Pfizer announced updated progression-free survival (PFS) results from the Phase 3 PALOMA-2 trial reinforcing the clinical benefit of IBRANCE (palbociclib) combined with letrozole. The data demonstrate that the combination of IBRANCE plus letrozole reduced the risk of disease progression by 44 percent and improved median PFS by more than one year compared to letrozole plus placebo (27.6 months [95% CI: 22.4, 30.3] vs 14.5 months [95% CI: 12.3, 17.1]) when used as the initial treatment for postmenopausal women with estrogen receptor-positive, human epidermal growth factor receptor 2-negative (ER+, HER2-) metastatic breast cancer (HR=0.56 [95% CI: 0.46, 0.69]). This updated, post-hoc analysis included a median follow-up of more than three years, which is the longest to date of any Phase 3 study of a CDK 4/6 inhibitor.
The updated data are consistent with results from the primary analysis for PALOMA-2, which showed a median PFS for women treated with IBRANCE plus letrozole of 24.8 months (95% CI: 22.1, NE) compared with 14.5 months (95% CI: 12.9, 17.1) for women treated with letrozole plus placebo (HR=0.58 [95% CI: 0.46,0.72], p<0.0001). Consistent with findings from the primary analysis, the updated data demonstrate that clinical benefit was observed across all patient subgroups receiving the combination of IBRANCE and letrozole. Overall survival data were not yet mature at the time of this updated PFS analysis.
“There currently is no cure for metastatic breast cancer, so prolonging progression-free survival and delaying the need for additional anticancer therapies are critical factors in treating these patients,” said Hope Rugo, MD, lead author and professor of medicine and director of Breast Oncology and Clinical Trials Education at the University of California San Francisco Helen Diller Family Comprehensive Cancer Center. “The updated findings from PALOMA-2 provide additional evidence to support the use of palbociclib with an aromatase inhibitor as a standard of care in the first-line setting for postmenopausal patients with hormone receptor-positive (HR+), HER2- metastatic breast cancer across all patient subgroups.”
At SABCS, 10 additional Pfizer-sponsored abstracts will be presented evaluating IBRANCE, several of which explore further analysis of PALOMA-2 along with three real-world studies of patients treated with IBRANCE in clinical practice. These real-world data include patients who have received IBRANCE in combination with endocrine therapy in various settings and across age groups, including young women (aged 50 years and under, which functioned as a surrogate for premenopausal status in the analysis).
The safety profile of IBRANCE in the PALOMA-2 updated analysis is consistent with previous reports and will be presented at SABCS. In the primary analysis, the most common adverse reactions (≥20%) of any grade reported in the PALOMA-2 study of IBRANCE plus letrozole vs placebo plus letrozole included neutropenia (80% vs 6%), infections (60% vs 42%), leukopenia (39% vs 2%), fatigue (37% vs 28%), nausea (35% vs 26%), alopecia (33% vs 16%), stomatitis (30% vs 14%), diarrhea (26% vs 19%) and anemia (24% vs 9%).
IBRANCE was the first CDK 4/6 inhibitor approved by any regulatory authority, and now is approved in more than 75 countries. These global approvals are based on data from the PALOMA program, including PALOMA-2 as well as the Phase 3 PALOMA-3 trial, which evaluated IBRANCE in combination with fulvestrant in pre-, peri- and postmenopausal women with HR+, HER2- metastatic breast cancer whose disease progressed on or after prior endocrine therapy. Pre- and peri-menopausal women enrolled in PALOMA-3 received the LHRH agonist goserelin.
To date, IBRANCE has been prescribed to more than 90,000 patients worldwide.