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Biomedical subjects

R M Orr

Publications and source records attributed to R M Orr.

At least 19 recordsLinked to original sources
PubMed2001

Technology evaluation: fomivirsen, Isis Pharmaceuticals Inc/CIBA vision.

Fomivirsen (ISIS-2922, Vitravene) is an antisense 21 mer phosphorothioate oligonucleotide with sequence complementarity to the coding region of the major immediate-early gene of human cytomegalovirus (CMV). Developed by Isis Pharmaceuticals Inc, fomivirsen is the first antisense oligonucleotide to receive approval for licensing and is marketed by Novartis' CIBA Vision. Fomivirsen is administered by intravitreal injection to AIDS patients for the treatment of CMV-induced retinitis. In August 1998, the FDA approved the marketing of Vitravene for the local treatment of CMV retinitis [296420], [296780], and both European and Brazilian registration approval followed in the summer of 1999 [335238].

AIDS-Related Opportunistic Infections↗
PubMed2001

GTI-2040. Lorus Therapeutics.

Loris Therapeutics (formerly GeneSense Therapeutics) is developing the antisense oligonucleotide GTI-2040, directed against the R2 component of ribonucleotide reductase, for the potential treatment of cancer [348194]. It is in phase I/II trials [353796] and Lorus had anticipated phase II trials would be initiated in July 2001. By August 2001, GTI-2040 was undergoing a phase II trial as a monotherapy for the potential treatment of renal cell carcinoma, and was about to enter a phase II combination study for this indication with capecitabine (Hoffmann-La Roche). At this time, the company was also planning a phase II trial to study the drug's potential in the treatment of colorectal cancer [418739]. GTI-2040 has been tested in nine different tumor models, including tumors derived from colon, liver, lung, breast, kidney and ovary. Depending on the tumor model, significant inhibition of tumor growth, disease stabilization and dramatic tumor regressions was observed [347683]. Lorus filed an IND to commence phase I/II trials with GTI-2040 in the US in November 1999 [347683], and received approval for the trials in December 1999 [349623]. As of January 2000, these trials had commenced at the University of Chicago Cancer Research Center; it was reported in February 2000 that dosing to date had been well tolerated with no apparent safety concerns [357449]. Lorus has entered into a strategic supply alliance with Proligo to provide the higher volumes of drug product required for the planned multiple phase II trials [385976]. In February 1998, Genesense (now Lorus) received patent WO-09805769. Loris also received a patent (subsequently identified as WO-00047733) from the USPTO in January 2000, entitled 'Antitumor antisense sequences directed against components of ribonucleotide reductase' covering the design and use of unique antisense anticancer drugs, including GTI-2040 and GTI-2501 [353538].

Animals↗
PubMed2000

Induction of apoptosis by a novel copper-based anticancer compound, casiopeina II, in L1210 murine leukaemia and CH1 human ovarian carcinoma cells.

The activity of casiopeina II [Cu(1,4-dimethyl-1, 10-phenanthroline)(glycine)NO(3)], a novel anticancer agent, was tested in two cell lines, L1210 murine leukaemia, CH1 human ovarian carcinoma, cisplatin-resistant and sensitive. Exposure of the cells to a range of concentrations of casiopeina II indicates that this copper complex kills cells by apoptosis and necrosis. Condensed chromatin and nuclear fragmentation were observed after exposure to casiopeina II. The caspase inhibitor Z-Val-Ala-DL-Asp-fluoromethylketone (Z-VAD-FMK) almost completely inhibited apoptosis induced by cisplatin; however, casiopeina II-induced apoptosis was inhibited only by 50-70%. These data are consistent with caspase activation (measured by Z-Asp-Glu-Val-Asp-7-amino-4-trifluoromethylcoumarin; Z-DEVD-AFC) by casiopeina II and cisplatin and confirm that caspases are activated in the apoptotic cell death induced by casiopeina II. DNA fragmentation was observed in L1210 cells, but not in CH1 cells. No difference in susceptibility to induction of apoptosis by casiopeina II was found between sensitive and cisplatin resistant cells. In this work we show that the novel copper-based antineoplastic agent casiopeina II is highly active against murine and human cancer cell lines, including cell lines resistant to cisplatin.

