Bing Chen

Re-administration of adeno-associated virus (AAV)-mediated gene therapy remains challenging due to neutralizing antibodies (NAbs) induced by the initial dose. We previously conducted a single-arm trial showing that single-dose administration of AAV-hOTOF gene therapy in individuals with OTOF-related deafness is safe and leads to hearing improvements. Here we initially demonstrate that AAV1-hOTOF re-administration to the contralateral ear in Otof^−/− mice with peak serum NAb titers successfully rescued hearing with limited immune activation. After a protocol amendment of our trial, four patients (aged 2.2–3.4 years) with pre-existing NAbs (titers 1:135–1:3,645), who had previously received a single dose of the gene therapy, were enrolled to receive a second dose in the contralateral ear, as part of the ongoing trial, with a follow-up ranging from 26 weeks to 52 weeks. The primary endpoint was the occurrence of dose-limiting toxicities at 6 weeks and secondary endpoints included safety and auditory function. No dose-limiting toxicity occurred within 6 weeks. In the secondary outcomes, the 26-week average auditory brainstem response threshold in the second treated ear improved from >95 dB at baseline to 43 dB, 63 dB, 80 dB and 53 dB in patients 1–4, respectively. Safety assessment showed that all adverse events were grade 1–2, except one grade 3 decreased neutrophil count; no serious adverse events occurred. These data provide preliminary insights on the safety and efficacy of re-administration of AAV1-hOTOF gene therapy in patients with congenital deafness. Longer follow-up and larger cohorts are needed to establish the safety and efficacy of repeated administration of gene therapies. Trial registration no.: ChiCTR2200063181.

Sensorineural hearing loss (SNHL) is recognized as one of the most common sensory disorders and is characterized by irreversible damage to cochlear hair cells (HCs). Our research, which utilized the HEI-OC1 cell line for drug screening, revealed that inhibiting the JAK/STAT signaling pathway protects HEI-OC1 cells from cisplatin-induced ototoxicity. Further studies with cochlear explants showed that ifidancitinib, an inhibitor of both JAK1 and JAK3, offered superior protection compared with other JAK inhibitors. Additionally, in vivo studies with adult mice demonstrated that mice treated with ifidancitinib had lower auditory brainstem response (ABR) thresholds than those treated with cisplatin alone, along with improved morphology in HCs, nerve fibers, and pre- and postsynaptic structures. Western blot and MitoSOX Red assays demonstrated that the JAK/STAT signaling pathway promoted intracellular ROS accumulation and cell apoptosis. Furthermore, ELISA showed that ifidancitinib significantly decreased the levels of proinflammatory markers such as TNF-α, CD38, IL-6, and IL-1β. STRING analysis revealed that ifidancitinib’s protective effects on hearing were mediated through regulation of the JAK/STAT5–IL2 axis, which was further confirmed using an interleukin 2 (IL-2) inhibitor and animal-free IL-2 protein. This study underscores the importance of the JAK/STAT signaling pathway in HC survival, highlighting its potential as a therapeutic target for the prevention and treatment of SNHL.

Background: To create and develop a delivery approach for clinical inner ear gene therapy, we conducted a study of trans-round window membrane (RWM) microinjection using a pipetting microneedle via transcanal endoscopic ear surgery (TEES). Methods: The implementation of the trans-RWM microinjection surgery involved seven cadaveric specimens, and the surgical procedures and the pipetting microneedle were developed and optimized. The TEES procedures included tympanic cavity visualization, RWM exposure, stapes footplate perforation, and trans-RWM microinjection. The feasibility of different pipetting microneedles was evaluated during microinjection. Results: Exposure of the RWM microinjection site could be easily achieved in TEES, and the soft-connected pipetting microneedle was most suitable for the trans-RWM microinjection. The fluid outflow from stapes perforation could be visibly observed during the microinjection, which indicated inner ear drug delivery was successful. This inner ear drug delivery approach was successfully applied in the clinical trial. Conclusion: The trans-RWM microinjection via the soft-connected pipetting microneedle in TEES was proved to be a feasible delivery approach of the inner ear gene therapy.

Loss of cochlear hair cells (HCs) leads to permanent hearing loss in mammals, and regenerative medicine is regarded as an ideal strategy for hearing recovery. Limited genetic and pharmaceutical approaches for HC regeneration have been established, and the existing strategies cannot achieve recovery of auditory function. A promising target to promote HC regeneration is MEK/ERK signaling because dynamic shifts in its activity during the critical stages of inner ear development have been observed. Here, we first showed that MEK/ERK signaling is activated specifically in supporting cells (SCs) after aminoglycoside-induced HC injury. We then selected 4 MEK/ERK signaling inhibitors, and PD0325901 (PD03) was found to induce the transdifferentiation of functional supernumerary HCs from SCs in the neonatal mammalian cochlear epithelium. We next found that PD03 facilitated the generation of HCs in inner ear organoids. Through genome-wide high-throughput RNA sequencing and verification, we found that the Notch pathway is the downstream target of MEK/ERK signaling. Importantly, delivery of PD03 into the inner ear induced mild HC regeneration in vivo. Our study thus reveals the importance of MEK/ERK signaling in cell fate determination and suggests that PD03 might serve as a new approach for HC regeneration.

Purpose: The narrow supralabyrinthine space affects surgical procedures. To study the effect of temporary transposition of geniculate ganglion of facial nerve versus nontransposition on lesion recurrence and facial nerve function in patients with petrous bone cholesteatoma. Methods: A total of 18 patients with petrous bone cholesteatoma involving the facial nerve were treated in our hospital from November 2016 to March 2023. The main surgical method is the extended supralabyrinthine approach assisted by a microscope and an endoscope. We collected and retrospectively analyzed their medical records. Results: Temporary facial nerve transposition was performed in five patients, and nontransposition was performed in 13 patients. Cholesteatoma recurred in three patients with facial nerve nontransposition, whereas none in patients with facial nerve transposition. In this study, except for one case with a second operation, postoperative facial paralysis in other cases was improved to varying degrees, and there was no significant difference between the two groups. Conclusion: Temporary transposition of geniculate ganglion of facial nerve will not affect the postoperative nerve function of patients and can reduce the possibility of cholesteatoma recurrence of the petrous bone.