Class Of Antineoplastic Agents Research Articles

Cardiovascular disease burden in patients with urological cancers: The new discipline of uro-cardio-oncology.

Cancer remains a major cause of mortality worldwide, and urological cancers are the most common cancers among men. Several therapeutic agents have been used to treat urological cancer, leading to improved survival for patients. However, this has been accompanied by an increase in the frequency of survivors with cardiovascular complications caused by anticancer medications. Here, we propose the novel discipline of uro-cardio-oncology, an evolving subspecialty focused on the complex interactions between cardiovascular disease and urological cancer. In this comprehensive review, we discuss the various cardiovascular toxicities induced by different classes of antineoplastic agents used to treat urological cancers, including androgen deprivation therapy, vascular endothelial growth factor receptor tyrosine kinase inhibitors, immune checkpoint inhibitors, and chemotherapeutics. In addition, we discuss possible mechanisms underlying the cardiovascular toxicity associated with anticancer therapy and outline strategies for the surveillance, diagnosis, and effective management of cardiovascular complications. Finally, we provide an analysis of future perspectives in this emerging specialty, identifying areas in need of further research.

Palladium (II) compounds containing oximes as promising antitumor agents for the treatment of osteosarcoma: An in vitro and in vivo comparative study with cisplatin

Drug resistance, evasion of cell death and metastasis are factors that contribute to the low cure rate and disease-free survival in osteosarcomas (OS). In this study, we demonstrated that a new class of oxime-containing organometallic complexes called Pd-BPO (O3) and Pd-BMO (O4) are more cytotoxic than cisplatin (CDDP) for SaOS-2 and U2OS cells using the MTT assay. Annexin-FITC/7-AAD staining demonstrated a greater potential for palladium-oxime complexes to induce death in SaOS-2 cells than CDDP, an event confirmed using the pan-caspase inhibitor Z-VAD-FMK. Compared to CDDP, only palladium-oxime complexes eradicated the clonogenicity of SaOS-2 cells after 7 days of treatment. The involvement of the lysosome-mitochondria axis in the cell death-inducing properties of the complexes was also evaluated. Using LysoTracker Red to label the acidic organelles of SaOS-2 cells treated with the O3 and O4 complexes, a decrease in the fluorescence intensity of this probe was observed in relation to CDDP and the control. Lysosomal membrane permeabilization (LMP) was also induced by the O3 and O4 complexes in an assay using acridine orange (A/O). The greater efficiency of the complexes in depolarizing the mitochondrial membrane compared to SaOS-2 cells treated with CDDP was also observed using TMRE (tetramethyl rhodamine, ethyl ester). For in vivo studies, C. elegans was used and demonstrated that both complexes reduce body bends and pharyngeal pumping after 24 h of treatment to the same extent as CDDP. We conclude that both palladium-oxime complexes are more effective than CDDP in inducing tumor cell death. The toxicity of these complexes to C. elegans was like that induced by CDDP. These results encourage preclinical studies aimed at developing more effective drugs for the treatment of osteosarcoma (OS). Furthermore, we propose palladium-oxime complexes as a new class of antineoplastic agents.

Expert consensus on the management of breast cancer antibody-drug conjugates infusion

Antibody-drug conjugates (ADC) are a new class of antineoplastic agents whose structure is composed of a monoclonal antibody covalently attached to a cytotoxic drug via a chemical linker. The introduction and clinical application of ADC change the treatment pattern of human epidermal growth factor receptor 2 (HER2) and triple-negative breast cancer, which is put forward new requirements for the standardized use and management of ADC drugs for medical staff. ADC drugs infusion norms and the prevention and management of adverse reactions are important prerequisites for ensuring drug efficacy and safety. Therefore, the Breast Cancer Case Manager Branch of the Chinese Medical Education Association and the consensus formulation group on targeted drug infusion norms jointly formulated an expert consensus on management of breast cancer antibody-drug conjugates infusion norms. The aim is to provide practical guidance and the early prevention and timely management of related adverse reactions of ADC drugs such as Trastuzumab Emtansine, Trastuzumab Deruxtecan, and Sacituzumab Govitecan for clinical staff.

Antibody-drug conjugates: the evolving field of targeted chemotherapy for breast cancer treatment.

