Pharmacogenomics of cisplatin-induced ototoxicity

The role of genetic variants in the prediction of hearing loss due to cisplatin chemoradiotherapy

BACKGROUND

Concomitant high-dose cisplatin with radiotherapy is commonly used for treating head and neck squamous cell carcinoma (HNSCC). Cisplatin, often used with radiotherapy, is known for causing irreversible sensorineural hearing loss, with individual variability suggesting a genetic component. This study aims to enhance the predictive ability of the clinical prediction model for cisplatin-induced hearing loss (CIHL) in HNSCC patients, as outlined in Theunissen et al., by incorporating significant genetic variants.

METHODS

Conducted at the Netherlands Cancer Institute, this retrospective study included 74 patients treated between 1997 and 2011. Thirty-one SNPs that were previously associated with CIHL or other cisplatin-induced toxicities were identified and incorporated into the model. The primary outcome measured was the change in decibels at posttreatment 1-2-4 kHz hearing levels per additional minor allele of these SNPs, evaluated using linear mixed-effects regression models. The model's predictive accuracy was determined by the area under the curve (AUC) using 10-fold cross-validation.

RESULTS

The rs2289669 SNP in the SLC47A1/MATE1 gene was linked to a significant 2.67 dB increase in hearing loss per allele (95% CI 0.49-4.86, p = 0.017). Incorporating rs2289669 improved the model's AUC from 0.78 to 0.83, a borderline significant improvement (p = 0.073).

CONCLUSIONS

This study underscores the importance of the rs2289669 SNP in CIHL and demonstrates the potential of combining genetic and clinical data for enhanced predictive models in personalized treatment strategies.

The Effects of Substance Misuse on Auditory and Vestibular Function: A Systematic Review

BACKGROUND

Chronic substance misuse is an ongoing and significant public health concern. Among a myriad of health complications that can occur, substance misuse potentially causes ototoxic effects. Case reports, retrospective chart data, and a few cohort studies suggest that certain prescription opioids and illicit drugs can have either temporary or permanent effects on auditory and/or vestibular function. Given the steady rise of people with a substance-use disorder (SUD), it is of growing importance that audiologists and otolaryngologists have an insight into the potential ototoxic effects of substance misuse.

OBJECTIVES

A systematic review was conducted to (1) synthesize the literature on the illicit drugs, prescription opioids, and alcohol misuse on the auditory and vestibular systems, (2) highlight common hearing and vestibular impairments for each substance class, and (3) discuss the limitations of the literature, the potential mechanisms, and clinical implications for clinicians who may encounter patients with hearing or vestibular loss related to substance misuse, and describe opportunities for further study.

DESIGN

Systematic searches were performed via PubMed, Scopus, and Google Scholar, and the final updated search was conducted through March 30, 2022. Inclusion criteria included peer-reviewed articles, regardless of study design, from inception until the present that included adults with chronic substance misuse and hearing and/or vestibular complaints. Articles that focused on the acute effects of substances in healthy people, ototoxicity from already known ototoxic medications, the relationship between hearing loss and development of a SUD, articles not available in English, animal work, and duplicates were excluded. Information on the population (adults), outcomes (hearing and/or vestibular data results), and study design (e.g., case report, cohort) were extracted. A meta-analysis could not be performed because more than 60% of the studies were single-case reports or small cohort.

RESULTS

The full text of 67 studies that met the eligibility criteria were selected for the review. Overall, 21 studies reported associations between HL/VL related to illicit drug misuse, 28 studies reported HL/VL from prescription opioids, and 20 studies reported HL/VL related to chronic alcohol misuse (2 studies spanned more than one category). Synthesis of the findings suggested that the misuse and/or overdose of amphetamines and cocaine was associated with sudden, bilateral, and temporary HL, whereas HL from the combination of a stimulant and an opioid often presented with greater HL in the mid-frequency range. Reports of temporary vertigo or imbalance were mainly associated with illicit drugs. HL associated with misuse of prescription opioids was typically sudden or rapidly progressive, bilateral, moderately severe to profound, and in almost all cases permanent. The misuse of prescription opioids occasionally resulted in peripheral VL, especially when the opioid misuse was long term. Chronic alcohol misuse tended to associate with high-frequency sudden or progressive sensorineural hearing loss, or retrocochlear dysfunction, and a high occurrence of central vestibular dysfunction and imbalance.

CONCLUSIONS

Overall, chronic substance misuse associates with potential ototoxic effects, resulting in temporary or permanent hearing and/or vestibular dysfunction. However, there are notable limitations to the evidence from the extant literature including a lack of objective test measures used to describe hearing or vestibular effects associated with substance misuse, small study sample sizes, reliance on case studies, lack of controlling for confounders related to health, age, sex, and other substance-use factors. Future large-scale studies with prospective study designs are needed to further ascertain the role and risk factors of substance misuse on auditory and vestibular function and to further clinical management practices.

Cancer survivors and neurotoxic chemotherapy: hearing loss and tinnitus

OBJECTIVES

Little is known about hearing loss and tinnitus associated with neurotoxic chemotherapy. Study evaluated for differences in occurrence rates and effects of hearing loss and tinnitus in survivors who received a platinum alone, a taxane alone or a platinum and taxane containing regimen.

METHODS

Total of 273 survivors with breast, gastrointestinal, gynaecological or lung cancer completed self-report measures of hearing loss and tinnitus and had an audiometric assessment that obtained pure tone air conduction thresholds bilaterally at frequencies of between 0.25 kHz to 16.0 kHz. To adjust for age-related and gender-related changes in hearing, each survivor's audiogram was evaluated using the National Health and Nutrition Examination Survey-modified Occupational Safety and Health Administration standards. Survivor was classified as having hearing loss if at any frequency they scored poorer than the 50th percentile for their age and gender. Survivors were categorised as having tinnitus if they reported that for >10% of their time awake, they were consciously aware of their tinnitus. Differences among the chemotherapy groups were evaluated using parametric and non-parametric tests.

RESULTS

For most of the demographic and clinical characteristics, no differences were found among the three chemotherapy groups. Occurrence rates for audiogram-confirmed hearing loss ranged from 52.3% to 71.4%. Occurrence rates for tinnitus ranged from 37.1% to 40.0%. No differences were found among the three chemotherapy groups in the occurrence rates or effects of hearing loss and tinnitus.

CONCLUSION

These findings suggest that regardless of the chemotherapy regimen common mechanistic pathway(s) may underlie these two neurotoxicities.

Rapamycin Perfluorocarbon Nanoparticle Mitigates Cisplatin-Induced Acute Kidney Injury

For nearly five decades, cisplatin has played an important role as a standard chemotherapeutic agent and been prescribed to 10-20% of all cancer patients. Although nephrotoxicity associated with platinum-based agents is well recognized, treatment of cisplatin-induced acute kidney injury is mainly supportive and no specific mechanism-based prophylactic approach is available to date. Here, we postulated that systemically delivered rapamycin perfluorocarbon nanoparticles (PFC NP) could reach the injured kidneys at sufficient and sustained concentrations to mitigate cisplatin-induced acute kidney injury and preserve renal function. Using fluorescence microscopic imaging and fluorine magnetic resonance imaging/spectroscopy, we illustrated that rapamycin-loaded PFC NP permeated and were retained in injured kidneys. Histologic evaluation and blood urea nitrogen (BUN) confirmed that renal structure and function were preserved 48 h after cisplatin injury. Similarly, weight loss was slowed down. Using western blotting and immunofluorescence staining, mechanistic studies revealed that rapamycin PFC NP significantly enhanced autophagy in the kidney, reduced the expression of intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1), as well as decreased the expression of the apoptotic protein Bax, all of which contributed to the suppression of apoptosis that was confirmed with TUNEL staining. In summary, the delivery of an approved agent such as rapamycin in a PFC NP format enhances local delivery and offers a novel mechanism-based prophylactic therapy for cisplatin-induced acute kidney injury.

