Phase I and Pharmacology Study of Ropidoxuridine (IPdR) as Prodrug for Iododeoxyuridine-Mediated Tumor Radiosensitization in Advanced GI Cancer Undergoing Radiation.

PURPOSE: Iododeoxyuridine (IUdR) is a potent radiosensitizer; however, its clinical utility is limited by dose-limiting systemic toxicities and the need for prolonged continuous infusion. 5-Iodo-2-pyrimidinone-2'-deoxyribose (IPdR) is an oral prodrug of IUdR that, compared with IUdR, is easier to administer and less toxic, with a more favorable therapeutic index in preclinical studies. Here, we report the clinical and pharmacologic results of a first-in-human phase I dose escalation study of IPdR + concurrent radiation therapy (RT) in patients with advanced metastatic gastrointestinal (GI) cancers. PATIENTS AND METHODS: Adult patients with metastatic GI cancers referred for palliative RT to the chest, abdomen, or pelvis were eligible for study. Patients received IPdR orally once every day × 28 days beginning 7 days before the initiation of RT (37.5 Gy in 2.5 Gy × 15 fractions). A 2-part dose escalation scheme was used, pharmacokinetic studies were performed at multiple time points, and all patients were assessed for toxicity and response to Day 56. RESULTS: Nineteen patients were entered on study. Dose-limiting toxicity was encountered at 1,800 mg every day, and the recommended phase II dose is 1,200 mg every day. Pharmacokinetic analyses demonstrated achievable and sustainable levels of plasma IUdR ≥1 µmol/L (levels previously shown to mediate radiosensitization). Two complete, 3 partial, and 9 stable responses were achieved in target lesions. CONCLUSIONS: Administration of IPdR orally every day × 28 days with RT is feasible and tolerable at doses that produce plasma IUdR levels ≥1 µmol/L. These results support the investigation of IPdR + RT in phase II studies.

High-throughput screening of a diversity collection using biodefense category A and B priority pathogens.

One of the objectives of the National Institutes of Allergy and Infectious Diseases (NIAID) Biodefense Program is to identify or develop broad-spectrum antimicrobials for use against bioterrorism pathogens and emerging infectious agents. As a part of that program, our institution has screened the 10 000-compound MyriaScreen Diversity Collection of high-purity druglike compounds against three NIAID category A and one category B priority pathogens in an effort to identify potential compound classes for further drug development. The effective use of a Clinical and Laboratory Standards Institute-based high-throughput screening (HTS) 96-well-based format allowed for the identification of 49 compounds that had in vitro activity against all four pathogens with minimum inhibitory concentration values of ≤16 µg/mL. Adaptation of the HTS process was necessary to conduct the work in higher-level containment, in this case, biosafety level 3. Examination of chemical scaffolds shared by some of the 49 compounds and assessment of available chemical databases indicates that several may represent broad-spectrum antimicrobials whose activity is based on novel mechanisms of action.

Liquid Chromatographic Determination of NSC 737664 (ABT-888: an Inhibitor of Poly(ADP-ribose) Polymerase (PARP)) in Plasma and Urine in a Phase 0 Clinical Trial.

A gradient reversed-phase high performance liquid chromatographic method was developed for determining NSC 737664 (2-[(2R)-2-methylpyrrolidin-2-yl]-1H-benzimidazole-4-carboxamide; ABT-888) in human plasma and urine. Chromatographic separation used a mobile phase composed of 0.1% formic acid in water and 0.1% formic acid in acetonitrile, and a C18 column (150 mm × 4.6 mm, 5µ). Quantitation was performed using UV detection at 300 nm. Chromatographic peak identity was confirmed using positive-ion electrospray ionization mass spectrometry. The method was shown to be specific, accurate and reproducible, and thereby appropriate for monitoring plasma and urine levels of the agent in support of a phase 0 clinical study.