Cytotoxic Chemotherapeutic Agents Research Articles

Dose Optimization in Oncology Drug Development: An International Consortium for Innovation and Quality in Pharmaceutical Development White Paper.

The landscape of oncology drug development has witnessed remarkable advancements over the last few decades, significantly improving clinical outcomes and quality of life for patients with cancer. Project Optimus, introduced by the U.S. Food and Drug Administration, stands as a groundbreaking endeavor to reform dose selection of oncology drugs, presenting both opportunities and challenges for the field. To address complex dose optimization challenges, an Oncology Dose Optimization IQ Working Group was created to characterize current practices, provide recommendations for improvement, develop a clinical toolkit, and engage Health Authorities. Historically, dose selection for cytotoxic chemotherapeutics has focused on the maximum tolerated dose, a paradigm that is less relevant for targeted therapies and new treatment modalities. A survey conducted by this group gathered insights from member companies regarding industry practices in oncology dose optimization. Given oncology drug development is a complex effort with multidimensional optimization and high failure rates due to lack of clinically relevant efficacy, this Working Group advocates for a case-by-case approach to inform the timing, specific quantitative targets, and strategies for dose optimization, depending on factors such as disease characteristics, patient population, mechanism of action, including associated resistance mechanisms, and therapeutic index. This white paper highlights the evolving nature of oncology dose optimization, the impact of Project Optimus, and the need for a tailored and evidence-based approach to optimize oncology drug dosing regimens effectively.

DNA-protein crosslinks are key to platinum-based chemotherapeutic cytotoxicity

DNA-protein crosslinks are key to platinum-based chemotherapeutic cytotoxicity

Innovative Nanoparticulate Strategies in Colon Cancer Treatment: A Paradigm Shift.

As a major public health issue, colorectal cancer causes 9.4% of total cancer-related deaths and comprises 10% of new cancer diagnoses worldwide. In the year 2023, an estimated 153,020 people are expected to receive an identification of colorectal cancer (CRC), resulting in roughly 52,550 fatalities anticipated as a result of this illness. Among those impacted, approximately 19,550 cases and 3750 deaths are projected to occur in individuals under the age of 50. Irinotecan (IRN) is a compound derived from the chemical structure of camptothecin, a compound known for its action in inhibiting DNA topoisomerase I. It is employed in the treatment strategy for CRC therapies. Comprehensive in vivo and in vitro studies have robustly substantiated the anticancer efficacy of these compounds against colon cancer cell lines. Blending irinotecan in conjunction with other therapeutic cancer agents such as oxaliplatin, imiquimod, and 5 fluorouracil enhanced cytotoxicity and improved chemotherapeutic efficacy. Nevertheless, it is linked to certain serious complications and side effects. Utilizing nano-formulated prodrugs within "all-in-one" carrier-free self-assemblies presents an effective method to modify the pharmacokinetics and safety portfolio of cytotoxic chemotherapeutics. This review focuses on elucidating the mechanism of action, exploring synergistic effects, and innovating novel delivery approaches to enhance the therapeutic efficacy of irinotecan.

Design, synthesis, and evaluation of cyclic C7-bridged monocarbonyl curcumin analogs containing an o-methoxy phenyl group as potential agents against gastric cancer

The structure-activity relationship (SAR) between toxicity and the types of linking ketones of C7 bridged monocarbonyl curcumin analogs (MCAs) was not clear yet. In the pursuit of effective and less cytotoxic chemotherapeutics, we conducted a SAR analysis using various diketene skeletons of C7-bridged MCAs, synthesized cyclic C7-bridged MCAs containing the identified low-toxicity cyclopentanone scaffold and an o-methoxy phenyl group, and assessed their anti-gastric cancer activity and safety profile. Most compounds exhibited potent cytotoxic activities against gastric cancer cells. We developed a quantitative structure-activity relationship model (R 2 > 0.82) by random Forest method, providing important information for optimizing structure. An optimized compound 2 exhibited in vitro and in vivo anti-gastric cancer activity partly through inhibiting the AKT and STAT3 pathways, and displayed a favorable in vivo safety profile. In summary, this paper provided a promising class of MCAs and a potential compound for the development of chemotherapeutic drugs.

