Results from a
Phase 3 clinical trial comparing Athenex’s (
ATNX -17.4%) oral paclitaxel (and oral absorption technology encequidar) to the intravenous (IV) formulation in metastatic breast cancer patients showed superior response and survival but with a mixed safety profile. The data are being presented at the San Antonio Breast Cancer Symposium.
In the intent-to-treat population, the tumor response rate in the oral paclitaxel group was 35.8% (n=95/265) versus 23.4% (n=32/137) (p=0.011). In the population with evaluable post-baseline scan, the response rates were 50.3% and 29.6%, respectively (p=0.0005). Median duration of response was greater in the oral group (27.9 months) compared to the IV group (16.9 months).
Median overall survival (OS) was 27.9 months compared to 16.9 months for IV paclitaxel (p=0.035).
Median progression-free survival favored oral paclitaxel, 9.3 months vs. 8.3 months, but the separation thus far was not statistically significant (p=0.077).
Investors appear to be reacting to the safety data. The rates of alopecia (hair loss), severity of neuropathic adverse events (17% vs. 57%) and serious neuropathic symptoms (1% vs. 8%) were lower in patients receiving oral paclitaxel, but higher rates of neutropenia, infection and gastrointestinal adverse events were observed. The toxicity profiles of oral and IV pactlitaxel were generally similar.
