Hui Wang

Gene therapy is a promising approach for hereditary deafness. We recently showed that unilateral AAV1-hOTOF gene therapy with dual adeno-associated virus (AAV) serotype 1 carrying human OTOF transgene is safe and associated with functional improvements in patients with autosomal recessive deafness 9 (DFNB9). The protocol was subsequently amended and approved to allow bilateral gene therapy administration. Here we report an interim analysis of the single-arm trial investigating the safety and efficacy of binaural therapy in five pediatric patients with DFNB9. The primary endpoint was dose-limiting toxicity at 6 weeks, and the secondary endpoint included safety (adverse events) and efficacy (auditory function and speech perception). No dose-limiting toxicity or serious adverse event occurred. A total of 36 adverse events occurred. The most common adverse events were increased lymphocyte counts (6 out of 36) and increased cholesterol levels (6 out of 36). All patients had bilateral hearing restoration. The average auditory brainstem response threshold in the right (left) ear was >95 dB (>95 dB) in all patients at baseline, and the average auditory brainstem response threshold in the right (left) ear was restored to 58 dB (58 dB) in patient 1, 75 dB (85 dB) in patient 2, 55 dB (50 dB) in patient 3 at 26 weeks, and 75 dB (78 dB) in patient 4 and 63 dB (63 dB) in patient 5 at 13 weeks. The speech perception and the capability of sound source localization were restored in all five patients. These results provide preliminary insights on the safety and efficacy of binaural AAV gene therapy for hereditary deafness. The trial is ongoing with longer follow-up to confirm the safety and efficacy findings. Chinese Clinical Trial Registry registration: ChiCTR2200063181 .

Advancements in gene therapy have achieved significant milestones in treating human diseases, offering renewed hope to patients with limited options. Key to this progress are vectors, which include both viral and non-viral methodologies that impact the success of gene therapy. Over the past two decades, three widely used viral vectors-lentiviruses (LV), adenoviruses (Ad), and adeno-associated viruses (AAV)-have enabled notable preclinical and clinical successes, including the approval of Luxturna for a genetic retinal disease and CAR-T therapies for blood cancers. Recently, the first-in-human dual AAV therapy for hereditary hearing loss, which overcomes large gene delivery, has showcased the restoration of auditory function for patients. Additionally, non-viral vectors such as lipid nanoparticles (LNP) and N-acetylgalactosamine (GalNAc) have led to successful gene therapy products. This review focuses on both viral and non-viral delivery systems in gene therapy, highlighting their current state and future perspectives in treating human diseases.

Adeno-associated virus (AAV)-mediated gene therapy is widely applied to treat numerous hereditary diseases in animal models and humans. The specific expression of AAV-delivered transgenes driven by cell type-specific promoters should further increase the safety of gene therapy. However, current methods for screening cell type-specific promoters are labor-intensive and time-consuming. Herein, we designed a “multiple vectors in one AAV” strategy for promoter construction in vivo. Through this strategy, we truncated a native promoter for Myo15 expression in hair cells (HCs) in the inner ear, from 1,611 bp down to 1,157 bp, and further down to 956 bp. Under the control of these 2 promoters, green fluorescent protein packaged in AAV-PHP.eB was exclusively expressed in the HCs. The transcription initiation ability of the 2 promoters was further verified by intein-mediated otoferlin recombination in a dual-AAV therapeutic system. Driven by these 2 promoters, human otoferlin was selectively expressed in HCs, resulting in the restoration of hearing in treated Otof −/− mice for at least 52 weeks. In summary, we developed an efficient screening strategy for cell type-specific promoter engineering and created 2 truncated Myo15 promoters that not only restored hereditary deafness in animal models but also show great potential for treating human patients in future.

Importance: OTOF gene therapy (GT) has been shown to improve hearing and speech. The efficacy of GT remains to be compared against cochlear implantation (CI), the current gold standard for congenital deafness. Objective: To evaluate treatment outcomes in auditory and speech perception between patients with congenital deafness treated with GT, CI, or both. Design, Setting, and Participants: This nonblind cohort study was conducted between December 2022 and November 2024. GT patients received follow-up at 3, 6, and 12 months; CI patients received 1-time evaluation at the corresponding time intervals or longer (3, 6, or 12 months). The study was conducted at a single class A tertiary hospital in China. Participants with congenital severe to complete hearing loss, aged 1 to 18 years, who received GT or CI were enrolled. They were matched on duration of deafness, hearing thresholds, and speech ability at the presurgical baseline. Of 1568 participants screened, 72 participants enrolled. Participants were excluded if they had inner ear malformations or vestibular-cochlear nerve abnormalities. Exposures: GT only vs CI; bimodal (unilateral GT plus contralateral CI) vs bilateral CI; GT (CI turned off [CI-off]) vs unilateral CI. Main Outcomes and Measures: The primary outcomes were auditory and speech perception evaluated by questionnaires, including the Infant-Toddler Meaningful Auditory Integration Scale/Meaningful Auditory Integration Scale (IT-MAIS/MAIS), and tests, including audiometry, speech, and music tests. The main secondary outcome was auditory information processing ability assessed by mismatch negativity (MMN). Results: A total of 11 GT patients (6 male [55%]; mean [SD] age at baseline, 3.7 [2.8] years) and 61 CI patients (34 male [56%]; mean [SD] age at baseline, 1.9 [1.5] years) were enrolled. The mean (SD) auditory brainstem response thresholds were restored from greater than 95.0 (0.0) decibels normalized hearing level (dB nHL) to 54.8 (15.9) dB nHL in 9 GT patients at 12 months. For GT-only vs CI in auditory and speech perception, GT patients performed better in IT-MAIS/MAIS at 6 months (median [IQR] score, 31.0 [30.0-32.0] vs 23.5 [19.0-26.3]; P = .01) and 12 months (median [IQR] score, 32.0 [31.0-32.0] vs 28.0 [24.5-30.5]; P = .007). GT patients showed shorter latencies of MMN at 6 months (median [IQR], 0.20 [0.05-0.21] seconds vs 0.23 [0.22-0.25] seconds; P = .006). For bimodal patients at 12 months, GT (CI-off) patients performed better than unilateral CI patients in speech in a noisy environment (median [IQR] disyllable, -1.0 [-3.0 to 2.4] dB sound pressure level (SPL) vs 5.3 [3.1 to 12.1] dB SPL; P = .03); GT plus CI patients performed better than bilateral CI patients in singing in-tune rates (median [IQR], 66.6% [53.7%-83.9%] vs 37.1% [30.3%-56.3%]; P = .04); GT plus CI patients showed shorter latencies of MMN at 12 months (median [IQR], 0.08 [0.07-0.10] seconds vs 0.21 [0.15-0.23] seconds, P = .01). Conclusions and Relevance: GT patients showed stable hearing recovery and exhibited more rapid improvements in auditory and speech performance than CI patients, while outperforming CI patients in speech in noise performance and music perception. These findings suggest that GT may provide a novel effective treatment alternative for patients with genetically driven congenital deafness.