http://nova.newcastle.edu.au/vital/access/services/Feed ${session.getAttribute("locale")} 5 http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:12336 Mitotane (o,p'-DDD or (1,1-dichloro-2-[o-chlorophenyl]-2-[p-chlorophenyl]ethane, DDD) is the drug of choice for non-resectable and metastatic adrenocortical carcinomas (ACC). Measurement of mitotane and metabolites,o,p'-DDE (1,1-dichloro-2-[p-chlorophenyl]-2-[o-chlorophenyl]ethene, DDE) and o,p'-DDA (1,1-[o,p'-dichlorodiphenyl] acetic acid, DDA)provides a better understanding of mitotane pharmacokinetics and pharmacodynamics. We have developed a simple, robust and efficient high performance liquid chromatography (HPLC) method to measure mitotane and its two main metabolites,DDE and DDA.The method involves a single ethanol extraction of mitotane, DDE, DDA, and an internal standard (int std) p,p'-DDD (1,1-dichloro-2,2-bis(p-chlorophenyl)ethane) with an extraction efficiency of 77–88%. All compounds are measured simultaneously using a reversed-phase phenyl HPLC column with an isocratic elution of mobile phase at a flow rate of 0.6 ml/min followed by UV detection at λ226nm. Inter and intraday validation demonstrates good reproducibility and accuracy. Limits of quantitation are 0.2μg/ml for mitotane and DDE, and 0.5μg/ml for DDA. The method has been evaluated in plasma from 23 patients on mitotane therapy, revealing DDA concentrations 1–18 times higher than the parent compound. 2013-01-07T03:20:04.793Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:12335 Background: Biliary tract cancers (BTC) have a poor prognosis, and there is no consensus on the best chemotherapy regimen. This study determined the response rate for Wxeddose-rate (FDR) gemcitabine combined with cisplatin. Methods: This multicentre phase II trial enrolled 50 patients with inoperable locally advanced or metastatic BTC. Treatment consisted of FDR gemcitabine 1,000 mg/m² (10 mg/m²/min) and cisplatin 20 mg/m² on days 1 and 8 of a 21-day cycle. The primary endpoint was response rate. Secondary endpoints included safety, response duration (RD), progression-free (PFS) and overall survival (OS), and cancer antigen 19-9 response. Results: Thirteen patients (26%, 95% CI 14.6–40.4) had a partial response, and 12 (24%) had stable disease. The median RD was 8.3 months (95% CI 6.91–9.99); median PFS 4 months (95% CI 2.5–6.77); and median OS 6.8 months (95% CI 5.0–8.7). Treatment was well tolerated. Grade 3 and grade 4 nausea, vomiting, and fatigue were uncommon. Thirty-eight per cent of patients discontinued treatment because of toxicity, patient or clinician preference. Conclusions: This treatment combination had moderate activity with acceptable toxicity, supporting previous results that this combination has a role to play. The study does not suggest that FDR gemcitabine is superior to bolus infusion. 2013-01-07T01:50:04.401Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:12304 Purpose: Oxaliplatin (OHP) in combination with 5-Xuorouracil/leucovorin (FOLFOX) is clinically used as frontline therapy in patients with advanced colorectal carcinoma (CRC), with response rates ranging from 46 to 71%. This combination is now considered a standard treatment for metastatic CRC and also in the post-operative adjuvant setting. Reversible, cumulative, peripheral sensory neuropathy is the principal dose-limiting toxicity of OHP therapy. Pyridoxine (vitamin B6) has been shown to reduce cisplatin and Xuoropyrimidine-related neurotoxicity but its administration with OHP has not yet been studied. Low doses of pyridoxine are free of side effects; it can be given orally. If pyridoxine administration with oxaliplatin has no adverse effect on OHP cytotoxicity effects, it will be a simple and cost-effective way to minimise OHP-induced neurotoxicity. Methods: In vitro simultaneous combination of OHP and pyridoxine was studied in 6 CRC cell lines (HT29, Widr, SW480, HCT116, H630 and SW1116), in an ovarian cancer cell line (A2780) and