Antibody-drug conjugates (ADCs) are a class of antineoplastic agents whose structure is composed of three main components: a monoclonal antibody (mAB) targeting a specific target antigen, a cytotoxic payload, and a linker binding the antibody to the payload. By combining the specificity of mABs with the high potency of the payloads, ADCs constitute a smart drug delivery system with improved therapeutic index. After recognition and binding of the mAB to its target surface antigen, ADCs are internalized by endocytosis by the tumor cell, releasing the payloads into the cytoplasm, where they exert their cytotoxic activity, eventually leading to cell death. The composition of some of the new ADCs confers additional functional properties that allow expanding their activity to neighboring cells not expressing the target antigen, constituting a valuable strategy to overcome tumor heterogeneity. Some of these 'off-target effects', such as the bystander effect, are possibly the mechanism underlying the antitumor activity demonstrated in patients with low expression of the target antigens, which represents an important paradigm shift in anticancer targeted therapy. Three ADCs are currently approved for the treatment of breast cancer (BC); two anti-HER2 (human epidermal growth factor receptor 2) ADCs (trastuzumab emtansine and trastuzumab deruxtecan); and one Trop-2-targeted ADC (sacituzumab govitecan). Based on the unprecedented efficacy data demonstrated by these agents, ADCs have been incorporated as part of standard regimens for all subtypes of advanced BC, as well as for high-risk early HER2-positive BC. Despite the remarkable advances, several hurdles still remain to overcome, including the development of reliable biomarkers for patient selection, prevention, and management of potentially severe toxicities, ADC resistance mechanisms, post-ADC resistance patterns, and optimal treatment sequencing and combinations. In this review, we will summarize the currently available evidence related to the use of these agents, as well as explore the current landscape of ADC development for BC treatment.

Topoisomerase I poisons-induced autophagy: Cytoprotective, Cytotoxic or Non-protective.

Topoisomerase I inhibitors represent a widely used class of antineoplastic agents that promote both single-stranded and double-stranded breaks in the DNA of tumor cells, leading to tumor cell death. Topotecan and irinotecan are the clinically relevant derivatives of the parent drug, camptothecin. As is the case with many if not most anticancer agents, irinotecan and topotecan promote autophagy. However, whether the autophagy is cytotoxic, cytoprotective, or non-protective is not clearly defined, and may depend largely upon the genetic background of the tumor cell being investigated. This review explores the available literature regarding the nature of the autophagy induced by these clinically utilized topoisomerase I inhibitors in preclinical tumor models with the goal of determining whether the targeting of autophagy might have potential as a therapeutic strategy to enhance the antitumor response and/or overcome drug resistance.

Designing a novel fusion protein from Streptococcus agalactiae with apoptosis induction effects on cervical cancer cells

Cervical cancer remains life-threatening cancer in women around the world. Due to the limitations of conventional treatment approaches, there is an urgent need to develop novel and more efficient strategies against cervical cancer. Therefore, the researchers attend to the alternative anti-cancer compounds like bacterial products. Rib and α are known as surface proteins of Streptococcus agalactiae with immunologic effects. In the present study, we designed a new anti-cancer fusion protein (Rib-α) originating from S. agalactiae with in silico methods, and then, the recombinant gene was cloned in the pET-22 (+) expression vector. The recombinant protein was expressed in E. coli BL21. To purify the expressed protein, we applied the Ni-NTA column. The molecular mechanism by which Rib-α is cytotoxic to cancer cells has been discussed based on MTT, flow cytometry, and real-time PCR methods. The engineered fusion protein suppressed the proliferation of the cancer cells at 180 μg/ml. Cytotoxic assessment and morphological changes, augmentation of apoptotic-related genes, upregulation of caspase-3 mRNA, and flow cytometric analysis confirmed that apoptosis might be the principal mechanism of cell death. According to our findings, Rib-α fusion protein motivated the intrinsic apoptosis pathway. Therefore, it can be an exciting candidate to discover a new class of antineoplastic agents.

Potential interactions between antineoplastic agents and medicines used to treat Covid-19.

