Acousia Therapeutics GmbH, a clinical-stage biotechnology company developing treatments for acute and chronic inner ear hearing loss, announced on Friday positive top-line efficacy results from its completed Phase 2a PROHEAR Study.

ACOU085 (bimokalner) is a proprietary, first-in-class small molecule that has demonstrated robust and reproducible efficacy across multiple preclinical hearing loss models, including drug-induced ototoxicity, Acousia said.

The exploratory, placebo-controlled, split-body Phase 2a PROHEAR Study assessed the otoprotective efficacy of a 6 mg transtympanic dose of ACOU085 compared to placebo in testicular cancer patients at risk of cisplatin-induced sensorineural hearing loss.

According to the company, among the young, hearing-healthy participants, more than 90% developed ototoxicity in at least one ear, as defined by ASHA criteria, after three cisplatin cycles (300 mg/m2). The hearing loss primarily affected the extended high-frequency range (10–16 kHz), with mild to moderate 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. Further analysis of the PROHEAR Study results, including post-hoc evaluations, is ongoing and will be submitted for publication in a peer-reviewed journal.

ACOU085 is an etiology-agnostic otoprotective agent, administered via a standard transtympanic injection using a proprietary slow-release gel formulation.

Cisplatin-induced hearing loss is a severe, permanent side effect caused by irreversible damage to the cochlea's outer hair cells (OHCs). Acousia says that by modulating the biologically validated Kv7.4 potassium channel target (encoded by KCNQ4) in OHCs, ACOU085 has demonstrated significant potential to reduce cisplatin-induced hearing loss and preserve OHC integrity in preclinical studies.