cancer cells via dual signaling pathways of RhoA/ROCK and CDC42/MRCK

Ethnopharmacological relevanceZhuidu Formula (ZDF) is composed of triptolide, cinobufagin and paclitaxel, which are the active ingredients of Tripterygium wilfordii Hook. F, dried toad skin and Taxus wallichiana var. chinensis (Pilg) Florin, respectively. Modern pharmacological studies show that triptolide, cinobufagin, and paclitaxel are well-known natural compounds that exert anti-tumor effects by interfering with DNA synthesis, inducing tumor cell apoptosis, and inhibiting the dynamic balance of the tubulin. However, the mechanism by which the three compounds inhibit triple-negative breast cancer (TNBC) metastasis is unknown. ObjectiveThe objective of this investigation was to examine the inhibitory essences of ZDF on the metastasis of TNBC and elucidate its potential mechanism. Materials and methodsCell viability of triptolide (TPL), cinobufagin (CBF), and paclitaxel (PTX) on MDA-MB-231 cells was assessed employing a CCK-8 assay. The drug interactions of the three drugs on MDA-MB-231 cells were determined in vitro utilizing the Chou-Talalay method. MDA-MB-231 cells were identified for migration, invasion and adhesion in vitro through the implementation of the scratch assay, transwell assay and adhesion assay, respectively. The formation of cytoskeleton protein F-actin was detected by immunofluorescence assay. The expressions of MMP-2 and MMP-9 in the supernatant of the cells were determined by ELISA analysis. The Western blot and RT-qPCR were employed to explore the protein expressions associated with the dual signaling pathways of RhoA/ROCK and CDC42/MRCK. The anti-tumor efficacy of ZDF in vivo and its preliminary mechanism were investigated in the mouse 4T1 TNBC model. ResultsThe results demonstrated that ZDF could significantly reduce the viability of the MDA-MB-231 cell, and the combination index (CI) values of actual compatibility experimental points were all less than 1, demonstrating a favorable synergistic compatibility relationship. It was found that ZDF reduces RhoA/ROCK and CDC42/MRCK dual signaling pathways, which are responsible for MDA-MB-231cell migration, invasion, and adhesion. Additionally, there has been a significant reduction in the manifestation of cytoskeleton-related proteins. Furthermore, the expression levels of RhoA, CDC42, ROCK2, and MRCKβ mRNA and protein were down-regulated. ZDF significantly decreased the protein expressions of vimentin, cytokeratin-8, Arp2 and N-WASP, and inhibited actin polymerization and actomyosin contraction. Furthermore, MMP-2 and MMP-9 levels in the high-dose ZDF group were decreased by 30% and 26%, respectively. ZDF significantly reduced the tumor volume and protein expressions of ROCK2 and MRCKβ in tumor tissues without eliciting any perceptible alterations in the physical mass of the mice, and the reduction was more pronounced than that of the BDP5290 treated group. ConclusionThe current investigation demonstrates that ZDF exhibits a proficient inhibitory impact on TNBC metastasis by regulating cytoskeletal proteins through the dual signaling pathways of RhoA/ROCK and CDC42/MRCK. Furthermore, the findings indicate that ZDF has significant anti-tumorigenic and anti-metastatic characteristics in breast cancer animal models.

The effect of propofol on chemosensitivity of paclitaxel in cervical cancer cells.

Propofol is a drug with potential anticancer effect. This study aimed to explore the effect of propofol on chemosensitivity of cervical cancer cells to paclitaxel. HeLa and CaSki cells were selected for drug experiments. Cell viability was evaluated via CCK-8 assay, and the combination index (CI) was calculated by CompuSyn software. A clinically relevant concentration and IC30 of propofol were selected in combination with 5 nM paclitaxel. BrdU incorporation, transwell, and flow cytometry assays were utilized to evaluate cell proliferation, migration, invasion, and apoptosis. The expression of β-tubulin, stathmin 1, and GAPDH proteins was evaluated by Western blot. The stathmin 1 cDNA plasmid was used to establish stathmin 1-overexpressing CaSki cells. At clinically relevant concentrations (0-80 μM), propofol did not affect cancer cell viability, but high concentrations (100-800 μM) reduced cell viability. The CI values of propofol with IC30 (200 μM in HeLa; 400 μM in CaSki) combined with 5 nM paclitaxel were <1. The effect of propofol with IC30 combined with paclitaxel on cell proliferation, migration, invasion, and apoptosis were stronger than individual effect, while 30 μM propofol had no effect. The Western blot results showed 30 μM propofol did not affect β-tubulin and stathmin 1 expression in cells, although paclitaxel upregulated β-tubulin expression while downregulating stathmin 1 expression. Compared with paclitaxel alone, cotreatment with propofol at its IC30 and paclitaxel decreased stathmin 1 expression but had no effect on β-tubulin expression. High stathmin 1 expression weakened the effect of paclitaxel on cell viability and apoptosis, while propofol partially reversed these effect. Propofol at clinically relevant concentrations had no effect on the malignant biological behaviors of cervical cancer cells, while propofol at high concentrations decreased.Propofol with IC30 and paclitaxel had synergetic effect on cancer cells through a reduction in stathmin 1 expression.

