Winning early U.S. approval of promising cancer treatments could wind up costing drugmakers up to $10 million in fines if they don’t confirm their drugs’ effectiveness in follow-up studies within a restrictive timeframe, FDA officials said, according to a Bloomberg report.

Before a drug can win expedited approval, the FDA may also start requiring that follow-up trials be underway, John Johnson, a clinical team leader at the agency’s Division of Drug Oncology Products, and colleagues said in a report published online in the Journal of the National Cancer Institute.

The agency’s accelerated-approval program came under scrutiny last year when New York-based Pfizer, the world’s biggest drugmaker, withdrew its leukemia drug Mylotarg after 10 years on the U.S. market and the FDA moved to revoke its 2008 clearance of Basel, Switzerland-based Roche’s Avastin for breast cancer. A drug can be pulled if subsequent studies don’t show it prolongs survival or improves quality of life.

Follow-up studies had yet to be completed as of last July for 14 accelerated approvals granted over the past 12 years, according to the report. Among them was the 1999 clearance of Pfizer’s arthritis drug Celebrex to treat a rare colon condition and a 2005 approval of London-based GlaxoSmithKline’s Arranon for lymphoma, the authors said.

The agency could confirm efficacy faster by requiring that such trials be in progress before granting an accelerated approval, the report said.

A 2007 law authorized the FDA to fine drugmakers as much as $10 million for “lack of due diligence” in conducting trials to confirm the benefits of drugs that win accelerated approval, according to the report.

“The FDA believes that this will be an effective new tool for dealing with lack of due diligence,” Johnson and his colleagues wrote.

As quoted in MedPage Today, Susan Ellenberg, Ph.D., of the University of Pennsylvania, wrote that the FDA is "routinely castigated for proceeding too cautiously and slowly, and at the same time, for rushing drugs to market too rapidly without adequate study."

"What some might consider a happy medium will inevitably leave many other scientists, clinicians and consumers dissatisfied," she wrote, citing the example of bevacizumab (Avastin) for breast cancer.