its cisplatin-resistant subline (ADDP) and in an oestrogen-dependent breast cancer cell line (MCF-7). Three fixed concentrations of pyridoxine: 1, 10 and 25 μM were combined with varying concentrations of OHP, and the growth inhibitory effects were evaluated using the MTT cell growth assay. Results: Oxaliplatin induced consistent cytotoxicity in all cell lines with GI₅₀ values between 0.23 and 7.6 μM. Addition of pyridoxine at concentrations of 1–25 μM does not affect OHP cytotoxicity. Conclusions: Administration of pyridoxine, at concentrations extending across possible therapeutic plasma levels in humans, does not antagonise OHP antitumour effects in a range of relevant tumour cell lines. This study provides a foundation for clinical studies to test whether pyridoxine can minimise OHP-related neurotoxicity, and clinicians can be confident that pyridoxine is very unlikely to reverse the antitumour effects of OHP, as seems to be the case with Ca/Mg infusions. This could prove to be a cost-effective way to minimise OHP-related neurotoxicity, allowing more effective less toxic treatment and better outcomes in patients. 2012-12-18T22:38:01.006Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:10494 Purpose: To determine whether adding bevacizumab, with or without mitomycin, to capecitabine monotherapy improves progression-free survival (PFS) in patients with metastatic colorectal cancer (mCRC) in an open-label, three-arm randomized trial. Patients and Methods: Overall, 471 patients in Australia, New Zealand, and the United Kingdom with previously untreated, unresectable mCRC were randomly assigned to the following: capecitabine; capecitabine plus bevacizumab (CB); or capecitabine, bevacizumab, and mitomycin (CBM). We compared CB with capecitabine and CBM with capecitabine for progression-free survival (PFS). Secondary end points included overall survival (OS), toxicity, response rate (RR), and quality of life (QOL). Results: Median PFS was 5.7 months for capecitabine, 8.5 months for CB, and 8.4 months for CBM (capecitabine v CB: hazard ratio [HR], 0.63; 95% CI, 0.50 to 0.79; P < .001; C v CBM: HR, 0.59; 95% CI, 0.47 to 0.75; P < .001). After a median follow-up of 31 months, median OS was 18.9 months for capecitabine and was 16.4 months for CBM; these data were not significantly different. Toxicity rates were acceptable, and all treatment regimens well tolerated. Bevacizumab toxicities were similar to those in previous studies. Measures of overall QOL were similar in all groups. Conclusion: Adding bevacizumab to capecitabine, with or without mitomycin, significantly improves PFS without major additional toxicity or impairment of QOL. 2012-03-22T02:00:04.244Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:7152 A paper in this issue exemplifies two issues that deserve consideration in the clinical research and practice of oncology: 1) adverse events that occur in response to anticancer therapy may be due to excipients rather than the active agent, and the use of a different formulation may be effective; 2) differences in pharmacology and metabolism need to be considered whenever a drug is applied in different ethnic groups. 2011-02-02T23:10:34.915Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:1259 Cantharidin and its analogues have been of considerable interest as potent inhibitors of the serine/threonine protein phosphatases 1 and 2A (PP1 and PP2A). However, limited modifications to the parent compounds is tolerated. As part of an on-going study we have developed a new series of cantharidin analogues, the cantharimides. Inhibition studies indicate that cantharimides possessing a D- or L-histidine, are more potent inhibitors of PP1 and PP2A (PP1 IC₅₀=3.22±0.7 μM; PP2A IC₅₀=0.81±0.1 μM and PP1 IC₅₀=2.82±0.6 μM; PP2A IC₅₀=1.35±0.3 μM, respectively) than norcantharidin (PP1 IC₅₀=5.31±0.76 μM; PP2A IC₅₀=2.9±1.04 μM) and essentially equipotent with cantharidin (PP1 IC₅₀=3.6±0.42 μM; PP2A IC₅₀=0.36±0.08 μM). Cantharimides