Dual role of quercetin in enhancing the efficacy of cisplatin in chemotherapy and protection against its side effects: a review

Chemotherapy has opened a new window in cancer therapy. However, the resistance of cancer cells has dramatically reduced the efficacy of chemotherapy. Cisplatin is a chemotherapeutic agent and its potential in cancer therapy has been restricted by resistance of cancer cells. As a consequence, the scientists have attempted to find new strategies in elevating chemotherapy efficacy. Due to great anti-tumour activity, naturally occurring compounds are of interest in polychemotherapy. Quercetin is a flavonoid with high anti-tumour activity against different cancers that can be used with cisplatin to enhance its efficacy and also are seen to sensitise cancer cells into chemotherapy. Furthermore, cisplatin has side effects such as nephrotoxicity and ototoxicity. Administration of quercetin is advantageous in reducing the adverse effects of cisplatin without compromising its anti-tumour activity. In this review, we investigate the dual role of quercetin in enhancing anti-tumour activity of cisplatin and simultaneous reduction in its adverse effects.

Integrating pharmacogenomics into clinical trials of hearing disorders

In 2019, the U.S. Food and Drug Administration issued guidance to increase the efficiency of drug development and support precision medicine, including tailoring treatments to those patients who will benefit based on genetic variation even in the absence of a documented mechanism of action. Although multiple advancements have been made in the field of pharmacogenetics (PGx) for other disease conditions, there are no approved PGx guidelines in the treatment of hearing disorders. In studies of noise-induced hearing loss (NIHL), some progress has been made in the last several years associating genomic loci with susceptibility to noise damage. However, the power of such studies is limited as the underlying physiological responses may vary considerably among the patient populations. Here, we have summarized previous animal studies to argue that NIHL subtyping is a promising strategy to increase the granularity of audiological assessments. By coupling this enhanced phenotyping capability with genetic association studies, we suggest that drug efficacy will be better predicted, increasing the likelihood of success in clinical trials when populations are stratified based on genetic variation or designed with multidrug combinations to reach a broader segment of individuals suffering or at risk from NIHL.

Cisplatin Chemotherapy and Cochlear Damage: Otoprotective and Chemosensitization Properties of Polyphenols

Significance: Cisplatin is an important component of treatment regimens for different cancers. Notwithstanding that therapeutic success often results from partial efficacy or stabilizing the disease, chemotherapy failure is driven by resistance to drug treatment and occurrence of side effects, such as progressive irreversible ototoxicity. Cisplatin's side effects, including ototoxicity, are often dose limiting. Recent Advances: Cisplatin ototoxicity results from several mechanisms, including redox imbalance caused by reactive oxygen species production and lipid peroxidation, activation of inflammation, and p53 and its downstream pathways that culminate in apoptosis. Considerable efforts in research have targeted development of molecular interventions that can be concurrently administered with cisplatin or other chemotherapies to reduce side effect toxicities while preserving or enhancing the antineoplastic effects. Evidence from studies has indicated some polyphenols, such as curcumin, can help to regulate redox signaling and inflammatory effects. Furthermore, polyphenols can exert opposing effects in different types of tissues, that is, normal cells undergoing stressful conditions versus cancer cells. Critical Issues: This review article summarizes evidence of curcumin antioxidant effect against cisplatin-induced ototoxicity that is converted to a pro-oxidant activity in cisplatin-treated cancer cells, thus providing an ideal chemosensitivity combined with otoprotection. Polyphenols can modulate the adaptive responses to stress in the cisplatin-exposed cochlea. These adaptive effects can result from the interaction/cross talk between the cell's defenses, inflammatory molecules, and the key signaling molecules of signal transducers and activators of transcription 3 (STAT-3), nuclear factor κ-B (NF-κB), p53, and nuclear factor erythroid 2-related factor 2 (Nrf-2). Future Directions: We provide molecular evidence for alternative strategies for chemotherapy with cisplatin addressing the otoprotection and chemosensitization properties of polyphenols. Antioxid. Redox Signal. 36, 1229-1245.

Pharmacological treatment with annexin A1-derived peptide protects against cisplatin-induced hearing loss

Cisplatin is an antineoplastic agent widely used, and no effective treatments capable of preventing cisplatin-induced ototoxicity and neurotoxicity in humans have yet been identified. This study evaluated the effect of the anti-inflammatory annexin A1 (AnxA1)-derived peptide Ac_2-26 in a cisplatin-induced ototoxicity model. Wistar rats received intraperitoneal injections of cisplatin (10mg/kg/day) for 3 days to induce hearing loss, and Ac_2-26 (1mg/kg) was administered 15minutes before cisplatin administration. Control animals received an equal volume of saline. Hearing thresholds were measured by distortion product otoacoustic emissions (DPOAE) before and after treatments. Pharmacological treatment with Ac_2-26 protected against cisplatin-induced hearing loss, as evidenced by DPOAE results showing similar signal-noise ratios between the control and Ac_2-26-treated groups. These otoprotective effects of Ac_2-26 were associated with an increased number of ganglion neurons compared with the untreated cisplatin group. Additionally, Ac_2-26 treatment produced reduced immunoreactivity on cleaved caspase 3 and phosphorylated ERK levels in the ganglion neurons, compared to the untreated group, supporting the neuroprotective effects of the Ac_2-26. Our results suggest that Ac_2-26 has a substantial otoprotective effect in this cisplatin-induced ototoxicity model mediated by neuroprotection and the regulation of the ERK pathway.

TCERG1L allelic variation is associated with cisplatin-induced hearing loss in childhood cancer, a PanCareLIFE study

In children with cancer, the heterogeneity in ototoxicity occurrence after similar treatment suggests a role for genetic susceptibility. Using a genome-wide association study (GWAS) approach, we identified a genetic variant in TCERG1L (rs893507) to be associated with hearing loss in 390 non-cranial irradiated, cisplatin-treated children with cancer. These results were replicated in two independent, similarly treated cohorts (n = 192 and 188, respectively) (combined cohort: P = 5.3 × 10-10, OR 3.11, 95% CI 2.2-4.5). Modulating TCERG1L expression in cultured human cells revealed significantly altered cellular responses to cisplatin-induced cytokine secretion and toxicity. These results contribute to insights into the genetic and pathophysiological basis of cisplatin-induced ototoxicity.

Effect of cisplatin chemotherapy on the inner ear function and serum prestin concentration

PURPOSE

One of the main side effects of chemotherapy with cisplatin is irreversible sensorineural hearing loss. This study was conducted to assess the correlation between the serum prestin concentration as a potential cochlear biomarker and audiologic findings in patients after cisplatin chemotherapy.

METHODS

A total of 52 patients aged 18-75 years were included in this prospective study. All the subjects were recruited from the radiotherapy and oncology center of a tertiary hospital in Rasht, Iran. Audiologic parameters evaluations and serum prestin concentrations were measured at baseline and after 1-3 weeks of chemotherapy. The inner ear function was evaluated by pure-tone audiometry (PTA) and distortion product of otoacoustic emission (DPOAE). A repeated-measure analysis of variance was performed to evaluate the relationship between the PTA, DPOAE, serum prestin concentration and cumulative cisplatin dose.

RESULTS

Fifty-two patients (36 females) participated in this study. The PTA results showed that ototoxicity was more frequent among the patients with a high cumulative dose of cisplatin (χ2 trend = 15.25; P < 0.001). DPOAE responses revealed that 38.5% of the patients had ototoxicity change after 40-80 mg of cisplatin administration. After receiving 40-80 mg of cisplatin, serum prestin concentration increased from 130 to 230 pg/ml. There is a significant positive correlation between prestin concentration after receiving more than 80 mg of cisplatin and the ototoxic changes in the DPOAE response.

CONCLUSION

The present study showed correlations between prestin concentrations and ototoxicity diagnosis by DPOAE findings. An early rise in prestin concentration is particularly important and an early sign of hearing loss. Future studies are recommended to investigate the effect of varying doses of cisplatin on prestin concentration and any association between ototoxicity and clinicopathological features.

