Pharmacologic ascorbate enhances the therapeutic index of ATM-inhibitor based chemoradiation for colorectal cancer

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Background: Ataxia telangectasia mutated protein (ATM) is one of the key sensors of DNA damage and specific inhibitors of ATM are potent radiosensitizers. However, their clinical utility with radiation (RT) is limited because they lack tissue specificity and increase normal tissue injury. Pharmacologic (high dose) ascorbate (P-AscH-) selectively increases oxidative stress in tumors while functioning as a donor antioxidant and reducing RT damage in normal tissues. We hypothesized that P-AscH- could enhance the therapeutic index of ATM-inhibitor based chemoradiation (CRT) for colorectal cancer (CRC) by simultaneously enhancing efficacy and reducing RT bowel injury. Methods: Human HCT116, SW480, and HT29 and murine CT26 and MC38 CRC models were used. Clonogenic survival was assessed following single-fraction RT (2-8 Gy) +/- P-AscH- (5 pM/cell) +/- veliparib (PARP), VE821 (ATR), or KU60019 (ATM). Catalase expression was induced using HCT116 cells expressing a doxycycline inducible catalase transgene. DNA double strand breaks (DSBs) were quantified using neutral comet assays 0-24 hours post RT. Cell cycle phases were assessed using flow cytometry. ATM and pATM localization were assessed using IF. Jejunal toxicity was assessed using IHC in fixed tissues following single fraction (10 Gy) whole abdominal RT in c57blj/6 mice. Tumor growth delay was assessed following RT (5 Gy x 3) +/- drug treatment in unilateral flank tumors. Results: Veliparib, VE821, and KU60019 were potent radiosensitizers in HCT116, SW480, HT29, MC38, and CT26 CRC tumor models and P-AscH- further reduced clonogenic survival with DRIs in all lines except for HT29. In contrast, P-AscH- enhanced survival of cultured HUVEC and FHs-74 cells exposed to RT. Enhanced cell kill with P-AscH- is H202 mediated as it is completely attenuated by inducible catalase expression. P-AscH- significantly increased the number of DNA DSBs in tumors after RT in vitro. Despite the increase in DNA DSBs, P-AscH-significantly decreased nuclear localization of activated P-ATM after RT and significantly decreased the fraction of cells in G2/M phases of the cell cycle. In vivo, RT + P-AscH- + KU60019 induced more tumor growth delay/clearance than all other combinations in unilateral MC38 or HCT116 flank tumors. Finally, P-AscH- significantly reduced loss of jejunal crypt cell density, epithelial architecture, and markers of lipid and protein oxidation following whole abdominal RT. Conclusions: P-AscH- selectively enhances the efficacy of ATM-based CRT in CRC tumor models while simultaneously decreasing RT-mediated small bowel toxicity. In tumors, P-AscH- enhances DNA DSBs by stimulating an H202 flux and prevents activation of DNA repair pathways and cell cycle checkpoints by inhibiting RT-induced activation of ATM. Selective radioprotectors like P-AscH- could facilitate the clinical translation ATM inhibitors as radiosensitizers.

BIMG-07. PHARMACOLOGICAL ASCORBATE ENHANCES RADIATION AND TEMOZOLOMIDE EFFECTIVENESS IN GLIOBLASTOMA BY A MECHANISM MEDIATED BY REDOX ACTIVE IRON