Abstract A049: Epithelial to mesenchymal transition confers sensitivity to cytotoxic agent Ophiobolin A via alterations in mitochondrial function and metabolic pathways

Abstract Triple negative breast cancer (TNBC) is characterized by its high metastatic potential, resistance to therapeutics and elevated degree of disease reoccurrence. In patients with TNBC, metastasis occurs in approximately half of all cases and is tightly correlated with poor overall survival, made worse by limited therapeutic options. Metastatic events are hypothesized to be facilitated by the epithelial to mesenchymal transition (EMT), gaining enhanced self-renewal, migration, invasion and multidrug resistant capabilities. Thus, targeting these cells remains a primary therapeutic goal, despite significant difficulty. Previous attempts in pursuing these cells through cytotoxic chemotherapeutics or targeted agents has largely failed to significantly improve patient outcomes. However, the fungus-derived sesterterpenoid Ophiobolin A (OpA) has demonstrated nanomolar cytotoxic capabilities and a high therapeutic index, specific to EMT+cells in breast cancer. The properties conferring this sensitivity, and possible novel therapeutic target, though, remain unclear. As the drug-like small molecule presents a major therapeutic opportunity, the details of its mechanism of action must be determined. To this end, we generated mitochondrial cybrids and quantified activity in individual electron transport chain (ETC) complexes, and found OpA to act in a mitochondria-targeted manner. Expanding upon this, we designed an EMT based model of breast cancer and examined alterations in mitochondrial function and metabolic pathways. Targeted liquid chromatography-mass spectronomy of metabolites indicated significant variations in many of those involved in glycolysis, OXPHOS and glutaminolysis. Flow cytometry further revealed a significant decrease in membrane potential and increase in mitochondrial reactive oxygen species (ROS), indicating mitochondrial damage. Dynamic changes between OXPHOS and glycolysis were also detected via Seahorse Bioanalyzer. Transmission electron microscopy (TEM) images and fluorescent microscopy showed distinct alterations in mitochondrial morphology, spatial dynamics and network integrity. Finally, using targeted fluorescent staining, an increase in mitochondrial labile iron was uncovered. This work reveals novel metabolic variations in the context of EMT and exploitable therapeutic targets. Thus, based on these EMT-specific responses, we conclude that EMT imparts distinct alterations to mitochondrial function and metabolic pathways, conferring sensitivity to the cytotoxic effects of OpA. Citation Format: Haleigh Parker, Kayla Haberman, Alexander Kornienko, Antonio Evidente, Daniel Romo, Benny Kaipparettu, Joseph Taube. Epithelial to mesenchymal transition confers sensitivity to cytotoxic agent Ophiobolin A via alterations in mitochondrial function and metabolic pathways [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Breast Cancer Research; 2023 Oct 19-22; San Diego, California. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_1):Abstract nr A049.

Advances in the study of marketed antibody-drug Conjugates (ADCs) for the treatment of breast cancer.

Breast cancer continues to have a high incidence rate among female malignancies. Despite significant advancements in treatment modalities, the heterogeneous nature of breast cancer and its resistance to various therapeutic approaches pose considerable challenges. Antibody-drug conjugates (ADCs) effectively merge the specificity of antibodies with the cytotoxicity of chemotherapeutic agents, offering a novel strategy for precision treatment of breast cancer. Notably, trastuzumab emtansine (T-DM1) has provided a new therapeutic option for HER2-positive breast cancer patients globally, especially those resistant to conventional treatments. The development of trastuzumab deruxtecan (T-DXd) and sacituzumab govitecan (SG) has further broadened the applicability of ADCs in breast cancer therapy, presenting new hopes for patients with low HER2 expression and triple-negative breast cancer. However, the application of ADCs presents certain challenges. For instance, their treatment may lead to adverse reactions such as interstitial lung disease, thrombocytopenia, and diarrhea. Moreover, prolonged treatment could result in ADCs resistance, complicating the therapeutic process. Economically, the high costs of ADCs might hinder their accessibility in low-income regions. This article reviews the structure, mechanism of action, and clinical trials of commercially available ADCs for breast cancer treatment, with a focus on the clinical trials of the three drugs, aiming to provide insights for clinical applications and future research.