[Screening for bilateral vestibulopathy in outpatients with unsteadiness]

Objective:This study aimed to find bilateral vestibulopathy（BVP） patients in outpatients with unsteadiness and investigate their clinical characteristics. Methods:According to the common manifestation and etiologies of BVP, 2075 outpatients who were diagnosed as imbalance, follow up on chemotherapy, bilateral Menière's disease, systemic lupus erythematosus（SLE） and vasculitis from January 2018 to October 2019 were searched based on the hospital information system. After completing a telephone screening interview, eligible individuals whose symptoms were in consistent with the diagnostic criteria of BVP were scheduled for questionnaires and video head impulse test（vHIT）. Results:A total of 131 patients replied and complained chronic unsteadiness. The response rates of patients with bilateral Menière's disease, chemotherapy, SLE and vasculitis were 10.0%, 0%, 0.3% and 1.2%, respectively. Unsteadiness is uncommon or mild in outpatients with vasculitis, SLE and chemotherapy. Twenty-nine patients presented with typical symptoms of BVP and only 3 were diagnosed as BVP after vHIT. The horizontal vHIT gain was significantly lower among patients who reported very severe life impact than those reported mild to severe impact in older patients, as well as in male patients（both P<0.01）. However, no significant differences were noted in younger and female patients（P=0.396, 0.180, respectively）. Conclusion:BVP accounts for 2.3% in outpatients with unsteadiness, and only 10.3% of patients who presents with typical symptoms meet the diagnostic criteria, suggesting vestibular function test is of great significance in making diagnosis.

Early Physiological and Cellular Indicators of Cisplatin-Induced Ototoxicity

Cisplatin chemotherapy often causes permanent hearing loss, which leads to a multifaceted decrease in quality of life. Identification of early cisplatin-induced cochlear damage would greatly improve clinical diagnosis and provide potential drug targets to prevent cisplatin's ototoxicity. With improved functional and immunocytochemical assays, a recent seminal discovery revealed that synaptic loss between inner hair cells and spiral ganglion neurons is a major form of early cochlear damage induced by noise exposure or aging. This breakthrough discovery prompted the current study to determine early functional, cellular, and molecular changes for cisplatin-induced hearing loss, in part to determine if synapse injury is caused by cisplatin exposure. Cisplatin was delivered in one to three treatment cycles to both male and female mice. After the cisplatin treatment of three cycles, threshold shift was observed across frequencies tested like previous studies. After the treatment of two cycles, beside loss of outer hair cells and an increase in high-frequency hearing thresholds, a significant latency delay of auditory brainstem response wave 1 was observed, including at a frequency region where there were no changes in hearing thresholds. The wave 1 latency delay was detected as early cisplatin-induced ototoxicity after only one cycle of treatment, in which no significant threshold shift was found. In the same mice, mitochondrial loss in the base of the cochlea and declining mitochondrial morphometric health were observed. Thus, we have identified early spiral ganglion-associated functional and cellular changes after cisplatin treatment that precede significant threshold shift.

Impact of genetic factors on platinum-induced gastrointestinal toxicity

Severe gastrointestinal (GI) toxicity is a common side effect after platinum-based chemotherapy. The incidence and severity of GI toxicity vary among patients with the same chemotherapy. Genetic factors involved in platinum transport, metabolism, detoxification, DNA repair, cell cycle control, and apoptosis pathways may account for the interindividual difference in GI toxicity. The influence of gene polymorphisms in the platinum pathway on GI toxicity has been extensively analyzed. Variations in study sample size, ethnicity, design, treatment schedule, dosing, endpoint definition, and assessment of toxicity make it difficult to precisely interpret the results. Hence, we conducted a review to summarize the most recent pharmacogenomics studies of GI toxicity in platinum-based chemotherapy and identify the most promising avenues for further research.

Hearing and Other Neurologic Problems

Ototoxicity and other neurologic toxicities are potential consequences of exposure to common therapeutic agents used during treatment of childhood cancer, including platinum and vinca alkaloid chemotherapy, cranial radiation, surgery involving structures critical to cochlear and neurologic function, and supportive care medications such as aminoglycoside antibiotics and loop diuretics. This article provides an overview of ototoxicity and other neurologic toxicities related to childhood cancer treatment, discusses the challenges that these toxicities may pose for survivors, and presents an overview of current recommendations for surveillance and clinical management of these potentially life-altering toxicities in survivors of childhood cancers.

Potential use of n-3 PUFAs to prevent oxidative stress-derived ototoxicity caused by platinum-based chemotherapy

Platinum-based compounds are widely used for the treatment of different malignancies due to their high effectiveness. Unfortunately, platinum-based treatment may lead to ototoxicity, an often-irreversible side effect without a known effective treatment and prevention plan. Platinum-based compound-related ototoxicity results mainly from the production of toxic levels of reactive oxygen species (ROS) rather than DNA-adduct formation, which has led to test strategies based on direct ROS scavengers to ameliorate hearing loss. However, favorable clinical results have been associated with several complications, including potential interactions with chemotherapy efficacy. To understand the contribution of the different cytotoxic mechanisms of platinum analogues on malignant cells and auditory cells, the particular susceptibility and response of both kinds of cells to molecules that potentially interfere with these mechanisms, is fundamental to develop innovative strategies to prevent ototoxicity without affecting antineoplastic effects. The n-3 long-chain polyunsaturated fatty acids (n-3 PUFAs) have been tried in different clinical settings, including with cancer patients. Nevertheless, their use to decrease cisplatin-induced ototoxicity has not been explored to date. In this hypothesis paper, we address the mechanisms of platinum compounds-derived ototoxicity, focusing on the differences between the effects of these compounds in neoplastic versus auditory cells. We discuss the basis for a strategic use of n-3 PUFAs to potentially protect auditory cells from platinum-derived injury without affecting neoplastic cells and chemotherapy efficacy.

Comparison of radiation and chemoradiation-induced sensorineural hearing loss in head and neck cancer patients

Aim

The purpose of this study was to assess and compare the incidence and severity of sensorineural hearing loss (SNHL) in head-and-neck patients undergoing radiotherapy (RT) and concurrent cisplatin-based chemoradiotherapy (CRT).

Materials and Methods

Pure tone audiometry (PTA) was performed at 0.25-12 kHz on 35 RT and 25 CRT patients after 12-month followed up. The hearing loss was evaluated according to the Common Terminology Criteria for Adverse Events (CTCAE) criteria.

Results

SNHL increased to 84% in patients who had received CRT, compared with 26% increasing in patients who had treated with RT. There was an increased risk of SNHL at all frequencies for ears received a cochlear mean dose >50 Gy in RT group, compared to those receiving cochlear mean dose >30 Gy in CRT group. SNHL was more severe at higher frequencies in both patient groups.

Conclusion

Characteristic of radiation-induced SNHL is different from CRT-induced SNHL, especially in threshold radiation dose and PTA frequency.

Review of nutritional status, body composition, and effects of antineoplastic drug disposition

The overall survival for children with cancer in high income countries is excellent. However, there are many disparities that may negatively affect survival, which are particularly problematic in low income countries, such as nutritional status at diagnosis and throughout therapy. Nutritional status as well as concomitant foods, supplements, and medications may play a role in overall exposure and response to chemotherapy. Emerging science around the microbiome may also play a role and should be further explored as a contributor to disease progression and therapeutic response. This article highlights some of these issues and proposes additional areas of research relevant to nutritional status and pharmacology that are needed in pediatric oncology.

