Pfizer drug shows significant promise in late-stage breast cancer

US drugs behemoth Pfizer (NYSE: PFE) has presented encouraging data from a randomized Phase II clinical trial that showed PD-0332991 (PD-991) in combination with Novartis' Femara (letrozole) significantly extended progression-free survival (PFS) compared with letrozole alone in post-menopausal patients with estrogen receptor positive (ER+), human epidermal growth factor receptor 2 negative (HER2-) locally advanced or metastatic breast cancer.

PD-0332991 is among the most promising candidates in Pfizer’s drug development pipeline, with the potential for generating $5 billion in annual sales for breast and other tumor types, according to Citigroup analyst Andrew Baum, quoted by Bloomberg. The analysts noted that Pfizer is at least two years ahead of its closest competitors, Eli Lilly and Novartis, with similar cancer drugs in development.

For patients treated with the combination of PD-991 plus letrozole, median PFS was 26.1 months, a statistically significant improvement compared to the median PFS in women who received letrozole alone, which was 7.5 months (HR=0.37 [95% CI: 0.21, 0.63]; P <0.001). These data were presented earlier this week at the Annual San Antonio Breast Cancer Symposium, USA.