Breakthrough therapy and fast track designation programs both are intended to expedite the development and review of drugs for serious or life-threatening conditions, but there are differences in what needs to be demonstrated to qualify for the programs. A breakthrough therapy designation is for a drug that treats a serious or life-threatening condition and preliminary clinical evidence indicates that the drug may demonstrate substantial improvement on a clinically significant endpoint(s) over available therapies. In contrast, a fast track designation is for a drug that treats a serious or life-threatening condition, and nonclinical or clinical data demonstrate the potential to address unmet medical needs for the serious condition.
As with the other programs, breakthrough designation is aimed at treatments of serious illness. Like fast track, breakthrough applications may be reviewed on a rolling basis. However, unlike the fast track designation, which may include theoretical and mechanism-of-action rationale based on nonclinical data, or evidence of actual nonclinical activity, breakthrough therapy demonstrates preliminary clinical of substantial improvement over available therapies.Preliminary clinical evidence is generally that which is sufficient to show substantial improvement in effectiveness or safety over available therapies, but not strong enough to establish safety and effectiveness for the purpose of approval.
As with fast track, breakthrough designation earns additional FDA attention, resources and action:
FDA intends to expedite the development and review of a breakthrough therapy by intensively involving senior managers and experienced review and regulatory health project management staff in a proactive, collaborative, cross-disciplinary review. Where appropriate, FDA also intends to assign a cross-disciplinary project lead for the review team to facilitate an efficient review of the drug development program. The cross-disciplinary project lead will serve as a scientific liaison between members of the review team (e.g., medical; clinical pharmacology; pharmacology-toxicology; chemistry, manufacturing, and controls (CMC); compliance; biostatistics), facilitating coordinated internal interactions and communications with a sponsor through the review division's regulatory health project manager." – "In addition, such a product could be eligible for priority review if supported by clinical data at the time of BLA, NDA, or efficacy supplement submission.
There are multiple approaches that a sponsor may utilize to show substantial improvement. For example, a head-to-head comparison of the new drug to the current standard of care in an early stage trial may offer enough evidence of a meaningful basis for the breakthrough designation. Early patient data without a direct comparison in a clinical trial study that provides better understanding of disease progression may also suffice. For instance, if a certain cancer type has an 80 percent progression rate in a one-year period, yet a drug in early trials shows a 10 percent progression during the same timeframe, a head-to-head trial to prove substantial improvement may not be needed.