GSTM1 null and GSTT1 null: predictors of cisplatin-caused acute ototoxicity measured by DPOAEs

Preventing the ototoxicity caused by cisplatin is a major issue yet to be overcome. Useful preventive treatments will soon be available. Consequently, the next step is to filter out those patients who are more prone to develop ototoxicity. The aim of this study was to prospectively evaluate potential predictive markers of acute ototoxicity as determined by measures of distortion product otoacoustic emissions (DPOAEs). A total of 118 patients from our previous DPOAE analysis were put under evaluation. Ototoxic cases were divided according to unilateral (n = 45) or bilateral (n = 23) involvement. The clinicopathological characteristics, hearing test results, germline GSTT1, GSTM1, and GSTP1 polymorphisms, and common laboratory parameters were included in the new analysis. Univariate and multivariate statistical tests were applied. According to multivariate logistic regression, the only independent predictor of unilateral ototoxicity (vs. non-affected) was a GSTM1 null genotype (OR = 4.52; 95%CI = 1.3-16.3), while for bilateral damage, the GSTT1 null genotype (OR = 4.76; 1.4-16) was a predictor. The higher starting serum urea level was characteristic of bilateral ototoxicity; however, the only independent marker of bilateral (vs. unilateral) ototoxicity was the presence of GSTT1 null genotype (OR = 2.44; 1.23-4.85). Different processes, involving the GSTM1 and GSTT1 genotypes, respectively, govern the development of acute unilateral and bilateral ototoxicities. Further research is needed to clarify these processes. Based on the above findings, patients whom are at risk may be selected for otoprotective therapies. KEY MESSAGES: The acute ototoxicity was determined by DPOAE in 118 testicular cancer patients. GSTM1 null was the only marker of unilateral ototoxicity (vs. non-affected). The only marker of bilateral hearing loss (vs. non-affected) was the GSTT1 null. GSTT1 null was also the marker of bilateral vs. unilateral ototoxicity. A high-risk group may be selected for new, individualized otoprotective treatment.

The Relationship Between Cisplatin-related and Age-related Hearing Loss During an Extended Follow-up

OBJECTIVES

Cisplatin-related hearing loss (HL) is claimed to progress after treatment. This controlled longitudinal study with extended follow-up investigates HL in testicular cancer survivors (TCSs) after cisplatin-based chemotherapy (CBCT).

STUDY DESIGN

Controlled longitudinal study.

METHODS

Eighty-two TCSs treated with CBCT between 1980 and 1994 in Norway participated in two surveys (S1/S3), including pure-tone audiograms (0.125-8 kHz) and self-reported HL, 12 and 31 years after treatment, respectively. Hearing thresholds were age-adjusted based on age-matched hearing thresholds from the general population (controls). Hearing loss was defined as thresholds >20 dB at any frequency.

RESULTS

Between the two surveys, the prevalence of high-frequency HL (4, 6, and 8 kHz) increased from 73% to 94% but approached those of the aging general population after age adjustment. In TCSs aged >40 years at first survey, HL at the subsequent survey equaled that of controls. Self-reported HL increased from seven (9%) at S1 to 20 (26%) at S3. At S1, age-adjusted HL was identified in all (seven) TCSs reporting decreased hearing whereas at S3, hearing thresholds did not differ from controls in seven out of 20 patients reporting HL.

CONCLUSION

CBCT-related ototoxicity causes high-frequency HL, but in contrast to reports from follow-up studies from the first post-treatment decade, no major progression was found beyond the first post-treatment decade for frequencies 0.125-8 kHz. Importantly, with extended follow-up, hearing thresholds of patients approach those of the general population, possibly due to a less-than-additive effect with age-related hearing loss (ARHL) in CBCT-treated patients. Age-and sex-matching is strongly advised in long-term follow-up of CBCT-related ototoxicity. Specificity for detecting ototoxicity with self-reported questionnaires decreases with extended follow-up.

LEVEL OF EVIDENCE

3 Laryngoscope, 130:E515-E523, 2020.

Toxicity, risk factors and management of cisplatin-induced toxicity: A prospective study

Background and propose

Cisplatin is a cytotoxic drug that triggers several toxicities. However, nephrotoxicity and ototoxicity remain major clinical limitations. The aim of our study was to evaluate the incidence of chemotherapy toxicity induced by cisplatin and to analyze the influence of risk factors in the Tunisian population.

Methods

We performed a prospective descriptive study in a period of four months. Patients were eligible if they had pathologically confirmed malignancies and treated with cisplatin-regimen chemotherapy. Nephrotoxicity and digestive toxicity were graded according to the World Health Organization toxicity scale and ototoxicity was scored clinically according to the Common Terminology Criteria for Adverse Events (CTCAE). Multivariate logistic regression analysis was performed to evaluate the influence of clinical variables on cisplatin-induced toxicity.

Results

A total of 150 patients were included. Forty-four percent of patients developed cisplatin-regimen toxicity: 15% developed cisplatin-induced nephrotoxicity, 9% cisplatin-induced ototoxicity and 27% digestive toxicity. In the multivariate analysis, age >65 years (OR= 6.129, p = 0.010), metastatic cancer (OR = 0.171, p = 0.007) and cumulative dose (OR= 1.004 mg/m2; p = 0.042) were strong predisposing factors for CDDP-induced nephrotoxicity. The cumulative dose was an independent prognostic indicator for digestive toxicity (OR = 0.997, p = 0.002).

Conclusion

In our study, age >65 years and metastatic cancer were risk factors for cisplatin-induced nephrotoxicities. We also found the correlation between cumulative dose and nephrotoxicity or digestive toxicity.

Are There Cochlear Dead Regions Involved in Hearing Loss after Cisplatin Ototoxicity?

BACKGROUND

The most common complaint of patients affected by chemotherapy-induced hearing loss is difficulty understanding speech in noisy environments despite the use of hearing aids. Cochlear dead regions, those areas with damaged or absent inner hair cells and dendrites, may account for this type of hearing loss. However, it is unknown whether this condition is associated with cisplatin agents.

OBJECTIVE

The aim of this study was to determine whether cisplatin is associated with hearing loss and cochlear dead regions.

METHODS

This prospective cross-sectional study was conducted in patients participating in routine audiological monitoring during and after chemotherapy treatment. Adults undergoing audiological evaluation who had completed chemotherapy treatment were invited to participate. Patients were divided into 3 groups according to pure tone thresholds. Group 1 patients had thresholds over 70 dB (HL) at 2,000 Hz and higher frequencies. Group 2 patients had thresholds below 70 dB (HL) up to 2,000 Hz. Patients in the control group had normal thresholds at all frequencies. The threshold equalizing noise test (TEN[HL]) was used to identify cochlear dead regions by repeating thresholds in the presence of TEN noise played from a compact disc. The presence of cochlear dead regions was established when the masked threshold was 10 dB or greater above the TEN level and 10 dB or greater above the absolute threshold at any frequency.

RESULTS

Twelve patients were included in study group 1, 10 patients in study group 2, and 7 patients in the control group. Cochlear dead regions were present in all patients with hearing loss and in none of the control group. For groups 1 and 2, mean differences between absolute and masked thresholds were 21 and 16 dB at 500 Hz; 22 and 15 dB at 1,000 Hz; 31 and 17 dB at 2,000 Hz; 32 and 20 dB at 3,000 Hz; and 31 and 21 dB at 4,000 Hz, respectively. Nevertheless, analysis of variance testing with Bonferroni analysis showed a difference between groups 1 and 2 only at 2,000, 3,000, and 4,000 Hz.

CONCLUSION

We found unresponsive or dead cochlear regions in patients who had undergone cisplatin chemotherapy even among patients with mild to moderate hearing loss.

Anti-Cancer and Ototoxicity Characteristics of the Curcuminoids, CLEFMA and EF24, in Combination with Cisplatin

In this study, we investigated whether the curcuminoids, CLEFMA and EF24, improved cisplatin efficacy and reduced cisplatin ototoxicity. We used the lung cancer cell line, A549, to determine the effects of the curcuminoids and cisplatin on cell viability and several apoptotic signaling mechanisms. Cellular viability was measured using the MTT assay. A scratch assay was used to measure cell migration and fluorescent spectrophotometry to measure reactive oxygen species (ROS) production. Western blots and luminescence assays were used to measure the expression and activity of apoptosis-inducing factor (AIF), caspases-3/7, -8, -9, and -12, c-Jun N-terminal kinases (JNK), mitogen-activated protein kinase (MAPK), and proto-oncogene tyrosine-protein kinase (Src). A zebrafish model was used to evaluate auditory effects. Cisplatin, the curcuminoids, and their combinations had similar effects on cell viability (IC₅₀ values: 2-16 μM) and AIF, caspase-12, JNK, MAPK, and Src expression, while caspase-3/7, -8, and -9 activity was unchanged or decreased. Cisplatin increased ROS yield (1.2-fold), and curcuminoid and combination treatments reduced ROS (0.75-0.85-fold). Combination treatments reduced A549 migration (0.51-0.53-fold). Both curcuminoids reduced auditory threshold shifts induced by cisplatin. In summary, cisplatin and the curcuminoids might cause cell death through AIF and caspase-12. The curcuminoids may potentiate cisplatin's effect against A549 migration, but may counteract cisplatin's effect to increase ROS production. The curcuminoids might also prevent cisplatin ototoxicity.

