Small US firm Acadia Pharmaceuticals has made a very big impact on the country’s investors as positive data for its new schizophrenia drug has sent the company’s stock soaring.

Acadia’s shares doubled in value to $13.61 after Phase II data for the San Diego-based firm’s elective 5-HT2A inverse agonist ACP-103 demonstrated the effectiveness of the drug in treating schizophrenia when used in conjunction with both a generic typical antispsychotic, haloperidol, and Johnson & Johnson’s blockbuster Risperdal (risperidone), an atypical treatment. The co-therapy arm combining ACP-103 with low-dose risperidone demonstrated a statistically significant improvement in antipsychotic efficacy as compared to low-dose risperidone plus placebo, and comparable efficacy to high-dose risperidone plus placebo.

Co-therapy with ACP-103 also led to a faster onset of antipsychotic action and an improved side effect profile, Acadia noted. Importantly, patients in the ACP-103/risperidone co-therapy arm also had 50% less gain in weight than those in the risperidone high-dose arm.

Chief executive Uli Hacksell noted that "while achieving effective antipsychotic treatment comparable to a standard dose of risperidone, ACP-103, when added to a three-fold lower dose of risperidone, provided substantial advantages, including a faster onset of antipsychotic action.” He added that co-therapy with his firm’s drug “may provide important clinical advantages compared to current antipsychotic drug therapy."

Many analysts agree with Dr Hacksell and the question being asked now is when will Acadia sign up a partner to help get ACP-103 through Phase III clinical trials. The firm posted a net loss of $45 million in 2006 and ended the year with $83.3 million in cash and equivalents so an alliance is vital to further the drug. Sales estimates for ACP-103 have been put in the region of $500 million by 2012 and could top that if used with multiple antipsychotics.

Acadia will be hoping to get a slice of the $14 billion antipsychotics market, but the potential of the drug makes it an attractive target for other players in the sector.