James H. Doroshow

Molecular mechanisms underlying chronic inflammation-associated cancers.

Although it is now accepted that chronic inflammation plays an essential role in tumorigenesis, the underlying molecular mechanisms linking inflammation and cancer remain to be fully explored. Inflammatory mediators present in the tumor microenvironment, including cytokines and growth factors, as well as reactive oxygen species (ROS) and reactive nitrogen species (RNS), have been implicated in the etiology of inflammation-associated cancers. Epithelial NADPH oxidase (Nox) family proteins, which generate ROS regulated by cytokines, are upregulated during chronic inflammation and cancer. ROS serve as effector molecules participating in host defense or as chemo-attractants recruiting leukocytes to wounds, thereby influencing the inflammatory reaction in damaged tissues. ROS can alter chromosomal DNA, leading to genomic instability, and may serve as signaling molecules that affect tumor cell proliferation, survival, metabolism, angiogenesis, and metastasis. Targeting Noxs and their downstream signaling components may be a promising approach to pre-empting inflammation-related malignancies.

Enzymatic Defenses of the Mouse Heart Against Reactive Oxygen Metabolites: ALTERATIONS PRODUCED BY DOXORUBICIN

The endogenous defenses of the mouse heart against reactive oxygen metabolites were investigated. The activities of three enzymes capable of detoxifying activated oxygen were determined in both the heart and liver; cardiac muscle contains 150 times less catalase and nearly four times less superoxide dismutase than liver. Glutathione peroxidase activities were, however, similar to the two tissues. Assay of glutathione peroxidase in the heart after 6 wk of selenium depletion with both hydrogen peroxide and cumene hydroperoxide as substrates revealed a >80% drop in enzyme activity and gave no indication that murine cardiac tissue contains nonselenium-dependent glutathione peroxidase. The selenium-deficient state, which was characterized by markedly decreased cardiac glutathione peroxidase levels, led to significantly enhanced doxorubicin toxicity at a dose of 15 mg/kg i.p. Doxorubicin administration in selenium-sufficient animals resulted in a dose-dependent decrease in cardiac glutathione peroxidase activity; the decrease in enzyme activity lasted 72 h after 15 mg/kg i.p. In contrast, cardiac superoxide dismutase and hepatic superoxide dismutase and glutathione peroxidase were unaffected by this dose of doxorubicin. These results suggest that the major pathway in cardiac tissue for detoxification of reactive oxygen metabolites is via the concerted action of superoxide dismutase and selenium-dependent glutathione peroxidase. The latter enzyme may be depleted by a selenium-deficient diet or doxorubicin treatment, leaving the heart with limited mechanisms for disposing of hydrogen peroxide or lipid peroxides.

Interleukin-2 and lymphokine-activated killer cell therapy of solid tumors: analysis of toxicity and management guidelines.

The National Cancer Institute (NCI) Extramural IL2/LAK Working Group treated 93 patients with 114 cycles of high-dose intravenous (IV) interleukin-2 (IL-2) and lymphokine-activated killer (LAK) cells in three phase II trials. Thirty-six patients had metastatic melanoma, 35 had metastatic renal cell cancer, and 22 had colorectal cancer. All patients had a Karnofsky performance status greater than or equal to 80% and normal laboratory tests and organ function, and had received no more than one prior form of immunotherapy or chemotherapy. Objective responders were eligible to receive up to two additional courses of therapy at 12-week intervals. The most frequent toxicities were a capillary leak syndrome resulting in marked extravascular fluid shifts, and hypotension requiring treatment with large volumes of IV fluids and vasopressor agents. Laboratory and clinical evidence of hepatic and renal dysfunction were virtually universal. Intensive care-level support was routinely provided and the toxicity observations confirmed the need for this level of care. The life-threatening toxicities were cardiac and pulmonary. Five of the 27 patients who experienced significant respiratory compromise required intubation and mechanical ventilatory support. Twenty patients developed cardiac arrhythmias, the majority of which were supraventricular. There was a single episode of ventricular tachycardia requiring cardioversion. Four patients had transient cardiac ischemia, and an additional four had myocardial infarctions, one of which was fatal. With these exceptions, all toxicities were rapidly reversible. The occurrence of only a single therapy-related death and a very low incidence of other irreversible or life-threatening events is comparable to the level of toxicities often observed in other phase II trials. Although the intensity of this regimen limits this approach to a subset of cancer patients with excellent performance status and adequate organ function, because of the frequency and apparent durability of complete responses, this treatment warrants further investigation.

