Intratympanic Administration of OTO-313 Reduces Tinnitus in Patients With Moderate to Severe, Persistent Tinnitus: A Phase 1/2 Study

Intratympanic Gels for Inner Ear Disorders: A Scoping Review of Clinical Trials

OBJECTIVE

Intratympanic injections are a safe, well tolerated procedure routinely performed by ENT's specialists. Intratympanic injections of gels have the potential to deliver therapeutics into the cochlea through the round window membrane prolonging the release of drugs in the inner ear compartment. Aim of the present review is to summarize clinical trials testing pharmacological treatments for inner ear pathologies through intratympanic gel formulations.

DATA SOURCES

Online databases (Google scholar and PubMed) and registers (Clinicaltrials.gov and Euclinicaltrial) were used to identify clinical trials performed between 1990 and 2022.

REVIEW METHODS

PRISMA criteria have been followed. Clinical trials testing gel formulations administered through local intratympanic injections and targeting inner ear disorders were included. All the reports were identified by the authors working in pairs sequentially selecting only studies respecting the inclusion criteria.

RESULTS

A total of 45 clinical studies have been noticed; the gels for intratympanic injection are in the form of poloxamers or hyaluronic acid combinations; the trials found target different kind of inner ear disorders: acquired-stable SNHL, tinnitus, acute sudden SNHL, Meniere disease, cisplatin induced ototoxicity and hearing preservation in patients undergoing cochlear implant surgery.

CONCLUSION

Few studies listed do not provide the specific kind of gel formulation used but only report the intratympanic delivery vehicle as "gel" or "thermogel". Multiple clinical studies have been targeting several forms of inner ear disorders by injecting different compounds through poloxamer and hyaluronic acid formulations. Larger and more advanced clinical stages are necessary to confirm the efficacy of these chemical compounds.

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.

Current Therapeutic Trends for Tinnitus Cure and Control: A Scoping Review

The present scoping review assessed knowledge updates in tinnitus management. We included randomized trials, non-randomized studies, systematic reviews, meta-analyses, and observational studies in last 5 years on patients with tinnitus using Population, Concept, and Context mnemonic. We excluded studies on tinnitus epidemiology, technique-specific comparative studies for tinnitus assessment, review articles, or case reports. We used an artificial intelligence-powered tool MaiA for overall workflow management. Data charting elements included study identifiers, study design, population, interventions used, their outcomes on tinnitus scales, and treatment recommendations if any. Charted data from selected sources of evidence was presented using tables and a concept map. We also identified five evidence-based clinical practice guidelines (CPGs) [from the United States, Europe, and Japan regions] in our review of total 506 results, 205 underwent screening based on eligibility criteria and 38 were included for the final charting. We found three major categories of interventions in our review: Medical technology therapies; Behavioural/habituation therapies; and Pharmacological, herbal/complementary, and alternative medicine therapies. Although evidence-based guidelines on tinnitus therapy did not recommend stimulation therapies, majority of the tinnitus research to date is focused on stimulation. It is highly recommended that clinicians consider CPGs when making treatment recommendations and make the distinction between established management approaches with good evidence and emerging treatment approaches for tinnitus management.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-023-03910-2.

Hearing loss: The final frontier of pharmacology

Despite a prevalence greater than cancer or diabetes, there are no currently approved drugs for the treatment of hearing loss. Research over the past two decades has led to a vastly improved understanding of the cellular and molecular mechanisms in the cochlea that lead to hearing deficits and the advent of novel strategies to combat them. Combined with innovative methods that enable local drug delivery to the inner ear, these insights have paved the way for promising therapies that are now under clinical investigation. In this review, we will outline this renaissance of cochlear biology and drug development, focusing on noise, age-related, and chemotherapy-induced hearing dysfunction.