Experimental drug slows incurable breast cancer: study

Pfizer's experimental breast cancer drug stopped the progression of an incurable form of the disease for more than two years in a study, a dramatic delay for those with the second deadliest cancer in women.

Patients were given the medicine, PD 0332991, along with Novartis' Femara. The findings, reported Wednesday at the San Antonio Breast Cancer Symposium in Texas, showed no tumor progression for a median of 26.1 months, compared with 7.5 months in those who had Femara alone. Results were from the second of three stages of testing usually needed for U.S. approval.

The medicine is the first in a new class of agents that works by blocking a protein critical in the cancer cell cycle, said lead researcher Richard Finn. It's also among the most promising in New York-based Pfizer's drug development pipeline, with the potential for generating $5 billion in annual sales for breast and other tumor types, Andrew Baum, an analyst at Citigroup in London, advised investors.

The findings are noteworthy because of the size of the benefit and comparative safety of the experimental treatment, said Claudine Isaacs of Georgetown Lombardi Comprehensive Cancer Center in Washington. The study, involving 165 patients, was small and must be confirmed in larger trials, she said.

It included women with tumors fueled by the hormone estrogen, the most common type of breast cancer. All had metastatic disease, which had spread to other parts of the body and is no longer considered curable. -- Bloomberg News