Pharmacological ascorbate (P-AscH^-; high dose intravenous infusions of vitamin C generating milli-molar plasma concentrations) has re-emerged as an anti-cancer therapy. Phase 1 clinical trials combining P-AscH^- with chemotherapy and ionizing radiation demonstrate safety and promising clinical outcomes in a variety of malignancies. In a first-in-human trial, subjects with newly diagnosed glioblastoma (GBM) and undetectable MGMT promoter methylation were treated with P-AscH^-, ionizing radiation, and temozolomide. Results demonstrate median progression-free survival (PFS) of 10 months and median overall survival (OS) of 23 months, comparing favorably to historical GBM patients expressing MGMT. P-AscH^-‘s anti-cancer mechanism is dependent upon the presence of redox active labile iron. In the presence of redox active iron, the formation of hydrogen peroxide, which causes oxidative stress and eventual cell death, selectively forms in cancer cells. Treatment with P-AscH^- increased cancer cells’ labile iron pool, further enhancing sensitivity to P-AscH^-. We investigated the capability of MR imaging (T₂* relaxation time) to measure the redox active iron and predict response to P-AscH^-. T₂* relaxation time is influenced by in-field inhomogeneities, such as redox active paramagnetic iron. The active phase 2 trial evaluating P-AscH^-, radiation, and temozolomide for GBM, obtains T₂* imaging prior to (baseline) and immediately after ascorbate infusion (NCT02344355). A preliminary analysis of the baseline scan for the first 15 subjects suggests those with faster GBM T₂* relaxation times (≤ 58 ms) have more redox active labile iron pools as well as an improved median PFS (11.4 months) compared to those with slower T₂* relaxation times (> 58 ms; median PFS of 8.5 months). Pre-clinical studies evaluating the effectiveness of iron nano-particle supplementation in GBM animal models are on-going. (Supported by P01 CA217797, R01 CA169046, U01 CA140206, T32 CA078586, P30 CA086862, as well as the Gateway for Cancer Research grant G-17–1500.)

Effects of GC4419 (avasopasem manganese) on chronic kidney disease in head and neck cancer patients treated with radiation and cisplatin

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Background: Nephrotoxicity is a major complication of platinum-based chemotherapy and ranges in incidence from 31-68%. The effects of platinum-based chemotherapeutics on long-term renal outcomes (chronic kidney disease, CKD) profoundly affect morbidity and mortality. Concurrent chemoradiotherapy (CRT) including cisplatin is standard for locally advanced squamous cell head and neck cancer (HNC) but is accompanied by the risk of CKD. In a randomized, multi-center, placebo-controlled Phase 2b trial ( NCT02508389 ) of GC4419 (avasopasem manganese) in HNC patients receiving CRT, avasopasem reduced the duration, incidence, and severity of severe oral mucositis (Anderson et al, JCO 2019). Avasopasem did not appear to alter the safety profile of CRT in that trial, including incidence of adverse events of kidney injury or azotemia. Methods: Pre- and post-treatment markers of kidney function including blood urea nitrogen (BUN), serum creatinine (sCr), and estimated glomerular filtration rate (eGFR) were retrospectively evaluated for a subset of 52 of the trial patients who received 3 cycles x 100 mg/m2 cisplatin plus placebo or 30 or 90 mg of avasopasem intravenously prior to RT, and 7 comparator patients who received the same CRT outside the study. Kidney function was evaluated between 3- and 24-months post-completion of cisplatin-radiation therapy by two-way analysis of variance (ANOVA) as defined by the Kidney Disease Improving Global Outcomes (KDIGO) CKD staging. Results: Baseline patient characteristics were skewed towards a male population but were balanced across all treatment arms with regards to baseline kidney function (comparator + placebo, n = 19; 30 mg GC4419, n = 18; 90 mg GC4419, n = 15). Treatment with 90 mg GC4419 demonstrated normal BUN values (10-20 mg/dL) at 3, 6, and 18 months and normal sCr values (0.6-1.2 mg/dL) between 3 and 24 months as compared to the placebo arm + comparator group, which exhibited statistically elevated BUN and sCr (p < 0.05). Treatment with 90 mg GC4419 also demonstrated significantly higher eGFR between 3 and 24 months post-chemoradiation (p < 0.05) compared to the placebo arm + comparator group. 90 mg GC4419 treatment significantly reduced the incidence of CKD compared to the placebo arm and comparator group, as determined by fold change in sCr values and eGFR measurements < 60 mL/min (stage G3a/b, G4, or G5 CKD). Conclusions: Avasopasem has the potential to reduce the incidence and severity of CKD in patients receiving cisplatin therapy. Clinical trial information: NCT02508389 .

