Alkermes has delivered a schizophrenia candidate in ALKS 3831 that looks good for regulatory approval, but the commercial case based around weight gain could be much more challenging. The second of two phase III trials, shows that the agent, a combination of the antipsychotic olanzapine with samidorphan, caused patients to gain significantly less weight than olanzapine alone. This was a co-primary endpoint in the Enlighten-2 trial. The fact that ALKS 3831 did nevertheless cause weight gain, might make it difficult for Alkermes to set a price that payers will find acceptable, since olanzapine is generic. A second co-primary endpoint, was also met with a lower proportion of patients taking ALK 3831 gaining 10% or more of body weight over baseline, compared with olanzapine. That second endpoint provides potential niche for ALKS 3831 – poaching those patients who see a rapid weight gain in the first weeks after starting olanzapine. In any case, the result was better than in the first trial of ALKS 3831, Enlighten-1, which found greater weight gain when compared to olanzapine. Alkermes shares fell 2% in early trading today.
|ALKS 3831||Olanzapine||p value|
|Average weight gain (% of body weight)||4.21||6.59||0.003|
|Percent of patients gaining 10% of body weight||17.8||29.8||0.003|