Intravenous N-Acetylcysteine to Prevent Cisplatin-Induced Hearing Loss in Children: A Nonrandomized Controlled Phase I Trial

PURPOSE

Cisplatin-induced hearing loss (CIHL) is common and permanent. As compared with earlier otoprotectants, we hypothesized N-acetylcysteine (NAC) offers potential for stronger otoprotection through stimulation of glutathione (GSH) production. This study tested the optimal dose, safety, and efficacy of NAC to prevent CIHL.

PATIENTS AND METHODS

In this nonrandomized, controlled phase Ia/Ib trial, children and adolescents newly diagnosed with nonmetastatic, cisplatin-treated tumors received NAC intravenously 4 hours post-cisplatin. The trial performed dose-escalation across three dose levels to establish a safe dose that exceeded the targeted peak serum NAC concentration of 1.5 mmol/L (as identified from preclinical models). Patients with metastatic disease or who were otherwise ineligible were enrolled in an observation-only/control arm. To evaluate efficacy, serial age-appropriate audiology assessments were performed. Integrated biology examined genes involved in GSH metabolism and post-NAC GSH concentrations.

RESULTS

Of 52 patients enrolled, 24 received NAC and 28 were in the control arm. The maximum tolerated dose was not reached; analysis of peak NAC concentration identified 450 mg/kg as the recommended phase II dose (RP2D). Infusion-related reactions were common. No severe adverse events occurred. Compared with the control arm, NAC decreased likelihood of CIHL at the end of cisplatin therapy [OR, 0.13; 95% confidence interval (CI), 0.021-0.847; P = 0.033] and recommendations for hearing intervention at end of study (OR, 0.082; 95% CI, 0.011-0.60; P = 0.014). NAC increased GSH; GSTP1 influenced risk for CIHL and NAC otoprotection.

CONCLUSIONS

NAC was safe at the RP2D, with strong evidence for efficacy to prevent CIHL, warranting further development as a next-generation otoprotectant.

Prevalence and risk factors for cisplatin-induced hearing loss in children, adolescents, and young adults: a multi-institutional North American cohort study

BACKGROUND

Cisplatin is used to treat a wide range of childhood cancers and cisplatin-induced hearing loss (CIHL) is a common and debilitating toxicity. We aimed to address persistent knowledge gaps in CIHL by establishing benchmarks for the prevalence of and risk factors for CIHL.

METHODS

In this multi-institutional cohort study, children (age 0-14 years), adolescents, and young adults (age 15-39 years) diagnosed with a cisplatin-treated tumour from paediatric cancer centres, who had available cisplatin dosing information, and primary audiology data for central review from consortia located in Canada and the USA were eligible for inclusion. Audiology was centrally reviewed and CIHL graded using the consensus International Society of Pediatric Oncology (SIOP) Boston Ototoxicity Scale. We assessed the prevalence of moderate or severe CIHL (SIOP grade ≥2) at latest follow-up and end of therapy, in each demographic, diagnosis, and treatment group and their relative contributions to risk for CIHL. Secondary endpoints explored associations of cisplatin dose reductions and CIHL with survival. We also examined whether cisplatin dose reductions and CIHL were associated with survival outcomes.

FINDINGS

We included 1481 patients who received cisplatin. Of the 1414 (95·5%) participants who had audiometry at latest follow-up (mean 3·9 years [SD 4·2] since diagnosis), 620 (43·8%) patients developed moderate or severe CIHL. The highest prevalence of CIHL was seen in the youngest patients (aged <5 years; 360 [59·4%] of 606 patients) and those with a CNS tumour (221 [50·9%] of 434 patients), hepatoblastoma (110 [65·9%] of 167 patients), or neuroblastoma (154 [62·1%] of 248 patients). After accounting for cumulative cisplatin dose, higher fractionated doses were associated with risk for CIHL (for each 10mg/m2 increase per day, adjusted odds ratio [aOR] 1·15 [95% CI 1·07-1·25]; for each 50 mg/m2 increase per cycle aOR 2·16 [1·37-3·51]). Vincristine exposure was newly identified as a risk factor for CIHL (aOR 3·55 [2·19-5·84]). Dose reductions and moderate or severe CIHL were not significantly associated with survival differences.

INTERPRETATION

Using this large, multicentre cohort, benchmarks were established for the prevalence of CIHL in patients treated with cisplatin. Variations in cisplatin dosing confer additive risk for developing CIHL and warrant investigation as a potential approach to decrease the burden of therapy.

FUNDING

US National Institutes of Health and National Institute on Deafness and Other Communication Disorders, US National Institutes of Health and National Cancer institute, St Baldrick's Foundation, Genome Canada, Genome British Columbia, Canadian Institutes of Health Research, the Canada Foundation for Innovation, University of British Columbia, British Columbia Children's Hospital Research Institute, British Columbia Provincial Health Services Authority, Health Canada, and C17 Research Network.

Hearing Loss Risk in Pediatric Patients Treated with Cranial Irradiation and Cisplatin-Based Chemotherapy

PURPOSE

Cranial radiation therapy (RT) and cisplatin-based chemotherapy are essential to treating many pediatric cancers but cause significant ototoxicity. The objective of this study is to determine the relationship between the RT dose and the risk of subsequent hearing loss in pediatric patients treated with cisplatin.

METHODS AND MATERIALS

This retrospective study of cisplatin-treated pediatric patients examined ototoxicity from cranial RT. Ototoxicity was graded for each ear according to the International Society of Pediatric Oncology (SIOP) consensus ototoxicity scale. The RT dose to the cochlea was calculated using the mean, median, maximum, and minimum dose received to determine the most predictive parameter for hearing loss. Multivariable logistic regression models then examined risk factors for hearing loss.

RESULTS

In 96 children (161 ears) treated with RT + cisplatin, the minimum cochlear RT dose was most predictive of hearing loss. A higher cochlear RT dose was associated with increased hearing loss (odds ratio per 10 Gy dose increase = 1.64; P = .043), with an added risk in those receiving an autologous bone marrow transplantation (hazard ratio = 10.47; P < .001).

CONCLUSIONS

This research supports further testing of the minimum cochlear RT dose as a more predictive dose parameter for risk of ototoxicity. The cochlear RT dose was additive to the risk of hearing loss from underlying cisplatin-based chemotherapy. Exposure to autologous bone marrow transplantation was the strongest predictor of developing hearing loss, placing these children at particularly high risk for hearing loss across all cochlear doses. Future prospective studies are crucial to further inform RT dose thresholds and minimize the risk of hearing loss in childhood cancer survivors.