Cancer patients with Covid-19 are exposed to treatment combinations that can potentially result in interactions that adversely affect patient outcomes. This study aimed to identify potential drug-drug interactions between antineoplastic agents and medicines used to treat Covid-19. We conducted a search for potential interactions between 201 antineoplastic agents and 26 medicines used to treat Covid-19 on the Lexicomp® and Micromedex® databases. The following data were extracted: interaction severity ("major" and "contraindicated") and interaction effects (pharmacokinetic and pharmacodynamic). We also sought to identify the therapeutic indication of the antineoplastic drugs involved in the potential drug-drug interactions. A total of 388 "major" or "contraindicated" drug-drug interactions were detected. Eight drugs or combinations (baricitinib, lopinavir/ritonavir, atazanavir, darunavir, azithromycin, chloroquine, hydroxychloroquine, and sirolimus) accounted for 91.5% of these interactions. The class of antineoplastic agents with the greatest potential for interaction was tyrosine kinase inhibitors (accounting for 46.4% of all interactions). The findings show that atazanavir, baricitinib, and lopinavir/ritonavir can affect the treatment of all common types of cancer. The most common pharmacokinetic effect of the potential drug-drug interactions was increased plasma concentration of the antineoplastic medicine (39.4%). Covid-19 is a recent disease and pharmacological interventions are undergoing constant modification. This study identified a considerable number of potential drug-drug interactions. In view of the vulnerability of patients with cancer, it is vital that health professionals carefully assess the risks and benefits of drug combinations.

Acute Myeloid Leukemia/Myelodysplastic Syndrome (AML/MDS) Associated with PARP Inhibitors: A Real-World Analysis

Introduction: Poly (ADP-ribose) polymerase inhibitors (PARPi's) represent a newer class of antineoplastic agents targeting cancers with defective DNA-damage repair. PARPi's indications include subtypes of ovarian, fallopian tube and primary peritoneal cancer as well as subsets of patients with breast pancreatic and prostate cancers. There are currently 4 PARPi approved by the Food and Drug Administration (FDA): olaparib (approved 12/19/2014), rucaparib (approved 12/19/2016), niraparib (approved 3/27/2017), and talazoparib (approved 10/16/2018). The incidence of AML/MDS is known to be increased following chemotherapy, with a standardized incidence ratio (observed number of cases of AML/MDS among those treated with chemotherapy/expected number of cases in the general population) of 5.8 among patients with ovarian cancer, and 3.8 among patients with breast cancer (Morton et al, JAMA Onc 2018). All 4 PARPi also carry the potential risk of AML/MDS as an adverse event (AE), but a causal relationship has not been established. Notably, almost all patients treated with a PARPi would have exposure to cytotoxic chemotherapy prior to or during PARPi therapy. For patients treated with PARPi's in clinical trials, the duration of therapy prior to cases of AML/MDS emerging ranged from <1 month to 28 months. The incidence of AML/MDS observed in clinical trials with olaparib was <1.5%, rucaparib 1.1%, niraparib 0.8%, and talazoparib 0.3%. Real-world data regarding this rare but life-threatening AE in PARPi-treated patients is needed. We evaluated reports of AML/MDS associated with PARPi's in the post-approval setting. Methods: The FDA Adverse Events Reporting System (FAERS) database was queried for AEs associated with any of the 4 approved PARPi's, from the date of the initial FDA approval for each agent (irrespective of the indication) through March 31, 2020. The FAERS database contains de-identified reports of product-related AEs, coded using the Medical Dictionary for Regulatory Activities (MedDRA) and classified as serious or non-serious. Cases reported outside the United States were excluded. The proportion of AML/MDS reports was analyzed overall and by PARPi. To account for the variation in length of time on the market due to the different approval dates, reports of AML/MDS for each PARPi were analyzed in the first 17 months after approval (the post-marketing period for the most recently approved agent). The indication for which the PARPi was used, the sex and age of the patient experiencing the AE, and the seriousness and outcome of the AE were assessed. Comparisons of the proportion of AML/MDS cases by agent were made using the Chi-square test; statistical significance was determined at a two-sided α=0.05. Results: A total of 12823 post-marketing AE reports were associated with PARPi's, with 88 (0.7%) reporting cases of AML/MDS (Table). The largest proportion of AML/MDS cases were associated with olaparib (54 of a total of 2121 AE reports; 2.5%, p<0.00001 vs. all other PARPi), followed by niraparib (23 of a total of 5879 AE reports; 0.4%) and rucaparib (11 of a total of 4707 AE reports; 0.2%). No AML/MDS cases were associated with talazoparib (0 of a total 116 AE reports). During the first 17 months following each agent's approval, 14 cases of AML/MDS were reported in association with olaparib, 10 with rucaparib, 9 with niraparib, and 0 with talazoparib. The majority of cases of AML/MDS occurred in women (73%), and the most common indication for treatment was ovarian cancer (52%). The median age of the patients in the AML/MDS reports was 66 years. Nearly all cases were classified as serious (98%), and the outcome of the AE was death for 28% of cases, hospitalization for 17% of cases. Conclusions: Our retrospective analysis found that AML/MDS associated with PARPi's was reported rarely in the post-marketing setting, and that 60% involved olaparib. This study is limited by its retrospective design, and the possibility of under-reporting of cases to the FAERS database. Additionally, the time elapsed since approval differed by agent, and lower observed incidence of AML/MDS for some agents may reflect the limited duration of surveillance. No data is available in the case reports regarding length of exposure to chemotherapy. This real-world analysis complements existing clinical trial data and provides insight into AML/MDS associated with 4 different PARPi's in clinical practice. Disclosures Gajra: Cardinal Health: Current Employment. Zettler:Cardinal Health: Current Employment. Klink:Cardinal Health: Current Employment. Feinberg:Cardinal Health: Current Employment.

