Pfizer Inc. recently announced promising results from its mid-stage study, evaluating its experimental breast cancer treatment.
The company announced detailed results from the Phase II study, known as PALOMA-1, evaluating palbociclib in combination with letrozole versus letrozole alone in post-menopausal women with estrogen receptor positive (ER+), human epidermal growth factor receptor 2 negative (HER2-) locally advanced or metastatic breast cancer.
According to Pfizer, patients receiving the combination of palbociclib plus letrozole had a median progression-free survival (PFS) of 20.2 months compared to a median PFS of 10.2 months for patients receiving letrozole only. The improvement in PFS, which was the study’s primary endpoint, was considered statistically significant. Results of the 165-patient study were presented by Dr. Richard S. Finn, associate professor of medicine at University of California, Los Angeles (UCLA) at the American Association of Cancer Research (AACR) Annual Meeting 2014 in San Diego.
“These data demonstrate the potential of palbociclib to be a major advance in the treatment of women with this type of advanced breast cancer,” said Dr. Mace Rothenberg, senior vice president of Clinical Development and Medical Affairs and chief medical officer for Pfizer Oncology. “We are proud to be at the forefront of research and development with respect to this promising new class of investigational anticancer agents and have initiated a broad clinical development program for palbociclib that includes breast and non-breast cancers.”
Additionally, the initial data showed that patients receiving palbociclib in combination with letrozole had an overall survival (OS) of 37.5 months compared to an OS of 33.3 months for patients receiving letrozole alone. Researchers noted that it is still too early to define the drug’s impact on survival, but the initial improvement in OS, a secondary endpoint, is not considered statistically significant. According to Pfizer, a follow-up on OS analysis will be conducted following the accrual of additional events. The drug was generally well-tolerated.
Palbociclib is among a new class of cancer drugs that target specific proteins to block tumors. It is an investigational oral targeted agent that selectively inhibits cyclin-dependent kinases (CDKs) 4 and 6 to regain cell cycle control and block tumor cell proliferation. In April 2013, the US Food and Drug Administration (FDA) granted palbociclib Breakthrough Therapy designation for the initial treatment of women with advanced or metastatic ER+, HER2- breast cancer. The designation was based on interim data from the PALOMA-1 trial.
Pfizer has initiated two late-stage studies evaluating the drug in advanced/metastatic breast cancer. The Phase III study, known as PALOMA-2 or Study 1008, is evaluating palbociclib in combination with letrozole versus letrozole plus placebo as a first-line treatment for post-menopausal patients with ER+, HER2- advanced breast cancer. PALOMA-3, also known as Study 1023, is evaluating palbociclib in combination with fulvestrant versus fulvestrant plus placebo in women with hormone receptor positive (HR+), HER2- metastatic breast cancer whose disease has progressed after prior endocrine therapy.
Source: Pfizer Inc.
Last updated: 4/7/14; 3:05pm EST