Investigation of Astaxanthin Effect on Cisplatin Ototoxicity in Rats by Using Otoacoustic Emission, Total Antioxidant Capacity, and Histopathological Methods

BACKGROUND

Cisplatin-induced ototoxicity is related to oxidative stress. Astaxanthin is one of the most powerful antioxidants in nature.

AIMS/OBJECTIVES

To investigate the protective effect of astaxanthin on cisplatin-induced ototoxicity.

MATERIALS AND METHODS

Thirty-five Sprague Dawley female rats were divided into 5 groups: control, cisplatin, and cisplatin with 10, 20, and 40 mg/kg astaxanthin groups. Cisplatin group received a single intraperitoneal injection of 14 mg/kg cisplatin. While saline was administered in the control group, in the other 3 groups, 10, 20, and 40 mg/kg daily doses of astaxanthin were administered through orogastric cannula before administration of cisplatin. Baseline and 10th day otoacoustic emission tests were administered. An intracardiac blood sample was taken to measure total antioxidant capacity (TAC), and the cochleas of the animals were investigated histopathologically.

RESULTS

Hearing level of astaxanthin 40 mg/kg + cisplatin group was higher at 24 kHz and 32 kHz frequencies compared to the cisplatin group. The TAC value of the cisplatin group was lower than both the control and astaxanthin + cisplatin groups (P < .05). On histopathological examination, the other groups were deformed compared to the control group, but no statistically significant difference was observed between the astaxanthin + cisplatin and cisplatin groups.

CONCLUSIONS AND SIGNIFICANCE

Astaxanthin showed protective effect at high frequencies when it was administered at high dose. Thus, astaxanthin may have protective effect against cisplatin-induced ototoxicity.

A Review of Cisplatin-Associated Ototoxicity

Cisplatin, an effective antineoplastic drug used in the treatment of many cancers, has ototoxic potential, thus placing cancer patients, receiving this treatment, at risk of hearing loss. It is therefore important for health care professionals managing these patients to be aware of cisplatin's ototoxic properties and its clinical signs to identify patients at risk of developing a hearing impairment. Eighty-five English peer-reviewed articles and two books, from January 1975 to July 2015, were identified from PubMed, ScienceDirect, and EBSCOhost. An overview of cisplatin-associated ototoxicity, namely its clinical features, incidence rates, molecular and cellular mechanisms, and risk factors, is presented in this article. This review further highlights the importance of a team-based approach to complement an audiological monitoring program in reducing any further loss in the quality of life of affected patients, as there is currently no otoprotective agent routinely recommended for the prevention of cisplatin-associated ototoxicity.

Role of epigenetic mechanisms in cisplatin-induced toxicity

Cisplatin (CDDP) is a highly effective antineoplastic agent, widely used in the treatment of various malignant tumors. However, its major problems are side effects associated to toxicity. Considerable inter-individual differences have been reported for CDDP-induced toxicity due to genetic and epigenetic factors. Genetic causes are well described; however, epigenetic modifications are not fully addressed. In the last few years, many evidences were found linking microRNA to the development of CDDP-mediated toxicity, particularly nephrotoxicity. In this review, we described how genetic and epigenetic modifications can be important determinants for the development of toxicity in patients treated with CDDP, and how these alterations may be interesting biomarkers for monitoring toxicity induced by CDDP. Considering the validation in different studies, we suggest that miR-34a, -146b, -378a, -192, and -193 represent an attractive study group to evaluate potential biomarkers to detect CDDP-related nephrotoxicity.

Predictors of cisplatin-induced ototoxicity and survival in chemoradiation treated head and neck cancer patients

OBJECTIVES

Cisplatin-induced ototoxicity is a common permanent consequence of curative chemoradiation for locally advanced head and neck squamous cell carcinoma (HNSCC). Predictors of ototoxicity in HNSCC were examined.

MATERIALS AND METHODS

In this prospective, observational cohort study, 206 adult HNSCC patients underwent audiometric testing at baseline, during and after treatment with cisplatin-based chemoradiation. Ototoxicity was defined as ≥grade 2 audiometric change from baseline (CTCAE v4.02). Relationships between clinical and pharmacogenetic (TPMT, COMT, ACYP2, CTR1, OCT2, MATE1, ABCC2, ABCC3, and ABCG2) covariates and ototoxicity, progression-free (PFS) and overall survival (OS) were assessed by Cox regression.

RESULTS

Weekly cisplatin resulted in lower ototoxicity risk while PFS and OS were similar compared to high dose cisplatin (P = 0.00035; HR = 0.18; 95% CI, 0.07-0.46). COMT (rs9332377) carriers had higher ototoxicity risk (P = 0.00556; HR = 1.72; 95% CI, 1.17-2.52) while MATE1 (rs2289669) A/A carriers were protected from ototoxicity (P = 0.01062; HR = 0.46; 95% CI, 0.26-0.84). Absence of the protective MATE1 allele among those who carry the risk allele in COMT predicted increased ototoxicity risk, (P = 0.00414; HR = 3.22; 95% CI, 1.45-7.17 and P = 0.00022; HR = 4.89; 95% CI, 2.11-11.36). Survival outcomes did not differ between carriers of protective or risk alleles.

CONCLUSIONS

Weekly cisplatin dosing, COMT and MATE1 are predictors of ototoxicity without affecting treatment efficacy. COMT and MATE1 genotyping and weekly dosing may be a potential strategy for mitigating cisplatin-induced ototoxicity in HNSCC.

Ototoxicity in locally advanced head and neck cancer patients treated with induction chemotherapy followed by intermediate or high-dose cisplatin-based chemoradiotherapy

BACKGROUND

This study evaluated ototoxicity in locally advanced head and neck cancer patients treated in the CONDOR study with docetaxel/cisplatin/5-fluorouracil (TPF) followed by conventional radiotherapy with concomitant cisplatin 100 mg/m² on days 1, 22, and 43 (cis100+RT) versus accelerated radiotherapy with concomitant cisplatin weekly 40 mg/m² (cis40+ART).

METHODS

Sixty-two patients were treated in this study. Audiometry was performed at baseline, during TPF, before start of chemoradiotherapy, and 1, 4, 8, and 12 months after treatment.

RESULTS

A complete dataset of audiometric data was available of 12 patients treated with high-dose cisplatin and of 11 patients treated with intermediate-dose cisplatin. Patients in the high-dose group showed significant more hearing loss than in the intermediate group at 4 kHz ([z = 1.98; P = .04] and 8 kHz [z = 2.07; P < .03]). Interindividual variation was high in both groups.

CONCLUSION

After induction TPF, more ototoxicity was observed in chemoradiotherapy with cis100+RT than after chemoradiotherapy with cis40+ART.

Contribution of the GSTP1 c.313A>G variant to hearing loss risk in patients exposed to platin chemotherapy during childhood

BACKGROUND AND AIM

Ototoxicity is a potential adverse effect of chemotherapy with platin drugs, such as cisplatin and carboplatin, in children. Hearing loss (HL) affecting frequencies below 4 kHz can compromise speech perception. The aim of this study was to investigate whether genetic variants previously implicated in ototoxicity are associated with HL overall and HL below 4 kHz in pediatric oncology patients treated with cisplatin or carboplatin.

MATERIALS AND METHODS

Patients given cisplatin or carboplatin for a pediatric cancer at least 5 years prior to the start of the study were enrolled. The patients underwent comprehensive audiological evaluations and genotyping to detect the presence of the GJB2 c.35delG, GSTP1 c.313A>G, and MT-RNR1 m.1555A>G polymorphisms.

