Perilymphatic application of alpha-melanocyte stimulating hormone ameliorates hearing loss caused by systemic administration of cisplatin

Platinum-Based Combination Therapy: Molecular Rationale, Current Clinical Uses, and Future Perspectives

Platinum drugs are common in chemotherapy, but their clinical applications have been limited due to drug resistance and severe toxic effects. The combination of platinum drugs with other drugs with different mechanisms of anticancer action, especially checkpoint inhibitors, is increasingly popular. This combination is the leading strategy to improve the therapeutic efficiency and minimize the side effects of platinum drugs. In this review, we focus on the mechanistic basis of the combinations of platinum-based drugs with other drugs to inspire the development of more promising platinum-based combination regimens in clinical trials as well as novel multitargeting platinum drugs overcoming drug resistance and toxicities resulting from current platinum drugs.

Current Strategies to Combat Cisplatin-Induced Ototoxicity

Cisplatin is widely used for the treatment of a number of solid malignant tumors. However, ototoxicity induced by cisplatin is an obstacle to effective treatment of tumors. The basis for this toxicity has not been fully elucidated. It is generally accepted that hearing loss is due to excessive production of reactive oxygen species by cells of the cochlea. In addition, recent data suggest that inflammation may trigger inner ear cell death through endoplasmic reticulum stress, autophagy, and necroptosis, which induce apoptosis. Strategies have been extensively explored by which to prevent, alleviate, and treat cisplatin-induced ototoxicity, which minimize interference with antitumor activity. Of these strategies, none have been approved by the Federal Drug Administration, although several preclinical studies have been promising. This review highlights recent strategies that reduce cisplatin-induced ototoxicity. The focus of this review is to identify candidate agents as novel molecular targets, drug administration routes, delivery systems, and dosage schedules. Animal models of cisplatin ototoxicity are described that have been used to evaluate drug efficacy and side effect prevention. Finally, clinical reports of otoprotection in patients treated with cisplatin are highlighted. For the future, high-quality studies are required to provide reliable data regarding the safety and effectiveness of pharmacological interventions that reduce cisplatin-induced ototoxicity.

Developments in delivery of medications for inner ear disease

INTRODUCTION

Hearing loss, tinnitus and balance disturbance represent common diseases that have tremendous impact on quality of life. Despite the high incidence of inner ear disease in the general population, there are currently no dedicated pharmacologic interventions available to treat these problems.

AREAS COVERED

This review will focus on how treatment of inner ear disease is moving toward local delivery at the end organ level. The authors will discuss current practice, ongoing clinical trials and potential areas of development such as hair cell regeneration and neurotrophin therapy.

EXPERT OPINION

The inner ear is accessible through the middle ear via the oval and round windows allowing diffusion of drugs into the perilymph. With a better understanding of the physiology of the inner ear and the underlying molecular causes of inner ear disease there is great potential for the development of novel therapeutics that can be locally administered. At present, there is a rapid development of drugs to target diverse inner ear diseases that cause sensorineural hearing loss and balance dysfunction.

Association of skin color, race/ethnicity, and hearing loss among adults in the USA

Epidemiologic studies of hearing loss in adults have demonstrated that the odds of hearing loss are substantially lower in black than in white individuals. The basis of this association is unknown. We hypothesized that skin pigmentation as a marker of melanocytic functioning mediates this observed association and that skin pigmentation is associated with hearing loss independent of race/ethnicity. We analyzed cross-sectional data from 1,258 adults (20-59 years) in the 2003-2004 cycle of the National Health and Nutritional Examination Survey who had assessment of Fitzpatrick skin type and pure-tone audiometric testing. Audiometric thresholds in the worse hearing ear were used to calculate speech- (0.5-4 kHz) and high-frequency (3-8 kHz) pure-tone averages (PTA). Regression models were stratified by Fitzpatrick skin type or race/ethnicity to examine the association of each factor with hearing loss independent of the other. Models were adjusted for potential confounders (demographic, medical, and noise exposure covariates). Among all participants, race/ethnicity was associated with hearing thresholds (black participants with the best hearing followed by Hispanics and then white individuals), but these associations were not significant in analyses stratified by skin color. In contrast, in race-stratified analyses, darker-skinned Hispanics had better hearing than lighter-skinned Hispanics by an average of -2.5 dB hearing level (HL; 95% CI, -4.8 to -0.2) and -3.1 dB HL (95% CI, -5.3 to -0.8) for speech and high-frequency PTA, respectively. Associations between skin color and hearing loss were not significant in white and black participants. Our results demonstrate that skin pigmentation is independently associated with hearing loss in Hispanics and suggest that skin pigmentation as a marker of melanocytic functioning may mediate the strong association observed between race/ethnicity and hearing loss.

Light microscopy study of cisplatin-induced ototoxicity in rats

BACKGROUND

Although most studies on animal ototoxicity employ scanning electron microscopy, all cochlear structures may be identified with light microscopy. This paper describes a simple method of histological assessment of cisplatin-induced ototoxicity in rats, and relates morphological changes to functional changes in hearing detected by distortion product evoked otoacoustic emissions.

MATERIALS AND METHODS

Male Wistar rats were injected with 8 mg/kg/day cisplatin, or with an equivalent volume of saline solution, for three consecutive days. They underwent distortion product evoked otoacoustic emission testing at baseline and at 24 or 48 hours after the last administration. At the end of the experiment, the animals were sacrificed and their cochleae were retrieved and prepared for haematoxylin and eosin staining.

RESULTS

A four-point scoring system was used to grade injury to the external ciliated cells, as indicated by the number of cells absent from the basal turn of the cochlear duct. A four-point scoring system was also used to grade stria vascularis injury, as indicated by the degree of shrinkage of the intermediate cells. Scores were significantly higher in groups treated with cisplatin compared with controls. Morphological changes were confirmed by decreased distortion product evoked otoacoustic emission amplitudes in animals treated with cisplatin.

CONCLUSION

This method is simple to perform with routine histology equipment and is appropriate for the study of acute, cisplatin-induced ototoxicity in rats.