Euthymics Bioscience's Phase IIb/IIIa study of amitifadine has failed to produce positive results in treating major depressive disorder (MDD) at 50mg or 100mg doses.
The Triple Reuptake Inhibitor Anti-Depressant Effects (TRIADE) trial did not show a statistically significant difference in the primary endpoint of change in the Montgomery-Åsberg Depression Rating Scale compared to placebo.
Designed to assess the safety and efficacy of the serotonin-preferring triple reuptake inhibitor antidepressant, the study involved MDD patients who had failed to respond to first-line antidepressants.
However, supported by a lack of side effects with the 100mg dose and signs of efficacy in post-hoc analyses, an active comparator arm indicated that the drug could show efficacy at higher doses.
Massachusetts General Hospital Clinical Trials Network and Institute executive director and TRIADE principal investigator Dr Maurizio Fava said that given the robust efficacy of the comparator paroxetine in the study, amitifadine was under-dosed.
"However, the good tolerability of amitifadine allows for a significant dose escalation in the next study, aimed at replicating the positive findings of a previously conducted proof-of-concept study in patients with a new-onset major depressive episode," Fava said.
Euthymics president and CEO Anthony McKinney said; "Amitifadine continues to have the potential to fulfil a critical unmet need among depression patients as one of the few monotherapy antidepressants for non-responders that has both a favorable sexual function and weight profile."
Amitifadine was well-tolerated at both the doses in the study without exhibiting any associated side-effects compared to paroxetine, which led to considerable sexual dysfunction.
The single molecule, which acts on serotonin, norepinephrine and dopamine, is also being studied as a treatment for alcohol abuse disorder.