Combination Curcuma longa and Phyllanthus niruri Extract Potentiate Antiproliferative in Triple Negative Breast Cancer MDAMB-231 Cells.

Triple negative breast cancer cells (TNBC) are a small part of cancer-inducing cells in breast cancer, which are characterized by high metastatic and self-renewal. Self-renewal has the ability to renew itself and loses control of proliferation. Curcuma longa extract (CL) and Phyllanthus niruri extract (PN) known to have anti-proliferative effects on cancer cells. However, the effects of combination CL and PN on TNBC proliferation still unclear. This study aimed to evaluate the antiproliferative effects of the combination CL and PN on TNBC MDAMB-231 and attempted to elucidate the underlying molecular mechanisms. The dried rhizomes of Curcuma longa and the herbs of Phyllanthus niruri were macerated with ethanol for 72 h.The antiproliferative and synergistic effects of combination CL and PN were investigated using 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay. Combination index values were calculated using CompuSyn (ComboSyn, Inc, Paramus, NJ). The cell cycle and apoptosis assay were determined by propidium iodide (PI) and PI-AnnexinV assay under flow cytometer, respectively. The intracellular ROS levels were evaluated using 2',7'-Dichlorodihydrofluorescein diacetate (DCFDA) assay. The mRNA expressions of proliferation-related genes in the cells were determined using bioinformatic assay. The CL and PN single treatment caused a potent and dose-dependent decrease in the percentage of viable cells with IC50 value of 13 μg/mL and 45 μg/mL for 24 h, respectively. The combination index values of the different combinations ranged from 0.08 - 0.90, indicating slightly strong to very strong synergistic effects. The combination of CL and PN also remarkably induced the S- and G2/M-phases cell cycle arrest that leading to apoptosis induction. Furthermore, the combination of CL and PN treatment induced the intracellular reactive oxygen species (ROS) levels. Mechanistically, the AKT1, EP300, STAT3 and EGFR signaling as potential targets of combination CL and PN in antiproliferation and antimetastatic of TNBC. The combination of CL and PN exerted promising antiproliferative effects in TNBC. Therefore, CL and PN may be considered a potential source for the development of potent anticancer drugs for breast cancer treatment.

Abstract A35: Overcoming Venetoclax Resistance in Acute Myeloid Leukemia (AML) via the Novel Imipridone ONC213

