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The Food and Drug Administration has granted Priority Review to Ibrance (palbociclib) for the treatment of patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative metastatic breast cancer.

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Also recently receiving the designation is Xalkori (crizotinib) for the treatment of patients with metastatic non-small cell lung cancer (NSCLC) whose tumors are ROS1-positive. Xalkori is a kinase inhibitor.


Ibrance, marketed by Pfizer, is an oral, first-in-class inhibitor of cyclin-dependent kinases (CDKs) 4 and 6, key regulators of the cell cycle that trigger cellular progression.


Ibrance is currently approved for use in combination with letrozole as a treatment for postmenopausal women with ER-positive, HER2-negative advanced breast cancer as initial endocrine-based therapy for their metastatic disease (OT 3/10/15 issue). This indication is approved under accelerated approval based on progression-free survival, and continued approval for this indication may be contingent upon verification and description of clinical benefit in the ongoing confirmatory trial, PALOMA-2.


The drug's approval for this new indication will be based on data from the Phase III PALOMA-3 study, which evaluated treatment with Ibrance plus fulvestrant versus fulvestrant plus placebo in 521 patients with HR-positive, HER2-negative metastatic breast cancer, regardless of menopausal status, whose disease progressed after endocrine therapy, including those with and without prior treatment for their metastatic disease (OT 8/10/15 issue). The trial was stopped early based on the efficacy seen in the interim analysis for the patients treated with Ibrance.


Xalkori has previously received Breakthrough Therapy designation for this indication (OT 5/25/15 issue). And Xalkori is currently approved in the U.S. for the treatment of patients with metastatic NSCLC whose tumors are anaplastic lymphoma kinase (ALK)-positive, as detected by an FDA-approved test (OT 12/25/13 issue). If approved for this additional indication, Xalkori would be the first FDA-approved biomarker-driven therapy for the treatment of ROS1-positive metastatic NSCLC, according to a news release from the drug's manufacturer, Pfizer Inc.


Xalkori's application is based on a data analysis from an expansion cohort of a global Phase I study that evaluated the drug in 50 patients with ROS1-positive advanced NSCLC. The data showed marked antitumor activity for the patients in the cohort-with three complete responses and 33 partial responses. Median duration of response for the patients was 17.6 months. The safety profile of Xalkori in ROS1-rearranged advanced NSCLC was similar to that observed in patients with ALK-positive advanced NSCLC.


The FDA's Priority Review designation shortens the time to complete a drug's review and aims to deliver a decision on marketing approval designation for drugs that may offer major advances in treatment or provide a treatment where no adequate therapy exists within six months under the Prescription Drug User Fee Act (PDUFA).


The FDA action dates for both Ibrance and Xalkori for their designated indications are in April.