Phase1 clinical trial of high doses of Seleno-L-methionine (SLM), in sequential combination with axitinib in previously treated and relapsed clear cell renal cell carcinoma (ccRCC) patients

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Background: The overexpression of hypoxia induced factor (HIF) 1a/2a in ccRCC leads to up-regulation of vascular endothelial growth factor (VEGF) that results in increased angiogenesis, tumor metastasis, and treatment resistance. Using several preclinical xenograft models, it has been demonstrated that therapeutic doses and schedules of the selenium-containing molecules, seleno-L-methionine (SLM) and methylselenocysteine (MSC) caused enhanced degradation of HIF1α/2α, down-regulation of oncogenic miRNA-210 and 155, up-regulation tumor suppressor miRNA-664 and LET-7b, and stabilization of tumor vasculature, yielding higher tumor drug uptake and protection from toxic side effects when combined with chemotherapeutic and VEGF-targeted agents. Methods: This is a phase I (3+3 design) dose finding trial of SLM (2500, 3000 or 4000 µg) given orally twice daily for 14 days, followed by once a day in combination with the standard dose of axitinib to patients with metastatic RCC. Primary endpoint is safety, secondary endpoint is efficacy including overall response rate (ORR), progression free survival (PFS) and overall survival (OS). Results: To date, 9 patients with metastatic RCC; who failed one or more prior lines of treatment; are enrolled. The first 3 patients were treated at 4000 µg, the second and third 3 patients were treated at 2500 and 3000 µg respectively. No dose limiting toxicity (DLT) is encountered. Six patients are evaluable to date. Of the 4000 µg cohort, 2 patients achieved complete remission (CR) at 18 and 20 months, 1 patient with partial response (PR) at 19 month. Of the 2500 µg cohort, one patient achieved PR at 9 months, 1 patient had stable disease for 9 months before progression, and 1 patient had disease progression at 4 months. The 3000 µg cohort is too early to evaluate for efficacy. Of interest the 4000μg SLM dose yielded a plasma selenium concentration of 40-50μM which is comparable with SLM dose determined synergistic with anti-cancer drugs in preclinical models. Conclusions: High dose SLM is safe in combination with axitinib, with promising efficacy, further data to be presented at the meeting. Clinical trial information: NCT02535533.

A multicenter, open-label, expanded phase 2 study to evaluate the safety and efficacy of etirinotecan pegol, a polymer conjugate of irinotecan, in women with recurrent platinum-resistant or refractory ovarian cancer

OBJECTIVE

Etirinotecan pegol (EP) is a novel polyethylene glycol conjugated form of irinotecan with documented activity in platinum-resistant ovarian cancer (PROC). We report the results of the expanded portion of a phase II study of EP in patients with PROC who received prior pegylated liposomal doxorubicin (PLD) or who were unable to receive it.

METHODS

This multicenter, open-label, phase II study evaluated EP q21d for PROC. The primary endpoint was objective response rate (ORR) by Response Evaluation Criteria in Solid Tumors version 1.0. Secondary endpoints included progression-free survival (PFS), overall survival (OS), and safety. Patient populations evaluated included a modified intent-to-treat (mITT) group consisting of all patients who received at least one dose and with measurable disease and a primary efficacy (pEFF) group (subset of the mITT population who received prior PLD).

RESULTS

One hundred thirty-nine patients were enrolled. Of the 132 patients in the mITT group, 20 achieved an ORR (15.2%; 95% CI 9.5-22.4); median PFS and OS were 4.4 months and 10.2 months, respectively. In the pEFF group (n=104), 15 patients (14.4%; 95% CI 8.3-22.7) achieved an ORR; median PFS and OS were 4.4 months and 10.9 months, respectively. The most common grade 3/4 toxicities were diarrhea (20%), abdominal pain (17%), vomiting (14%), dehydration (13%), and nausea (13%). Severe diarrhea was reduced to 15% with strict adherence to screening and management guidelines.

CONCLUSIONS

This study confirms the activity and safety of single-agent EP in patients with PROC, including patients who received prior PLD. Further evaluation earlier in the disease course and in combination is warranted.

