ACAD Stock Clocks Worst Day In 2 Years After Alzheimer’s Psychosis Drug Misses Main Goal — Citi Cuts Drug’s Success Odds To 20%

Citi’s Yigal Nochomovitz trimmed his price target to $33 from $40 and kept a Buy rating following the company’s update.

• In the mid-stage portion of the RADIANT program, patients on 60 mg once daily remlifanserin improved 12.6 points on a scale of hallucinations and delusions at week six, versus 10.4 points on placebo.
• A key secondary measure of overall symptom severity favored 60 mg more clearly. 
• Management will keep two late-stage Alzheimer’s studies running, drop the weak 30 mg arm, and may tighten who gets enrolled.

Shares of Acadia Pharmaceuticals (ACAD) clocked their worst day since August 2024 on Thursday after remlifanserin, its experimental treatment for hallucinations and delusions in Alzheimer’s disease psychosis, missed the primary endpoint of a mid-stage study.

Shares closed down 13% from Wednesday’s close of $25.43 as investors digested a near-miss that the company still called “Phase 3 enabling.” Citi also slashed remlifanserin’s chance of success further into the low double digits.  

A Narrow Miss, A Stronger Secondary Signal

In the mid-stage portion of the RADIANT program, patients on 60 mg once daily remlifanserin improved 12.6 points on a scale of hallucinations and delusions at week six, versus 10.4 points on placebo. The gap produced an effect size of 0.26 and a p-value of 0.0603 — just shy of the usual 0.05 cutoff. A p-value is a statistical measure of how likely the observed difference between drug and placebo would appear by chance if the drug actually had no effect. A 30 mg dose barely beat placebo.

A key secondary measure of overall symptom severity favored 60 mg more clearly: a 1.3-point drop versus 0.9 on placebo, with a 0.37 effect size and a nominal p-value of 0.0077. Safety looked clean, with side effects and dropouts similar to placebo and no QT or cognition red flags.

What It Means For ACAD’s Pipeline

Remlifanserin is Acadia’s most important late-stage growth bet beyond marketed Nuplazid for Parkinson’s disease psychosis and Daybue for Rett syndrome.

Management will keep two late-stage Alzheimer’s studies running, drop the weak 30 mg arm, and may tighten who gets enrolled. The same drug is also in a mid-stage trial for Lewy body dementia psychosis.

The readout on Thursday lowers the odds that Alzheimer’s psychosis becomes a near-term blockbuster, even if commercial sales still underpin the company.

Acadia still cites multi-billion-dollar peak-sales potential across both psychosis programs. Full data are due in November.

Street Cuts The Odds

Citi’s Yigal Nochomovitz trimmed his price target to $33 from $40 and kept a Buy rating following the company’s update. He said the result does not give high conviction that late-stage data will clear both statistical significance and a clinically meaningful bar. Citi cut remlifanserin’s chance of success to 20% from 35%.

How Did ACAD Retail Traders React?

On Stocktwits, retail sentiment around ACAD stock rose from bullish to extremely bullish territory over the past 24 hours, while message volume rose from low to high levels.

A Stocktwits user said they are now awaiting November’s full data readout.

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Another user added more shares.

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ACAD stock has dropped 17% year-to-date. 

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