STRC Research

Holt 2021 — Dual AAV STRC delivery rescues hearing in neonatal mice

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Holt 2021 — Dual AAV STRC Delivery (Science Advances)

Journal: Science Advances, December 2021
PMID: 34910522
PMC: PMC8673757
Lab: Jeffrey Holt, Boston Children’s Hospital / Harvard Medical School

Key Ideas

  • P1 neonatal intracochlear injection of dual-AAV STRC cDNA. Timing matters: P1 is before OHC maturation, maximizing transduction window.
  • ABR threshold rescue of 50-60 dB across frequencies. DPOAE amplitudes also restored.
  • OHC stereocilia bundle morphology restored in 59-65% of cells — close to the 60% Iranfar 2026 also reports independently.
  • Key author quote: “STRC mutations did not cause early hair cell death, unlike other hearing loss mutations.” This is the mechanistic argument for why treatment can work even after early life: the cells are still alive.
  • This work became the scientific basis for Regeneron’s AAV.104 program, acquired from Decibel Therapeutics in 2023 for $109M.
  • Holt stated 4-6 year timeline to human trials in 2022. First-in-human realistically 2026-2028.

My Thoughts

The OHC survival observation is load-bearing for Misha’s case. DFNB16 is not a hair cell death disease in the way DFNB9 (OTOF) or some syndromes are. The cells are structurally intact — they just lack the tip link accessory protein. That means the treatment window is longer than typical deafness conditions, and Misha’s existing hair cells at age 4 are almost certainly alive and addressable.

The $109M Decibel acquisition and Regeneron AAV.104 program make this the commercial-track path to watch. Regeneron has the manufacturing scale, regulatory experience (post-CHORD DB-OTO), and financial motivation to push this forward faster than an academic lab could.

The 4-6 year timeline from 2022 puts first-in-human at 2026-2028 — Misha is 4 now. If AAV.104 phases are standard, pediatric expansion comes after adult first-in-human (or the CHORD OTOF data may argue for direct pediatric inclusion, given DB-OTO’s 10-month-to-16-year age range). Realistic Misha access: 2029-2032 if everything goes well.

Connections

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