Phase I trial of Adozelesin using the treatment schedule of daily x5 every 3 weeks.

CC-1065 is a unique alkylating agent that preferentially binds in the minor groove of double-stranded DNA at adenine-thymine-rich sites. Although it has broad antitumor activity in preclinical models its development was discontinued because of deaths observed during preclinical toxicology studies. Adozelesin is a potent synthetic analog that was chosen for clinical development because it had a similar preclinical antitumor spectrum, but did not produce deaths similar to CC-1065 at therapeutic doses. Phase I evaluations using a variety of Adozelesin treatment schedules have been conducted. This report describes our experience using a multiple dose treatment schedule. Endpoints including antitumor response, maximum tolerated dose, dose limiting toxicity as well as other toxicities and the recommended Phase II starting dose were determined. Adozelesin was given as a 10 minute IV infusion for 5 consecutive days every 21 days or upon recovery from toxicity. The dose range evaluated was 6-30 mcg/m2/day. All patients had refractory solid tumors and had received prior cytotoxic treatment. Thirty-three patients (22 men: 11 women) were entered onto the study and 87 courses were initiated. Dose limiting toxicity was cumulative myelosuppression (leucopenia, thrombocytopenia). The maximum tolerated dose was 30 mcg/m2/day. The only other significant toxicity was an anaphylactoid syndrome that occurred in 2 patients. A partial response was observed in a patient with refractory soft tissue sarcoma. The recommended Phase II starting dose of Adozelesin using a 10 minute IV infusion for 5 consecutive days is 25 mcg/m2/day to be repeated every 4-6 weeks to allow recovery from myelotoxicity, based on our experience. Additional Phase I and II studies with Adozelesin are recommended.

Phase I study of adozelesin administered by 24-hour continuous intravenous infusion.

BACKGROUND: Adozelesin, a synthetic analogue of the antitumor antibiotic CC-1065, is the first of a class of potent sequence-specific alkylating agents to be brought to clinical trial. In preclinical in vitro testing, it has demonstrated antitumor activity at picomolar concentrations. PURPOSE: We conducted a phase I study of adozelesin to (a) determine a recommended dose for phase II testing using a 24-hour intravenous infusion, (b) characterize the toxic effects of the drug using this schedule, and (c) document any antitumor activity observed. METHODS: Adozelesin was given as a 24-hour continuous intravenous infusion. Treatments were initially scheduled every 3 weeks, but the prolonged myelosuppression observed necessitated a final dosing interval of every 6 weeks. The starting dose of 30 micrograms/m2 was escalated using a modified Fibonacci scheme until dose-limiting toxicity was encountered. RESULTS: Twenty-nine patients were entered in the study. Successive dose levels used were 30, 60, 100, 150, 120, and 100 micrograms/m2. Prolonged thrombocytopenia and granulocytopenia were dose limiting. No antitumor responses were observed. CONCLUSION: We recommend that the phase II dose of adozelesin given as a continuous 24-hour intravenous infusion be 100 micrograms/m2, repeated every 6 weeks. Other potentially less myelosuppressive schedules could be pursued.

Phase I study of adozelesin (U-73,975) in patients with solid tumors.

During a phase I clinical and pharmacologic trial, 26 patients with refractory solid tumors were treated with increasing doses of adozelesin by brief intravenous infusion every 3 weeks. Overall, adozelesin was well tolerated. The dose-limiting toxicity was myelosuppression, mainly thrombocytopenia and leukopenia. Nonhematologic toxicity was generally mild, with fatigue (36%), local reaction at the infusion site (24%), nausea or vomiting (20%) and hypersensitivity reaction (16%) being the most common adverse effects. There were no objective clinical responses. The maximally tolerated dose on this schedule was 188 micrograms/m2 with the recommended phase II starting dose being 150 micrograms/m2 on an every 3 week schedule. Adozelesin merits broad investigation at the phase II level.

A phase I clinical and pharmacokinetic study of the oral and the oral/intravenous administration of menogaril.