RESULTS

HL was identified in 31/61 patients (50.8%), including 28/42 treated with cisplatin (66.6%) and 3/19 treated with carboplatin (15.8%). HL was associated with higher mean doses of cisplatin (p = .002) and carboplatin (p = .010). The c.313A>G variant of GSTP1 (heterozygous or homozygous) was detected in 31/61 patients (50.8%). An association between this variant allele and HL involving frequencies ≤ 4 kHz was identified (p = .020; 10-fold vs. non-carriers). No associations with HL were observed for GJB2 or MT-RNR1 gene variants.

CONCLUSION

The GSTP1 c.313A>G variant may increase the risk of low-frequency HL in pediatric oncology patients treated with cisplatin or carboplatin chemotherapy.

Genetic and Modifiable Risk Factors Contributing to Cisplatin-induced Toxicities

Effective administration of traditional cytotoxic chemotherapy is often limited by off-target toxicities. This clinical dilemma is epitomized by cisplatin, a platinating agent, which has potent antineoplastic activity due to its affinity for DNA and other intracellular nucleophiles. Despite its efficacy against many adult-onset and pediatric malignancies, cisplatin elicits multiple off-target toxicities that can not only severely impact a patient's quality of life but also lead to dose reductions or the selection of alternative therapies that can ultimately affect outcomes. Without an effective therapeutic measure by which to successfully mitigate many of these symptoms, there have been attempts to identify a priori those individuals who are more susceptible to developing these sequelae through studies of genetic and nongenetic risk factors. Older age is associated with cisplatin-induced ototoxicity, neurotoxicity, and nephrotoxicity. Traditional genome-wide association studies have identified single-nucleotide polymorphisms in ACYP2 and WFS1 associated with cisplatin-induced hearing loss. However, validating associations between specific genotypes and cisplatin-induced toxicities with enough stringency to warrant clinical application remains challenging. This review summarizes the current state of knowledge with regard to specific adverse sequelae following cisplatin-based therapy, with a focus on ototoxicity, neurotoxicity, nephrotoxicity, myelosuppression, and nausea/emesis. We discuss variables (genetic and nongenetic) contributing to these detrimental toxicities and currently available means to prevent or treat their occurrence.

Toward Cochlear Therapies

Sensorineural hearing impairment is the most common sensory disorder and a major health and socio-economic issue in industrialized countries. It is primarily due to the degeneration of mechanosensory hair cells and spiral ganglion neurons in the cochlea via complex pathophysiological mechanisms. These occur following acute and/or chronic exposure to harmful extrinsic (e.g., ototoxic drugs, noise...) and intrinsic (e.g., aging, genetic) causative factors. No clinical therapies currently exist to rescue the dying sensorineural cells or regenerate these cells once lost. Recent studies have, however, provided renewed hope, with insights into the therapeutic targets allowing the prevention and treatment of ototoxic drug- and noise-induced, age-related hearing loss as well as cochlear cell degeneration. Moreover, genetic routes involving the replacement or corrective editing of mutant sequences or defected genes are showing promise, as are cell-replacement therapies to repair damaged cells for the future restoration of hearing in deaf people. This review begins by recapitulating our current understanding of the molecular pathways that underlie cochlear sensorineural damage, as well as the survival signaling pathways that can provide endogenous protection and tissue rescue. It then guides the reader through to the recent discoveries in pharmacological, gene and cell therapy research towards hearing protection and restoration as well as their potential clinical application.

Vestibulotoxicity Associated With Platinum-Based Chemotherapy in Survivors of Cancer: A Scoping Review

Background: Cochleotoxicity following the treatment with platinum-based chemotherapy is well documented. The potential for vestibulotoxicity is still unclear. This scoping review examined the extent of current research literature, summarized research findings and identified research gaps regarding vestibular-related adverse effects associated with platinum-based chemotherapy in survivors of cancer.

Methods: Inclusion criteria followed the PICO principles: Participants, adult, and pediatric cancer patients of any cancer type; Intervention, platinum-based chemotherapy (such as cisplatin, carboplatin, and oxaliplatin); Control, none or any; Outcomes, vestibular-related adverse effects. English language articles published since 1978 were retrieved. Seventy-five eligible studies were identified from a systematic literature search, and relevant data were charted, collated, and summarized.

Results: Testing for vestibulotoxicity predominately featured functional evaluation of the horizontal semicircular canal using the caloric and rotational tests. The rate of abnormal vestibular function test results after chemotherapy administration varied from 0 to 50%. The results of objective testing did not always correspond to patient symptoms. There is tentative support for patients with pre-existing loss of vestibular function to be more likely to experience vestibular toxicity after dosing with cisplatin.

Conclusions: A number of studies reported significant evidence of vestibular toxicities associated with platinum-based chemotherapy, especially cisplatin. This scoping review emphasizes that vestibular toxicity needs more attention and comprehensive evaluation. Specifically, studies that analyse cumulative dose of platinum-based chemotherapy, affected sites of lesion in vestibular end organs, and the correlation and temporal patterns of cochlear and vestibular toxicity are needed.

The curcuminoid, EF-24, reduces cisplatin-mediated reactive oxygen species in zebrafish inner ear auditory and vestibular tissues

Cisplatin is a widely used chemotherapy drug that can damage auditory and vestibular tissue and cause hearing and balance loss through the intracellular release of reactive oxygen species (ROS). Curcumin has anticancer efficacy and can also counteract cisplatin's damaging effect against sensory tissue by scavenging intracellular ROS, but curcumin's applicability is limited due to its low bioavailability. EF-24 is a synthetic curcumin analog that is more bioavailable than curcumin and can target cancer, but its effects against cisplatin-mediated ROS in auditory and vestibular tissue is currently unknown. In this study, we employed a novel zebrafish inner ear tissue culture system to determine if EF-24 counteracted cisplatin-mediated ROS release in two sensory endorgans, the saccule and the utricle. The zebrafish saccule is associated with auditory function and the utricle with vestibular function. Trimmed endorgans were placed in tissue culture media with a fluorescent reactive oxygen species indicator dye, and intracellular ROS release was measured using a spectrophotometer. We found that cisplatin treatment significantly increased ROS compared to controls, but that EF-24 treatment did not alter or even decreased ROS. Importantly, when equimolar cisplatin and EF-24 treatments are combined, ROS did not increase compared to controls. This suggests that EF-24 may be able to prevent intracellular ROS caused by cisplatin treatment in inner ear tissue.

Applying U.S. national guidelines for ototoxicity monitoring in adult patients: perspectives on patient populations, service gaps, barriers and solutions

OBJECTIVES

To promote establishment of effective ototoxicity monitoring programs (OMPs), this report reviews the U.S. national audiology guidelines in relation to "real world" OMP application. Background is provided on the mechanisms, risks and clinical presentation of hearing loss associated with major classes of ototoxic medications.

DESIGN

This is a non-systematic review using PubMed, national and international agency websites, personal communications between ototoxicity experts, and results of unpublished research. Examples are provided of OMPs in various healthcare settings within the U.S. civilian sector, Department of Defense (DoD), and Department of Veterans Affairs (VA).

STUDY SAMPLE

The five OMPs compared in this report represent a convenience sample of the programs with which the authors are affiliated. Their opinions were elicited via two semi-structured teleconferences on barriers and facilitators of OMP, followed by a self-administered questionnaire on OMP characteristics and practices, with responses synthesized herein. Preliminary results are provided from an ongoing VA clinical trial at one of these OMP sites. Participants were 40 VA patients who received cisplatin chemotherapy in 2014-2017. The study arms contrast access to care for OMP delivered on the treatment unit versus usual care as provided in the audiology clinic.

RESULTS

Protocols of the OMPs examined varied, reflecting their diverse settings. Service delivery concerns included baseline tests missed or completed after the initial treatment, and monitoring tests done infrequently or only after cessation of treatment. Perceived barriers involved logistics related to accessing and testing patients, such as a lack of processes to help patients enter programs, patients' time and scheduling constraints, and inconvenient audiology clinic locations. Use of abbreviated or screening methods facilitated monitoring.

