Cochlear implants and hearing aids are inherently limited in their ability to restore ‘natural’ hearing. Biological therapy to treat inner ear pathology still is evolving rapidly with several ongoing clinical trials, though none are available for clinical practice to date. This is an excellent article that details the current application of major categories of biological therapeutics under the headings: growth factors, apoptosis inhibitors, monoclonal antibodies, and gene therapy in otology applications. Examples of ongoing work in this field are promising and are as below:
- Various growth factors such as insulin-like growth factor 1 (IGF-1) has been applied in a phase 1 study by a group in Japan in 26 patients who failed steroid therapy for idiopathic sudden sensorineural hearing loss (ISSHL). Animal investigations analysing topical IGF-1’s efficacy for facial nerve regeneration have also shown initial positive results. Epidermal growth factor (EGF) and basic fibroblast growth factor (bFGF) has shown encouraging results for tympanic membrane (TM) repair.
- Apoptosis inhibitors studies evaluating AM-111, a c-Jun N-terminal kinase (JNK) inhibitor, have determined positive protective effect against noise-induced trauma. AM-111 has also shown some promise to help safeguard against hair cell loss following labyrinthitis.
- Among monoclonal antibodies, preliminary studies have shown inner ear protective effect of etanercept, a tumour necrosis factor (TNF) inhibitor that fuses the TNF receptor to the end of an IgG1 antibody. When etanercept was delivered via an osmotic mini pump into the scala tympani, it improved hearing preservation rates during CI insertion in guinea pigs.
- The integration of gene therapy for ear-related conditions generally has targeted genetic disorders, hair cell regeneration, and delivery of neurotrophins to the inner ear. Clinical trials are underway to evaluate its safety and efficacy in the preservation and regeneration of inner and outer hair cells.
This paper makes it easy to update knowledge in the vast ongoing research in this field of biologics for otological disorders. It is like a ray of sunshine showing us the future direction of curing, rather than managing, deafness. With our ageing population, the treatment modalities would certainly be in demand if and when available for clinical practice.