Prevention of doxorubicin cardiac toxicity in the mouse by N-acetylcysteine.

This study was undertaken to investigate the effect of exogenous sulfhydryl compound administration on the toxicity of doxorubicin in mice. Pretreatment of CDF1 mice with a pharmacologic dose (2,000 mg/kg) of n-acetyl-l-cysteine 1 h before doxorubicin (20 mg/kg, i.p.) decreased lethality from 100% (n = 44) to 37.7% (n = 53), P less than 0.001. Variation in the timing and dose of n-acetylcysteine significantly diminished its protective activity. Pretreatment with n-acetylcysteine also significantly reduced long-term mortality in animals receiving multiple doses of doxorubicin; 10 wk after the third of three doxorubicin doses (5 mg/kg, i.p.) administered at 2-wk intervals, survival in the n-acetylcysteine pretreated group was 51.4% (n = 35) compared with 16.7% (n = 30) for animals receiving saline before doxorubicin, P less than 0.01. In this experiment, n-acetylcysteine pretreatment also diminished doxorubicin-related losses in total body weight and heart wet weight by 55.2% (P less than 0.05), and 60.9% (P less than 0.02), respectively, compared with animals pretreated with saline. N-acetylcysteine pretreatment also ablated electron microscopic evidence of doxorubicin cardiomyopathy without alleviating morphological features of its toxic effects on the liver or small intestinal mucosa. The cardioprotective action of n-acetylcysteine may be partially explained by the 429 +/- 60% increase in cardiac nonprotein sulfhydryl content (P less than 0.01) that was measured one hour after n-acetylcysteine administration; nonprotein sulfhydryl concentration in the liver at the same time was insignificantly different from control levels. Treatment with n-acetylcysteine also increased the nonprotein sulfhydryl content of P388 leukemia cells nearly threefold; however, it did not after the chemotherapeutic activity of doxorubicin against this murine tumor. Whereas n-acetylcysteine blocked doxorubicin cardiac toxicity, it did not affect the uptake or metabolism of doxorubicin in the heart or liver. These results suggest that the concentration of free sulfhydryl groups in the heart may play a role in the development of doxorubicin cardiac toxicity and that augmenting cardiac nonprotein sulfhydryl group content with n-acetylcysteine may provide a means to enhance the chemotherapeutic index of doxorubicin.

CellMiner: A Web-Based Suite of Genomic and Pharmacologic Tools to Explore Transcript and Drug Patterns in the NCI-60 Cell Line Set

High-throughput and high-content databases are increasingly important resources in molecular medicine, systems biology, and pharmacology. However, the information usually resides in unwieldy databases, limiting ready data analysis and integration. One resource that offers substantial potential for improvement in this regard is the NCI-60 cell line database compiled by the U.S. National Cancer Institute, which has been extensively characterized across numerous genomic and pharmacologic response platforms. In this report, we introduce a CellMiner (http://discover.nci.nih.gov/cellminer/) web application designed to improve the use of this extensive database. CellMiner tools allowed rapid data retrieval of transcripts for 22,379 genes and 360 microRNAs along with activity reports for 20,503 chemical compounds including 102 drugs approved by the U.S. Food and Drug Administration. Converting these differential levels into quantitative patterns across the NCI-60 clarified data organization and cross-comparisons using a novel pattern match tool. Data queries for potential relationships among parameters can be conducted in an iterative manner specific to user interests and expertise. Examples of the in silico discovery process afforded by CellMiner were provided for multidrug resistance analyses and doxorubicin activity; identification of colon-specific genes, microRNAs, and drugs; microRNAs related to the miR-17-92 cluster; and drug identification patterns matched to erlotinib, gefitinib, afatinib, and lapatinib. CellMiner greatly broadens applications of the extensive NCI-60 database for discovery by creating web-based processes that are rapid, flexible, and readily applied by users without bioinformatics expertise.

Stereospecific PARP trapping by BMN 673 and comparison with olaparib and rucaparib.