Abstract Older adults make up most of the AML patient population and have an especially dismal prognosis due to limited therapeutic options. The Bcl-2 inhibitor, venetoclax (VEN), was approved for use in combination with low-dose cytarabine or a hypomethylating agent [azacitidine (AZA) or decitabine] in AML patients who are ≥75 years old or ineligible for intensive chemotherapy (IC). Due to superior survival data and tolerability, the combination of VEN and AZA has become a new standard of care for older patients and those unfit for IC. Though this was a promising therapeutic option for these patients, resistance to this therapy results in a 1-year overall survival rate of only 30-40% and the median overall survival following treatment failure is less than three months, highlighting the urgent need of new therapies to address this. Previous studies have found VEN resistance can be overcome by targeting mitochondria and Mcl-1. Our studies on ONC213, a novel imipridone, have found that it has potent antileukemic activity against both AML cell lines and primary patient samples. It reduces Mcl-1 and targets mitochondria of AML cells – and was thus a promising agent to overcome VEN resistance. When used in combination, ONC213 and VEN are highly synergistic in both AML cell lines and primary patient samples, including those intrinsically resistant to VEN. The combination also targets AML progenitor cells determined by colony formation assays and shows in vivo efficacy in a cell line derived xenograft mouse model (median survival of 57 days vs 37 days in control mice, p=0.002). To determine if ONC213 could overcome acquired resistance to VEN and AZA, we developed VEN and AZA double resistant ML-2 and MV4-11 AML cells (designated ML-2/VEN+AZA-R and MV4-11/VEN+AZA-R) by stepwise increasing concentrations of VEN and AZA at 1:3 fixed ratio over an extended period. ML-2/VEN+AZA-R and MV4-11/VEN+AZA-R AML cells demonstrate 437- and 1156-fold, respectively, increase in VEN+AZA (1:3 ratio) IC50 compared to parental cells (5,285.3 nM vs 12.1 nM and 6,704.3 nM vs 5.8 nM, respectively). ONC213 can resensitize resistant cells to VEN and the combination of ONC213 and VEN is highly synergistic in both ML-2/VEN+AZA-R and MV4-11/VEN+AZA-R cells as evident by a combination index (CI) value of &amp;lt; 0.05. ONC213 alone and in combination with VEN suppress oxidative phosphorylation (OXPHOS) and Mcl-1 in AML cells, including those with inherent resistance to VEN or with acquired resistance to VEN+AZA. Overexpression of Mcl-1 can partially rescue cells from combination therapy. These results suggest that ONC213 suppresses OXPHOS and Mcl-1 to overcome VEN resistance. Here we demonstrate that VEN resistance can be addressed through dual targeting of mitochondria and Mcl-1 using the novel imipridone, ONC213. ONC213 resensitizes VEN + AZA resistant cells to VEN and offers a new approach to combat VEN+AZA resistance in AML. Citation Format: Jenn L. Carter, Yongwei Su, Holly Edwards, Lisa Polin, Joshua E. Allen, Varun V. Prabhu, Jay Yang, Maik Huettermann, Yubin Ge. Overcoming Venetoclax Resistance in Acute Myeloid Leukemia (AML) via the Novel Imipridone ONC213 [abstract]. In: Proceedings of the AACR Special Conference: Acute Myeloid Leukemia and Myelodysplastic Syndrome; 2023 Jan 23-25; Austin, TX. Philadelphia (PA): AACR; Blood Cancer Discov 2023;4(3_Suppl):Abstract nr A35.

Abstract 595: Targeting metabolic vulnerability in brain-metastatic HER2+ breast cancer

Abstract Introduction: Human epidermal growth factor receptor 2 positive (HER2+) breast cancer tumors have increased risk of brain metastases at an advanced stage. The brain’s microenvironment is relatively low in lipids; therefore, breast cancer cells that colonize the brain have an increased expression of fatty acid synthesis enzymes. This presents a potential vulnerability that could be targeted. There is an established feed-forward relationship between HER2 and fatty acid synthase (FASN) where HER2 signaling activates FASN signaling. FASN inhibition has been shown to decrease cell invasion in a preclinical breast cancer model. We hypothesize that targeting HER2+ breast cancer cells with a HER2 tyrosine kinase inhibitor (TKI) or HER2 antibody-drug conjugate (ADC) in combination with a FASN inhibitor will lead to synergistic cell death. We also hypothesize that FASN inhibitors alone impede outgrowth and invasion of HER2+ breast cancer cells. Methods: We performed combinatorial drug-screening using the Chou-Talalay method in vitro using HER2+ breast cancer cell spheroids and tested the impact of FASN inhibitors alone on the outgrowth of these spheroids embedded in Matrigel. The HER2+ cell lines we used include JIMT-1, JIMT-1-BR3, SUM190, and SUM-190-BR3. JIMT-1-BR3 and SUM190-BR3 are brain-seeking subclones of the primary cell lines generated by serial passaging through mice with collection of cells in the brain. In combinatorial drug-screening, we calculated combination index (CI) values for the combination of each of two FASN inhibitors (TVB-2640 and BI-99179) with each of three clinically approved HER2 TKIs (Tucatinib, Lapatinib, and Neratinib) and each of two ADCs (Trastuzumab deruxtecan and Trastuzumab emtansine). The experiments were performed in both media supplied with fetal bovine serum (FBS) and with lipid-stripped FBS, to mimic the brain microenvironment. Results: Drug screening revealed that FASN inhibitors are toxic only at high doses in cell viability assays. However, we calculated combination index (CI) values using the Chou-Talalay method indicative of synergy for the combinations of the FASN inhibitors with the HER2-targeting drugs. Moreover, we discovered that the FASN inhibitors TVB-2640 and BI-99179 alone significantly impede the outgrowth of the spheroids embedded in Matrigel. Conclusions: Based on these promising preliminary data, we will evaluate these results in vivo. Breast cancer patients harboring brain metastases are difficult to treat, and they suffer from severe symptoms impacting daily life and have poor survival rates. Our ultimate goal is to launch a clinical trial to test one or more of these drug combinations to provide an additional therapeutic option that may improve patients’ lives and decrease mortality. Citation Format: Habib Serhan, Liwei Bao, Xu Cheng, Sofia Merajver, Aki Morikawa, Nathan Merrill. Targeting metabolic vulnerability in brain-metastatic HER2+ breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 595.

