Phase I pharmacokinetic studies evaluating single and multiple doses of oral GW572016, a dual EGFR-ErbB2 inhibitor, in healthy subjects.

GW572016 is a dual EGFR-ErbB2 inhibitor that has promise as an anticancer agent. Two phase I studies were conducted to determine the safety, tolerability and pharmacokinetics of single and multiple doses given to healthy subjects. The single dose study evaluated two groups of eight subjects in an ascending dose, 4-way cross-over, while the multiple dose study evaluated twenty-seven healthy volunteers in an ascending dose, double-blind, randomized, placebo-controlled, staggered parallel design. No serious adverse events were seen in either study. The most common adverse events for subjects receiving GW572016 were headache, diarrhea, rash, cold symptoms, gastrointestinal symptoms, and elevated LFTs, which were similar between treatment and placebo groups. Absorption of single doses of GW572016 was slightly delayed, with median t(lag) of 15 minutes (range 0-90 minutes) and achieved peak serum concentrations at a median of three hours (range 1.5-6 hours) post-dose. Serum concentrations after multiple doses of GW572016 demonstrated no significant accumulation at the 25 mg dose, and approximately 50% accumulation at the 100 mg and 175 mg doses, achieving steady state in six to seven days. A modest time-dependent increase in serum concentrations also was detected with multiple doses of GW572016. Single and multiple oral doses of GW572016 were well tolerated in healthy subjects, and resulted in dose-related systemic exposure of GW572016.

Biochemical modulation of 5-fluorouacil through dihydropyrimidine dehydrogenase inhibition: a Southwest Oncology Group phase II trial of eniluracil and 5-fluorouracil in advanced resistant colorectal cancer.

PURPOSE: To investigate the hypothesis that a systemic agent designed to inhibit dihydropyrimidine dehydrogenase (DPD), the first enzyme in the fluoropyrimidine degradative pathway, could improve the effective amount of 5-fluorouracil (5-FU) delivered to a tumor resulting in enhanced response. PATIENTS AND METHODS: Eligibility included cytologically or pathologically verified diagnosis of colorectal cancer that recurred during or within 12 months of completion of adjuvant therapy, representing patients generally considered resistant to fluorinated pyrimidine therapy. Stratification was into two cohorts: recurrence while receiving adjuvant therapy, and relapse within 12 months of completing adjuvant therapy. Treatment consisted of 28 days of oral therapy every five weeks with eniluracil and 5-FU administered in a 10:1 ratio. The daily dose of eniluracil was 10 mg/m2 with 5-FU 1 mg/m2, divided into two doses. RESULTS: Twenty-five patients are evaluable for response: 9 relapsed during therapy and 16 relapsed within one year of adjuvant therapy. In the first group, there was one partial response (9%; 95% CI 0-41%); in the second cohort there was one confirmed complete response (5%; 95% CI 0-23%) and one unconfirmed partial response, for an overall response rate of 10%. CONCLUSIONS: This regimen lacks significant activity in this target population. Pre-treatment intratumoral DPD expression was not assessed, therefore the mechanism of fluorinated pyrimidine resistance cannot be specifically attributed to elevated DPD levels. Attempting restoration of chemotherapy sensitivity through blockade of enzymes or signal transduction molecules responsible for resistance is rational, provided that tumor target expression is the basis for trial entry.