ACOU085 shows promise for cisplatin-induced hearing loss in patients with testicular cancer

Topline results from the phase 2a PROHEAR study (NCT06521190) suggest that ACOU085 (bimokalner), an investigational Kv7.4 potassium channel activator, may help mitigate cisplatin-induced sensorineural hearing loss in patients receiving chemotherapy for testicular cancer.¹

According to Acousia Therapeutics, patients who developed ototoxicity during

cisplatin treatment experienced less worsening of pure-tone audiometry (PTA) thresholds in ears treated with transtympanic ACOU085 compared with placebo-treated ears.

"This is an important and encouraging milestone toward establishing Kv7.4 activation as a novel therapeutic approach for multiple forms of hearing loss,” said Professor Hubert Löwenheim, Chair of Otorhinolaryngology – Head & Neck Surgery at Tübingen University Medical Center and scientific supervisor of the PROHEAR study, in a news release on the results.¹ “This broad therapeutic potential addresses a significant unmet medical need, which current device-based solutions only partially meet. The clinical results for ACOU085 create a compelling opportunity to advance Kv7.4 modulation into broader patient populations.”

About the PROHEAR study

The PROHEAR trial was a randomized, placebo-controlled, split-body study that enrolled young men (aged 18 to 45 years) with testicular cancer who were scheduled to receive cisplatin-based chemotherapy and were at risk of cisplatin-induced sensorineural hearing loss.

In the study, patients received a 6 mg transtympanic dose of ACOU085 in 1 ear and placebo in the contralateral ear, allowing for within-patient comparisons.² The primary end point assessed the proportion of patients demonstrating a difference of at least 10 dB between ears at high and extended-high frequencies after completion of chemotherapy.

Investigators reported that more than 90% of participants developed ototoxicity in at least 1 ear after 3 cycles of cisplatin at a cumulative dose of 300 mg/m². Hearing loss primarily affected the extended high frequency range (10 to 16 kHz) and was generally mild to moderate in severity.

In those who developed ototoxicity, ACOU085 was associated with a clinically meaningful prevention of hearing-threshold deterioration measured by PTA at affected frequencies compared with placebo. Additional analyses are ongoing, and the full results are expected to be submitted for publication in a peer-reviewed journal.

About ACOU085

ACOU085 is a first-in-class small molecule formulated for transtympanic administration using a slow-release gel. The drug is designed to activate the Kv7.4 potassium channel, encoded by the KCNQ4 gene, which is highly expressed in cochlear outer hair cells and plays an important role in auditory function and potassium homeostasis. Preclinical studies have suggested that modulation of Kv7.4 may enhance outer hair cell resilience and reduce damage caused by ototoxic insults.

REFERENCES

1. Promising first-in-patient results for ACOU085 (INN: Bimokalner) in cisplatin-induced ototoxicity. Acousia Therapeutics GmbH. June 12, 2026. Accessed June 15, 2026. https://www.prnewswire.com/news-releases/promising-first-in-patient-results-for-acou085-inn-bimokalner-in-cisplatin-induced-ototoxicity-302798031.html

2. ACOU085 for hearing loss prevention in testicular cancer patients receiving cisplatin (PROHEAR). ClinicalTrials.gov. Last updated September 19, 2024. Accessed June 15, 2026. https://clinicaltrials.gov/study/NCT06521190