Elafibranor emerged as a potential chemotherapeutic drug for non-muscle invasive bladder cancer

Intravesical infusion of chemotherapeutics is highly recommended by several clinical guidelines for treating nonmuscle invasive bladder cancer (NMIBC). However, cytotoxic chemotherapeutics can cause a series of side effects, which greatly limits their application. Herein, a starvation therapy strategy was proposed, and elafibranor (ELA) was validated as a safe chemotherapeutic for NMIBC. The results showed that 20 μM ELA was sufficient to inhibit the proliferation and migration of bladder cancer cells and increase the level of intracellular reactive oxygen species (ROS). Furthermore, 2 mg/kg ELA treatment blocked the growth of primary tumors in an immunodeficient model by inhibiting proliferation and inducing apoptosis and improved the survival time of immunocompetent model mice. ELA treatment up to 10 mg/kg met the general safety requirements. We also established a patient-derived conditional reprogramming cell (CRC) model to assess the clinical translational potential of ELA. The antitumor effect and antitumor specificity of ELA treatment were confirmed. This work not only identified a promising chemotherapeutic for NMIBC but also provided a potential methodological system for drug discovery.

Microfluidic nanoparticle synthesis for oral solid dosage forms: A step toward clinical transition processes

Nanomedicine provides various opportunities for addressing medical challenges associated with drug bioavailability, stability, and efficacy. In particular, oral nanoparticles (NPs) represent an alternative strategy to enhance the solubility and stability of active ingredients through the gastrointestinal tract. The nanocarriers could be used for both local and systemic targeting, enabling controlled release of encapsulated drugs. This approach allows more efficient therapies.In this work, we aim to develop reliable oral solid dosage forms incorporating NPs produced by either one pot synthesis or continuous production, following protocols that yield highly consistent outcomes, promoting their technology transfer and clinical use.Microfluidics technology was selected to allow an automated and highly productive synthetic approach suitable for the highly throughput production.In particular, innovative systems, which combine advantage of NPs and solid dosage formulation, were designed, developed, and characterized demonstrating the possibility to obtaining oral administration. The resulting NPs were thus carried on oral dosage forms, i.e., pellets and minitablets. NPs resulted stable after dosage forms manufacturing, leading to confidence also on protection of encapsulated drugs. Indomethacin was used as a tracer to test biopharmaceutical behaviour.Anti-inflammatories or cytotoxic chemotherapeutics could be vehiculated leading to a breakthrough in the treatment of severe diseases allowing the oral administration of these drugs. We believe that the advancement achieved with the results of our work paves the way for the progression of nanoproducts into clinical transition processes.

Mint3-depletion-induced energy stress sensitizes triple-negative breast cancer to chemotherapy via HSF1 inactivation

Given the lack of therapeutic targets, the conventional approach for managing triple-negative breast cancer (TNBC) involves the utilization of cytotoxic chemotherapeutic agents. However, most TNBCs acquire resistance to chemotherapy, thereby lowering the therapeutic outcome. In addition to oncogenic mutations in TNBC, microenvironment-induced mechanisms render chemoresistance more complex and robust in vivo. Here, we aimed to analyze whether depletion of Munc18-1 interacting protein 3 (Mint3), which activates hypoxia-inducible factor 1 (HIF-1) during normoxia, sensitizes TNBC to chemotherapy. We found that Mint3 promotes the chemoresistance of TNBC in vivo. Mint3 depletion did not affect the sensitivity of human TNBC cell lines to doxorubicin and paclitaxel in vitro but sensitized tumors of these cells to chemotherapy in vivo. Transcriptome analyses revealed that the Mint3–HIF-1 axis enhanced heat shock protein 70 (HSP70) expression in tumors of TNBC cells. Administering an HSP70 inhibitor enhanced the antitumor activity of doxorubicin in TNBC tumors, similar to Mint3 depletion. Mint3 expression was also correlated with HSP70 expression in human TNBC specimens. Mechanistically, Mint3 depletion induces glycolytic maladaptation to the tumor microenvironment in TNBC tumors, resulting in energy stress. This energy stress by Mint3 depletion inactivated heat shock factor 1 (HSF-1), the master regulator of HSP expression, via the AMP-activated protein kinase/mechanistic target of the rapamycin pathway following attenuated HSP70 expression. In conclusion, Mint3 is a unique regulator of TNBC chemoresistance in vivo via metabolic adaptation to the tumor microenvironment, and a combination of Mint3 inhibition and chemotherapy may be a good strategy for TNBC treatment.