with non-polar or acidic amino acid residues are only poor inhibitors of PP1 and PP2A. 2010-04-27T06:56:12.482Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:989 Purpose: Marked interindividual variation in drug disposition and toxicity pose an ongoing challenge to chemotherapy dosage individualization. The aim of this study was to evaluate pretreatment clinical features, genotype and functional indicators of drug clearance as predictors of vinorelbine clearance, and myelotoxicity that could inform dosage optimization. Patients and methods: Forty-one patients with cancer received a 60 mg intravenous dose of vinorelbine. Pretreatment routine body size measurements and blood tests were performed. Midazolam clearance and hepatic technetium labeled sestamibi (99mTc-MIBI) clearance were used to investigate CYP3A and ABCB1 (MDR1, P-glycoprotein) phenotype respectively and selected single nucleotide polymorphisms in CYP3A and ABCB1 were documented. A limited blood sampling strategy was employed and vinorelbine concentrations were determined by high-performance liquid chromatography. Posterior Bayesian estimates of vinorelbine clearance were obtained for each patient using population pharmacokinetic modeling. Myelotoxicity was estimated from the fractional survival of neutrophils post-treatment. Results: There was 4.3-fold variation in vinorelbine clearance across the cohort. In a multivariable analysis, pretreatment estimated creatinine clearance (P < .01) and hepatic 99mTc-MIBI clearance (P = .01) were independent predictors of vinorelbine clearance. Fractional survival of neutrophils ranged from 1.3% to 100% and was significantly correlated with vinorelbine clearance (P < .01). Body-surface area was the only pretreatment predictor of fractional survival of neutrophils independent of vinorelbine clearance (P = .02). Conclusion: Specific indicators of drug clearance provide predictive information about vinorelbine pharmacokinetics, and body-surface area, probably reflecting normal bone marrow reserve, provides an additional pharmacodynamic indicator. Use of a fixed dose of vinorelbine with modifications guided by pretreatment measures is worthy of prospective evaluation. 2010-04-27T06:43:17.404Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:2497 Purpose: The serine/threonine protein phosphatases 1 (PP1) and 2A (PP2A) are key enzymes in regulating entry into the cell cycle, mitosis and apoptosis. Inhibition of PP1 and PP2A is associated with enhanced S-phase entry culminating in G2/M arrest and apoptotic cell death. Thymidylate synthase (TS) is a key regulatory enzyme in DNA synthesis, inhibition of which is often a first-line treatment for colorectal carcinoma. In this study the effect of combining PP inhibition with TS inhibition in two colorectal cell lines was examined. Methods: Cantharidin and nolatrexed were used to inhibit PP and TS activity, respectively. The MTT cytotoxicity assay and cell cycle analysis were performed following single-drug treatment of HT29 and HCT116 colorectal cell lines. The median effect method was used to determine a combination index (CI), where drug antagonism was indicated by a CI>1.1, additivity by a CI between 0.9 and 1.1, and synergism by a CI<0.9. Results: Both cell lines were equally sensitive to cantharidin alone (GI50 values 5.4 and 7.3 mgrM), which induced a significant increase in the S-phase population of both cell lines within 6 h with a concomitant increase in DNA synthesis. This response culminated in G2/M cell cycle arrest within 24 h and subsequent cell death. In response to nolatrexed alone, HT29 cells were more sensitive than HCT116 cells (GI50 1.9 mgrM vs 9.8 mgrM), with G1/S-phase cell cycle arrest occurring within 24 h in both cell lines. In HT29 cells, this was followed by cell death, whereas in HCT116 cells, a proportion of cells died following arrest but the predominant event was re-entry into the cell cycle. The simultaneous exposure of HT29 cells to