Cutaneous Toxicities of PI3K Inhibitors: A Series of Two Cases and Review of the Literature

Phosphoinositide 3-kinase (PI3K) inhibitors are a class of antineoplastic agents currently approved for the treatment of multiple hematologic malignancies and breast cancer. These medications have specific molecular targets to limit toxicity; however, cutaneous adverse effects are frequently reported and can require cessation of therapy. Morbilliform, eczematous, psoriasiform, and pityriasis rubra pilaris-like eruptions are most common, though exfoliative dermatitis and Stevens-Johnson syndrome/toxic epidermal necrolysis have also been reported. We highlight two cases of photo-accentuated skin reactions to duvelisib, a p110-d and p110-g isoform inhibitor. Both cases required oral corticosteroids and interruption of therapy for definitive management due to severity. Though one patient was able to later continue on therapy, both patients experienced recurrence with repeat exposure to duvelisib, establishing a notable temporal correlation. Thus, these cases contribute a novel presentation of adverse reactions to PI3K inhibitors to existing literature.

Immune Checkpoint Inhibitor (ICPI) induced Nephrotoxicity – An Insight.

Immune check point inhibitors (ICPIs) are a new class of anti-neoplastic agents being increasingly used by oncologists to treat various malignancies. These drugs have been associated with varied side effects and have a nephrotoxic potential. Many cases of ICPI induced acute kidney injury are increasingly being reported. Their use in CKD patients on dialysis as well as in kidney transplant recipients is associated with various challenges. This review discusses the use of ICPIs in CKD, dialysis and renal transplant patients and their nephrotoxic potential

Multiple Facets of Autophagy and the Emerging Role of Alkylphosphocholines as Autophagy Modulators.

Autophagy is a highly conserved multistep process and functions as passage for degrading and recycling protein aggregates and defective organelles in eukaryotic cells. Based on the nature of these materials, their size and degradation rate, four types of autophagy have been described, i.e. chaperone mediated autophagy, microautophagy, macroautophagy, and selective autophagy. One of the major regulators of this process is mTOR, which inhibits the downstream pathway of autophagy following the activation of its complex 1 (mTORC1). Alkylphosphocholine (APC) derivatives represent a novel class of antineoplastic agents that inhibit the serine–threonine kinase Akt (i.e. protein kinase B), which mediates cell survival and cause cell cycle arrest. They induce autophagy through inhibition of the Akt/mTOR cascade. They interfere with phospholipid turnover and thus modify signaling chains, which start from the cell membrane and modulate PI3K/Akt/mTOR, Ras-Raf-MAPK/ERK and SAPK/JNK pathways. APCs include miltefosine, perifosine, and erufosine, which represent the first-, second- and third generation of this class, respectively. In a high fraction of human cancers, constitutively active oncoprotein Akt1 suppresses autophagy in vitro and in vivo. mTOR is a down-stream target for Akt, the activation of which suppresses autophagy. However, treatment with APC derivatives will lead to dephosphorylation (hence deactivation) of mTOR and thus induces autophagy. Autophagy is a double-edged sword and may result in chemotherapeutic resistance as well as cancer cell death when apoptotic pathways are inactive. APCs display differential autophagy induction capabilities in different cancer cell types. Therefore, autophagy-dependent cellular responses need to be well understood in order to improve the chemotherapeutic outcome.

Cardioprotection in cancer therapy: novel insights with anthracyclines.