Effects of temozolomide on tumor mutation burden and microsatellite instability in melanoma cells.

The efficacy of combination therapy with an immune checkpoint inhibitor (ICI) and cytotoxic chemotherapeutic agents has been investigated in cancer, including melanoma. Before ICIs were introduced, dacarbazine or temozolomide (TMZ) were used to treat melanoma. Several studies using glioma or colorectal cancer cells showed that TMZ can increase the tumor mutation burden (TMB) and induce mismatch repair (MMR) deficiency associated with microsatellite instability (MSI). These could increase immunoreactivity to an ICI, but this has not been evaluated in melanoma cells. We investigated the effects of TMZ on MSI status and TMB in melanoma cells. To evaluate the TMB, we performed whole-exome sequencing using genomic DNA from the human melanoma cell lines Mel18, A375, WM266-4, G361, and TXM18 before and after TMZ treatment. Polymerase chain reaction amplification of five mononucleotide repeat markers, BAT25, BAT26, NR21, NR24, and MONO27, was performed, and we analyzed changes in the MSI status. In all cell lines, the TMB was increased after TMZ treatment (the change amount of TMB with ≤ 5% variant allele frequency [VAF] was 18.0-38.3 mutations per megabase) even in the condition without obvious cytological damage. MSI after TMZ treatment was not observed in any cells. TMZ increased TMB but did not change MSI status in melanoma cells.

Epidemiological and therapeutic profiles of lung cancer patients in the Hokushin Region Japan: a retrospective hospital administrative database study

ObjectiveThis study was performed to validate the epidemiology, initial treatment, and clinical practice of lung cancer patients in the Hokushin region, Japan.MethodsWe retrospectively surveyed data of 5503 newly diagnosed and registered lung cancer patients in 22 principal hospital-based cancer registries in Hokushin region linked with health insurance claims data for registered patients between 2016 and 2017.ResultsThe patients consisted of 3677 (66.8%) men and 1826 (33.2%) women with a mean (range) age of 72.2 (27–103) years). Diagnoses were small cell lung cancer (n = 512, 9.4%), squamous cell carcinoma (n = 1083, 19.7%), and non-squamous non-small cell lung cancer (NSCLC; n = 3906, 70.9%). The population with stage I disease in Toyama prefecture (41.1%) was smaller than in the other three prefectures associated with reduced selection of initial surgical therapy and increased frequencies of stage IV disease (33.2%) and best supportive care (18.6%). Initial chemotherapy for stage IV non-squamous NSCLC consisted of tyrosine kinase inhibitors in 39.3% of cases for EGFR and 4% of cases for ALK-positive non-squamous NSCLC, followed by platinum compounds (25.9%) non-platinum compounds (12.9%), and immune checkpoint inhibitors (10.2%). Carboplatin was the commonly prescribed first-line cytotoxic chemotherapeutic agent (65.4% of patients under 75 years and in 96.7% of patients over 75 years).ConclusionThis study revealed real-world data on epidemiological and treatment status in lung cancer in four prefectures in Hokushin region, Japan. Simultaneous analysis of nationwide registry and insurance data could provide valuable insights for the development of lung cancer screening and medical treatment strategies. In addition, the comparative data analysis with other lesions or countries will be useful for evaluating the differences in clinical practice of cancer managements.

