A randomized, double-blind, placebo-controlled phase 2 study of intratympanic OTO-313 in patients with moderate to severe subjective tinnitus

PURPOSE: This was a randomized, double-blind, placebo-controlled Phase 2 study to evaluate the efficacy and safety of intratympanic OTO-313 in patients with subjective unilateral tinnitus. METHODS: Patients with moderate to severe unilateral tinnitus of 2–12 months duration were enrolled. A single intratympanic injection of OTO-313 or placebo was administered to the affected ear and patients were evaluated during a 16-weeks follow-up period. Efficacy was assessed using the Tinnitus Functional Index (TFI), daily ratings of tinnitus loudness and annoyance, and Patient Global Impression of Change (PGIC). RESULTS: Intratympanic administration of OTO-313 and placebo produced reductions in tinnitus with a similar percentage of TFI responders at Weeks 4, 8, 12, and 16. Reductions in daily ratings of tinnitus loudness and annoyance, and PGIC scores were also similar between OTO-313 and placebo groups. No significant differences in mean TFI scores between OTO-313 and placebo were observed for pre-specified strata regarding tinnitus duration (≥ 2 to ≤ 6 months and > 6 to ≤ 12 months) and TFI baseline scores (≥ 32 to ≤ 53 points and ≥ 54 to 100 points), although the results numerically favored OTO-313 in patients in the ≥ 2 to ≤ 6 months strata. These results also demonstrated an unexpectedly high placebo response particularly amongst patients with chronic tinnitus, despite training implemented to mitigate placebo response. OTO-313 was well-tolerated with a similar incidence of adverse events compared to placebo. CONCLUSIONS: OTO-313 did not demonstrate a significant treatment benefit relative to placebo due in part to a high placebo response. OTO-313 was safe and well-tolerated.