Anthracyclines are a class of antineoplastic agents that remain critical to modern-day cancer treatment. However, their propensity to cause cardiotoxic effects limits their use and can cause increased morbidity and mortality among patients with cancer. Currently available methods to minimize the impact of anthracycline cardiotoxicity have not been widely successful. While it is largely accepted that the generation of oxygen radicals contributes to the development of anthracycline cardiotoxicity, the exact mechanisms of cardiomyocyte injury remain unclear. In this review, we discuss the current state of basic and translational research on the cardiotoxic mechanisms of anthracyclines that have led to the discovery of new therapeutic targets. Pending validation in patient populations, these recent advances have the potential to be translated into clinical approaches that will minimize anthracycline cardiotoxicity and improve outcomes in cancer survivors.

Chemotherapy for Lung Cancer in the Era of Personalized Medicine.

Although recent advances in molecular targeted therapy and immuno-oncology have revolutionized the landscape of lung cancer therapeutics, cytotoxic chemotherapy remains an essential component of lung cancer treatment. Extensive evidence has demonstrated the clinical benefit of chemotherapy, either alone or in combination with other treatment modalities, on survival and quality of life of patients with early and advanced lung cancer. Combinational approaches with other classes of anti-neoplastic agents and new drug-delivery systems have revealed promising data and are areas of active investigation. Chemotherapy is recommended as a standard of care in patients that have progressed after tyrosine kinase inhibitors or immune checkpoint inhibitors. Chemotherapy remains the fundamental means of lung cancer management and keeps expanding its clinical implication. This review will discuss the current position and future role of chemotherapy, and specific consideration for its clinical application in the era of precision medicine.

Ixabepilone: new perspectives for its use in breast cancer

Despite significant advances in recent years, the drug therapy for breast cancer (BC) is still based on chemotherapy. The introduction of new effective cytostatic agents with a favorable toxicity profile is likely to remain an urgent objective for modern pharmacology in oncology. Ixabepilone, first in a new class of antineoplastic agents, the epothilones, has demonstrated high efficacy in the treatment of breast cancer both in its early stages and in patients, who have received 2 or more lines of chemotherapy. The article discusses the results of major studies, as well as the last meta-analysis of Ixabepilone studies in locally advanced and metastatic breast cancer. It presents the results of two large randomized studies of Ixabepilone in adjuvant regimens in patients with early breast cancer with an unfavourable prognosis.

Incidence of nonvalvular atrial fibrillation on ibrutinib compared to other tyrosine kinase inhibitors: A large multi-institution general practice study.

e22076Background: Tyrosine kinase inhibitors (TKIs) are a widely used class of antineoplastic agents. Meta-analysis of clinical trials has demonstrated an increased incidence of atrial fibrillation...

Abstract 116: Erufosine, a third-generation alkylphosphocholine with cytotoxic and cytostatic effects in breast and colorectal cancer cells