Effect of whole-brain radiotherapy with platinum-based chemotherapy in non-small cell lung cancer patients with multiple metastases including brain metastases

Current guidelines recommend that cytotoxic chemotherapy be considered first in non-small cell lung cancer (NSCLC) patients with multiple metastases, and whole-brain radiotherapy (WBRT) is not initially recommended even if brain metastases are present. However, cytotoxic chemotherapeutic agents are less effective in brain metastases due to poor blood–brain barrier permeability. We investigated the effect of WBRT in combination with cytotoxic chemotherapy on survival in NSCLC patients who were EGFR, ALK, and PD-L1 negative, had an ECOG PS of 2, and had multiple metastases including brain metastases. From January 2005 to December 2018, histologically confirmed NSCLC patients who were EGFR, ALK, and PD-L1 negative, had an ECOG PS of 2, and had multiple metastases including brain metastases were included in this study. Patients were classified into two groups based on receiving WBRT prior to or concurrently with administration of first-line chemotherapeutic agents or receiving chemotherapy only. We compared intracranial progression-free survival (iPFS) and overall survival (OS). Of the 240 NSCLC patients with brain metastases at diagnosis and an ECOG PS of 2, 67 patients were EGFR, ALK, and PD-L1 negative with multiple metastases including brain metastases. Among those patients, 43 (64.2%) received WBRT prior to or concurrently with platinum-based chemotherapy. Patients who received WBRT prior to or concurrently with chemotherapy had better iPFS (7.7 months [4.8–10.6] vs. 3.5 months [2.1–4.9], p = 0.009) and OS (10.8 months [5.9–15.7] vs. 6.1 months [1.9–10.3], p = 0.038) than those who did not receive WBRT. In multivariate analyses, WBRT was significantly associated with iPFS (HR: 1.94 and 95% CI 1.11–3.40, p = 0.020) and OS (HR: 1.92 and 95% CI 1.08–3.42, p = 0.027). In NSCLC patients who are EGFR, ALK, and PD-L1 negative, have an ECOG PS of 2, and have multiple metastases including brain metastases, WBRT prior to or concurrently with chemotherapy could improve iPFS and OS. Therefore, the combination of WBRT with cytotoxic chemotherapy should be considered in these patients.

Natural products as drug candidates for breast cancer (Review).

Progression of early-stage breast cancer to advanced-stage metastatic disease represents a major cause of death in women. Long-term conventional and targeted therapy for breast cancer includes multi-drug combinations of cytotoxic chemotherapeutics and pathway-selective small molecule inhibitors. These treatment options are frequently associated with systemic toxicity, intrinsic/acquired therapy resistance and emergence of a drug-resistant cancer stem cell population. This stem cell population has a chemo-resistant, cancer-initiating, premalignant phenotype that is accompanied by cellular plasticity and metastatic potential. These limitations emphasize an unmet need to identify testable alternatives against therapy-resistant metastatic breast cancer. Natural products such as dietary phytochemicals, nutritional herbs and their constitutive bioactive agents have documented human consumption, and lack detectable systemic toxicity and resultant off-target unfavorable side effects. Because of these advantages, natural products may represent testable alternatives for therapy-resistant breast cancer. The present review discusses published evidence for growth inhibitory efficacy of natural products on cellular models for molecular subtypes of clinical breast cancer and development of drug-resistant stem cell models. Collectively, this evidence validates mechanism-based experimental approaches to screen and prioritize efficacious bioactive agents from natural products as novel drug candidates that may function as therapeutic alternatives for breast cancer.

Current Bioanalysis of Molecularly Targeted Drugs Using Liquid Chromatography–Tandem Mass Spectrometry

Molecular targeted drugs (MTDs), such as tyrosine kinase inhibitors, have been actively developed and widely used in recent years due to their high selectivity and therapeutic efficacy compared to conventional cytotoxic chemotherapeutic agents. Bioanalysis of MTDs for therapeutic drug monitoring (TDM) is performed by many medical and clinical laboratories, and the implementation of TDM for MTDs can lead to better control of tumor progression, reduce tumor recurrence, and minimize side effects. Since bioanalysis of MTDs often requires high detection sensitivity with a limit of quantitation of 1 ng/mL or less, many of the reported analytical methods are performed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). This review highlights recent bioanalytical methods for MTDs using LC-MS/MS. We selected articles on bioanalysis of MTDs of signal transduction inhibitors that (1) were published after 2017, (2) used human samples (whole blood, plasma, serum, urine), and (3) underwent analytical validation. Typical analytical conditions, notable pretreatment techniques, LC separations, and measurement techniques are outlined.

