The US Food and Drug Administration is planning to tighten its scrutiny of companion diagnostics, the agency's Commissioner Margaret Hamburg has told the assembled throng at the American Society of Clinical Oncology meeting in Chicago.

She began by saying that "this is an exciting time for the oncology community", noting that the last decade has "witnessed significant improvement in cancer drug development". In 2012, 40% of new entities that the FDA approved were for oncology indications.

Dr Hamburg said that cancer is being redefined based on growing knowledge of molecular pathways, which has led to the use of companion diagnostics to identify the right therapies for the right patients. Just last week, the FDA approved GlaxoSmithKline's melanoma drugs Tafinlar (dabrafenib) and Mekinist (trametinib), together with a genetic test from France's bioMerieux to identify the V600E or V600K mutations in the BRAF gene these drugs target.

She went on to say that "advanced diagnostics such as these are a cornerstone of personalised precision medicine" but unfortunately not all complex diagnostics have been developed using the same standards. Dr Hamburg mentioned the withdrawal from the market of the OvaSure early-stage ovarian cancer screening test in 2008, which was a laboratory developed test found to be ineffective soon after launch.

The commissioner said that "historically, the FDA "exercised enforcement discretion" for these devices because they were "relatively simple low-risk tests performed on a few patients that were evaluated by physicians seen in the same facility as the laboratory". However, tests have changed dramatically and Dr Hamburg claimed that “a risk-based framework is under development that will ensure the diagnostics used in cancer treatment will provide medical professionals with a critical baseline for confidence in the test they order".

Value of breakthrough designation

She also spoke about breakthrough therapy designation introduced by the agency nearly a year ago. Dr Hamburg said that in addition to all of the features of a fast-track designation, a company that receives the former gets "more intensive guidance on an efficient drug development programme beginning as early as Phase I, as well as the involvement of senior FDA management throughout the process".

As of May 23, the FDA Center for Drug Evaluation and Research has received 51 requests for breakthrough designations, she concluded, of which about 20 have been granted. Eight of those have been for oncology drugs.