Abstract Introduction Breast and colorectal cancers are highly malignant diseases with low 5-year survival rate (<21%) in advanced stages, which highlights the need of finding new therapeutic options. Considering this, we are interested in exploring the anticancer potential of erufosine, a membrane targeting synthetic lipid analogue belonging to a class of antineoplastic agents known as alkylphosphocholines (APCs). Properties such as intravenous administration and significantly reduced hemolytic activity as compared to previous APC generations, and efficient cytotoxic effects against malignant cells make it an attractive anticancer compound. Materials and Methods In the present experiments, we studied the effects of erufosine against breast (MDA-MB-231 and MCF-7) and colorectal (SW480 and SW620) cancer cell lines. Following exposure to erufosine (0.78-100µM) for 24, 48 and 72h, cytotoxic effects were measured by MTT dye reduction assay and inhibitory concentrations (IC) were identified by GraphPad Prism software 6. Erufosine mediated cytostatic effects were highlighted by means of propidium iodide (PI) based labeling of the DNA followed by flow cytometry analysis. Furthermore, the cells were exposed to increasing concentrations of erufosine (IC25, 50, 75) and alterations in cell cycle relevant genes (CCNA1, CCND1, CCNE1, CCNE2, CDK1, CDK4) were investigated by qRT-PCR methodology. Results Erufosine was highly active against the selected cell lines (IC50 < 10µM, 24h) and induced significant arrest in the G2/M phase of the cell cycle. The cytostatic effects were more pronounced in the two metastatic cell lines of breast (MDA-MB-231) and colorectal (SW620) cancers. At molecular levels, erufosine induced expression of CCNA1 (≥ 2fold) in SW480, SW620, and MCF-7 cells, while the expression was inhibited in MDA-MB-231 cells at high concentrations (IC50, IC75). There were no significant alterations (≤ 2fold) in the expression levels of CCND1, CCNE1 and CDK4 in the four cell lines. CCNE2 was significantly downregulated in breast cancer cell lines only. Noteworthy, alterations in CDK1 were associated with cell lines from primary cancers, where the expression was upregulated in SW480 cells and downregulated in MCF-7 cells. Conclusion Antineoplastic effects of erufosine contribute to decreased proliferation of breast and colorectal cancer cell lines. This synthetic lipid induces arrest in G2/M phase and alterations in cell cycle relevant genes in the selected panel of breast and colorectal cancer cells. Characteristics like in vivo stability, minimal hemolytic activity, no toxicity to bone marrow and antineoplastic effects (cytotoxic/cytostatic) against cancer cells make it an attractive therapeutic compound. Further understanding at molecular levels supported by in vivo experimentation will pave the way to validate its therapeutic potential against cancers. Citation Format: Asim Pervaiz, Saqib Mahmood, Martin R. Berger. Erufosine, a third-generation alkylphosphocholine with cytotoxic and cytostatic effects in breast and colorectal cancer cells [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 116. doi:10.1158/1538-7445.AM2017-116

FK228 augmented temozolomide sensitivity in human glioma cells by blocking PI3K/AKT/mTOR signal pathways

Temozolomide is a novel cytotoxic agent currently used as first-line chemotherapy for glioblastoma multiforme (GBM). Romidepsin (FK228), a histone deacetylase inhibitor, is a promising new class of antineoplastic agent with the capacity to induce growth arrest and/or apoptosis of cancer cells. However, combination of the two drugs in glioma remains largely unknown. In the present study, we evaluated the combinatory effects of FK228 with TMZ in glioma, and its molecular mechanisms responsible for these effects. Glioma cell lines were treated with TMZ, FK228 or the combination of drugs. The resistance effect including cytotoxicity and apoptosis was determined in glioma cells, respectively. We further evaluated the effects of FK228 in the PI3K/Akt-signaling pathway in vitro. Mice engrafted with 5×106 LN382 cells were treated with TMZ, FK228 or the combination of two drugs, and tumor weights and volumes were measured, respectively. FK228 enhanced the cytotoxic effects of TMZ in glioma cells compared to vehicle-treated controls or each drug alone. The combination of FK228 and TMZ-induced apoptosis was demonstrated by increased expression of cleaved-Caspase 3, Bax, cleaved-PARP, and decreased Bcl-2 expression. Furthermore, the expression of key components of the PI3K/Akt-signaling pathway showed that combination of FK228 and TMZ block PI3K/Akt pathways in vitro. This block effect was also confirmed in vivo in mice models. Mice treated with both FK228 and TMZ drugs showed significantly reduced tumor weights and volumes, compared to each drug alone. Our results suggested that FK228 augmented temozolomide sensitivity in human glioma cells partially by blocking PI3K/AKT/mTOR signal pathways. It thus may provide a promising target for improving the therapeutic outcome of TMZ-resistant gliomas, although further studies will be needed.

BRCA1/2 associated cancer susceptibility: a clinical overview

AbstractThe most frequently identified genetic cause of breast cancer is the germline mutation ofBRCA1and 2 genes. The carriers of these mutations are at high risk for breast and ovarian cancers and increased risk for pancreatic and prostate cancers. Personal and family history are routinely used to identify individuals at risk for carrying such mutations. Genetic counselling is required to guide them through genetic testing and risk management. Positive testing corresponds to a deleterious mutation, whereas negative testing is considered as uninformative; variants of unknown clinical significance are also classified as uninformative.The most effective risk reduction strategy involves bilateral prophylactic mastectomy and bilateral salpingo-oophorectomy, eliminating 90% of breast and 97% of ovarian cancer risks, respectively. Before and until such surgery, surveillance with physical examination, mammography and magnetic resonance mammography, starting at 25–30 years of age, are recommended for the early diagnosis of breast cancer; semi-annual surveillance with physical examination, transvaginal ultrasound and serum CA-125 is recommended for women who have not had prophylactic surgery. Carriers diagnosed with breast cancer run a high risk for a new breast primary and this information should be used accordingly. PARP inhibitors is a new class of antineoplastic agents, already approved for advancedBRCA1/2mutant (germline or somatic) ovarian cancer.Multigene panel testing may follow a negativeBRCAgenetic test, often identifying other genetic causes of cancer, expanding its role in oncology. Further adoption of PARP inhibitors, refinement in estimation of BRCA-associated cancer risks and wider population testing, through NGS technology, may become available in the near future.

