Phase I and pharmacologic study of PN401 and fluorouracil in patients with advanced solid malignancies

Manuel Hidalgo, Miguel A. Villalona-Calero, S. Gail Eckhardt, Ronald L. Drengler, Gladys Rodriguez, Lisa A. Hammond, Sami G. Diab, Geoffrey Weiss, Allison M. Garner, Elizabeth Campbell, Karen Davidson, Arthur Louie, James D. O'Neil, Reid Von Borstel, Daniel D. Von Hoff, Eric K. Rowinsky

Research output: Contribution to journalArticlepeer-review

20 Scopus citations


Purpose: To assess the feasibility of administering PN401, an oral uridine prodrug, as a rescue agent for the toxic effects of fluorauracil (5- FU), and to determine the maximum-tolerated dose of 5-FU when given with PN401, with an 8-hour treatment interval between these agents. Patients and Methods: Patients with advanced solid malignancies were treated with escalating doses of 5-FU, given as a rapid intravenous infusion weekly for 3 consecutive weeks every 4 weeks. PN401 was administered orally 8 hours after 5-FU administration, to achieve sustained plasma uridine concentrations of at least 50 μmol/L. Initially, patients received 6 g of PN401 orally every 8 hours for eight doses (schedule 1). When dose-limiting toxicity (DLT) was consistently noted, patients then received 6 g of PN401 every 2 hours for three doses and every 6 hours thereafter for 15 doses (schedule 2). Results: Twenty-three patients received 50 courses of 5-FU and PN401. Among patients on schedule 1, DLT (grade 4 neutropenia complicated by fever and diarrhea) occurred in those receiving 5-FU 1,250 mg/m2/wk. Among patients on schedule 2, 5-FU 1,250 mg/m2/wk was well tolerated, but grade 4, protracted (> 5 days) neutropenia was consistently noted in those treated with higher doses of the drugs. Nonhematologic effects were uncommon and rarely severe. The pharmacokinetics of 5-FU, assessed in 12 patients on schedule 2, were nonlinear, with the mean area under the time-versus-concentration curve (AUC) increasing from 298 ± 44 to 962 ± 23 μmol/L and mean clearance decreasing from 34 ± 4 to 15.6 ± 0.38 L/h/m2 as the dose of 5-FU was increased from 1,250 to 1,950 mg/m2/wk. 5-FU AUCs achieved with 5-FU 1,250 mg/m2/wk for 6 weeks along with the intensified PN401 dose schedule were approximately five- fold higher than those achieved with 5-FU alone. Plasma uridine concentrations increased with each of the three PN401 doses given every 2 hours, and uridine steady-state concentrations were greater than 50 μmol/L. Conclusion: Treatment with oral PN401 beginning 8 hours after 5-FU administration is well tolerated and results in sustained plasma uridine concentrations above therapeutic-relevant levels. The recommended 5-FU dosage for phase II evaluations is 1,250 mg/m2/wk for 3 weeks every 4 weeks with the intensified PN401 dose schedule (schedule 2). At this dose, systemic exposure to 5-FU as measured by AUC was five-fold higher than that observed after administration of a conventional 5-FU bolus.

Original languageEnglish (US)
Pages (from-to)167-177
Number of pages11
JournalJournal of Clinical Oncology
Issue number1
StatePublished - Jan 2000
Externally publishedYes

ASJC Scopus subject areas

  • Oncology
  • Cancer Research


Dive into the research topics of 'Phase I and pharmacologic study of PN401 and fluorouracil in patients with advanced solid malignancies'. Together they form a unique fingerprint.

Cite this