Anti-PARP drugs were initially developed as catalytic inhibitors to block the repair of DNA single-strand breaks. We recently reported that several PARP inhibitors have an additional cytotoxic mechanism by trapping PARP–DNA complexes, and that both olaparib and niraparib act as PARP poisons at pharmacologic concentrations. Therefore, we have proposed that PARP inhibitors should be evaluated based both on catalytic PARP inhibition and PARP–DNA trapping. Here, we evaluated the novel PARP inhibitor, BMN 673, and compared its effects on PARP1 and PARP2 with two other clinical PARP inhibitors, olaparib and rucaparib, using biochemical and cellular assays in genetically modified chicken DT40 and human cancer cell lines. Although BMN 673, olaparib, and rucaparib are comparable at inhibiting PARP catalytic activity, BMN 673 is ∼100-fold more potent at trapping PARP–DNA complexes and more cytotoxic as single agent than olaparib, whereas olaparib and rucaparib show similar potencies in trapping PARP–DNA complexes. The high level of resistance of PARP1/2 knockout cells to BMN 673 demonstrates the selectivity of BMN 673 for PARP1/2. Moreover, we show that BMN 673 acts by stereospecific binding to PARP1 as its enantiomer, LT674, is several orders of magnitude less efficient. BMN 673 is also approximately 100-fold more cytotoxic than olaparib and rucaparib in combination with the DNA alkylating agents methyl methane sulfonate (MMS) and temozolomide. Our study demonstrates that BMN 673 is the most potent clinical PARP inhibitor tested to date with the highest efficiency at trapping PARP–DNA complexes. Mol Cancer Ther; 13(2); 433–43. ©2013 AACR.

Loss of 53BP1 Causes PARP Inhibitor Resistance in Brca1-Mutated Mouse Mammary Tumors

UNLABELLED Inhibition of PARP is a promising therapeutic strategy for homologous recombination-deficient tumors, such as BRCA1-associated cancers. We previously reported that BRCA1-deficient mouse mammary tumors may acquire resistance to the clinical PARP inhibitor (PARPi) olaparib through activation of the P-glycoprotein drug efflux transporter. Here, we show that tumor-specific genetic inactivation of P-glycoprotein increases the long-term response of BRCA1-deficient mouse mammary tumors to olaparib, but these tumors eventually developed PARPi resistance. In a fraction of cases, this resistance is caused by partial restoration of homologous recombination due to somatic loss of 53BP1. Importantly, PARPi resistance was minimized by long-term treatment with the novel PARP inhibitor AZD2461, which is a poor P-glycoprotein substrate. Together, our data suggest that restoration of homologous recombination is an important mechanism for PARPi resistance in BRCA1-deficient mammary tumors and that the risk of relapse of BRCA1-deficient tumors can be effectively minimized by using optimized PARP inhibitors. SIGNIFICANCE In this study, we show that loss of 53BP1 causes resistance to PARP inhibition in mouse mammary tumors that are deficient in BRCA1. We hypothesize that low expression or absence of 53BP1 also reduces the response of patients with BRCA1-deficient tumors to PARP inhibitors.

The clinical features of hepatic angiosarcoma: A report of four cases and a review of the English literature

Four cases of hepatic angiosarcoma are reported with a review of 99 other cases in the English literature. Angiosarcoma of the liver is associated with chronic exposure to thorotrast, vinyl chloride, arsenicals, radium and possibly copper and with chronic idiopathic hemochromatosis. Although 40% of patients have hepatic fibrosis or cirrhosis at autopsy, the nature of the association between chronic liver disease and hepatic angiosarcoma is unknown. The clinical presentation of hepatic angiosarcoma is nonspecific with abdominal pain, weakness and weight loss common complaints and with hepatomegaly, ascites and jaundice common findings. Liver function tests are usually abnormal but there is no one liver function test or set of tests specific for the tumor. The occurrence of thrombocytopenia and disseminated intravascular coagulation is characteristic of hepatic angiosarcoma and may be related to local consumption of clotting factors and formed blood elements in the tumor. Catastrophic intraabdominal bleeding is also characteristic and occurs in one-fourth of all cases. This complication is likely related to the high incidence of clotting abnormalities and the vascular nature of the neoplasm. Selective hepatic arteriogram and open liver biopsy are the foundations of diagnostic evaluation. Percutaneous liver biopsy should be avoided. Failure to appreciate the possibility of hepatic angiosarcoma in the proper clinical setting, leading to blind percutaneous biopsy, may result in failure to make the diagnosis at the cost of significant morbidity and mortality. Survival of patients with hepatic angiosarcoma is brief; only 3% live longer than 2 years. Treatment of the tumor to date is empirical. There are probably a few patients who might benefit from radical surgery with curative intent. For all others chemotherapy is indicated. Adriamycin is active against hepatic angiosarcoma, but optimal dose and mode of administration require further investigation. Further study is also required to delineate the cause of hepatic angiosarcoma in the 60% of cases without definite epidemiologic association.