Protective Effects of Momordica charantia (Bitter Melon) against Methotrexate- induced Kidney Damage

Background: Methotrexate is a cytotoxic chemotherapeutic agent that has severe side effects, such as nephrotoxicity. Momordica charantia is a bright yellow-orange fruity plant that has been shown to have antioxidant, antidiabetic, and anti-inflammatory properties. Objective: This study scrutinized the protective effects of Momordica charantia extract against methotrexate- induced nephrotoxicity. Methods: 24 Sprague Dawley male rats were divided into three experimental groups (8 rats in each): Control (C); Methotrexate (MTX); and Methotrexate plus Momordica charantia (MTX+MC). All rats were fed ad libitum and tap water. Methotrexate was administered at 20 mg/kg intraperitoneally as a single dose. In the MTX+MC group, MC was administered at a dose of 50mg/kg for 5 days orally. At the end of the 5th day, the rats were decapitated and kidney samples were taken to analyze glutathione (GSH), malondialdehyde (MDA), myeloperoxidase (MPO), 8-hydroxy-2'-deoxyguanosine (8-OHdG) and caspase-3 activity. Data was analyzed with GraphPad Prism 5.0. Results: Findings showed that while there was a significant increase in MDA, MPO, 8-OHdG levels, and an essential reduction in GSH levels in the MTX-treated group when compared with the control group, bitter melon treatment significantly reversed MDA, MPO, and 8-OHdG levels (p< 0.001). GSH level elevation was observed in the MTX-MC group when compared to the MTX-treated group (p< 0.001). Conclusion: This study showed that bitter melon is thought to have a protective effect against kidney damage caused by methotrexate. With future studies, we believe that the use of bitter melon extract as a protective agent in kidney damage caused by drug-induced oxidative damage will bring an innovative approach to treatment.

Seamless phaseII/III design: a useful strategy to reduce the sample size for dose optimization.

The traditional more-is-better dose selection paradigm, originally developed for cytotoxic chemotherapeutics, can be problematic when applied to the development of novel molecularly targeted agents. Recognizing this issue, the US Food and Drug Administration initiated Project Optimus to reform the dose optimization and selection paradigm in oncology drug development, emphasizing the need for greater attention to benefit-risk considerations. We identify different types of phase II/III dose-optimization designs, classified according to trial objectives and endpoint types. Through computer simulations, we examine their operating characteristics and discuss the relevant statistical and design considerations for effective dose optimization. Phase II/III dose-optimization designs are capable of controlling family-wise type I error rates and achieving appropriate statistical power with substantially smaller sample sizes than the conventional approach while also reducing the number of patients who experience toxicity. Depending on the design and scenario, the sample size savings range from 16.6% to 27.3%, with a mean savings of 22.1%. Phase II/III dose-optimization designs offer an efficient way to reduce sample sizes for dose optimization and accelerate the development of targeted agents. However, because of interim dose selection, the phase II/III dose-optimization design presents logistical and operational challenges and requires careful planning and implementation to ensure trial integrity.

Pharmacological impact of microRNAs in head and neck squamous cell carcinoma: Prevailing insights on molecular pathways, diagnosis, and nanomedicine treatment.

Head and neck squamous cell carcinoma is a disease that most commonly produce tumours from the lining of the epithelial cells of the lips, larynx, nasopharynx, mouth, or oro-pharynx. It is one of the most deadly forms of cancer. About one to two percent of all neo-plasm-related deaths are attributed to head and neck squamous cell carcinoma, which is responsible for about six percent of all cancers. MicroRNAs play a critical role in cell proliferation, differentiation, tumorigenesis, stress response, triggering apoptosis, and other physiological process. MicroRNAs regulate gene expression and provide new diagnostic, prognostic, and therapeutic options for head and neck squamous cell carcinoma. In this work, the role of molecular signaling pathways related to head and neck squamous cell carcinoma is emphasized. We also provide an overview of MicroRNA downregulation and overexpression and its role as a diagnostic and prognostic marker in head and neck squamous cell carcinoma. In recent years, MicroRNA nano-based therapies for head and neck squamous cell carcinoma have been explored. In addition, nanotechnology-based alternatives have been discussed as a promising strategy in exploring therapeutic paradigms aimed at improving the efficacy of conventional cytotoxic chemotherapeutic agents against head and neck squamous cell carcinoma and attenuating their cytotoxicity. This article also provides information on ongoing and recently completed clinical trials for therapies based on nanotechnology.

