Nyxoah has reported positive pivotal results from the U.S. ACCCESS study of its Genio hypoglossal nerve stimulation system in people with obstructive sleep apnea and complete concentric collapse of the soft palate. At 12 months, 77.2% of the full analysis population met the prespecified Apnea-Hypopnea Index responder definition, while 87.7% met the Oxygen Desaturation Index responder threshold. No device-related serious adverse events were reported through 12 months, and Nyxoah is preparing a premarket approval supplement seeking to expand the U.S. indication into this currently underserved patient group.
The result addresses an important anatomical limitation in the existing neurostimulation market. Patients with complete concentric collapse have traditionally been poor candidates for commercially available unilateral hypoglossal nerve stimulation in the United States because the pattern of airway closure differs from the collapse those devices were originally designed and validated to treat. Genio uses bilateral stimulation and already has European authorization covering CCC patients, while its current U.S. labeling includes the population within a warning because safety and effectiveness had not previously been established with dedicated U.S. clinical data.
What does a 77.2% AHI responder rate actually mean?
Apnea-Hypopnea Index measures how many episodes of complete or partial breathing interruption occur per hour of sleep. Under the Sher criteria used in ACCCESS, a responder needed at least a 50% reduction from baseline AHI and a final AHI below 20 events per hour at the 12-month polysomnography assessment.
A 77.2% responder rate therefore does not mean 77.2% of patients were completely cured of sleep apnea. It means more than three-quarters achieved a clinically defined reduction in breathing disturbances that met both relative and absolute thresholds. The p-value for this co-primary efficacy endpoint was below 0.001.
Oxygen Desaturation Index measures how frequently blood oxygen falls by a defined amount during sleep. An ODI responder in ACCCESS needed at least a 25% reduction from baseline, and 87.7% met that threshold at 12 months.
How large was the ACCCESS pivotal study?
The primary full analysis involved 47 patients who were implanted, activated and completed at least one in-study polysomnography assessment. Nyxoah had originally planned to enroll as many as 106 patients but stopped recruitment earlier after determining the enrolled population would be sufficient for the prespecified statistical analysis. Missing data were handled through a multiple-imputation method specified in the protocol and statistical analysis plan before the final analysis.
That relatively small sample size means the headline responder rates should be interpreted alongside the complete dataset, which Nyxoah plans to present at the International Surgical Sleep Society annual meeting in October. Regulators will also review adverse events, implantation performance, subgroup results and other information beyond the two headline percentages when considering the PMA supplement.
Why are patients with complete concentric collapse different?
During drug-induced sleep endoscopy, physicians can observe how the upper airway collapses while a patient is sedated. In complete concentric collapse, tissue at the level of the soft palate closes inward in a circular pattern rather than predominantly collapsing in one direction.
This matters for nerve stimulation because conventional unilateral systems stimulate one hypoglossal nerve to move the tongue and related airway structures. The anatomical response may be insufficient in some patients with CCC, which is why this collapse pattern has historically excluded patients from certain commercially available U.S. stimulation therapies.
Genio approaches stimulation bilaterally, activating both hypoglossal nerves through a leadless implanted stimulator that is powered by an external wearable component. Nyxoah believes this architecture can produce a broader opening of the airway and therefore remain effective in anatomies where unilateral systems are unsuitable.
How does Genio differ from other implanted sleep apnea devices?
Genio does not contain an implanted battery and does not rely on conventional leads extending from a pulse generator. The implanted component is powered and controlled through an external wearable activation system used during sleep, while stimulation is delivered bilaterally. The U.S.-approved platform is also designed to be compatible with full-body 1.5T and 3T MRI under specified conditions.
These differences create potential advantages around battery replacement and lead management, but they also create their own user requirements because patients must apply the external activation component before sleep. Long-term adoption will depend not only on efficacy but on implant procedure, comfort, adherence, durability and how patients compare the wearable-powered architecture with competing systems.
Is Genio already FDA approved?
Yes, but not yet specifically with established efficacy for the CCC population targeted by ACCCESS. The FDA approved Genio System 2.1 in August 2025 for a subset of adults with moderate-to-severe obstructive sleep apnea, including an AHI range of 15 to 65.
The current action is therefore an indication-expansion strategy rather than a request for first U.S. market entry. Nyxoah is preparing a PMA supplement under Breakthrough Device designation to add dedicated CCC evidence to the U.S. indication. European use in CCC patients has been permitted since 2021.
Why could this matter commercially?
Obstructive sleep apnea affects a large patient population, yet positive-airway-pressure treatment is difficult for some people to tolerate consistently. Hypoglossal nerve stimulation has consequently become an important alternative for selected patients, creating a growing implantable-device market.
An expanded CCC indication could differentiate Genio by opening a group that has historically been excluded from unilateral stimulation options. The commercial advantage would depend on how large the eligible population proves to be, reimbursement, surgeon adoption and whether real-world results reproduce the pivotal responder rates.
What should patients and clinicians watch next?
The full ACCCESS dataset at the October sleep-surgery meeting will provide greater clarity around baseline severity, absolute AHI changes, adverse events and durability. Nyxoah will then need to complete its FDA PMA supplement and persuade the agency that the 47-patient full analysis provides enough evidence to establish safety and effectiveness in CCC.
The company has already demonstrated that Genio can reach the U.S. market. ACCCESS asks a more strategically important follow-up question: can bilateral neurostimulation extend treatment to an anatomical group that the current U.S. category has largely left behind?