Impact of perioperative care on the post-operative recovery of women undergoing surgery for gynaecological tumours

To assess perioperative care in patients undergoing abdominal surgery for gynaecological tumours and how it relates to post-operative (PO) complications and oral PO feeding. Ninety-one women undergoing major abdominal surgery for gynaecological tumours were enrolled. Data included mechanical bowel preparation (MBP), prescribed diet, length of fast, start date of oral diet and progression of food consistency, anaesthetic technique, use of opioids and intravenous hydration (IH). Outcomes evaluated were nausea, vomiting and abdominal distension. The median pre-operative length of fast was 11.4 h. PO digestive complications occurred in 46.2% of the patients. Median intraoperative total IH and crystalloids were significantly higher in patients with abdominal distension during the first and second PO day. MBP with mannitol implied greater intraoperative IH and was significantly associated with a higher incidence of immediate PO nausea. Post-operative IH was also associated with gastrointestinal complications. The best cut-off point for the cumulative fluid load PO for determining a longer PO hospital stay was 4 L. Performing MBP before surgery and excessive IH are factors related to major digestive complications in our study population. Changes in pre-operative fasting time and PO refeeding should be considered to reduce the gastrointestinal complications and PO recovery time.

Abstract 3729: Targeting breast cancer stem cells via oxidative stress with inhibitors of hydroperoxide metabolism and decyl-triphenylphosphonium

Cancer stem cells (CSCs) exhibit lower intracellular reactive oxygen species (ROS) levels than non-CSCs, which may be due to the increased expression of free radical scavenging systems. Exogenous agents may be useful to increase ROS and selectively kill CSCs by oxidative stress. Here we tested a combination approach to increase ROS as an effective strategy to eradicate breast CSCs and metastases. Buthionine sulfoximine (BSO) and auranofin (AU) were used to deplete glutathione (GSH) and inhibit thioredoxin reductase (TR), respectively, while mitochondrial-targeted decyltriphenylphosphonium (dTPP) was used to elevate ROS levels. In vitro clonogenicity assays using SUM159 cells showed that treatment with dTPP alone resulted in &lt;30% survival, while AU+BSO, BSO+dTPP and AU+BSO+dTPP all resulted in &lt;1% survival. These effects were reversible with N-acetylcysteine pre-treatment. The Aldefluor+ (CSC) population was also measured following drug treatment in vitro. dTPP or AU treatment alone resulted in &lt;50% of CSCs remaining, while BSO+AU or BSO+dTPP resulted in &lt;25% of CSCs remaining, and treatment with all three compounds resulted in &lt;1% of CSCs remaining. In a preclinical model of breast cancer metastasis, long-term adjuvant treatment with each individual compound significantly reduced the amount of metastases and increased survival, with dTPP treatment alone resulting in 100% survival rate. Interestingly, the combination of all three compounds resulted in increased metastases compared to the single agents. This may potentially be a stress-induced effect resulting from drug toxicity. In conclusion, the approach of increasing ROS in breast cancer cells may be an effective way to target CSCs and useful for adjuvant therapy to reduce metastases in patients.

Citation Format: Sarah J. Conley, Trenton Baker, Rebecca Theisen, Elizabeth Gheordunescu, Yueming Zhu, Nukhet Aykin-Burns, Melissa Fath, Douglas Spitz, Max Wicha. Targeting breast cancer stem cells via oxidative stress with inhibitors of hydroperoxide metabolism and decyl-triphenylphosphonium. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3729. doi:10.1158/1538-7445.AM2013-3729

Acute toxicity of 3,3',4,4',5-pentachlorobiphenyl (PCB 126) in male Sprague-Dawley rats: effects on hepatic oxidative stress, glutathione and metals status

