Objective: Lapatinib, a tyrosine kinase inhibitor targeting epidermal growth factor receptor (EGFR) and human epidermal growth factor receptor 2 (HER2), also inhibits breast cancer resistance protein (BCRP) involved in resistance to topotecan. The aim of this multicenter study was to assess the efficacy of the combination topotecan-lapatinib in epithelial ovarian cancer relapsing after a first line of chemotherapy.
Methods: Patients having relapsed within 6 months (n = 20) or between 6 and 12 months (n = 19) received weekly topotecan (3.2 mg/m given intravenously on days 1, 8, and 15) and daily oral lapatinib (1250 mg). Translational studies were performed on tumor and serum.
Results: An objective (partial) response was observed for 5 patients (14%), all with late relapse. The rates of overall benefits, including responses and stabilizations, were 37% and 62% in patients having relapsed within or after 6 months, respectively. Corresponding median time to progression were 58 and 94 days. The most frequent toxicity was hematological, including grade 4 neutropenia (18%) and thrombocytopenia (3%). None of the tumors overexpressed HER2 or EGFR, and no mutation was found. Two Kras mutations were identified. Positive expressions of BCRP and cyclin A (median, 70% and 40%) were not correlated to the response to treatment.
Conclusions: This study failed to demonstrate a clinical benefit of lapatinib-topotecan compared to previously described activity with topotecan alone in a context of low levels of EGFR and HER2 expressions, and no biomarkers could be identified. The absence of correlation between BCRP expression and clinical outcomes suggests that other mechanisms of resistance to topotecan could predominate.