Animals↗
PubMed2000

Patent review: therapeutic applications for antisense oligonucleotides 1999-2000.

Over 200 patents disclosing antisense sequences have been published in the last year. 30 Of these, in which a therapeutic application is claimed, have been reviewed in this article. We have classified these under the headings of antibacterial, antiviral, inflammation, cardiovascular, apoptosis and anticancer. Although not exhaustive or covering all diseases, major areas of antisense research have been addressed.

Animals↗
PubMed2000

Technology evaluation: electroporation therapy, Genetronics Inc.

Genetronics Inc has developed a MedPulser and a needle array applicator that delivers electric pulses to tumors and induces a transient permeabilization. Used in conjunction with intratumoral injections of anticancer drugs, this form of therapy, termed electroporation therapy, allows for intracellular accumulation of cytotoxic drugs without the toxic side effects associated with systemic administration. Accrual of preclinical data of electroporation therapy with bleomycin has led to clinical studies in patients with cutaneous and subcutaneous tumors. In 1999, objective responses were reported in a phase II study involving 30 patients with head and neck cancer with minimal side effects [328332]. Other indications for this form of treatment include liver and pancreatic cancers, Kaposi's sarcoma and melanoma [273388,290144]. Genetronics Inc and Ethicon Endo-Surgery (Johnson & Johnson Development Corp) are reviewing all clinical data from phase II studies prior to the initiation of a pivotal clinical trial in head and neck cancer.

Animals↗
PubMed1999

Technology evaluation: leukemia therapy, University of Pennsylvania.

The University of Pennsylvania is developing an antisense oligonucleotide (AS ON) as a potential treatmentfor myelogenous leukemia. The 24-mer phosphorothioate (PS) ON targets the c-myb gene (codons 2 to 9), a regulator of transcription. In a pilot study, patient bone marrow was purged with the PS ON before being returned to the patient. In January 1997, it was reported that out of six evaluable patients, four demonstrated marked hematological remission with normalized white blood cell counts. A second phase I trial was initiated, in which myelogenous leukemia patients were treated with systemic infusions of the PS ON at doses of 0.3 to 2.0 mg/kg/dayfor 7 days. By January 1997, 18 patients had been treated, 12 showed stable disease and one patient in blast crisis experienced a transient reversal to the chronic phase of the disease. No dose-related toxicity was noted and c-myb mRNA and protein levels were halved. Preclinical studies in leukemic mice showed that the myb AS PS ON increased survival times 2- to 4-fold and reduced leukemic proliferation in the brain [229790]. The ON was originally developed and patented at Temple University and was being jointly developed by Lynx Therapeutics, however, this collaboration was terminated in 1996 [264351]. New phase I studies are starting in 1999, with INX-3001 (University of Pennsylvania c-myb AS PS) supported by the NIH and Inex Pharmaceuticals Corporation.

Animals↗
PubMed1997

Pharmacokinetics of G3139, a phosphorothioate oligodeoxynucleotide antisense to bcl-2, after intravenous administration or continuous subcutaneous infusion to mice.