Abstract 1638: Validation of a novel pan-Ras inhibitor, ADT-007, against lethal variants of prostate cancer

Abstract Metastatic prostate cancer is the second leading cause of cancer deaths in US men. Most early-stage PCa are dependent on overexpression of the androgen receptor (AR) and are therefore sensitive to androgen deprivation therapies. However, eventual resistance to standard medical castration and secondary chemotherapies including next-generation AR-targeting agents like abiraterone or enzalutamide and taxanes (Docetaxel or cabazitaxel) is nearly universal. Further, neuroendocrine PCa or NEPC, a poorly differentiated aggressive variant of PCa that lacks AR expression, and the presence of cancer stem-like cells with self-renewal and differentiation (epithelial to mesenchymal trans-differentiation or EMT) capacities significantly contribute to the development of clinically most aggressive and lethal variants of PCa. Endogenous Ras/ERK/MAPK signaling is known to drive prostate tumor formation, cancer progression, cell migration, and the acquisition of mesenchymal phenotype (EMT) in metastatic prostate cancers. Ras family members are responsible for modulating the function of most of the receptors upregulated in advanced PCa, including AR, so that AR can be functional even in the absence of physiologic levels of androgen. Previous studies have reported that the NSAID, sulindac, inhibits Ras-induced transformation and directly binds Ras. In this study, we show that a non-COX inhibitory sulindac derivative, ADT-007, is a potent drug candidate against lethal PCa. First, we performed single-cell RNA sequencing as a biomarker-based drug screen and showed that chemo-resistant, drug-tolerant, stem-cell-like PCa cell clusters had high expression of Ras genes, indicating that the Ras inhibitor, ADT-007, may be effective in targeting these aggressive subclones. Next, using several cell-based assays on a large panel of lethal PCa cell lines representing metastatic castration-resistant PCa (mCRPC), NEPC as well as African American ancestry, we showed that ADT-007 is highly effective as a single-agent and in combination with taxanes. Combination index values were &amp;lt;0.7, and BLISS scores were &amp;gt;10, indicating very high synergy. Finally, using pre-vs-post-treatment bulk RNAseq, we demonstrated that ADT-007 is indeed effective in downregulating KRas and NRas in a dose-dependent manner. In addition, ingenuity pathway analysis (IPA) predicted significant downregulation of cell cycle, DNA replication, CCND1, AR, and the lncRNA ELDR, and upregulation of autophagy and interferon pathway genes, and the microRNA miR-96. Finally, using PCa patient datasets, we showed that ADT-007 is potentially capable of reversing the expression of several genes associated with biochemical recurrence. Thus, our results show that ADT-007 is a novel drug candidate that circumvents subclonal aggressiveness, drug resistance, and stemness in lethal PCa through simultaneous inhibition of multiple oncogenic factors/pathways. Citation Format: Taraswi Mitra Ghosh, Adam B. Keeton, Xi Chen, Salsabil Ahmed, Razan S. Waliagha, Gary A. Piazza, Amit K. Mitra. Validation of a novel pan-Ras inhibitor, ADT-007, against lethal variants of prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1638.

