Interventions for tinnitus in adults: an overview of systematic reviews

Hearing loss drug discovery and medicinal chemistry: Current status, challenges, and opportunities

Hearing loss is a severe high unmet need condition affecting more than 1.5 billion people globally. There are no licensed medicines for the prevention, treatment or restoration of hearing. Prosthetic devices, such as hearing aids and cochlear implants, do not restore natural hearing and users struggle with speech in the presence of background noise. Hearing loss drug discovery is immature, and small molecule approaches include repurposing existing drugs, combination therapeutics, late-stage discovery optimisation of known chemotypes for identified molecular targets of interest, phenotypic tissue screening and high-throughput cell-based screening. Hearing loss drug discovery requires the integration of specialist therapeutic area biology and otology clinical expertise. Small molecule drug discovery projects in the global clinical portfolio for hearing loss are here collated and reviewed. An overview is provided of human hearing, inner ear anatomy, inner ear delivery, types of hearing loss and hearing measurement. Small molecule experimental drugs in clinical development for hearing loss are reviewed, including their underpinning biology, discovery strategy and activities, medicinal chemistry, calculated physicochemical properties, pharmacokinetics and clinical trial status. SwissADME BOILED-Egg permeability modelling is applied to the molecules reviewed, and these results are considered. Non-small molecule hearing loss assets in clinical development are briefly noted in this review. Future opportunities in hearing loss drug discovery for human genomics and targeted protein degradation are highlighted.

Presence of hearing loss is predictive of return for further stages of tinnitus therapy following initial education and counseling

OBJECTIVE

Identify clinical factors that predict the likelihood of patients returning for further evaluation and treatment following stage 1 education and counselling in a staged tinnitus habituation program.

DESIGN

Retrospective cross-sectional study. Demographics, audiometric findings and Tinnitus Handicap Inventory (THI) scores were used for predictive modelling to determine the likelihood of patients returning for subsequent therapy.

STUDY SAMPLES

One hundred and ninety consecutive patients treated in an outpatient, staged tinnitus habituation program.

RESULTS

Improvements in THI scores were observed in all subjects (n = 119, d = 0.49, p < 0.001), both for those without hearing loss (n = 13, d = 0.54, p = 0.03) and those with hearing loss (n = 106, d = 0.48, p < 0.001) following Stage 1 education and counselling. Subjects with hearing loss were 14 times more likely to return for Stage 2 evaluation (p < 0.001) following completion of Stage 1 education and counselling.

CONCLUSION

Subjects with idiopathic subjective non-pulsatile tinnitus across all degrees of tinnitus severity benefit from group education and counselling alone. Subjects with hearing loss, irrespective of most hearing loss configurations, are more likely to return for subsequent stages of the program.

A process for prioritising systematic reviews in tinnitus

Objective: To develop an innovative prioritisation process to identify topics for new or updated systematic reviews of tinnitus research.Design: A two-stage prioritisation process was devised. First, a scoping review assessed the amount of randomized controlled trial-level evidence available. This enabled development of selection criteria for future reviews, aided the design of template protocol and suggested the scale of work that would be required to conduct these reviews. Second, using the pre-defined primary and secondary criteria, interventions were prioritised for systematic review.Study sample: Searches identified 1080 records. After removal of duplicates and out of scope works, 437 records remained for full data charting.Results: The process was tested, using subjective tinnitus as the clinical condition and using Cochrane as the systematic review platform. The criteria produced by this process identified three high priority reviews: (1) Sound therapy using amplification devices and/or sound generators; (2) Betahistine and (3) Cognitive behaviour therapy. Further secondary priorities were: (4) Gingko biloba, (5) Anxiolytics, (6) Hypnotics, (7) Antiepileptics and (8) Neuromodulation.Conclusions: A process was developed which successfully identified priority areas for Cochrane systematic reviews of interventions for subjective tinnitus. This technique could easily be transferred to other conditions and other types of systematic reviews.

Medicines discovery for auditory disorders: Challenges for industry

Currently, no approved medicines are available for the prevention or treatment of hearing loss. Pharmaceutical industry productivity across all therapeutic indications has historically been disappointing, with a 90% chance of failure in delivering a marketed drug after entering clinical evaluation. To address these failings, initiatives have been applied in the three cornerstones of medicine discovery: target selection, clinical candidate selection, and clinical studies. These changes aimed to enable data-informed decisions on the translation of preclinical observations into a safe, clinically effective medicine by ensuring the best biological target is selected, the most appropriate chemical entity is advanced, and that the clinical studies enroll the correct patients. The specific underlying pathologies need to be known to allow appropriate patient selection, so improved diagnostics are required, as are methodologies for measuring in the inner ear target engagement, drug delivery and pharmacokinetics. The different therapeutic strategies of protecting hearing or preventing hearing loss versus restoring hearing are reviewed along with potential treatments for tinnitus. Examples of current investigational drugs are discussed to highlight key challenges in drug discovery and the learnings being applied to improve the probability of success of launching a marketed medicine.

Polish Translation and Validation of the Tinnitus Handicap Inventory and the Tinnitus Functional Index

Objective: The need for validated measures enabling clinicians to classify tinnitus patients according to the severity of tinnitus and screen the progress of therapies in our country led us to translate into Polish and to validate two tinnitus questionnaires, namely the Tinnitus Handicap Inventory (THI) and the Tinnitus Functional Index (TFI). Design: The original English versions of the questionnaires were translated into Polish and translated back to English by three independent translators. These versions were then finalized by the authors into a Polish THI (THI-Pl) and a Polish TFI (TFI-Pl). Participants from three laryngological centers in Poland anonymously answered the THI-Pl (N = 98) and the TFI-Pl (N = 108) in addition to the Polish versions of the Center for Epidemiologic Studies Depression Scale as a measure of self-perceived level of depression, and the Satisfaction With Life Scale to assess self-perceived quality of life. Both were used to determine discriminant validity. Two Visual Analog Scales were used to measure tinnitus annoyance and tinnitus loudness in order to determine convergent validity. Results: Similar to the original version of the THI, the THI-Pl showed a high internal consistency (Cronbach's α = 0.93). The exploratory factor analysis revealed that the questionnaire has a three-factorial structure that does not correspond to the original division for functional, catastrophic, and emotional subscales. Convergent and discriminant validities were confirmed. The TFI-Pl showed high internal consistency (Cronbach's α = 0.96) with the reliability ranging from 0.82 to 0.95 for its different subscales. Factor analysis confirmed an eight-factorial structure with factors assigning all items to appropriate subscales reported in the original version of the questionnaire. Discriminant and convergent validities were also confirmed for the TFI-Pl. Conclusion: We translated and validated the Polish versions of the THI and the TFI to make them suitable for clinical use in Poland.