Trial progresses of ACOU085 for cisplatin-induced ototoxicity in testicular cancer

The target enrollment has been met in the phase 2 PROHEAR trial (NCT06521190), assessing the safety and efficacy of ACOU085 (Bimokalner) in preventing ototoxic hearing loss induced by cisplatin-based chemotherapy in patients with metastatic testicular cancer.¹

According to Acousia Therapeutics, ACOU085 is a “first-in-class, etiology-agnostic otoprotective small molecule delivered via standard transtympanic administration in a proprietary slow-release gel formulation.” In preclinical models, the agent has demonstrated potential to reduce cisplatin-induced ototoxicity by preserving the integrity of the cochlea’s outer hair cells (OHCs), which, when irreversibly damaged, can cause permanent hearing loss. The company noted that this can occur in patients who receive cumulative doses of 300 mg/m² or greater of cisplatin.

"Today marks an important development milestone for Bimokalner," said Tim Boelke, MD, CEO and CMO of Acousia Therapeutics, in the news release from the company.¹ "This drug candidate has the potential to prevent the permanent inner ear damage frequently observed following cisplatin-based chemotherapy. As we reach full enrollment in the PROHEAR study, I want to express gratitude to all participating patients and clinical teams for their trust and commitment.”

PROHEAR is a double-blind, split-body trial that enrolled young (18 to 45 years), male patients with metastatic testicular cancer who are scheduled to receive cisplatin-based chemotherapy.² The trial recruited participants across 15 university hospitals in Germany.

Patients in the trial are randomly assigned to receive either ACOU085 or placebo administered prior to each cisplatin cycle. Patients will undergo several audiometric tests at baseline and at the completion of each cisplatin cycle to compare functional hearing metrics.

The primary end point is the proportion of patients who show a difference of at least 10 dB between the ears in at least 2 frequencies for air conduction in pure tone average (PTA) at high (4, 6, 8 kHz) and extended high frequencies (10, 12, 14, 16 kHz) between baseline and the end of chemotherapeutic cycle 3. Secondary end points include intraindividual differences in distortion product otoacoustic emissions, PTA bone, the Oldenburger Test, and the Freiburger Test.

In addition to providing a proof of principle for ACOU085, the PROHEAR trial is intended to provide translational target validation for Acousia Therapeutics' Kv7.4 activator programs. According to the company, ACOU085 modulates the biologically validated KCNQ4-encoded Kv7.4 potassium channel expressed in OHCs.

Overall, Boelke concluded in the news release, “The blinded preliminary results are promising, and we look forward to reviewing the full unblinded dataset in Q2–Q3 2026.”

REFERENCES

1. Acousia announces completion of patient enrollment in phase 2 PROHEAR study evaluating ACOU085 (INN: Bimokalner) for the prevention of cisplatin-induced ototoxicity. News release. Acousia Therapeutics GmbH. January 8, 2026. Accessed January 8, 2026. https://www.acousia.com/completion-of-patient-enrollment-phase-2-prohear-study-evaluating-acou085-for-prevention-of-cisplatin-induced-ototoxicity/

2. ACOU085 for hearing loss prevention in testicular cancer patients receiving cisplatin (PROHEAR). ClinicalTrials.gov. Last updated September 19, 2024. Accessed January 8, 2026. https://clinicaltrials.gov/study/NCT06521190