Phase I and pharmacokinetic study of lapatinib in combination with capecitabine in patients with advanced solid malignancies

Purpose This phase I trial ( EGF10005) assessed the safety, optimally tolerated regimen ( OTR), and pharmacokinetics of lapatinib and capecitabine in combination in patients with advanced solid malignancies. Patients and Methods Patients with previously treated, advanced solid malignancies were eligible. Cohorts of at least three patients each received once- daily oral lapatinib ( continuous) and capecitabine ( twice daily for 14 days every 21 days). Doses of lapatinib and capecitabine were escalated based on dose- limiting toxicities in the first treatment cycle until the OTR was reached. Additional patients were treated at the OTR dose level to further evaluate safety and for pharmacokinetic analyses. Results Forty- five patients were treated in the study. The OTR was determined to be lapatinib 1,250 mg/ d plus capecitabine 2,000 mg/ m(2)/ d. The majority of drug- related adverse events were grade 1 to grade 2 in severity, with few grade 3 and no grade 4 toxicities. The most common drug- related toxicities ( > 15% of patients) were diarrhea, nausea, rash, palmar- plantar erythrodysesthesia, mucositis, vomiting, and stomatitis. There were four confirmed responses ( one complete response and three partial responses). The pharmacokinetics ( area under the curve and maximum concentration) of lapatinib, capecitabine and its metabolites, fluorouracil, and alpha- fluoro- beta- alanine, were not meaningfully altered by coadministration. Conclusion Lapatinib and capecitabine administered on a 3- week schedule were well tolerated, and no pharmacokinetic interaction was observed. Clinical activity was observed in patients with previously treated, advanced solid malignancies.