The agency has allowed drugs to remain available even when follow-up studies showed they didn’t save lives, according to a report from the Government Accountability Office. And the FDA has never pulled a drug off the market due to a lack of required follow-up about its actual benefits — even when such info is more than a decade overdue, the Associated Press reports.

FDA officials tell the AP they have no plans to get more aggressive.The FDA responded that the report paints an overly negative picture of its so-called “accelerated approval” program, which is only used to approve drugs for the most serious diseases. “Millions of patients with serious or life-threatening illnesses have had earlier access to new safe and effective treatments,” the FDA responded.

The GAO found the FDA does little to track whether drugs approved based on preliminary results have lived up to their promise. In 1992, the FDA began granting “accelerated approval” to novel drugs based on so-called surrogate endpoints - measures that suggest the drug will make real improvements in patient health. An example - HIV drugs.

This allows drugmakers to get meds to market sooner without conducting long-term studies that can take years and cost hundreds of millions of dollars, the AP continues. However, a condition of the quicker approvals requires drugmakers to conduct follow-up studies to show the drug actually helped patients live longer.

But the GAO report identified several available drugs that never lived up to their initial promise. And in the 16 years the FDA has used accelerated approval, it has never yanked a drug, even when drug makers went more than a decade without submitting follow-up data. “FDA has fallen far short of where it should be for patient safety,” said Sen. Chuck Grassley, a Republican from Iowa, who requested the investigation, tells the AP.

Of the 144 studies the FDA has required under the program since 1992, more than one-third are still pending, according to the GAO. Investigators said the FDA does not regularly check whether drug makers are making progress on their required studies, although the agency is improving its oversight, the AP writes. “According to FDA officials, this task was a lower priority compared to other responsibilities,” the report says.

But FDA officials say they have overhauled their tracking system since the GAO completed its report. And an outside analysis by contractor Booz Allen Hamilton concluded last month that most companies are meeting their study requirements on time (look here for the FDA statement and the report).

In the case of Shire Laboratories’ low blood pressure treatment ProAmatine, the required study has gone incomplete for more than 13 years. The GAO found that ProAmatine has generated more than $257 million in sales, even though “the clinical benefit of the drug has never been established.” Shire did not respond to an AP request for comment.

In other cases, the FDA has failed to act even when company studies show drugs did not improve patient outcomes. The FDA approved AstraZeneca’s Iressa in 2003 based on early results showing it reduced the size of tumors. But later studies showed the drug didn’t help patients live longer. The FDA left the drug on the market, despite side effects including hundreds of reports of a sometimes fatal pneumonia. AstraZeneca PLC said in a statement the drug is only sold through a limited access program and “is not available to new patients.”

The GAO concluded that the FDA has no policy for pulling drugs off the market that were approved using surrogate endpoints. When GAO investigators confronted FDA officials about this lack of enforcement, they reportedly said it would be “difficult, if not impossible,” to draft a standard policy for withdrawals, since drugs vary case-by-case, according to the AP.

Some consumers advocates say that’s not good enough. “The FDA has talked a lot about doing more enforcement, but this is an area where they’re basically defending not enforcing the law,” Sidney Wolf, of the consumer advocacy group Public Citizen, tells the AP. He adds the lax policy sends a message to companies that there is no penalty for failing to complete studies.