CONCLUSIONS

The most effective OMPs integrated audiological management into care pathways of the clinical specialties that prescribe ototoxic medications. More OMP guidance is needed to inform evaluation schedules, outcome reporting, and determination of actionable ototoxic changes. Guidance is also lacking on the use of hearing conservation approaches suitable for the mass testing needed to support large-scale OMP efforts. Guideline adherence might improve with formal endorsement from organizations governing the medical specialty stakeholders in OMP such as oncologists, pulmonologists, infectious disease specialists, ototolaryngologists and pharmacists.

Time course and clinical characterization of cisplatin-induced ototoxicity after treatment for nasopharyngeal carcinoma in a South East Asian population

BACKGROUND

The purpose of this study was to characterize the clinical course of hearing loss in patients with nasopharyngeal carcinoma (NPC) and the clinical factors affecting its severity.

METHODS

The time course of hearing loss in patients with NPC was assessed using threshold shift from baseline and Common Terminology Criteria for Adverse Events (CTCAE) grade.

RESULTS

In the chemoradiotherapy (CRT) groups, the threshold shift was significantly higher from 3 months at 4 kHz (P = 2.30 × 10^-9 , concurrent CRT only) but not within 2 years posttreatment in the radiotherapy (RT) group. The CRT groups had worse CTCAE grades than the RT group (percentage of latest CTCAE grade ≥1: 64.9% vs 29.0%, respectively). Cumulative cisplatin dose and cochlear RT dose significantly affects threshold shifts, especially at high frequencies.

CONCLUSION

Although cisplatin led to high frequency hearing impairment from about 3 months posttreatment, RT conferred no significant hearing impairment in the first 2 years.

Pharmacogenetic variants in TPMT alter cellular responses to cisplatin in inner ear cell lines

Cisplatin is a highly-effective and widely-used chemotherapeutic agent that causes ototoxicity in many patients. Pharmacogenomic studies of key genes controlling drug biotransformation identified variants in thiopurine methyltransferase (TPMT) as predictors of cisplatin-induced ototoxicity, although the mechanistic basis of this interaction has not been reported. Expression constructs of TPMT*3A, *3B and *3C variants were generated and monitored in cultured cells. Cellular TPMT*3A levels were detected at >20-fold lower amounts than the wild type confirming the unstable nature of this variant. The expression of wild type TPMT (TPMT*1) in two murine ear cell lines, HEI-OC1 and UB/OC-1, significantly mitigated their susceptibility to cisplatin toxicity. Cisplatin treatment induced Tlr4 gene expression in HEI-OC1 cells and this response was blunted by the expression of wild type TPMT but not TPMT*3A. In line with the significant mitigation of TPMT*1-expressing cells to cisplatin cytotoxicity, these findings demonstrate a drug-gene interaction between increased TPMT activity and decreased susceptibility to cisplatin-induced toxicity of inner ear cells.

Analysis of Cisplatin-Induced Ototoxicity Risk Factors in Iranian Patients with Solid Tumors: a Cohort, Prospective and Single Institute Study

Background: Cisplatin has been associated with irreversible hearing damage. Up to now, there is no therapeutic intervention showing benefit in preventing Cisplatin-induced ototoxicity. The aim of this study was to determine risk factors contributing to hearing impairment after cisplatin administration in Iranian patients. Methods: Hearing thresholds of 124 patients before and after cisplatin administration were assessed with reference to pure-tone audiometry averages at several frequencies from 2006 to 2010. Mean values were calculated at each tested frequency in each ear at baseline and subsequent follow-up audiometry. Hearing impairment was assessed with the Münster score. Results: The mean age at diagnosis and the median cumulative Cisplatin dose were 47.3 years and 453.8 milligrams, respectively. Bilateral hearing loss, mostly of grade 1, and tinnitus were detected in 26% and 3.2% of patients. Logistic regression analysis showed that a high cumulative dose of cisplatin was the most important risk factor for developing hearing damage (P=0.034). The most significant changes in the status of the auditory system and the most severe threshold shift from base line (35 dB) were observed at a frequency of 8 kHz. Also, patients who received higher individual doses of Cisplatin showed significantly more tinnitus (P=0.002). Conclusions: The results are testament to benefits of routine audiometric monitoring program during cisplatin-based chemotherapy. Further research should be performed to understand other risk factors, such as genetic predictors of Cisplatin-induced ototoxicity.

Long-term ototoxicity in women after cisplatin treatment for ovarian germ cell cancer

OBJECTIVE

Evaluate long-term cisplatin-induced ototoxicity in women treated for malignant ovarian germ cell tumors (MOGCT).

METHODS

Seventy-four women treated for MOGCT in Norway (1980-2009) were analyzed: 41 had received cisplatin-based chemotherapy (CBCT) ("Cases") and 33 had no CBCT ("Controls"). Median follow-up was 15years. Hearing was assessed by pure tone audiometry and by the SCIN questionnaire. Air conduction thresholds were reported as absolute hearing thresholds and age-adjusted thresholds. Absolute and age-adjusted hearing loss were defined as thresholds of >20dB at any frequency. Tinnitus was evaluated using the Tinnitus Handicap Inventory. Serum Platinum Concentration (SPC) was determined.

RESULTS

Absolute hearing loss was identified in 21 Cases (51%) and 24 Controls (73%). After adjusting for age, only 9 Cases (22%) and 5 Controls (15%) remained. Age-adjusted hearing thresholds at 4, 6 and 8kHz were slightly but significantly higher in Cases compared to Controls. Subjective hearing loss was reported by 27% of Cases and 21% of Controls, who were significantly older. Elevated SPC values were detected up to 20years after CBCT, but SPC did not correlate significantly with age-adjusted hearing loss. The rate of tinnitus was similar in Cases and Controls.

CONCLUSION

Long-term MOGCT survivors treated with CBCT have small but significant reductions in age-adjusted hearing thresholds at 4, 6 and 8kHz versus Controls. Approximately one in four women experienced subjective hearing loss. To avoid overestimation of clinically relevant cisplatin-induced ototoxicity, absolute hearing thresholds should be age-adjusted and compared to an age-matched control group.

Cisplatin-Associated Ototoxicity: A Review for the Health Professional

Cisplatin is an effective drug used in the treatment of many cancers, yet its ototoxic potential places cancer patients, exposed to this drug, at risk of hearing loss, thus negatively impacting further on a patient's quality of life. It is paramount for health care practitioners managing such patients to be aware of cisplatin's ototoxic properties and the clinical signs to identify patients at risk of developing hearing loss. English peer-reviewed articles from January 1975 to July 2015 were assessed from PubMed, Science Direct, and Ebscohost. Seventy-nine articles and two books were identified for this review, using MeSH terms and keywords such as "ototoxicity", "cisplatin", "hearing loss", and "ototoxicity monitoring". This review provides an up-to-date overview of cisplatin-associated ototoxicity, namely, its clinical features, incidence rates, and molecular and cellular mechanisms and risk factors, to health care practitioners managing the patient with cancer, and highlights the need for a team-based approach to complement an audiological monitoring programme to mitigate any further loss in the quality of life of affected patients, as there is currently no otoprotective agent recommended routinely for the prevention of cisplatin-associated ototoxicity. It also sets the platform for effective dialogue towards policy formulation and strengthening of health systems in developing countries.

Effect of Ecklonia Cava Polyphenol Extract in House Ear Institute-Organ of Corti 1 Cells Against Cisplatin Ototoxicity: A Preliminary Study

Objective

Cisplatin is a widely used agent for the treatment of adult and childhood malignancies. Side effects such as nephrotoxicity, neurotoxicity, and ototoxicity lead to dose limitations. Ecklonia cava polyphenol extract (ECP) is a molecule obtained from algae that live in seawater in the Far East. ECP has recently been shown to have protective effects against oxidative stress. The aim of this study was to evaluate the possible protective effects of ECP on cisplatin ototoxicity.

Methods

In this study, we investigated the protective effects of ECP against cisplatin-induced cell death in mouse-derived House Ear Institute Organ of Corti (HEI-OC1) cochlear cells. Cisplatin (100 μM) and 1, 10, and 25 μM doses of ECP were administered to the cells, and the protective effects of ECP at 24 and 72 hours were investigated. Cell viability was evaluated by the WST-1 (water soluble tetrazolium salt).

