For those wondering the significance of "breakthrough therapy designations" from the FDA's website:
Breakthrough Therapy Designation
The Advancing Breakthrough Therapies for Patients Act will encourage and spur innovation on behalf of patients by providing greater regulatory certainty and predictability. This bipartisan legislation amends Section 506 of the Food, Drug, and Cosmetic Act to require FDA, at the request of a drug sponsor, to facilitate the development and expedite the review of the drug if it is intended for a serious or life-threatening disease or condition and preliminary clinical evidence indicates that the drug may demonstrate substantial improvement over existing therapies. If the FDA determines that a drug meets the criteria to be designated as a “breakthrough therapy” then the agency shall take such actions as are appropriate to expedite the development and review of the drug, including holding meetings with the drug sponsor throughout the drug development process; providing timely advice to the sponsor regarding the plan to develop the drug; enlisting a collaborative, cross-disciplinary approach by senior managers and experienced review staff; and minimizing the number of patients enrolled in trials and shortening the duration of trials, when scientifically appropriate. A designated breakthrough therapy may still seek fast-track product designation, accelerated approval, and priority review. The bill also requires FDA to undertake public awareness efforts to physicians, patient organizations, manufacturers, and others regarding breakthrough therapies.