Top-line data from the Phase III PALOMA-2 trial show that Pfizer’s Ibrance plus letrozole boosted progression-free survival (PFS) in certain patients with breast cancer.

The study met its primary endpoint demonstrating improvement in PFS for the combination compared with letrozole plus placebo in post-menopausal women with oestrogen receptor-positive, human epidermal growth factor receptor 2-negative (ER+, HER2-) advanced or metastatic breast cancer who had not received previous systemic treatment for their advanced disease.

Pfizer says it is using the data as “confirmatory evidence” for combining Ibrance (palbociclib) with letrozole in the first-line setting, in support of additional planned global regulatory submissions and a request for conversion of the accelerated approval for Ibrance to regular approval in the US.

“PALOMA-2 represents the third randomised study to demonstrate the benefit of Ibrance when added to hormonal therapy in the management of women with ER+, HER2- advanced breast cancer,” said Pfizer’s chief medical officer Mace Rothenberg, also noting that the drug “remains the only CDK 4/6 inhibitor with Phase III data in this disease”. 

Detailed efficacy and safety results will be submitted for presentation at the American Society of Clinical Oncology (ASCO) 2016 Annual Meeting.

Based on the results of PALOMA-1, Ibrance first was issued an accelerated approved by the US Food and Drug Administration in February 2015.

European regulators are currently reviewing the drug and, in the UK, it has completed the first step towards joining the UK's Early Access to Medicines Scheme, having been awarded 'Promising Innovative Medicine' status.