A Phase II Trial of Vorinostat (Suberoylanilide Hydroxamic Acid) in Metastatic Breast Cancer: A California Cancer Consortium Study

Purpose: The primary goal of this trial was to determine the response rate of single-agent vorinostat in patients with metastatic breast cancer. The secondary goals included assessment of time to progression, evaluation of toxicities, and overall survival. Experimental Design: From June 2005 to March 2006, 14 patients received vorinostat, 200 mg p.o., twice daily for 14 days of each 21 day cycle. Response and progression were evaluated using Response Evaluation Criteria in Solid Tumors (RECIST) criteria. Results: The median age for all patients was 60.5 years (range, 37-88). Eight patients were estrogen receptor and/or progesterone positive, four were Her-2 positive. Sites of metastatic disease included brain, liver, lungs, bones, pelvis, pleura, chest wall, and distant lymph nodes. Patients received a median of 1.5 prior (range, 0-2) chemotherapeutic regimens for metastatic disease. Fatigue, nausea, diarrhea, and lymphopenia were the most frequent clinically significant adverse effects. The median number of cycles delivered was 2 (range, 1-20). There were no complete or partial responses, and the study was terminated after the first stage; however, 4 patients were observed with stable disease with time to progression of 4, 8, 9, and 14 months. The median number of months that patients received treatment on this study was 1.7 (range, 0.5-14). Conclusions: Although not meeting the RECIST response criteria for adequate single-agent activity, the observed tolerable toxicities and the potential for clinical benefit in terms of stable disease suggest that further assessment of vorinostat as a part of combination therapy with either chemotherapeutic or targeted agents in metastatic breast might be undertaken.

Phase I Study of PARP Inhibitor ABT-888 in Combination with Topotecan in Adults with Refractory Solid Tumors and Lymphomas

A phase I trial of ABT-888 (veliparib), a PARP inhibitor, in combination with topotecan, a topoisomerase I-targeted agent, was carried out to determine maximum tolerated dose (MTD), safety, pharmacokinetics, and pharmacodynamics of the combination in patients with refractory solid tumors and lymphomas. Varying schedules and doses of intravenous topotecan in combination with ABT-888 (10 mg) administered orally twice a day (BID) were evaluated. Plasma and urine pharmacokinetics were assessed and levels of poly(ADP-ribose) (PAR) and the DNA damage marker γH2AX were measured in tumor and peripheral blood mononuclear cells (PBMC). Twenty-four patients were enrolled. Significant myelosuppression limited the ability to coadminister ABT-888 with standard doses of topotecan, necessitating dose reductions. Preclinical studies using athymic mice carrying human tumor xenografts also informed schedule changes. The MTD was established as topotecan 0.6 mg/m²/d and ABT-888 10 mg BID on days one to five of 21-day cycles. Topotecan did not alter the pharmacokinetics of ABT-888. A more than 75% reduction in PAR levels was observed in 3 paired tumor biopsy samples; a greater than 50% reduction was observed in PBMCs from 19 of 23 patients with measurable levels. Increases in γH2AX response in circulating tumor cells (CTC) and PBMCs were observed in patients receiving ABT-888 with topotecan. We show a mechanistic interaction of a PARP inhibitor, ABT-888, with a topoisomerase I inhibitor, topotecan, in PBMCs, tumor, and CTCs. Results of this trial reveal that PARP inhibition can modulate the capacity to repair topoisomerase I-mediated DNA damage in the clinic.