An 18-mer full-phosphorothioate oligonucleotide with sequence antisense to the first six codons of the open reading frame of bcl-2 (G3139) has shown efficacy against the DoHH2 lymphoma implanted in severe combined immunodeficient mice. This study evaluated the pharmacokinetics of 35S-labeled G3139 in female BALB/c mice after single i.v. bolus administration or s.c. infusion for 1 week. After 100 microg i.v. bolus (approximately 5 mg/kg), the radioactivity was rapidly distributed and eliminated, with low blood levels 6 hr after administration. Most of the initial plasma radioactivity was protein bound (98% at 5 min). Tissue to plasma ratios were 87 for kidney, 17 for liver, 5 for spleen, 2.5 for heart and lung and 3.5 for gut. High-performance liquid chromatographic determination of G3139 showed triexponential kinetics, with alpha, beta and gamma half-lives of 5 min, 37 min and 11 hr, respectively. After 106 microg/day s.c. infusion, plasma steady state was reached by day 3, when half of the radioactivity was protein bound and 66 to 86% of the radioactivity was associated with parent drug (0.9 microg/ml). The plasma half-life of elimination for G3139 was 22 hr. Tissue to plasma ratios were similar to those after i.v. bolus administration, but accumulation was observed in all organs including bone marrow, where the levels reached were in the cytotoxic range. G3139 was metabolized to at least three different products, all observed in plasma, liver and kidney. Two metabolites eluted before the parent compound and one after the parent compound. There was greater degradation in the liver 6 hr after i.v. administration than at 24 hr, 48 hr, 3 days and 7 days after s.c. administration. In the kidney, most radioactivity was G3139. All degradation products were found in the urine but only traces of parent drug were eliminated. After both routes of administration, most of the radioactivity was eliminated in the urine and to a lesser extent in the feces. Significantly more radioactivity was excreted in the urine after i.v. bolus, compared with s.c. infusion (33% on day 1 and 55% by day 3 for i.v. vs. 7.2% on day 1 and 12.9% by day 3 for s.c.). These data show that s.c. infusion resulted in less excretion and metabolism of the administered dose.

Animals↗
PubMed1996

The cytotoxic action of four ammine/amine platinum(IV) dicarboxylates: a flow cytometric study.

We have used flow cytometry to study the mechanism of cytotoxic action of a series of ammine/amine Pt(IV) dicarboxylates [ammine diacetatodichloro(cyclohexylamine) platinum(IV), JM216; ammine dibutyratodichloro(cyclohexylamine)platinum(IV), JM221; ammine diacetatodichloro(propylamine)platinum(IV), JM223; ammine dibenzoatodichloro(propylamine)platinum(IV), JM244]. JM216 has been shown to have clinical potential and has recently entered phase II trials. All the compounds caused a slowdown in S-phase transit followed by a block in G2. Cells died either through apoptosis (largely during S-phase) or by failing to overcome the G2 block (some days after treatment). In G2, the cells either divided or enlarged and died. At equitoxic doses, JM216 showed the most apoptotic cells and had the most platinum bound to the DNA; JM244 showed the fewest apoptotic cells and had the least platinum bound to DNA. We suggest that whether apoptosis was triggered or not was governed by the total amount of Pt bound to the DNA; the type of lesion was more important in determining whether a cell became blocked in G2.

Animals↗
PubMed1994

The role of apoptosis in cell killing by cisplatin: a flow cytometric study.

Cell killing of L1210 cells by cisplatin has been studied using flow cytometry and DNA gel electrophoresis. Ten hours after a supralethal dose of drug (100 microM), extensive apoptosis was induced. Cells were also susceptible to the induction of apoptosis by nutritional deprivation, for example by incubation in arginine-deficient medium. After treatment in full medium with doses of drug in the range 1-10 microM, cells experienced a slow-down in S-phase transit followed by a G2 block. Cells either overcame the G2 block and continued to cycle or enlarged and eventually died. There was no evidence to suggest that cells dying from the G2 block underwent apoptosis. The data were consistent with a dual mechanism of cell death-higher doses of drug led to rapid death through apoptosis; lower doses led to death at later times resulting from failure to overcome a block in G2.

Animals↗
PubMed1994

Evaluation of novel ammine/amine platinum (IV) dicarboxylates in L1210 murine leukaemia cells sensitive and resistant to cisplatin, tetraplatin or carboplatin.