Although polychlorinated biphenyl (PCBs) production, and new uses for PCBs, was halted in the 1970s in the United States, PCBs continue to be used in closed systems and persist in the environment, accumulating in fatty tissues. PCBs are efficacious inducers of drug metabolism and may increase oxidative events and alter many other biochemical and morphologic parameters within cells and tissues. The goal of the present study was to evaluate the effects of a single, very low dose of PCB 126 (3,3',4,4',5-pentachlorobiphenyl), a coplanar, dioxin-like PCB congener and aryl hydrocarbon receptor (AhR) agonist, on redox status, metals homeostasis, antioxidant enzymes, and cellular morphology. To examine these parameters, male Sprague-Dawley rats were fed a purified AIN-93 basal diet containing 0.2 ppm selenium for two weeks, then administered a single i.p. injection of corn oil (5 ml/kg body weight) or 1µmol PCB 126/kg body weight (326µg/kg body weight) in corn oil. Rats were maintained on the diet for an additional two weeks before being euthanized. This dose of PCB 126 did not alter feed intake or growth, but significantly increased liver weight (42%) and hepatic microsomal cytochrome P-450 (CYP1A) enzyme activities (10-40-fold increase). Hepatic zinc, selenium, and glutathione levels were significantly decreased 15%, 30%, and 20%, respectively, by PCB 126. These changes were accompanied by a 60% decrease in selenium-dependent glutathione peroxidase activity. In contrast, hepatic copper levels were increased 40% by PCB 126. PCB 126-induced pathology was characterized by hepatocellular hypertrophy and mild steatosis in the liver and a mild decrease in cortical T-cells in the thymus. This controlled study in rats fed a purified diet shows that even a single, very low dose of PCB 126 that did not alter feed intake or growth, significantly perturbed redox and metals homeostasis and antioxidant and enzyme levels in rodent liver.

The role of manganese superoxide dismutase in the growth of pancreatic adenocarcinoma

Chronic pancreatitis, K-ras oncogene mutations, and the subsequent generation of reactive oxygen species (ROS) appear to be linked to pancreatic cancer. ROS have also been suggested to be mitogenic and capable of stimulating cell proliferation. Cells contain antioxidant enzymes to regulate steady state levels of ROS produced by products of metabolism. The aims of our study were to determine antioxidant enzyme activity in pancreatic cancer cells and correlate enzyme activity with tumor growth, as well as determine whether tumor cell growth could be altered with antioxidant gene transfection. Western blots, enzyme activity, and enzyme activity gels were performed for manganese superoxide dismutase (MnSOD), copper/zinc, catalase, and glutathione peroxidase in normal human pancreas and in the human pancreatic cancer cell lines BxPC-3, Capan-1, MIA PaCa-2, and AsPC-1. Cell population doubling times were determined and correlated with antioxidant enzyme activity. MnSOD was overexpressed in MIA PaCa-2 using an adenoviral vector, and the effect on cell growth was determined. The cell pancreatic cancer lines BxPC-3, MIA PaCa-2, and AsPC-1 had decreased levels of MnSOD immunoreactive protein as well as activity and decreases in MnSOD levels correlated well with increased rates of tumor cell proliferation as determined by cell doubling time. No correlation could be found between cell growth and levels of copper/zinc superoxide dismutase, catalase, or glutathione peroxidase. Enforced expression of MnSOD by adenovirus transfection in the rapid growing cell line MIA PaCa-2 increased MnSOD immunoreactivity and MnSOD activity and decreased growth rate. Overexpression of MnSOD may be effective in growth suppression of pancreatic cancer.

Fine-needle aspiration biopsy of the liver: a multicenter study of 602 radiologically guided FNA

With improved radiologic techniques fine-needle aspiration (FNA) is becoming a rapid, effective diagnostic method in evaluating a wide range of liver masses. Review of six hundred two radiologically guided liver aspirates performed over a ten-year period forms the basis of this report.

Fine-needle aspiration biopsy of the liver: a multicenter study of 602 radiologically guided FNA

With improved radiologic techniques fine-needle aspiration (FNA) is becoming a rapid, effective diagnostic method in evaluating a wide range of liver masses. Review of six hundred two radiologically guided liver aspirates performed over a ten-year period forms the basis of this report.

The quality of psychiatric residency : the assessment of programs and options for distributing psychiatric residents in the service of health care reform

Recent health care reform initiatives proposed training fewer medical specialists, including psychiatrists, and determining the size and location of training programs via centralized regulatory mechanisms. Facing such potential future developments, the American Association of Directors of Psychiatric Residency Training appointed a Task Force on the Quality of Residency Programs to develop informed recommendations for the field. This paper describes the Task Force's considerations and recommendations concerning how the least damaging and most effective decisions could be made regarding the distribution of residency positions, program size, and the future funding of training stipends. The recommendations emphasize voluntary decisions, feedback from local and regional stakeholders regarding perceived needs and demands for psychiatrists, and Federal or regional funding of postgraduate training stipends that are not primarily tied to providing clinical services.

