Mixed Results Reported for Depression Drug in Mid-Stage Trial

ETS6103 fails to meet primary endpoint of noninferiority versus amitriptyline

Mixed results have been reported from a phase 2b trial evaluating the antidepressant activity and tolerance profile of ETS6103 (e-Therapeutics) in patients with major depressive disorder (MDD).

The study evaluated ETS6103 as a potential second-line treatment for patients with MDD who do not respond satisfactorily or who experience relapse when using the current first-line treatments––selective serotonin reuptake inhibitors (SSRIs). The trial’s primary objectives were to determine whether ETS6103 is capable of treating patients for whom SSRIs have not been successful, at a dose consistent with improved compliance, with more-favorable adverse event and tolerance profiles, compared with a tricyclic antidepressant, such as amitriptyline. An earlier phase 2a trial had supported the efficacy of ETS6103 compared with amitriptyline, and the phase 2b study was designed as a noninferiority study.

The randomized, double-blind trial enrolled 383 patients in Glasgow, United Kingdom. A total of 164 patients who did not respond adequately to first-line SSRI treatment were randomly assigned to one of three study arms, which included two dosage strengths of ETS6103 and one of amitriptyline. The patients were treated for eight weeks.

With regard to efficacy, the ETS6103 arms did not meet the primary endpoint of establishing noninferiority compared with amitriptyline. Specifically, while many patients responded to ETS6103, fewer achieved remission (a Montgomery–Åsberg Depression Rating Scale [MADRS] score of less than 11) compared with those treated with amitriptyline. Responses were observed, however, in all three treatment arms. In the two ETS6103 arms, some patients entered remission, and there were fewer adverse events and adverse event-related withdrawals in the ETS6103 groups compared with the amitriptyline group.

Source: e-Therapeutics; February 15, 2016.