Seventeen alkylamine ammine dicarboxylatodichloroplatinum(IV) complexes of general structure c,t,c-[PtCl2(OCOR1)2NH3(RNH2)], where R = aliphatic or alicyclic and R1 = aliphatic or aromatic, have been evaluated against L1210 cell lines with acquired resistance to cisplatin (10-fold), tetraplatin (34-fold) or carboplatin (14-fold) using an in vitro growth-delay assay. All of these compounds overcame cisplatin, tetraplatin and carboplatin resistance. Potency increased as the number of carbon atoms in the axial aliphatic ligands (R1) increased, for example comparing JM216 (R = cyclohexyl, R1 = CH3, IC50 = 1.2 microM) with JM274 (R = cyclohexyl, R1 = n-C4H9, IC50 = 0.05 microM) against the parent sensitive line (L1210/S). The most active compounds were those possessing aromatic ligands at R1, regardless of whether R = aliphatic or alicyclic, for example JM244 (R = n-C3H7, R1 = C6H5, IC50 = 0.028 microM) and JM2644 (R = c-C6H11, R1 = C6H5, IC50 = 0.031 microM) against L1210/S. For an alicyclic alkylamine series in which R is varied from c-C3H7 to C-C7H13, with R1 = n-C3H7 for each compound, cytotoxic potency was maximised at c-C6H11 (JM221, IC50 = 0.06 microM against L1210/S). Preliminary biochemical studies, at equitoxic doses, comparing JM221 (0.1 microM) with cisplatin (0.6 microM) identified five times more platinum associated with JM221 treated cells and 1.5 times more platinum bound to the DNA of JM221-treated cells. The lipophilic properties of some of these platinum(IV) dicarboxylates may contribute to both the potency and circumvention of resistance by these compounds.

Animals↗
PubMed1992

The role of platinum uptake and glutathione levels in L1210 cells sensitive and resistant to cisplatin, tetraplatin or carboplatin.

Three L1210 murine leukemia variants resistant to cisplatin, tetraplatin or carboplatin were compared with their sensitive parent line for differences in platinum accumulation, efflux and glutathione (GSH) content. All three resistant lines had reduced platinum accumulation compared with the sensitive line following exposure to each of the three drugs. There was no difference in the efflux of platinum between the sensitive and resistant lines indicating that reduced platinum accumulation was due to impaired uptake mechanisms. However, in cell survival experiments it was apparent that the resistant lines could tolerate higher intracellular platinum levels than the sensitive line. Intracellular GSH measurements revealed comparable levels in all but the L1210/carboplatin line which had a 2-fold elevation during the first 24 hours of culture. However, depletion of intracellular GSH with buthionin sulphoximine over a 72 hour period did not sensitize the resistant lines to the drugs. These studies have demonstrated that impaired platinum uptake is one of the mechanisms contributing to platinum drug resistance, while perturbations in GSH levels do not appear to play a role in these cell lines.

Animals↗
PubMed1991

Platinum coordination complexes which circumvent cisplatin resistance.

In the search for a platinum complex capable of oral administration, the poor bioavailability of established drugs has been circumvented by the discovery of a novel class of platinum (IV) ammine/amine dicarboxylate dichlorides. These compounds, when administered orally to mice carrying the ADJ/PC6 plasmacytoma, exhibit antitumor selectivities far superior to those of cisplatin or carboplatin (given intraperitoneally). Oral activity comparable to that of intraperitoneal cisplatin and carboplatin has also been demonstrated in a panel of human ovarian tumor xenografts. Platinum (IV) ammine/amine dicarboxylates retain cytotoxicity in cultures of L1210/cisplatin and L1210/tetraplatin acquired resistant cells. This property does not translate into a cisplatin-resistant variant of the ADJ/PC6 tumor, in the example of JM221. This result reflects experience with tetraplatin, a drug currently in phase I study, which is comparably ineffective against an ADJ/PC6/cisplatin variant. It is a moot point whether either L1210 or ADJ/PC6/cisplatin-resistant variants are clinically predictive screening models, since this issue must be determined ultimately by clinical study. We have attempted to resolve this dichotomy through the establishment of human ovarian carcinoma lines, both in vitro and in vivo, where there is evidence that response to platinum coordination complexes in the several models reflects that of the donor patient's tumor to platinum-based clinical therapy. The data herein for platinum (IV) ammine/amine dicarboxylates in these models gives encouragement to the notion that these novel compounds may be of value as oral therapeutic agents, whilst also providing an important lead to the discovery and development of a new generation of platinum drugs possessing broad clinical utility.

Animals↗
PubMed1989

Naloxone: report of a beneficial side effect.

We report two cases. The first was an unexpected, complete resolution of an acute unilateral neurologic deficit associated with anesthesia when naloxone was administered to reverse residual narcotic effect. The second was a complete resolution of postoperative unilateral electroencephalographic evidence of ischemia after naloxone administration in a patient following a carotid endarterectomy. A literature search suggests that naloxone may be useful in the treatment of acute and hyperacute stroke due to ischemia.