Serum analyte pattern characteristic of fulminant hepatic failure

Fulminant hepatic failure (FHF) is a poorly understood condition in which total liver failure occurs and is thought to be caused by a variety of conditions including Reye's syndrome, hepatitis, drug overdoses, and vascular insufficiency. While this condition is an uncommon one, it carries with it a high fatality rate and must therefore be diagnosed as rapidly as possible. Six patients have been observed over a two-year period with biopsy and/or autopsy-confirmed FHF: one with acute hepatitis B-delta; three with histories of alcoholism, two of them with cirrhosis; one with acute tylenol overdose; and one with hepatic vascular insufficiency. All of these patients, except one, exhibited a rapid, fatal downhill course after onset of symptoms. In all of these patients, a consistent elevation was observed in serum levels of aspartate aminotransferase (AST) or serum glutamate oxaloacetate transaminase (SGOT) and alanine aminotransferase (ALT) or serum glutamate pyruvate transaminase (SGPT) such that the ratio of AST to ALT was significantly greater than 1 and in serum levels of ammonia. Other liver function tests were found to be abnormal but not in so consistent a pattern, although total protein and albumin were found to be significantly decreased in all of these patients. The stereotypical elevation of the transaminases with high AST-to-ALT ratios and the rise in ammonia appear to characterize this life-threatening illness most reliably.

Expression of human Mn SOD in Chinese hamster ovary cells confers protection from oxidant injury

Manganese superoxide dismutase (Mn SOD) is an important component of antioxidant defense in aerobic cells because of its location in the mitochondria, a significant source of oxygen radicals and an important target of oxidant injury. To test the hypothesis that increased mitochondrial Mn SOD protects from oxidant injury, Chinese hamster ovary (CHO) cells were transfected with a eukaryotic expression vector containing the human Mn SOD cDNA. In recombinant CHO cells, Mn SOD activity was increased threefold over wild-type controls. Acute survival during paraquat exposure (0-500 microM) was significantly improved in CHO cells expressing human Mn SOD, with 71% of recombinant CHO cells surviving at the 50% lethal dose (LD50) for wild-type CHO controls. Cell growth following exposure to paraquat (100 microM) was also significantly improved in recombinant CHO cells. CHO cells expressing human Mn SOD continued to grow and divide after paraquat exposure, whereas growth of wild-type CHO cells was negligible. Protection against oxidant-induced injury was directly related to increased Mn SOD, occurring in the absence of changes in other antioxidant enzymes including catalase, Cu,Zn SOD, and glutathione associated cellular antioxidant mechanisms. We conclude that increased expression of human Mn SOD in vitro directly confers protection against oxidant injury.

Trace quantitation of 4-hydroxy-2-nonenal in biological samples as its oxime-bis-tert.-butyldimethylsilyl derivative using 3-hydroxynonanal as an internal standard

A gas chromatographic-mass spectrometric method for the determination of the lipid aldehyde 4-hydroxy-2-nonenal (4HNE) in trace quantities is described. The method utilizes the reaction of aldehydes with hydroxylamine leading to the formation of the oxime derivative. The aldehydes are recovered by octadecylsilyl solid-phase extraction and converted to the bis-tert.-butyldimethylsilyl derivatives for analysis using electron ionization. A novel 4HNE analogue, 3-hydroxynonanal, has been synthesized and is used as an internal standard. A limit of detection of approximately 1 pmol of 4 HNE in preparations of approximately 2.10(6) cells or 0.5 ml of whole blood, plasma or serum was observed. Standard addition analysis indicates that the method is accurate at these levels. Replicate analysis of the National Institutes of Standards and Technology Standard Reference Material SRM 909 indicates an average in-run precision of 8.1% and a between-run precision of 13.5% at an average concentration of 82.1 pmol/ml of reconstituted material.