Enanta Pharmaceuticals Inc (ENTA)

[dewophile]

Re Ziresovir (Ark bio F inhibitor)

They are planning a QT trial of the drug based on this listing, which suggests they are gearing up for a phase 3 - probably of a size and scope and with endpoints* that will meet US and EU regulators' satisfaction. I would also assume they study the drug in infants who are not yet hospitalized

https://clinicaltrials.gov/study/NCT06591845?term=ziresovir&aggFilters=status:not&rank=1

*The clinical endpoint used in the phase 3 trial was the "Wang bronchiolitis score". The authors concede " The main limitation of this trial is the use of the Wang bronchiolitis clinical score, a clinical tool that has not been fully validated in studies of RSV infection". Probably need some harder endpoints. The duration in the NICU was the only one I could find (see supplement); median 3 days ziresovir and 8 days placebo, but numbers were very small with N=9 tx and N=3 placebo.
Note that viral loads also didn't start to decline versus placebo until after day 2, which is probably related to the MOA. From the discussion:
"The antiviral effect of ziresovir was observed by day 3. A delayed effect in reducing the viral load is consistent with the mode of action of F protein inhibitors, which inhibit virus entry but have no direct effect on intracellular virus."