A review of a supplemental new drug application for a CDK 4/6 inhibitor, called Ibrance by Pfizer, has been accepted by the U.S. Food and Drug Administration (FDA).
This includes data from the phase 3 Paloma-2 trial, a study which used Ibrance and letrozole as an initial therapy for postmenopausal women with estrogen receptor-positive, human epidermal growth factor receptor 2-negative (ER+, HER2) metastatic breast cancer.
“Since its introduction in 2015, more than 45,000 patients have been prescribed Ibrance by more than 9,000 providers in the U.S.,” Liz Barrett, global president and general manager at Pfizer Oncology, said. “We are pleased that the Paloma-2 trial has further demonstrated the significant clinical benefit of Ibrance in the first-line setting, providing additional evidence for its continued use as a standard of care medicine.”
In the Paloma-1 and Paloma-3 trials using Ibrance plus letrozole, the most often reported side effect was neutropenia, caused by an abnormally low level of neutrophils, white blood cells used to fight off bacterial infections.
In both Paloma-1 and Paloma-3, Grade 3 and Grade 4 decreased neutrophil counts were reported with one death due to neutropenic sepsis observed in Paloma-3.
Pulmonary embolism -- a blockage in the pulmonary arteries -- was reported in 5 percent of patients using Ibrance plus letrozole and 1 percent of patients using Ibrance plus fulvestrant.
