Objective: To evaluate long-term efficacy and safety of DTBZ in patients with TD by examining change from baseline in Abnormal Involuntary Movement Scale (AIMS) scores and Clinical Global Impression of Change (CGIC).

Background: In the 12-week pivotal studies evaluating DTBZ for the treatment of TD (ARM-TD and AIM-TD), statistically significant improvements in TD symptoms were demonstrated and there were low rates of overall adverse events and discontinuations associated with DTBZ. The completed OLE study (SD-809-C-20) evaluated the long-term efficacy and safety of DTBZ in patients with TD.

Method: TD patients who completed ARM-TD or AIM-TD could enroll in this open-label, single-arm study, titrating up to a maximum total daily dose of 48 mg/day based on dyskinesia control and tolerability. The change from baseline in AIMS score was assessed by local site raters for this analysis. Treatment success was also evaluated locally according to physician assessment of patients being “Much Improved” or “Very Much Improved” on CGIC.

Results: 343 patients enrolled in the OLE study, with 6 patients excluded from all analyses. At Week 54 (n=249; total daily dose [mean±SE]: 38.7±0.66 mg), mean change from baseline in AIMS score was -4.8±0.28, and 66% of patients experienced treatment success. At Week 106 (n=194; total daily dose: 39.3±0.75 mg), mean change from baseline in AIMS score was -5.4±0.33, and 65% of patients experienced treatment success. At Week 145 (n=160; total daily dose: 39.4±0.83 mg), mean change from baseline in AIMS score was -6.6±0.37, and 73% of patients experienced treatment success. Treatment was generally well tolerated. There were 688 patient-years of exposure through Week 158, and exposure-adjusted incidence rates (incidence/patient-years) for akathisia/restlessness were 0.01, somnolence/sedation were 0.07, and symptoms which may represent parkinsonism or depression were 0.08 each.

Conclusion: Patients who received long-term treatment with DTBZ achieved sustained improvement in AIMS scores and treatment response rates that were indicative of clinically meaningful long-term benefit. DTBZ is well-tolerated with long-term use.  Results from this open-label trial with response-driven dosing suggest the possibility of increasing benefit over time.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/long-term-treatment-with-deutetrabenazine-dtbz-is-associated-with-continued-improvement-in-tardive-dyskinesia-td-results-from-the-completed-3-year-open-label-extension-ole-study/