Pfizer said that the phase 3 PENELOPE-B clinical trial of IBRANCE (palbociclib) in early breast cancer failed to meet its primary endpoint.
The collaborative late-stage trial is being held by the US pharma giant with the German Breast Group (GBG) sponsoring it.
The primary endpoint of the PENELOPE-B clinical trial is improved invasive disease-free survival (iDFS) in women having hormone receptor-positive (HR+), human epidermal growth factor-negative (HER2-) early breast cancer (eBC) who have residual invasive disease after being subjected to neoadjuvant chemotherapy.
Sibylle Loibl – Chair of German Breast Group said: “Reducing the risk of disease recurrence in patients who have residual disease after neoadjuvant chemotherapy is a complex clinical challenge.
“This unique trial was made possible through the collaboration and support from all the research partners involved. Despite this outcome, we believe that key learnings will emerge from the large number of biomarkers being analyzed from collected tumor tissue, which will help inform future breast cancer research.”
Pfizer said that there were no unexpected safety signals seen during the late-stage clinical trial.
The PENELOPE-B clinical trial is a randomized, double-blind, placebo-controlled study that compared one year of treatment of palbociclib plus at least five years of standard adjuvant endocrine therapy with placebo plus at least five years of standard adjuvant endocrine therapy.
Chris Boshoff – Pfizer Global Product Development Oncology Chief Development Officer said: “This is the first randomized Phase 3 study to establish mature iDFS results for a CDK4/6 inhibitor as part of the adjuvant treatment for early breast cancer.
“While we are disappointed with this result, we look forward to continuing to work with our research partners to understand subgroup data and how these could inform the development of our next-generation CDK inhibitors in early breast cancer.”
IBRANCE is an oral inhibitor of CDKs 4 and 6, which are key regulators of the cell cycle that stimulate cellular progression.
In the US, IBRANCE in combination with an aromatase inhibitor as initial endocrine based therapy has approval for the treatment of adults having HR+, HER2- advanced or metastatic breast cancer in postmenopausal women or in men, or with fulvestrant in patients having disease progression following endocrine therapy.
Presently, IBRANCE has approval in 95 plus countries. However, it is not indicated for the treatment of early breast cancer.