Results

Cisplatin (100 μM) reduced cell viability in both the 24^th and 72^nd hour evaluation. Although the 25 μM dose of ECP showed otoprotective effects in the 24^th hour, in the 72^nd hour this effect disappeared. Other doses of ECP showed no otoprotective effects in the 24^th and 72^nd hours.

Conclusion

Although ECP showed some protective effects in the 24^th hour against cisplatin ototoxicity, these effects disappeared by the 72^nd hour. Further studies using recurrent and higher doses of ECP are required.

Analysis of genetic and non genetic risk factors for cisplatin ototoxicity in pediatric patients

OBJECTIVE

The aim of this study was to analyse the genetic and non genetic risk factors for cisplatin ototoxicity.

METHODS

This study was conducted on 72 children who received cisplatin based chemotherapy. Brock and Muenster classifications were used to evaluate ototoxicity seen in these children. 6 single nucleotide polymorphisms (SNP); ERCC1 rs 11615, GSTP1 rs1138272, GSTP1 rs1695, LRP2 rs 2075252, TPMT rs 12201199, COMT rs 9332377, were evaluated as genetic factors by real time PCR. Non genetic factors such as cranial irradiation, cumulative doses of cisplatin, age, gender, administration of other ototoxic drugs were analysed as well. By using Chi-square test, risk factors were matched with the ototoxicity classifications. Significant risk factors were reevaluated using logistic regression modelling.

RESULTS

According to univariate analyses, male gender, co-treatment with aminoglycosides and mutant genotype of GSTP1 rs1695 were significantly related with cisplatin ototoxicity. Logistic regression modelling analyses also showed that male gender, co-treatment with aminoglycosides were found to be significantly related with cisplatin ototoxicity. Mutant genotype of GSTP1 rs1695 was not found to be significant, but close to the level of statistical significance.

CONCLUSION

Male gender, co-treatment with aminoglycosides are significant risk factors for cisplatin ototoxicity in pediatric patients. Mutant genotype of GSTP1 rs1695 seems to be a genetic risk factor in univariate analyses, although not confirmed by multivariate analyses. Therefore, GSTP1 rs1695 SNP needs to be studied in larger series.

Low, but Not High, Doses of Cisplatin Damage Cochlear Hair Cells in C57 Mouse Organotypic Cultures

AIMS

The purpose of this study was to investigate the characteristics of cisplatin-induced C57 mouse cochlear hair cell damage in vitro.

METHODS

Forty-seven cochleae harvested from 2- to 4-day-old C57 mice were used. Forty specimens were treated with different concentrations of cisplatin (10, 25, 50, 100, 400, and 1,000 μmol/l) for 48 h. The remaining seven specimens were used as a control group.

RESULTS

The rate of hair cell loss increased from 14.5 to 78.4% over cisplatin concentrations of 10 to 100 μmol/l, whereas hair cell loss decreased to 48.8 and 8.77% at concentrations of 400 and 1,000 μmol/l, respectively. Apoptosis was detected by DAPI staining in the areas of hair cell damage. Hair cell loss rates differed significantly among the cisplatin-treated groups. Linear regression analysis of cisplatin dose versus hair cell number showed a significant negative correlation for cisplatin doses up to 100 μmol/l and a positive correlation with further increases up to 1,000 μmol/l.

CONCLUSIONS

We conclude that cisplatin-induced hair cell damage was concentration dependent only up to a certain dose and that injury resistance may occur in cochlear cells treated with higher doses of cisplatin.

Evaluation of the protective effects of hesperetin against cisplatin-induced ototoxicity in a rat animal model

OBJECTIVES

We aimed to investigate the effects of hesperetin as a flavanon both histopathologically and immunohistochemically on cochlear apoptosis in a rat model of cisplatin-induced ototoxicity (CIO). The evaluation of the effects of hesperetin on cisplatin-induced hearing loss was performed using distortion product otoacoustic emission (DPOAE).

METHODS

Twenty-eight wistar albino rats were used in the current study. The rats were randomly divided into four groups with seven rats in each group. Group C was exposed to a single dose of cisplatin (12mg/kg) by intraperitoneal injection. Group CH received intraperitoneally cisplatin (12mg/kg) and hesperetin (20mg/kg). Group H was exposed to hesperetin (20mg/kg) intraperitoneally. The sham group (group S) received normal saline (6cc) intraperitoneally. The measurements of DPOAE and signal-noise ratios (SNR) were performed before the treatment and again on the first and 6 days after administration of the drugs. Rats were sacrificed and cochleae were dissected 10 days after drug administration. The cochlear tissue was assessed in all groups by histopathologic, immunohistochemical and TUNEL assay. In addition, serum oxidative stress markers and antioxidant parameters were analyzed.

RESULTS

There was a significant difference between the basal value and the sixth day at frequencies 8.4, 9.6 and 9.96 for group C. We also found a significant difference between the first and sixth day at frequencies 7.2, 8.4, 9.6 and 9.96. On the 6th day, there were significant differences between C and S groups at all frequencies except 2.4. We showed a significant difference between C and H groups at frequencies 4.8, 6.0, 8.4, 9.6 and 9.96. There was also a significant difference between C and CH groups at frequencies 2.4, and 3.6. We found lower levels of oxidants and higher levels of antioxidants in CH group as compared to C group. C group had a significantly greater number of TUNEL-positive cells than did S, H and CH groups. The number of TUNEL-positive cells in CH group was higher than in S and H groups. There was a significant difference between the positive PCNA cells of CH group compared to S and H groups in spiral ganglion and stria vascularis. In addition, there were no positive PCNA cells in C group.

CONCLUSIONS

Hesperetin may prevent ototoxicity by increased antioxidant enzymes and reduced oxidant parameters and protected against apoptosis resulting from a proliferation of cochlear cells in CIO.

Noncarboplatin-induced Sensorineural Hearing Loss in a Patient With an Intracranial Nongerminomatous Germ Cell Tumor

Treatment for intracranial germ cell tumors includes platinum-based chemotherapy and external beam radiation therapy, which are risk factors for hearing loss. In patients who experience significant sensorineural ototoxicity due to cochlear hair cell injury, dose reduction of chemotherapy may be necessary. This report describes an adolescent male, with excellent treatment response for an intracranial nongerminomatous germ cell tumor, who developed sensorineural hearing loss, which was central rather than cochlear in origin and unrelated to carboplatin. This patient highlights the need to carefully differentiate the type and etiology of sensorineural hearing loss in patients with brain tumors receiving ototoxic chemotherapy.

Long-term audiologic follow-up of carboplatin-treated children with retinoblastoma

BACKGROUND

Children treated for retinoblastoma with carboplatin have an increased risk for ototoxicity. Impaired hearing may have major consequences for these children, because they often suffer from reduced vision. Previous studies have shown limited information on the incidence and severity of carboplatin-induced ototoxicity and the used audiologic methods. The frequency of audiological testing is often limited and the audiologic follow-up time is relatively short.

OBJECTIVE

The aim of this study was to determine the long-term effects of carboplatin ototoxicity in children with retinoblastoma.

MATERIALS AND METHODS

In this retrospective non-randomized single center cohort study, we reviewed audiologic results of 25 patients. Experienced audiologists analyzed the pure-tone audiograms.

RESULTS

All patients had normal hearing prior to therapy and had a mean age of 11 months at first carboplatin administration. The mean audiologic follow-up was 12.0 years with a median of 11.6 (IQR 4.8) years. Three patients were excluded: two passed away and one could not participate in the audiologic tests. One of the 22 included patients developed sustained low-grade bilateral high-frequency hearing loss between 2 and 7 years after the last carboplatin dose. In one patient it was not possible to make a reliable conclusion due to a conductive hearing loss component. Twenty patients had normal hearing.

CONCLUSIONS

We observed no clear effect between carboplatin administration in young children and clinical significant ototoxicity in the long term. One child showed low-grade bilateral high-frequency hearing loss.