Purpose: The purpose of the study was to assess safety and efficacy of autologous muscle derived cells for urinary sphincter repair (AMDC-USR) in female subjects with predominant stress urinary incontinence.
Methods: A randomized, double-blind, multicenter trial examined intra-sphincteric injection of 150 × 106 AMDC-USR versus placebo in female subjects with stress or stress predominant, mixed urinary incontinence. AMDC-USR products were generated from vastus lateralis needle biopsies. Subjects were randomized 2:1 to receive AMDC-USR or placebo and 1:1 to receive 1 or 2 treatments (6 months after the first). Primary outcome was composite of ≥ 50% reduction in stress incontinence episode frequency (IEF), 24-h or in-office pad weight tests at 12 months. Other outcome data included validated subject-recorded questionnaires. Subjects randomized to placebo could elect to receive open-label AMDC-USR treatment after 12 months. Subject follow-up was up to 2 years.
Results: AMDC-USR was safe and well-tolerated with no product-related serious adverse events or discontinuations due to adverse events. Interim analysis revealed an unexpectedly high placebo response rate (90%) using the composite primary outcome which prevented assessment of treatment effect as designed and thus enrollment was halted at 61% of planned subjects. Post hoc analyses suggested that more stringent endpoints lowered placebo response rates and revealed a possible treatment effect.
Conclusions: Although the primary efficacy finding was inconclusive, these results inform future trial design of AMDC-USR to identify clinically meaningful efficacy endpoints based on IEF reduction, understanding of placebo response rate, and refinement of subject selection criteria to more appropriately align with AMDC-USR's proposed mechanism of action.
Keywords: Autologous myoblasts; Cell therapy; Skeletal muscle cells; Stress urinary incontinence; Urethra.