Abstract 2774: Moesin-induced adriamycin resistance through IL-6/MSN/STAT3 axis and therapeutic efficacy of atovaquone in chemotherapy resistant triple-negative breast cancer

Abstract Introduction: Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer with a high frequency of chemotherapy resistance. Moesin (MSN) is a cytoskeleton linker discovered as a novel oncogene in our previous proteomics analysis. Here, we evaluated the molecular mechanisms of MSN and how it functions in response to chemotherapy, which remains unclear in TNBC. Method: The 178 in-house TNBC patient cohort and METABRIC data set were enrolled for clinicopathologic analysis. The multiple TNBC four-cell lines were used to establish MSN knock-down and over-expressed in vitro models using a lentiviral system. RNA sequencing was analyzed with MDA-MB-231 parent cell and MDA-MB-231/ADR12 (adriamycin resistance cell line). Invasion and migration assay was done. The drug response based on MSN gene expression was observed by cell viability assay, western blot, and AV/PI flow cytometry. Drug resistance concerning cancer stemness was confirmed with sphere formation and ALDH activity assay. Immunofluorescence and immunoprecipitation were performed. The combination index(CI), which is to define the synergism of combined treatment was calculated with the Compusyn program. Results: The cohort with METABRIC and our in-house clinical data showed concordant findings that overexpressed MSN mRNA and protein expressions have a poor prognosis in TNBC patients. The MSN protein expression in TNBC was increased compared to the protein level in both the normal human tissues and non-TNBC cell lines. Overexpressed MSN induced high cell proliferation activity, invasion, and migration ability. The apoptosis rate (AV+/PI+) along with cleaved PARP and caspase-3 expression was increased in TNBC cell lines with MSN downregulation. Further tests to determine the role of MSN in adriamycin resistance showed an increased number and size of spheres in the MSN overexpressed cell lines. Moreover, the protein and mRNA levels of MSN expression in MDA-MB-231/ADR12 were significantly higher than the level in the matched parental cell line. MSN and phospho-STAT3(T705) were increased by treatment of IL-6 in TNBC cell lines. The direct binding between MSN and STAT3, and the co-localization of MSN and pSTAT3 were consistently confirmed by co-immunoprecipitation and immunofluorescence, which were all activated by IL-6. Blocking the STAT3 pathway with atovaquone restored ADR response in MSN overexpressed tumor cells. CI value on the combined treatment of ADR and atovaquone in the MDA-MB-231/ADR12 cell line showed higher synergetic efficacy than the parental cell line. Conclusion: This research demonstrates the involvement of the MSN in doxorubicin resistance through IL-6/MSN/STAT3 pathway and provides a novel therapeutic candidate for TNBC patients. Citation Format: Cheng Hyun Lee, Da Sol Kim, Soo Young Park, Han Suk Ryu. Moesin-induced adriamycin resistance through IL-6/MSN/STAT3 axis and therapeutic efficacy of atovaquone in chemotherapy resistant triple-negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2774.

Abstract 5483: Combined inhibition of CDK4/6 and AKT is highly active against the luminal androgen receptor (LAR) subtype of triple negative breast cancer (TNBC)

