I think ZEN-3309 was roadkill on the route to ZEN-3694.

"ZEN-3365 selected as Development Candidate from a panel of excellent compounds"
(ZEN-3365, ZEN-3309, ZEN-3293)

EpiCongressJuly 2014
https://www.zenithepigenetics.com/upload/media_element/16/01/zenith-epigenetics-presentation---epicongress-boston-july-2014.pdf

"FDA approved IND for ZEN-3365: Top investigators & institutions recruited for Phase 1 Jul 2014

Challenges: Prior to the Phase 1 launch, overlapping IP published by another group, ZEN-3365 discontinued Oct 2014

Change of plans: ZEN-3694 selected as DC, superior properties, mutiple back ups, IP published May 2015"

January 9, 2017
https://www.zenithepigenetics.com/upload/media_element/60/01/biotech-showcase---jpm-week---v3.pdf