Ibrance doubles progression-free survival in breast cancer

Pfizer’s Ibrance has shown a strong benefit as a second-line treatment for metastatic breast cancer, delaying the disease’s advance more than twice as long as standard treatment.

The news was announced on Saturday at ASCO in Chicago, the most important cancer congress of the year.

Ibrance (palbociclib) represents a major step forward in treating advanced hormone receptor-positive (HR+) and human epidermal growth factor receptor 2-negative (HER2-) breast cancer in women whose disease had progressed during or after endocrine therapy.

Pfizer’s new drug was approved by the FDA and launched in the US in February this year for use in first-line treatment combination with letrozole, but has now confirmed its benefits for women who have advanced after this first-line treatment.

Analysts knew the PALOMA3 trial would yield strong results, as it was stopped early in April because of positive results.

Now released, the data show the drug extended progression-free survival (PFS) to 9.2 months when combined with fulvestrant (Faslodex), compared to the 3.8 months in patients taking fulvestrant on its own.

The trial of 521 patients showed that those taking the combination had higher rates of neutropenia and leukopenia, but symptomatic adverse events were similar between the arms.

The drug has yet to demonstrate overall survival (OS) benefits either as a first- or second-line treatment. Nevertheless, the wider breast cancer community agree with Pfizer and the trial investigators that the drug represents major progress.

The Principal Investigator for the study, Nicholas Turner, MD, PhD, consultant medical oncologist at The Royal Marsden and Institute of Cancer Research in London said: “The current treatment options available for patients with this type of metastatic breast cancer present challenges for physicians and patients, as demonstrated by the limited clinical benefit of additional lines of endocrine therapy, and by the difficult side effects of chemotherapy.”

Turner told MedPage Today that the drug was likely to become a standard of care.

Other doctors in the field were also enthused.

“The future just got brighter for the large group of women with metastatic oestrogen and/or progesterone receptor positive breast cancer,” Charles Shapiro, MD, of the Tisch Cancer Institute at Mt Sinai Hospital in New York City commented to MedPage Today.

Dr Shapiro added that the study reminded him of Roche’s Herceptin (trastuzumab), which has transformed the overall survival times for women with another type of breast cancer, HER2+, when combined with chemotherapy.

For Pfizer, the results are encouraging, and analysts forecast the drug to reach peak annual sales of $4 billon.

The company is now talking to global regulatory authorities about filing the drug for this new indication. Ibrance is not yet approved in Europe, but Pfizer says it will file the drug for use in its first-line indication with the European Medicines Agency in the second half of 2015.

Related articles

10 new cancer drug highlights for ASCO

Don't miss your daily pharmaphorum news.
SUBSCRIBE free here.