OBJECTIVES: Since July 2012, a new therapy may be allocated Breakthrough Therapy status if it a) treats a serious and life-threatening condition, and b) preliminary evidence suggests substantial clinical improvement over existing therapies based on a clinically meaningful endpoint. For such agents, the FDA will expedite their development and review. This research aimed to systematically analyse all therapies have been approved under this new FDA expedited review pathway. METHODS: All publically available FDA documents relating to the approval of therapies under a breakthrough status were extracted up to 28^th November 2014 and their date, drug type, and supportive trial package were extracted. RESULTS: The FDA has approved 14 therapeutic agents designated as breakthrough therapies (to 1^st December 2014), 7 oncologics, 6 non-oncologics and 1 vaccine. 6/14 also simultaneously received FDA accelerated approval. 9 submissions were first approvals whereas 5 were line extensions. 7 of these submissions were based on Phase 3 trial data, 5 on phase 2, and 2 on phase 1 data. The average review time from submission to approval was 181 days (range: 126 – 242 days). There appeared no correlation between review times and the level of supportive clinical data (Phase 1: a mean of 158 days, Phase 2: 170 days, Phase 3: 196 days), whether the drug was a first approval or line extension (175 vs. 192 days), or whether it was approved under an accelerated FDA pathway or not (172 vs. 184 days)   CONCLUSIONS: The FDA breakthrough therapy designation is proving a popular means by which promising drugs can gain patient access on preliminary data packages from as little as Phase I supportive data. However, although this pathway has enabled earlier access, it does not speed the required review times with the average of 6 month review being in line with FDA priority review targets.