RE:What is Pre-BTD Submission to the FDA?I think I found the answer here, question #23:
https://www.fda.gov/regulatory-information/food-and-drug-administration-safety-and-innovation-act-fdasia/frequently-asked-questions-breakthrough-therapies
Can a sponsor get preliminary breakthrough therapy designation (BTD) advice from the review division prior to the submission of a formal BTD request?
A sponsor can contact the regulatory project manager (RPM) in the division to which the active IND is assigned and request the “Preliminary Breakthrough Therapy Designation (BTD) Advice Request” template. This template should then be submitted as a formal amendment to the IND and a subsequent teleconference between the sponsor and the review division will be set-up by the RPM. The review division will make a recommendation as to whether a request for a BTD is appropriate, may be too preliminary, or does not currently meet the criteria for a BTD. The Agency’s recommendation is advisory and is not to be interpreted to predict the Agency’s decision on the BTD request. NOTE: A Preliminary BTD Advice Request may be submitted to an active PIND, although a formal BTD request may not be submitted until the IND is opened.