The FDA prohibits pharmaceutical companies from sharing information about off-label uses of medicines with physicians. Many drugs received FDA approval for one disease, but also effectively treat other illnesses that aren't listed on the official label. Off-label prescribing is actually quite common. Physicians prescribe one in five medicines off-label.
Currently, doctors have to make these off-label prescribing decisions based on anecdotal evidence, since they have no access to drug companies' clinical trial data. If the FDA were to permit greater information sharing, it would enable doctors to treat patients more effectively.
Doctors have good reason to prescribe drugs off-label. Many drugs can treat a wide variety of diseases. In fact, the average drug can treat 18 different illnesses, according to researchers from the University of Illinois at Chicago, Stanford University, and the University of Chicago. For instance, the diabetes drug Metformin can treat breast cancer. And the cancer drug Bexarotene has the potential to treat Alzheimer's disease.
Doctors also prescribe drugs off-label to treat critically-ill patients after all approved medicines have failed. For instance, many patients with certain autoimmune diseases don't respond to approved therapies. As a last-resort, doctors will prescribe these patients Prograf, a drug approved to help prevent people's immune systems from rejecting organ transplants.