Thirty-five patients with advanced refractory cancer were enrolled on this phase I study of menogaril administered orally every 4 weeks at dosages ranging from 85 mg/m2 to 625 mg/m2. An additional 12 patients received alternating oral and IV doses of menogaril (250 mg/m2 IV; 250-500 mg/m2 oral) with accompanying blood and urine sampling for pharmacokinetics analysis. Nausea and vomiting were the dose-limiting toxicities at the 625 mg/m2 dosage level; vomiting was inadequately relieved by prophylactic antiemetics at this dosage level. Other toxicities included sporadic leukopenia at all dosage levels; at dosages of 500 mg/m2 and 625 mg/m2, leukopenia < 3000/microliters occurred in 7 of 24 patients. Anemia and thrombocytopenia were much less frequent toxicities. Among the patients receiving IV menogaril, peripheral vein phlebitis, leukopenia and anemia were the predominant toxicities. No antitumor responses were observed, yet one patient with non-small cell lung cancer experienced a 30% reduction in metastatic tumor nodules. For the patients receiving alternating oral and IV menogaril, comparative pharmacokinetic analyses were performed by HPLC. After oral administration, maximum plasma concentrations were achieved in an average of 6 hours; maximum plasma concentrations were less than one-quarter of those achieved after intravenous administration. The harmonic mean (+/- SD) terminal disposition half-life after oral dosing was 29.3 +/- 9.2 hours; mean systemic bioavailability was 33.6 +/- 10.5% after oral dosing. Forty-eight hours after an oral dose, mean cumulative urinary excretions of menogaril and the primary metabolite, N-demethylmenogaril, were 4.00 +/- 0.96% and 0.44 +/- 0.16%, respectively. Because of the poor tolerance of oral menogaril and minimal evidence of biological activity, this schedule of drug administration is not recommended for phase II evaluation. Based on this and other published studies of oral menogaril, frequent chronic low-intermediate dosages of the drug may be given orally with potentially better tolerance and antitumor activity.

Physical and genetic characterization of the cloned sbcB (exonuclease I) region of the Escherichia coli genome.

A 17-kilobase (kb) HindIII fragment containing the structural gene for exonuclease I (sbcB) from Escherichia coli K-12 was physically and genetically characterized. The monomeric molecular weight of exonuclease I was 53,700, based on sodium dodecyl sulfate-polyacrylamide gel electrophoresis of 35S-labeled E. coli mini- and maxicells. The gene was in close proximity to two unidentified proteins with molecular weights of 15,200 and 13,100. No other polypeptides appeared to be constitutively synthesized from the 17-kb fragment. Genetically, no portion of the histidine operon or the shikimic acid transport gene (shiA) was detected on the fragment. Although the entire 17-kb fragment in the vector pMB9 was too unstable to be useful, a 7.6-kb BamHI-EcoRI fragment inserted into a variety of vectors was stable. A detailed restriction map of the fragment is presented. Several derivatives in the runaway-replication vectors pMB06 and pMOB45 yielded 20- to 52-fold increases in exonuclease I activity after a switch in growth temperature to 40 degrees C. Of six exonuclease I mutants examined by DNA-DNA hybridization, one (xonA6) appeared to have arisen from a 1.2-kb insertion into the structural gene for exonuclease I.

Expression of the HIS3 gene of Saccharomyces cerevisiae in polynucleotide phosphorylase-deficient strains of Escherichia coli K-12.

The PstI and BamHI fragments, containing the HIS3 (imidazoleglycerol phosphate dehydratase) gene of yeast obtained from pYehis2, and the ColE1-derived plasmid pBR322 were ligated in vitro and used to transform hisB463 strains of Escherichia coli K-12. Expression of the cloned HIS3 gene from yeast was markedly enhanced (3--5-fold) in polynucleotide phosphorylase (pnp)-deficient strains of E. coli. The levels of both HIS3 and plasmid-encoded mRNAs were increased in pnp- strains carrying the chimeric plasmids, whereas there was little difference in the levels of pBR322-specific mRNAs in pnp+ and pnp- strains. This increase in HIS3 mRNA appeared to be related to specific stabilization of the eukaryotic message due to its unique structural features, since the half-life of the HIS3 mRNA increased from 1.5 to 18.7 min, whereas no increase in the half-lives of pBR322 vehicle mRNAs was observed. A physical map of the plasmid pYehis2 was constructed using restriction endonuclease and molecular cloning techniques.