A prospective, randomized, double-blind study assessing the clinical impact of integrated pharmacogenomic testing for major depressive disorder.

Objective: A prospective double-blind randomized control trial (RCT) to evaluate the benefit of a combinatorial, five gene pharmacogenomic test and interpretive report (GeneSight) for the management of psychotropic medications used in the treatment of major depression in an outpatient psychiatric practice.

Methods: Depressed adult outpatients were randomized to a treatment as usual (TAU, n=25) arm or a pharmacogenomic-informed GeneSight (n=26) arm. Subjects were blinded to their treatment group and depression severity was assessed by blinded study raters. Within two days of enrollment, clinicians of subjects in the guided group received the GeneSight report that categorized each of 26 psychotropic medications within a green, yellow, or red "bin" based on the relationship of each medication to a subject's pharmacokinetic and pharmacodynamic combinatorial gene variant profile. Antidepressant medication changes began within 2 weeks after baseline assessments. Depression severity was assessed by blinded study raters using the HAMD-17, PHQ-9, QIDS-SR, and QIDS-CR administered 4, 6, and 10 weeks after baseline assessment.

Results: Between-group trends were observed with greater than double the likelihood of response and remission in the GeneSight group measured by HAMD-17 at week 10. Mean percent improvement in depressive symptoms on HAMD-17 was higher for the GeneSight group over TAU (30.8% vs 20.7%; p=0.28). TAU subjects who had been prescribed medications at baseline that were contraindicated based on the individual subject's genotype (i.e., red bin) had almost no improvement (0.8%) in depressive symptoms measured by HAMD-17 at week 10, which was far less than the 33.1% improvement (p=0.06) in the pharmacogenomic guided subjects who started on a red bin medication and the 26.4% improvement in GeneSight subjects overall (p=0.08).

Conclusions: Pharmaco-genomic-guided treatment with GeneSight doubles the likelihood of response in all patients with treatment resistant depression and identifies 30% of patients with severe gene-drug interactions who have the greatest improvement in depressive symptoms when switched to genetically suitable medication regimens.