To the Editor:
Recently in Expert Opinion on Pharmacotherapy, Steger, Gnant, and Bartsch nicely reviewed the recent studies of palbociclib involving patients with breast cancer [1]. I believe it is important to highlight that ultimately the mechanism of action with palbociclib primarily appears to involve activating a tumor suppressor gene (Rb), in contrast to the many other recently approved kinase inhibitors which typically act more exclusively by inactivating oncogenic activity.
Since loss of tumor suppressor gene functions are more common gatekeeper and driver abnormalities in oncogenesis and progression than oncogenic activation, the success of palbociclib will hopefully stimulate more research aimed at developing agents which activate tumor suppressor gene products.
Declaration of interest
The author has no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.