I was looking at some of the details of the
Severe SNHL trial.
The bad news (and more of a reason why Phase 1 results can be less trustworthy) is that the sample is split into 30=24+6 into treatment versus placebo. There are several reasons why people should understand that these results are less meaningful than Phase 2 trials.
Firstly, because safety is the main concern, they have no problem making it 4:1. The reason is that they simply want as many people as possible taking the drug to look for adverse effects.
Secondly, it helps recruiting because people are more interested in joining a clinical trial with a higher probability of receiving the treatment. This is precisely why Phase 2a had poor design; it was a 3:1 design of
some treatment versus placebo. When the ratios are this skewed, the sample sizes have to be much larger to demonstrate statistical power.
The thing I'm saddened by is that even if 0/6 of the placebos in the severe trial have massive word score gains, it's still only 6 people -- still not out of the realm of possibility that it's from chance. Basically, the treatment arm has to crush the placebos for there to be some real encouragement.
BTW, this is pretty standard. For example, OTO-413 also had 3:1 recruitment for Phase 1/2. Safety, safety, safety.
If in the next Phase 2 trial, Frequency Therapeutics makes the ratio closer to 1:1, they will have greater recruitment problems (50% chance of receiving 1 dose). Recruitment is going to be longer and more expensive, in all likelihood.