the combination of nolatrexed and cantharidin in drug molar ratios of 1:1 and 1:2.5 for 72 h was synergistic producing composite CIs of 0.88 and 0.87, respectively. The sequence of nolatrexed followed by cantharidin 24 h later resulted in greater synergism (CI values of 0.75, 0.52, 0.55, 0.68 for molar ratios of 10:1, 1:1, 1:2.5, 1:10), whereas the reverse sequence was antagonistic, suggesting that the point of interaction is downstream of TS inhibition. In HCT116 cells only additive and antagonistic interactions were observed for any of the treatment combinations. The lack of synergism in these cells may be caused by the reduced sensitivity of these cells to nolatrexed as a single agent. Conclusion: The effect of TS inhibition can be enhanced by the inhibition of serine/threonine protein phosphatases. 2010-04-27T06:23:46.106Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:1773 Diels–Alder addition of furans (furan, furfuryl alcohol, and 3-bromofuran) to maelic anhydride yields three distinct 5,6-dehydronorcantharidins. Hydrogenation of (4,10-dioxatricyclo[5.2.1.0]decane-3,5-dione) (4a), in dry ethanol affords the monoester (7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic aid monoethyl ester) (6). Subsequent transesterification affords a series of monoesters (7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid monomethyl ester (7)), 7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid monopropyl ester (8), (7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid monohexyl ester (9)) and differentially substituted diesters (7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid 2-ethyl ester 3-isopropyl ester) (10), and (7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid 2-ethyl ester 3-phenyl ester) (11). Analogues were firstly screened for their ability to inhibit protein phosphatases 1 (PP1) and 2A (PP2A) as the lead compounds cantharidin (1) and norcantharidin (2) are known PP1 and PP2A inhibitors. Only analogues 4a, 6–8 displayed good PP1 and PP2A inhibition (PP1 IC50’s=2.0, 2.96, 4.71, and 4.82 μM, respectively; PP2A IC50’s=0.2, 0.45, 0.41, and 0.47 μM, respectively). All analogues were also screened for their anti-cancer potential against a panel of tumour cell lines, HL60, L1210, SW480, WiDr, HT29, HCT116, A2780, ADDP, and 143B, producing GI50 values ranging from 6 μM to >1000 μM. Analogues possessing good PP1 and/or PP2A inhibition also returned moderate to good anti-cancer activity. Analogues with substituents directly attached to the intact bicyclo[2.2.1]heptane skeleton were poor to moderate anti-cancer agents. This correlates well with their lack of PP1 or PP2A activity. Analogues capable of undergoing a facile ring opening of the anhydride or with a single carboxylate were good PP1 and PP2A inhibitors, largely correlating to the observed anti-cancer activity in all cases, except 11. Analogue 11, whist neither a PP1 nor a PP2A inhibitor shows anti-cancer activity comparable to 1 and 2. We believe that intracellular esterases generate the corresponding dicarboxylate, which is a potent PP1 and PP2A inhibitor, and that it is this species which is responsible for the observed anti-cancer activity. 2010-04-27T06:11:36.976Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:3263 Simple modifications to the anhydride moiety of norcantharidin have lead to the development of a series of analogues displaying modest PP1 inhibition (low μM IC₅₀s) comparable to that of norcantharidin (PP1 IC₅₀ = 10.3 ± 1.37 μM). However, unlike norcantharidin, which is a potent inhibitor of PP2A (IC₅₀ = 2.69 ± 1.37 μM), these analogues show reduced PP2A inhibitory action resulting in the development of selective PP1 inhibitory compounds. Data indicates that the introduction of two ortho-disposed substituents on an aromatic ring, or para-substituent favours PP1 inhibition over PP2A inhibition. Introduction of a p-morphilinoaniline substituent, 35, affords an inhibitor displaying PP1 IC₅₀ = 6.5 ± 2.3 μM; and