Abstract 4886: PARP-1 and γ-GCS inhibitors enhance platinum sensitivity in ovarian cancer

Abstract Background: Ovarian cancer is the most important cause of gynaecological cancer-related mortality globally. Approximately 80% of patients are diagnosed with advanced stage (FIGO stage III-IV) of ovarian cancer. The standard treatment approach for advanced EOC is primary debulking surgery followed by adjuvant chemotherapy using taxanes plus platinum. Resistance to platinum based chemo remains a key reason for treatment failure in advanced epithelial ovarian cancer (EOC). Therapeutic efficacy of Poly [ADP-ribose] polymerase 1 (PARP1) and Gamma-glutamyl cysteine Synthetase (γ-GCS)inhibitors in ovarian cancer remains undefined, either as a single agent or in combination with cisplatin. Material and Methods: We determined the combined effect of PJ34 (PARP1 inhibitor) and BSO (Buthionine-sulfoximine- (γ-GCS inhibitor) with cisplatin in ovarian cancer cell lines (OVSAHO, KURAMOCHI, and IGROV1) by MTT assay. PARP1 and GCS levels were analyzed by western blotting. We employed flow cytometry for cell cycle analysis as well as for apoptosis studies. Analysis was done using Graph Pad Prism-6. Results were considered to be statistically significant when p value was < 0.05. Results and Conclusion: Combination of cisplatin with PJ34 and BSO augmented cisplatin toxicity in vitro by decreasing cell proliferation and enhancing cell cycle block and cell death when compared with either single agent. A significant cell death (p= <0.05) was observed with the combination of cisplatin, BSO and PJ34. Conclusion: In conclusion, our study provide experimental evidence on the combined effect of PARP-1 and GCS inhibition on CDDP-induced cytotoxicity in epithelial ovarian cancer cells. We propose that PARP-1and BSO inhibitors can be combined with cytotoxic chemotherapeutic agents such as CDDP to enhance the cytotoxicity of chemotherapeutic agents and inhibit key signalling pathways involved in cell proliferation and apoptosis. Future comprehensive studies are needed to demonstrate further validation of above combination. Keywords: Ovarian Cancer, cisplatin, PARP-1, PJ34, γ -GCS, β-actin, Glutathione. Abbreviations: Epithelial Ovarian Cancer (EOC), cisplatin (CDDP), Glutathione (GSH), Gamma Glutamyl Cysteine Synthetase (γ-GCS), Poly (ADP ribosyl) polymerase-1 (PARP1), Nucleotide excision repair (NER),homologous repair (HR), Enzyme-linked immunosorbent assay (ELISA), Buthionine Sulfoximine (BSO), Quantitative Polymerase Chain Reaction (qPCR), Peripheral Blood (PB). Propidium Iodide(PI). Citation Format: Luxmi Devi, Ashok Sharma, Lalit Kumar. PARP-1 and γ-GCS inhibitors enhance platinum sensitivity in ovarian 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 4886.

Abstract 6252: HDAC inhibition increases Ewing sarcoma sensitivity to chemotherapy

