The ProHear Study found that the drug candidate Bimokalner produced a clinically meaningful reduction in pure-tone audiometry threshold shifts in testicular cancer patients who developed cisplatin-induced ototoxicity.
Acousia Therapeutics GmbH, a clinical-stage biotechnology company based in Tübingen, Germany, has announced positive top-line efficacy results from its completed Phase 2a ProHear Study, evaluating ACOU085 (Bimokalner) for the prevention of cisplatin-induced sensorineural hearing loss.
The exploratory, placebo-controlled, split-body trial assessed a 6 mg transtympanic dose of ACOU085 against placebo in testicular cancer patients considered at risk of cisplatin-induced ototoxicity. Among the young, hearing-healthy participants, more than 90% developed ototoxicity in at least one ear — as defined by ASHA criteria — following three cisplatin cycles at 300 mg/m². The hearing loss observed primarily affected the extended high-frequency range (10–16 kHz) and was characterized as mild to moderate in severity.
In patients who developed ototoxicity, treatment with ACOU085 resulted in a clinically meaningful prevention of pure-tone audiometry (PTA) threshold increases at affected frequencies compared to placebo following the final cisplatin cycle. Additional analysis, including post-hoc evaluations, is ongoing and will be submitted for publication in a peer-reviewed journal.
How ACOU085 Works
ACOU085 is a small molecule otoprotective agent administered via a standard transtympanic injection using a proprietary slow-release gel formulation. Cisplatin-induced hearing loss is a severe and permanent side effect driven by irreversible damage to the cochlea’s outer hair cells (OHCs). ACOU085 works by modulating the Kv7.4 potassium channel — encoded by KCNQ4 — in OHCs, a biologically validated target the company describes as etiology-agnostic, meaning it may have potential across multiple forms of hearing loss beyond cisplatin-induced damage.
“This is an important and encouraging milestone toward establishing Kv7.4 activation as a novel therapeutic approach for multiple forms of hearing loss. 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,” says Professor Hubert Löwenheim, chair of otorhinolaryngology — head and neck surgery at Tübingen University Medical Center and scientific supervisor of the ProHear Study, in a release.
Company Commentary
“Today represents an exciting advancement for cancer patients at risk of cisplatin-induced hearing loss,” says Tim Boelke, MD, CEO and CMO of Acousia Therapeutics GmbH, in a release. “Our novel drug candidate has the potential to prevent permanent inner ear damage commonly seen after cisplatin-based chemotherapy.”
The Acousia team is scheduled to attend the BIO International Convention in San Diego (June 22–25, 2026), where the company plans to discuss collaboration opportunities with strategic partners for the next phase of clinical development.