Abstract 5544: Attempts to synthesize 5,7-dihydroxy-3H-1,2-dithiolo[4,3-d]- pyrimidine, M-47, a potential new treatment for drug- resistant breast cancer

Abstract M-47, 5,7-Dihydroxy-3H-1,2-dithiolo[4,3-d]pyrimidine, represents a novel class of antineoplastic agents both in structure and apparent mechanism of action. The synthesis of M-47 has been shown to be problematic. Mass spectroscopy and HPLC suggest the presence of certain oxidative byproducts in minor quantities along with the desired analog. Repeated efforts to purify M-47 via crystallization, extraction, chemical modification, and various forms of chromatography have failed. Although enrichment of the sample in excess of 90% is possible, absolute purity has not been achieved. Despite the presence of minor impurities this analog was tested against a variety of cancer cell lines in vitro. Interestingly, M-47 displayed equipotent activity against certain breast cancer lines and their multidrug resistant progeny Furthermore, in vitro testing of various ratios of M-47 with its oxidative byproducts indicated that they possessed similar IC50's suggesting that cellular oxidation of M-47 might be a necessary step in its cytotoxic pathway. The profound activity of M-47, especially against drug-resistant tumor cells, warrants further investigation into the chemistry of these compounds, their biological activity and their possible mechanism of action. Note: This abstract was not presented at the meeting. Citation Format: Canio J. Marasco, Joseph A. Dunn, Paula J. Pera, Alexander E. Macubbin. Attempts to synthesize 5,7-dihydroxy-3H-1,2-dithiolo[4,3-d]- pyrimidine, M-47, a potential new treatment for drug- resistant breast cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5544. doi:10.1158/1538-7445.AM2015-5544

Context-Dependent Antagonism between Akt Inhibitors and Topoisomerase Poisons

Signaling through the phosphatidylinositol-3 kinase (PI3K)/Akt pathway, which is aberrantly activated in >50% of carcinomas, inhibits apoptosis and contributes to drug resistance. Accordingly, several Akt inhibitors are currently undergoing preclinical or early clinical testing. To examine the effect of Akt inhibition on the activity of multiple widely used classes of antineoplastic agents, human cancer cell lines were treated with the Akt inhibitor A-443654 [(2S)-1-(1H-indol-3-yl)-3-[5-(3-methyl-2H-indazol-5-yl)pyridin-3-yl]oxypropan-2-amine; ATP-competitive] or MK-2206 (8-[4-(1-aminocyclobutyl)phenyl]-9-phenyl-2H-[1,2,4]triazolo[3,4-f][1,6]naphthyridin-3-one;dihydrochloride; allosteric inhibitor) or with small interfering RNA (siRNA) targeting phosphoinositide-dependent kinase 1 (PDK1) along with cisplatin, melphalan, camptothecin, or etoposide and assayed for colony formation. Surprisingly different results were observed when Akt inhibitors were combined with different drugs. Synergistic effects were observed in multiple cell lines independent of PI3K pathway status when A-443654 or MK-2206 was combined with the DNA cross-linking agents cisplatin or melphalan. In contrast, effects of the Akt inhibitors in combination with camptothecin or etoposide were more complicated. In HCT116 and DLD1 cells, which harbor activating PI3KCA mutations, A-443654 over a broad concentration range enhanced the effects of camptothecin or etoposide. In contrast, in cell lines lacking activating PI3KCA mutations, partial inhibition of Akt signaling synergized with camptothecin or etoposide, but higher A-443654 or MK-2206 concentrations (>80% inhibition of Akt signaling) or PDK1 siRNA antagonized the topoisomerase poisons by diminishing DNA synthesis, a process that contributes to effective DNA damage and killing by these agents. These results indicate that the effects of combining inhibitors of the PI3K/Akt pathway with certain classes of chemotherapeutic agents might be more complicated than previously recognized.