Transtympanic sodium thiosulphate to prevent cisplatin-related hearing loss: a protocol for randomised controlled multicentre phase III trial, the SOUND trial

Introduction:

Cisplatin is a widely used chemotherapeutic anti-cancer drug. However, high-dose cisplatin is also known for its dose-limiting toxicities, including irreversible cisplatin-induced hearing loss (CIHL). Sodium thiosulphate (STS) can bind to cisplatin to form an inactive and harmless complex. A topical application is desired, allowing cisplatin to retain its systemic anti-cancer effect. 

Methods and analysis:

The SOUND trial is an investigator-initiated randomised controlled multicentre phase III trial to study the efficacy of transtympanic administration of STS against CIHL in a cohort of 100 patients with head and neck cancer treated with cisplatin at a dose of ≥200mg/m². Each subject will receive transtympanic STS injections in one ear, chosen by randomisation, before each cisplatin infusion. The contralateral ear serves as an internal control. The primary objective is efficacy (ie, clinically relevant benefit) of transtympanic STS injections against CIHL, defined as a difference in threshold shift of ≥10 decibels between baseline and 3 months after treatment in favour of the STS-treated ear. Secondary objectives include the difference in mean threshold shifts on frequencies essential for speech and extended high frequencies, as well as the difference between both ears in the gradation of hearing loss as defined by ototoxicity grading scales. 

Ethics and dissemination:

The medical ethics committee in the Netherlands approved the trial (Clinical Trials Information System (CTIS) 2023-503313-30-00). The results will be disseminated through the CTIS and peer-reviewed scientific journals. 

Trial registration number:

 CTIS 2023-503313-30-00 approved by Medical Research Ethics Committee NedMec.