Abstract Purpose: The survival rate of those with Ewing sarcoma (ES) has seen very little improvement over the past several decades and remains dismal for those with recurrent or metastatic disease. Current treatment for Ewing sarcoma includes a combination of cytotoxic chemotherapeutic agents and local control with radiation and/or surgery. The purpose of this study is to identify currently available targeted agents which may be combined with chemotherapy for use in Ewing sarcoma to improve patient outcomes. Methods: Novel targeted approaches for the treatment of ES were identified using RNA sequencing performed on ES patient tumors with bioinformatic analysis of gene expression. HDAC inhibitors were tested on patient cell lines at escalating doses and cell viability was assessed with CellTiter-Glo 2.0 and analyzed with GraphPad Prism to determine the IC50. Cells were treated with Panobinostat for 12 and 24 hours and RNA sequencing was performed. Cell cycle analysis was performed using Incucyte® Cell Cycle Lentivirus Reagent and analyzed using an Incucyte® S3. At 24- and 48-hours western blot analysis was performed to evaluate the effect on cell cycle and apoptosis. Combination studies with standard chemotherapy were performed and viability was assessed with CellTiter-Glo 2.0. At 24 hours of treatment with a combination of doxorubicin and HDAC inhibition western blot analysis was performed to evaluate changes in DNA damage and repair. Results: RNA analysis identified HDAC2 as a potential therapeutic target. The pan-HDAC inhibitors, Panobinostat and Belinostat, and the HDAC1/2 inhibitor, Romidepsin, were cytotoxic to all Ewing sarcoma cell lines tested with clinically relevant IC50s. Mechanistically, pathways involved in cell cycle progression and DNA repair were repressed by Panobinostat as shown by RNA sequencing and western blotting (Cyclin D1, pRb, CHK1). Additionally, cell cycle analysis has shown a G1 arrest in response to HDAC inhibition. HDAC inhibitors significantly decrease cell viability when combined with standard chemotherapy (upfront and relapse therapy) compared to that of chemotherapy alone. When combined with doxorubicin, CHK1 and CHK2 were significantly decreased and pH2AX was significantly increased indicating an accumulation of DNA damage. Conclusion: This work highlights that combining HDAC inhibitors with standard of care chemotherapy may be an effective treatment and improve outcomes for Ewing sarcoma patients. Future studies of HDAC inhibitors combined with chemotherapy drugs will aim to determine efficacy in xenograft models. Citation Format: Kaitlyn H. Smith, Chloe Sholler, Divya Gandra, Kimberly McKinney, Karl Dykema, Abhinav Nagulapally, Erin Trovillion. HDAC inhibition increases Ewing sarcoma sensitivity to chemotherapy [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 6252.

Circ_0001312 Silencing Suppresses Doxorubicin-Induced Cardiotoxicity via MiR-409-3p/HMGB1 Axis.

Doxorubicin (DOX) is a potent cytotoxic chemotherapeutic agent limited in clinical application owing to its cumulative and irreversible cardiotoxicity. Circ_0001312 is highly expressed in patients with heart failure. However, it is still unclear whether circ_0001312 plays any roles in DOX-induced cardiotoxicity.Human AC16 cardiomyocytes in functional group were stimulated with DOX. The levels of genes and proteins were detected by qRT-PCR and western blotting. The proliferation, apoptosis, as well as inflammatory and oxidative injury in cardiomyocytes were investigated. Dual-luciferase reporter, RNA immunoprecipitation, and pull-down assays were utilized to confirm the binding between miR-409-3p and circ_0001312 or HMGB1 (high-mobility group box 1). Exosomes were isolated by using the commercial kit and identified by transmission electron microscopy (TEM) and nanoparticle-tracking analysis (NTA).DOX impaired cardiomyocyte proliferation and induced apoptotic, inflammatory, and oxidative injury in cells. Furthermore, it promoted circ_0001312 expression, and the knockdown of circ_0001312 could reverse DOX-evoked cardiomyocyte injury. In terms of mechanics, circ_0001312 bound competitively to miR-409-3p to up-regulate HMGB1, which was a target of miR-409-3p. DOX decreased the miR-409-3p but increased the HMGB1 expression in cardiomyocytes. Functionally, miR-409-3p inhibition attenuated the protective action of circ_0001312 silencing on cardiomyocytes under DOX treatment. Moreover, miR-409-3p could abate DOX-evoked apoptosis, and inflammation and oxidative stress in cardiomyocytes, and these effects were counteracted by HMGB1 overexpression. In addition, circ_0001312 was secreted by exosomes and could be transmitted via exosomes.Circ_0001312 reversed the cytotoxic effects mediated by DOX on cardiomyocytes via the miR-409-3p/HMGB1 axis. Besides, it was released to the extracellular space by exosomes.