1Q26 Update. KCC2 Activator Is Safe in HVs - Significant for Broad New Class. OV329 Also Looking Safe as Dosing Continues - Making a Future Well Beyond a Better Vigabatrin Look Reasonable.

Research evidence excerpt

1Q26 Update. KCC2 Activator Is Safe in HVs - Significant for Broad New Class. OV329 Also Looking Safe as Dosing Continues - Making a Future Well Beyond a Better Vigabatrin Look Reasonable.

■ ...SAD and MAD cohorts, and comprehensive ophthalmic assessments showed no retinal changes, directly addressing the

safety liability that has constrained vigabatrin's clinical utility for decades. Layered on top of the statistically significant cortical

inhibition and GABA elevation data from AES in December 2025, we see OV329 as "a better vigabatrin" and possibly a

workhorse compound capable of unlocking the full therapeutic potential of GABA-AT inhibition at doses vigabatrin could

never safely reach. With Phase 2 FOS enrollment on track for Q2 2026 and an open-label photo paroxysmal response study

initiating Q3 2026, the promise of the drug should get clearer soon.

■ KCC2 recent data details. The key findings showed OV350 reached exposure levels consistent with the expected

pharmacologically active concentrations at the 50mg and 100mg doses. These support continued clinical development of

KCC2 activators, especially OV4071, which is twenty times more potent than OV350 in pharmacodynamic models. There wereBIOTECHNOLOGY

no treatment emergent serious AEs and the most frequently seen treatment emergent AE was headache, with a subset also

experiencing nausea and vomiting around meal times (thought to result from OV350's unique off-target effects). The PK was

predicted for all doses, and qEEG findings supported relevant central activity during expected exposure of OV350.

■ OV350 switch-er-ooo. Ovid is replacing OV350 after the first safety readout and plans to file the IND for OV4071 in early 2026,EQUITY

with Phase 1B studies starting 2Q26.