An investigational oral formulation of paclitaxel improved response compared with the intravenous (IV) formulation in women with metastatic breast cancer, according to a study presented at the San Antonio Breast Cancer Symposium. However, the oral form is taken with encequidar, which has a time-consuming administration that requires nine consecutive hours of fasting.
The pivotal, open-label, randomized, phase III study randomized 402 patients 2:1 to receive oral paclitaxel 205 mg/m² plus encequidar for three days per week (n=265) or IV paclitaxel 175 mg/m² every three weeks (n=137).
Improved survival with oral formulation of paclitaxel
Patients receiving the oral formulation had a better overall response rate (primary endpoint) compared with IV (35.8% vs. 23.4%; P=0.011). Responses in the oral paclitaxel cohort were also durable: Confirmed responses of more than 150 days occurred in 51% of responders in the oral group and 38% of responders in the IV group.
Ongoing analysis of overall survival favored the oral paclitaxel formulation at the time of reporting (P=0.035), with a median of 27.9 months in the oral cohort compared with 16.9 months in the IV cohort. Ongoing progression-free survival analysis also favored the oral cohort (9.3 months vs. 8.3 months, respectively; P=0.077).
There was a lower incidence and severity of neuropathy in the oral cohort compared with IV; at week 23, 17% of the oral group reported any-grade neuropathy compared with 57% of the IV group. Grade 3 neuropathic symptoms were observed in 1% of the oral group and 8% of the IV group.
The oral formulation had higher rates of neutropenia, infection, and gastrointestinal adverse events.