Obviously, I don't think CX717 should be scrapped: but here is the rationale on the part of the FDA that puts it at risk:
1) If you don't have a lot of headroom between the clinical dose and the potentially risky dose, there is the possibility that over millions of patient exposures, more vulnerable individuals might experience adverse effects that were thought to only occur with much higher doses.
2) In a population like adult ADHD, where use is going to be daily and longterm, the odds of #1 are higher, and one is trying to extrapolate from three months of use to years of use.
3) Adult ADHD patients are, for the most part, a healthy population relatively speaking. Any adverse medical effect would thus be in the context of what otherwise would have been physical health.
4) If #3 occurs, even to a small number of individuals, this will be interpreted as the FDA not doing its job. Which would lead to more congressional grandstanding. Very little--indeed no--price is paid by the FDA for excessive constraint and caution. A high price will be paid if anything unexpected sneaks through.
Gfp: One thought about the 200mg and 800mg doses. Stoll gave a hint regarding their thinking during the last CC. He referenced their belief--based on animal models--that 10-20mg/kg would be necessary for the treatment of hyperactivity, one of the two main domains of ADHD symptoms (inattention being the other). That translates into 750-1500mg on average. Thus the 800mg was near the bottom of what they thought they needed to show an effect on hyperactivity, whereas 200mg was probably near the bottom of what they thought they needed for inattention. A nonstimulant that addresses both is far more valuable as a competitor to stimulants (really the only drugs at present that address hyperactivity with any consistency) than one that only treats inattention.
Thus a mid-range dose would have been seen as superfluous--more than one needs for inattention, less than one needs for hyperactivity.
NeuroInvestment
AI
Market Data 
Markets 