Abstract The LAR subtype of TNBC is enriched for targetable biomarkers, including androgen receptor (AR) expression, PIK3CA mutations, and intact Rb. The purpose of this study was to investigate the most effective combinations of inhibitors of CDK4/6 (palbociclib), AR (enzalutamide), and PI3K-AKT (alpelisib/capivasertib) against preclinical models of LAR TNBC. MDA-MB-453 and MFM-223 (both AR positive/Rb-intact/PIK3CA-mutant) LAR TNBC cells were treated with each inhibitor alone or in different combinations. Drug sensitivity was measured as growth in 2D, colony formation, and CellTiterGlo viability. Synergistic drug effects were expressed as the combination index (CI) calculated by CompuSyn methods. Activation of cell cycle and PI3K-AKT signaling molecules in response to different inhibitors or siRNAs was measured by immunoblot analysis. An androgen response element (ARE) luciferase reporter assay was used to evaluate AR transcriptional activity. MDA-MB-453 and MFM-223 cells were sensitive to single-agent palbociclib, alpelisib, or capivasertib (IC50 ~500 nM) but not enzalutamide (IC50 15-25 µM). Palbociclib combined with either the PI3Kαi alpelisib or the AKTi capivasertib synergistically inhibited growth of both cell lines (CI values, 0.07-0.86). AR transcriptional reporter activity was not altered by any of these treatments. Treatment with palbociclib monotherapy (24 h) suppressed p-Rb and increased phosphorylation of AKTS473 and its substrates FOXO3A, GSK3β, and PRAS40, suggesting PI3K/AKT signaling mediates an adaptive response to CDK4/6 blockade. In MDA-MB-453 cells, palbociclib-induced phosphorylation of AKT substrates was suppressed by treatment with capivasertib but not with alpelisib alone or with the PI3Kβ/δ inhibitor AZD8186, suggesting that the compensatory activation of AKT was due to a mechanism independent of the PI3K isozymes. We next used RICTOR siRNAs to block mTORC2-mediated phosphorylation AKTS473 after palbociclib treatment. Gene silencing of RICTOR reduced levels of the mTORC2 substrate p-SGK1S422 but did not block phosphorylation of AKTS473 and its substrates in palbociclib-treated cells, suggesting that this adaptative response was mTORC2-independent. Mean CI values showed that the combination of palbociclib/capivasertib was clearly more synergistic than palbociclib/alpelisib in both cells lines (mean CI, 0.29 vs. 0.78). Currently, we are comparing both combinations in mice bearing established MDA-MB-453 xenografts. Further investigation of the mechanisms of adaptive activation of AKT upon blockade of CDK4/6 in TNBC cells are in progress. In sum, addition of an AKT inhibitor, but not PI3K inhibitors, to palbociclib suppressed the rebound activation of AKT following treatment with the CDK4/6i, supporting a testable therapeutic strategy in LAR TNBC with intact Rb. Citation Format: Maria del Rosario Chica-Parrado, Gun Min Kin, Chang-Ching Lin, Kyung-min Lee, Fabiana Napolitano, Dan Ye, Emmanuel Bikorimana, Saurabh Mendirata, Ariella Hanker, Carlos L. Arteaga. Combined inhibition of CDK4/6 and AKT is highly active against the luminal androgen receptor (LAR) subtype of triple negative breast cancer (TNBC). [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5483.

Abstract 2685: Synergistic antitumor effect of oncolytic virus and cytotoxic chemotherapy in gastric cancer

Abstract Introduction: The prognosis of advanced gastric cancer is extremely poor, and the development of novel effective treatment is necessary. Currently, platinum-based, fluoropyrimidine-based, and paclitaxel-based combinations are accepted worldwide as established first-line and second-line drug regimens. Pexa-Vec (pexastimogene devacirpvec; JX-594) engineered from the Wyeth vaccine strain has emerged as attractive oncolytic virotherapy in cancer treatment. Pexa-Vec demonstrated oncolytic, immunotherapeutic, and tumor vascular disrupting mechanisms of action. The aim of this study is to investigate the combination efficacy of JX-594 with paclitaxel in human gastric cancer cell lines and to identify potential biomarkers of oncolytic virotherapy. Method: The anti-proliferative activities of paclitaxel and JX-594 were performed using 49 human gastric cancer cell lines, and YCC-32 was selected for sensitive to JX-594 and resistance to paclitaxel. YCC-32 was treated with JX-594 and paclitaxel, alone and in combination. Cytotoxicity was evaluated by MTT assay. Compusyn and Combenefit software was used to evaluate synergistic efficacy. In addition, the synergism effect was evaluated in the xenograft mouse model in vivo. Tumors were implanted by subcutaneous injection of 5 x 106 YCC-32 cells into the right flank of nude mice. When tumors reached &amp;gt;100mm3, mice were treated with either PBS, 1 x 107 plaque-forming units (pfu) of JX-594 by intratumoral (IT), 5mg/kg paclitaxel by intraperitoneal (IP) injection, or combination every 7 days. Result: Cytopathic effect of Pexa-Vec and paclitaxel was observed in YCC-32 gastric cancer cell line. IC50 (half maximal inhibitory concentration) of JX-594 and paclitaxel were 0.0089 MOI and 7.021ng/ml in YCC-32 cell. JX-594 and paclitaxel in YCC-32 was used to assess the synergism of the two drugs in a dose-dependent manner. In YCC-32 cell line, in combination with JX-594 0.01 MOI and paclitaxel 7ng/ml had CI (combination index) value had 0.69, suggesting synergism. To assess the potential therapeutic benefit of combining JX-594 with paclitaxel in vivo, we employed YCC-32 xenograft models and observed the antitumor effects of JX-594, paclitaxel, and their combination. Paclitaxel, JX-594, and their combination reduced tumor growth compared to control at 64.1%, 59.2%, and 19.1% for YCC-32 xenografts. This result suggests that combined treatment with JX-594 and paclitaxel significantly enhanced tumor growth inhibition compared to monotherapy. Conclusion: Combination with JX-594 and paclitaxel showed enhanced antitumor effects in vitro and in vivo. This study shows combination synergism and provides a promising approach to combination therapy with an oncolytic virus on gastric cancer. For future research, additional studies on other gastric cancer cell lines and investigation of mechanisms are needed. Citation Format: Jee Hung Kim, YeLin Kim, Youkeun Shin, Dagyo Oh, Woo Sun Kwon, Tae Soo Kim, Namhee Lee, Keunhee Oh, Hyun Cheol Chung, Hei-Cheul Jeung, Sun Young Rha. Synergistic antitumor effect of oncolytic virus and cytotoxic chemotherapy in gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2685.