Journal Article↗
PubMed1988

Inhibition of human leukaemic thymidylate kinase and L1210 ribonucleotide reductase by dinucleotides of adenosine and thymidine and their phosphonate analogues.

Dinucleotides of adenosine and thymidine in the ApnT series (n = 3,4,5 and 6) and their corresponding phosphonate analogues, where a methylene group replaces the oxygen between the alpha and beta phosphorus atoms adjacent to thymidine, have been evaluated as inhibitors of human leukaemic thymidylate kinase (dTMP kinase, EC 2.7.4.9) and ribonucleotide reductase (EC 1.17.4.1) from L1210 cells. Ap3T, Ap4T, Ap2cpT and Ap3cpT were poor inhibitors of both enzymes. Ap5T, Ap6T and their phosphonate analogues were potent inhibitors of dTMP kinase, possibly acting as bisubstrate analogues (IC50 values: Ap5T, 7.9 microM; Ap4cpT, 5.8 microM; Ap6T, 5.4 microM; Ap4cpT, 4.0 microM). For CDP reductase, where these compounds may bridge activity/effector sites on the M1 subunit of the enzyme, Ap5T and Ap6T were inhibitors with IC50 values of 14.4 microM and 20.3 microM respectively. The phosphonate series of compounds was far less active. The thymidine moiety of the compounds was essential for inhibition since Ap5A was inactive against both enzymes. dTTP, although a poor inhibitor of thymidylate kinase was a potent negative effector of CDP reductase (IC50, 19.3 microM). Significantly, Ap5T was not hydrolysed to release dTTP under the conditions of the assay. These studies show that the activities of both enzymes may be modulated by nucleotide analogues.

Adenosine↗
PubMed1988

Dinucleotide analogues as inhibitors of thymidine kinase, thymidylate kinase, and ribonucleotide reductase.

P1-(Adenosine-5')-Pn-(thymidine-5') tri-, tetra-, penta-, and hexaphosphates (ApnT) plus the analogues with a methylene group alpha, beta to the thymidine residue (ApncpT) were synthesized by coupling the appropriate two nucleotides, having activated one by morpholine. These were tested as potential dinucleotide inhibitors of thymidine kinase, thymidylate kinase, and ribonucleotide reductase. All three enzymes bind ATP and thymidine or its nucleotides and therefore might be inhibited by dinucleotides containing adenosine and thymidine. Ap5T and Ap6T strongly inhibited all three enzymes (IC50 = 2.4-20 microM). Ap4cpT and Ap5cpT also strongly inhibited the two kinases (IC50 = 4-20 microM) but were much weaker inhibitors of the reductase (IC50 = 130 and 230 microM).

Adenine Nucleotides↗
PubMed1987

Synthesis and ribonucleotide reductase inhibitory activity of analogues of 2,3-dihydro-1H-imidazo[1,2-b]pyrazole (IMPY).

A series of derivatives of the ribonucleotide reductase inhibitory anti-tumour agent 2,3-dihydro-1H-imidazo[1,2-b]pyrazole (IMPY), including all the methyl analogues, have been synthesised. IMPY itself caused 50% inhibition of L1210 tumour-derived ribonucleotide reductase at a concentration of 0.39 mM, comparable with enzyme obtained from other sources. The analogues proved to be no better than IMPY, either as inhibitors of this enzyme or of the growth of L1210 cells in vitro. No correlation was apparent between biological activity and position of substitution.

Antineoplastic Agents↗
PubMed1983

Primary aortoduodenal fistula following radiotherapy.

Primary aortoduodenal fistula is a rare condition. Common causes include atherosclerosis, leading to formation of an aortic aneurysm (most common); syphilis; carcinoma of the pancreas; trauma; tuberculosis, and myocosis. Presented herein is the recognition and successful treatment of what appears to be the first patient with a primary aortoduodenal fistula following paraaortic radiotherapy. Once suspected, immediate surgical treatment is mandatory. Primary aortic control (closure or resection), along with resection of the diseased intestinal segment, would appear to be the safest and most acceptable treatment.

Aorta, Abdominal↗