Rexahn Pharmaceuticals, Inc, a clinical stage pharmaceutical company developing potential best in class oncology and central nervous system (CNS) therapeutics, announced clinical results with its investigational new drug, Serdaxin for the treatment of major depressive disorder (MDD).

The randomized, double blind, placebo controlled and dose ranging clinical trial enrolled 77 patients at multiple sites in the United States. The results of the subgroup analysis are compelling and warrant further study in a larger phase-2 trial.

In the subgroup analysis, the study showed that patients with severe MDD taking 5 mg of Serdaxin had significant improvement in Montgomery-Asberg Depression Rating Scale (MADRS) scores after eight weeks of treatment, compared to placebo. Among the 77 patients, 53 patients were classified as having severe MDD. Of the 14 patients treated with 5 mg of Serdaxin MADRS scores improved by 55.6 per cent, compared to only 34.0 per cent in the placebo group (n = 14), which was statistically significant (p<0.041) on an intent to treat basis.

In addition, 64.3 per cent of patients with severe MDD treated with the 5 mg of Serdaxin were considered Responders compared to 28.6 per cent in the placebo group (p<0.0581). A Responder is a patient with a change from baseline in MADRS score of greater than or equal to 50 per cent after treatment. Additionally, 42.9 per cent of patients in the treatment group were in remission with a MADRS score of less than or equal to 12 after treatment, at eight weeks versus 14.3 per cent in the placebo arm (p<0.209).

The trial also validates the earlier results which demonstrated Serdaxin to be safe and well tolerated without the appearance of serious side effects that are commonly linked to currently marketed antidepressant drugs, such as selective serotonin uptake inhibitors (SSRI), serotonin-norepinephrine reuptake inhibitors (SNRI), and tricyclic antidepressants (TCA). Even though the overall study did not achieve statistical significance, we believe, based on the statistically significant subgroup results, Rexahn plans to commence a phase-IIb clinical trial in second half this year.

“For the millions of people who are debilitated by depression, the promise of Serdaxin is worthy of further investigation and development. This clinical study demonstrated that Serdaxin is well tolerated, does not yet appear to have some of the side effects typically associated with other anti-depressants and improves patients’ MADRS scores. The notable effect of Serdaxin on patients with severe depression is also very encouraging,” said Robert A Riesenberg, a nationally recognized psychiatrist and principal investigator for this trial at the Atlanta Center for Medical Research.

“We are pleased with outcome of this phase-IIa clinical trial of Serdaxin. We look forward to further investigating how Serdaxin’s novel action as a dual serotonin and dopamine enhancer may be able to provide greater efficacy, fewer side effects, and potentially reduced relapse of MDD,” said Dr Chang Ahn, Rexahn’s chairman and chief executive officer.

Rexahn is currently in discussions with several major pharmaceutical companies with the goal of identifying a potential strategic partner to assist in the development and commercialization of Serdaxin. However, there can be no assurances that these discussions would result in a commercial arrangement.

Serdaxin is a potential CNS neuroprotective agent and antidepressant. Rexahn is currently investigating Serdaxin as a treatment for depression in phase-II clinical trials.

Rexahn Pharma is a clinical stage pharmaceutical company dedicated to developing best in class therapeutics for cancer, CNS disorders, and sexual dysfunction.