Abstract 6730: Preclinical testing of lestaurtinib (CEP701) as a single and combination agent for the treatment of Ewing sarcoma

Abstract Background: Multimodality treatment of Ewing sarcoma (EwS), a highly malignant bone and soft tissue tumor, provides a cure in most patients, but in the metastatic stage the prognosis remains bleak; new systemically effective therapeutic options are urgently needed. The multikinase inhibitor lestaurtinib (CEP701) is an orphan drug that has been clinically studied in various carcinomas, refractory neuroblastoma, and acute myeloid leukemia, but has not yet established itself as a standard therapy. Methods: We performed an in vitro screening of 142 compounds with different mechanisms of action at two different concentrations and measured cell viability 120 hours after the first of two days of treatment. Lestaurtinib was further tested as a lead compound in various cell biology assays in a group of EwS cell lines genetically representing clinically predominant tumor characteristics. Results: Lestaurtinib was among the 21 of 142 (14.8%) compounds tested that were sensitive, i.e., reduced cell viability to below 20% at 1 µM and/or 10 µM in at least four of five EwS cell lines tested. In an expanded group of six other EwS cell lines, 72 hours of treatment with lestaurtinib resulted in significantly reduced cell growth compared to human mesenchymal stem cells. In several colony formation assays, a significant reduction in the number or size of colonies was observed, both when treatment occurred prior to colony growth and when colonies that had already formed were treated. Lestaurtinib induced apoptosis with a significant increase in PI+/FTIC+-driven cells, significantly promoted anoikis, and prevented cell migration by FACS, low adherence flow cytometry analysis, and scratch assays, respectively. Cell cycle analyses by FACS showed significant G2-M cell cycle arrest after 24 hours of treatment. Lestaurtinib also displayed a synergistic cytotoxic effect with doxorubicin, an established agent for the treatment of EwS, and exhibited a favorable dose-reduction index in all EwS cell lines tested. Notably, treatment with lestaurtinib significantly reduced doxorubicin dose at high efficacy levels (Fa 0.97) and low combination index values. Conclusion: Our results highlight the in vitro efficacy of lestaurtinib in EwS and warrant further testing in an in vivomodel as a single agent and in combination with doxorubicin. Citation Format: Samet Dayi, Christiane Schaefer, Anne Albers, Kiruthiga Balusamy, Marc Hotfilder, Maximilian Kerkhoff, Leonhard Koch, Hatice Önder, Claudia Rössig, Uta Dirksen, Stefan K. Zöllner. Preclinical testing of lestaurtinib (CEP701) as a single and combination agent for the treatment of Ewing sarcoma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6730.

