# AK-OTOF (Akouos) by Eli Lilly

Canonical page: https://technooptimist.io/neurotech/ak-otof
Frontier: [Neurotech](https://technooptimist.io/neurotech.md) · Field: Hearing implants · Company: [Eli Lilly](https://technooptimist.io/companies/eli-lilly.md)
Stage: Pilot (3 of 5: Research → Proto → Pilot → Deploy → Scaling)
Updated: last update 2026-05-11, facts checked 2026-10-11
Goal: Restore natural hearing to people born deaf from OTOF mutations, about 200,000 worldwide, with a single injection into the inner ear instead of a lifelong cochlear implant.
Status: AK-OTOF-101 recruiting, now registered as Phase 3 with 48 planned patients; results due ~2028.
Next milestone: Expanded trial enrolling, registered as Phase 3

## Milestones

| Status | Milestone | Date | Slip |
| --- | --- | --- | --- |
| Done | Lilly agrees to buy Akouos for up to $610M | 18 Oct 2022 |   |
| Done | AK-OTOF-101 trial starts | 15 Sep 2023 |   |
| Done | First child, aged 11, hears within 30 days | Jan 2024 |   |
| Done | COSM 2026: 8 of 10 higher-dose children improve | May 2026 |   |
| Current | Expanded trial enrolling, registered as Phase 3 |   |   |
| Planned | Primary completion (estimated) | Oct 2028 |   |

## Upcoming events

- **Oct 2028**: Primary completion (estimated)

## Most important updates

- **11 May 2026**: AK-OTOF at COSM 2026: 8 of 10 children on the higher dose gained hearing, with no therapy-related adverse events. Updated AK-OTOF-101 results covered 18 participants across two dose levels, including early two-ear treatments. ([our story](https://technooptimist.io/stories/ak-otof-at-cosm-2026-8-of-10-children-on-the-higher-dose-gained-hearing-70a63566.md) · [original source](https://www.contemporarypediatrics.com/view/ak-otof-shows-early-hearing-restoration-potential-in-children-with-otof-mediated-hearing-loss))
- **24 Jan 2024**: Lilly's AK-OTOF gene therapy restored hearing in an 11-year-old born profoundly deaf within 30 days. The first child treated in the AK-OTOF-101 trial, an 11-year-old deaf since birth from OTOF mutations, regained hearing across all tested frequencies within 30 days. ([our story](https://technooptimist.io/stories/lilly-s-ak-otof-gene-therapy-restored-hearing-in-an-11-year-old-born-38efbc8d.md) · [original source](https://www.biospace.com/lilly-s-investigational-gene-therapy-restores-hearing-in-first-treated-patient))
- **18 Oct 2022**: Lilly agrees to buy hearing-loss gene therapy company Akouos for up to $610 million. Lilly agreed to acquire Akouos for $12.50 a share in cash, a 78% premium, plus a contingent value right worth up to $3 a share. ([our story](https://technooptimist.io/stories/lilly-agrees-to-buy-hearing-loss-gene-therapy-company-akouos-for-up-to-d1ec20e7.md) · [original source](https://www.biopharmadive.com/news/lilly-akouos-deal-acquisition-gene-therapy-hearing-loss/634350/))

## Current obstacles

- **Second to market**: Regeneron's Otarmeni, a similar dual-AAV OTOF therapy, won FDA approval in April 2026 and is free in the US, so AK-OTOF must show a clear edge.
- **Early, small dataset**: Results so far cover 18 children presented at a meeting, not a full paper; durability and speech outcomes need about 4 more years of follow-up.

## Physics limits

- **Needs living hair cells**: Adding a gene only helps when the hair cells are still alive and lack one protein. Most deafness comes from dead hair cells or other genes, which this kind of therapy cannot rescue.
- **Language has a timing window**: The brain's language circuits mature in early childhood, so hearing restored later may not bring normal speech. Years of follow-up are needed to see how much age at treatment matters.

## How it works

### Problem: Hair cells that cannot pass the signal on

Inner hair cells turn sound into signals for the hearing nerve. They need the protein otoferlin to pass them on; two broken OTOF genes leave a child deaf.

### Vector: Two viruses, half a gene each

OTOF is too large for one AAV shell, so AK-OTOF splits it across two Anc80 vectors; an inner hair cell that takes up both rebuilds the full gene.

### Delivery: A device instead of drilling

A single-use Akouos device infuses the dose into the cochlea; the procedure needs no skin incisions or bone drilling.

### Readout: Hearing tests and brainstem waves

Success is measured by listening tests and the auditory brainstem response (ABR), the brain's electrical reply to clicks, seen from day 30.

## Spec sheet

| Spec | AK-OTOF (Akouos) | Provenance |
| --- | --- | --- |
| Vector | Dual AAV, Anc80 capsid | reported |
| First-cohort dose | 4.1 × 10¹¹ vector genomes | reported |
| Treated (reported May 2026) | 18, at 2 dose levels | reported |
| Improved at higher dose | 8 of 10 children | reported |
| First hearing responses | From about day 30 | reported |
| First child, day 30 thresholds | 65–20 dB HL | reported |
| Planned enrollment | 48 (estimated) | reported |

Provenance: reported = stated by the company; estimated = our estimate; sample = a sample figure.

## About Eli Lilly

US drugmaker that leads in obesity and diabetes drugs. Tirzepatide (Mounjaro, Zepbound) is among the world's best-selling drugs, its GLP-1 pill was approved in 2026, and retatrutide gave about 28% weight loss in Phase 3. It bought Verve (gene editing) in 2025.

- Became the first drugmaker worth about $1 trillion (Nov 2025), thanks to tirzepatide.
- Foundayo (orforglipron), a daily GLP-1 pill with no food or water rules, was FDA-approved for obesity on 1 Apr 2026.
- Retatrutide gave 28.3% average weight loss at 80 weeks on the top dose in Phase 3 (May 2026).

- Founded: 1876
- Headquarters: US
- Status: public
- Listing: LLY (NYSE)
- Valuation: $1.1T (market cap, 2026-09)
- Staff: ~50,000
- Website: https://www.lilly.com
- People: David A. Ricks (Chair and CEO); Daniel Skovronsky (Chief Scientific Officer)
- Partners, customers, investors: Chugai Pharmaceutical (supplier); Isomorphic Labs (partner); Verve Therapeutics (partner)

Company page: https://technooptimist.io/companies/eli-lilly.md

## Related programs

More from Eli Lilly:

- [Tirzepatide (Mounjaro / Zepbound)](https://technooptimist.io/biotech/tirzepatide.md) (Scaling)
- [Orforglipron (Foundayo)](https://technooptimist.io/biotech/orforglipron.md) (Scaling)
- [Retatrutide](https://technooptimist.io/biotech/retatrutide.md) (Pilot)
- [VERVE-102 (PCSK9 base editor)](https://technooptimist.io/biotech/verve-102.md) (Proto)
- [Eloralintide](https://technooptimist.io/biotech/eloralintide.md) (Pilot)
- [ORN-252](https://technooptimist.io/biotech/orn-252.md) (Pilot)
- [KLN-1010](https://technooptimist.io/biotech/kln-1010.md) (Pilot)

Everything in Neurotech: https://technooptimist.io/neurotech.md

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