Phase I and pharmacokinetic study of the association of capecitabine–cisplatin in head and neck cancer patients

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Abstract
The combination of cisplatin and 5-fluorouracil (5-FU) is considered to be the standard treatment in induction chemotherapy for patients with squamous cell carcinoma of the head and neck. Capecitabine (Xeloda®) is an oral fluoropyrimidine that is preferentially activated at the tumoral level, exploiting the higher thymidine phosphorylase activity in tumoral tissue. This phase I trial was conducted in patients with locally recurrent or metastatic head and neck carcinoma. The treatment plan included cisplatin on day 1 every 21 days, followed by capecitabine twice daily from day 2 to day 15, with a 1-week rest period. Pharmacokinetic investigations concerned plasma measurement of unchanged capecitabine, 5′-deoxy-5-fluorocytidine, 5′-doxifluridine and 5-FU using an optimized high performance liquid chromatography method, and cisplatin measurement in plasma using a limited sampling procedure. Twenty-one patients were included (mean age 61 years, range 46–76 years). Dose (mg/m2) increments for cisplatin and capecitabine (b.i.d.), respectively, were as follows: level 1, 80 and 1000 (three patients); level 2, 100 and 1000 (12 patients); and level 3, 100 and 1125 (five patients). Dose-limiting toxicities occurring during the first cycle (grade ≥3) were observed on level 2 (one patient with diarrhea, nausea, vomiting, hand–foot syndrome, one toxic death due to renal failure and neutropenia, one patient with neutropenia) and on level 3 (one patient with diarrhea, one patient with hand–foot syndrome and one patient with neutrothrombocytopenia). Due to delayed side-effects, 14 patients (67%) had repeated cycles every 28 days instead of 21 days as initially planned. Objective response was obtained in seven patients (three complete responses and four partial responses). There was no evidence of pharmacokinetic–pharmacodynamic relationships with the drugs and metabolites investigated. Combination of capecitabine and cisplatin is feasible, with a very promising response rate. The recommended doses for further phase II studies are those of level 2 with cisplatin 100 mg/m2 on day 1 and capecitabine 1000 mg/m2 b.i.d. on days 1–14, every 28 days.