Abstract 1074: The potential of 18β-glycyrrhetinic acid benefit lenvatinib induced cytotoxicity on hepatocellular carcinoma

Abstract Hepatocellular carcinoma (HCC) is usually caused by long-term inflammation such as infected by hepatitis B and C viruses. The current standard treatment methods of HCC has included with general surgery, radiation, etc. However, the recurrence rate remain high even after standard treatment, it is necessary to find a better treatment option to control the progression of HCC. Lenvatinib is a multi-endothelial angiogenesis factor inhibitor which is a first-line target drug for the treatment of advanced HCC. Some studies indicated that activation of the PI3K/AKT pathway could lead to the resistance effect of lenvatinib in HCC. 18β-glycyrrhetinic acid (18β-GA) is a hydrolyzed product of glycyrrhizic acid in the intestine. Studies reported that 18β-GA can effectively treat inflammatory diseases and may have antitumor potential. Some studies also indicated that 18β-GA can down-regulate the signaling transduction of PI3K/AKT pathway in various type of cancers. Therefore, in this study, we focused on exploring whether 18β-GA can be used as an adjuvant to downregulate PI3K/AKT signaling and thus enhance the efficacy of lenvatinib on HCC cells and animal model. Here, we used the MTT assay to investigate the cytotoxicity of HCC cells (Huh7 and Hep3B) after various dose of lenvatinib and (or) 18β-GA treatment. We also used combination index (CI) to evaluate the suitable combination condition. In our results, the CI value of lenvatinib 30 μM combined with 18β-GA 100 μM is smaller than 1, which indicated the synergistic effect of combination. We confirmed the superior extrinsic/intrinsic apoptosis induction ability was found in lenvatinib combined with 18β-GA as compared to single treatment. The activation of Fas/FasL pathway, Annexin V, cleaved caspase-3, -8 and -9 were used to confirm the apoptosis induction by lenvatinib combined with 18β-GA. Transwell invasion and wound healing assays results also indicated the invasion/migration suppression ability of lenvatinib combined with 18β-GA on HCC cells. The phosphorylation of AKT were markedly decreased by lenvatinib combined with 18β-GA in HCC cells. Hep3B bearing animal data proved the superior tumor control of lenvatinib combined with 18β-GA. Additionally, the liver function and normal tissue pathology may not affect by combination of lenvatinib and 18β-GA. To conclude, our result demonstrated that 18β-GA may sensitize HCC to lenvatinib via inactivation of PI3K/AKT signaling pathway and induction of extrinsic/intrinsic apoptosis signaling. Citation Format: Yeh Pei-Wen, Yu-Chiang Liu, Yuan Chang, Jiann-Hwa Chen. The potential of 18β-glycyrrhetinic acid benefit lenvatinib induced cytotoxicity on hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1074.

Combination of the LARS1 Inhibitor, BC-LI-0186 with a MEK1/2 Inhibitor Enhances the Anti-Tumor Effect in Non-Small Cell Lung Cancer.

The mammalian target of rapamycin complex 1 (mTORC1) regulates cell growth and proliferation by growth factor coordination and amino acid availability. Leucyl-tRNA synthetase 1 (LARS1) senses the intracellular leucine concentration and mediates amino acid-induced activation of mTORC1. Thus, LARS1 inhibition could be useful in cancer treatment. However, the fact that mTORC1 can be stimulated by various growth factors and amino acids suggests that LARS1 inhibition alone has limitations in inhibiting cell growth and proliferation. We investigated the combined effects of BC-LI-0186, a LARS1 inhibitor, and trametinib, an MEK inhibitor, on non-small cell lung cancer (NSCLC). Protein expression and phosphorylation were observed by immunoblotting, and genes differentially expressed between BC-LI-0186-sensitive and -resistant cells were identified by RNA sequencing. The combined effect of the two drugs was inferred from the combination index values and a xenograft model. LARS1 expression was positively correlated with mTORC1 in NSCLC cell lines. BC-LI-0186 treatment of A549 and H460 cells maintained in media supplemented with fetal bovine serum revealed paradoxical phosphorylation of S6 and activation of mitogen- activated protein kinase (MAPK) signaling. Compared with BC-LI-0186-sensitive cells, -resistant cells showed enrichment of the MAPK gene set. The combination of trametinib and BC-LI-0186 inhibited the phosphorylation of S6, MEK, and extracellular signal-regulated kinase and their synergistic effects were confirmed in a mouse xenograft model. The combination of BC-LI-0186 and trametinib inhibited the non-canonical mTORC1-activating function of LARS1. Our study demonstrated a new therapeutic approach for NSCLC without targetable driver mutations.