PP2A IC₅₀ = 7.9 ± 0.82 μM (PP1/PP2A = 0.82); and a 2,4,6-trimethylaniline, 23, displaying PP1 IC₅₀ = 48 ± 9; and PP2A IC₅ 85 ± 3 μM (PP1/PP2A = 0.56). The latter shows a 7-fold improvement in PP1 versus PP2A selectivity when compared with norcantharidin. Subsequent analysis of 23 and 35 as potential PP2B inhibitors revealed modest inhibition with IC₅₀s of 89 ± 6 and 42 ± 3 μM, respectively, and returned with PP1/PP2B selectivities of 0.54 and 0.15. Thus, these analogues are the simplest and most selective PP1 inhibitors retaining potency reported to date. 2010-04-27T05:24:09.170Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:3264 A range of amines was reacted with norcantharidin (2) to provide the corresponding norcantharimides (9–43). Treatment of norcantharidin with allylamine afforded the corresponding allyl-norcantharimide (20) which was amenable to epoxidation (mCPBA, 22) and subsequent ring opening (MeOH/H⁺; 23) or alternatively, osmylation (OsO₄/NMO; 24). These simple synthetic modifications of 2 facilitated the development of a novel series of norcantharimides displaying modest to good broad spectrum cytotoxicity against HT29 and SW480 (colorectal carcinoma); MCF-7 (breast adenocarcinoma); A2780 (ovarian carcinoma); H460 (lung carcinoma); A431 (epidermoid carcinoma); DU145 (prostate carcinoma); BE2-C (neuroblastoma); and SJ-G2 (glioblastoma). Analogues possessing a C₁₀, C₁₂ or C₁₄ alkyl chain or a C₁₂ linked bis-norcantharimide displayed the highest levels of cytotoxicity. 2010-04-27T05:24:01.319Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:3265 Norcantharidin (3) is a potent PP1 (IC₅₀ = 9.0 ± 1.4 μM) and PP2A (IC₅₀ = 3.0 ± 0.4 μM) inhibitor with 3-fold PP2A selectivity and induces growth inhibition (GI₅₀ ~45 μM) across a range of human cancer cell lines including those of colorectal (HT29, SW480), breast (MCF-7), ovarian (A2780), lung (H460), skin (A431), prostate (DU145), neuroblastoma (BE2-C), and glioblastoma (SJ-G2) origin. Until now limited modifications to the parent compound have been tolerated. Surprisingly, simple heterocyclic half-acid norcantharidin analogues are more active than the original lead compound, with the morphilino-substituted (9) being a more potent (IC₅₀ = 2.8 ± 0.10 μM) and selective (4.6-fold) PP2A inhibitor with greater in vitro cytotoxicity (GI₅₀ ~9.6 μM) relative to norcantharidin. The analogous thiomorpholine-substituted (10) displays increased PP1 inhibition (IC₅₀ = 3.2 ± 0 μM) and reduced PP2A inhibition (IC₅₀ = 5.1 ± 0.41 μM), to norcantharidin. Synthesis of the analogous cantharidin analogue (19) with incorporation of the amine nitrogen into the heterocycle further increases PP1 (IC₅₀ = 5.9 ± 2.2 μM) and PP2A (IC₅₀ = 0.79 ± 0.1 μM) inhibition and cell cytotoxicity (GI₅₀ ~3.3 μM). These analogues represent the most potent cantharidin analogues thus reported. 2010-04-27T05:24:01.150Z ]]> http://nova.newcastle.edu.au/vital/access/manager/Repository/uon:5130 Cantharidin (1) and its derivatives are of significant interest as serine/threonine protein phosphatase 1 and 2A inhibitors. Additionally, compounds of this type have displayed growth inhibition of various tumour cell lines. To further explore both of these inhibition pathways, a number of amide–acid norcantharidin analogues (15–26) were prepared. Compounds 23 and 24, containing two carboxylic acid residues, showed good PP1 and PP2A activity, with IC₅₀ values of ~15 and ~3 μm, respectively. Substituted aromatic amide analogues 45, 48, 49, 52, 53, and 54 also displayed good PP1 and PP2A inhibition, with IC₅₀ values in the range of 15–10 μm (PP1) and 11–5 μm (PP2A). However, bulky ortho substituents on the aromatic ring caused the aromatic ring to be skewed from the NCO planarity, leading to a decrease in PP1 and PP2A inhibition. A number of analogues, 20, 22, 25 and 46, showed excellent tumour growth inhibition, with 46 in particular being more potent than the lead, norcantharidin 2. 2010-04-27T04:41:41.887Z ]]>