ALPK3 gene therapy reverses severe childhood cardiomyopathy in mouse and human models
核心洞察
Australian researchers developed an AAV9-based gene therapy delivering a healthy ALPK3 (搜索) gene that fully reversed established cardiomyopathy (搜索) in adult mice and restored function in human cardiac organoids.
The therapy not only halted disease progression in newborn mice but also reversed existing heart damage, restoring contractile function and structure to near-normal levels.
In human stem cell-derived models, the treatment restored contraction strength and rhythm, and also improved muscle contractility in tissue carrying TTN (搜索) mutations, the most common genetic cause of dilated cardiomyopathy (搜索).
Researchers at Australia's Murdoch Children's Research Institute have developed a gene therapy for severe paediatric cardiomyopathy (搜索) that not only halts disease progression but fully reverses established heart damage in preclinical models. The AAV9-based drug delivers a healthy copy of the ALPK3 (搜索) gene directly to heart muscle cells, and the developers hope that in the future, children with heart disease may be able to avoid risky organ transplants.
Mutations in the ALPK3 (搜索) gene cause cardiomyopathy (搜索), a group of conditions in which the heart's ability to pump blood is impaired, leading to heart enlargement, heart failure and an increased risk of death. Loss-of-function mutations in ALPK3, which encodes myogenic alpha protein kinase 3, have emerged as an important genetic cause of cardiomyopathy, accounting for around 2% of hypertrophic cardiomyopathy (搜索) cases. Biallelic variants cause a severe, and often lethal, form of neonatal cardiomyopathy, while autosomal dominant variants are strongly linked to adult-onset hypertrophic (and to a lesser extent dilated and arrhythmogenic) cardiomyopathy.
A cardiotropic vector restores heart structure and function
The therapeutic construct, AAV9-TNNT2-ALPK3 (搜索), uses a cardiomyocyte-specific TNNT2 promoter to drive expression of full-length ALPK3 (搜索). In the Alpk3W1538X mouse model, which recapitulates a severe ALPK3-truncating variant found in patients, neonatal administration via intraperitoneal injection at a dose of 2.5 × 10¹¹ viral genomes prevented cardiac dysfunction and disease progression.
By 12 weeks of age, treatment significantly lowered heart mass in Alpk3W1538X mice toward wild-type levels, reducing it by 63%. Biweekly echocardiography revealed near-complete restoration of almost all functional and structural parameters, including fractional shortening (31% ± 4% for control versus 50% ± 5% for treated mice; P < 0.0001), stroke volume (27 ± 4 µl versus 37 ± 5 µl; P = 0.0017), wall thickness and diastolic function (isovolumic relaxation time: 32 ± 7 ms versus 19 ± 2 ms; P < 0.0001). Sarcomeric structure, which was compromised in untreated mice, appeared similar to that of wild-type hearts following treatment.
Reversal of established disease in adult mice
To determine whether the therapy could restore function in mice with already-established cardiomyopathy (搜索), researchers treated 6-week-old mice and assessed cardiac function until 18 weeks of age. Before treatment, the adult mice demonstrated established disease, with reduced fractional shortening (36% ± 6% versus 59% ± 5% in wild-type; P < 0.0001), increased left ventricular mass and impaired diastolic function.
Delivery of AAV9-TNNT2-ALPK3 (搜索) in 6-week-old mice fully rescued systolic function back to wild-type levels at all timepoints after treatment. The therapy also reverted established hypertrophy to wild-type levels as early as 4 weeks after treatment, as evidenced by regression of both left ventricular mass and wall thickness, and completely restored diastolic function. As hypertrophy is already established at birth in this model, the authors note these findings indicate "true reversal of cellular and organ-level pathology rather than a protective effect preventing disease progression."
Restoring proteostasis at the sarcomere
Mechanistically, ALPK3 (搜索) orchestrates a protein quality control hub at the sarcomere to maintain turnover of contractile proteins. Quantitative proteomics and phosphoproteomics in treated mice revealed a global proteomic shift toward the wild-type state. Of roughly 6,000 detected proteins, 1,612 were differentially expressed between wild-type and untreated Alpk3W1538X mice; strikingly, only 81 proteins remained differentially expressed following ALPK3 gene therapy, representing a 95% reversal of the proteomic disease signature. This effect was even more pronounced in the phosphoproteome, with 98% normalization.
The therapy restored the balance of thick and thin filament proteins that is catastrophically disrupted in the disease model, and restored proteasome function that was significantly inhibited in untreated mice. These data suggest that ALPK3 (搜索) gene therapy acts in part by improving proteostasis, and that it has the potential to restore protein quality control in diverse cardiomyopathies.
Validation in human models and broader therapeutic potential
To independently validate the approach in a human model system, researchers differentiated a human pluripotent stem cell line carrying a loss-of-function ALPK3 (搜索) variant into cardiac organoids. Treatment with AAV6-ALPK3 restored active force production to wild-type levels and reduced the prevalence of asynchronous beating events, rescuing the severe sarcomeric disorganization caused by ALPK3 deficiency.
Using the foundational artificial intelligence model Geneformer, the team identified TTN (搜索) (encoding titin) as the most significantly damaging gene to delete in combination with ALPK3 (搜索). TTN-truncating variants account for up to 25% of dilated cardiomyopathy (搜索) cases, and the extreme size of the TTN gene (over 100,000 nucleotides) renders it unsuitable for conventional gene replacement therapy. In human cardiac organoids harboring TTN-truncating variants, AAV6-ALPK3 significantly restored force production to wild-type levels, confirming that ALPK3 gene therapy has potential to treat a broader spectrum of cardiomyopathies.
Clinical translation considerations
The AAV9-TNNT2-ALPK3 (搜索) vector (5.8 kb) exceeds the conventional 4.7-kb packaging capacity of the AAV genome. However, quantitative PCR showed no significant difference in DNA or RNA copy numbers for the two ends of the transgene, suggesting equivalent delivery of both ends of the viral genome and efficient production of full-length ALPK3 (搜索) mRNA. The authors note that the feasibility of clinical development of oversized AAV constructs is supported by the clinical approval and therapeutic success of Roctavian for the treatment of hemophilia.
Biodistribution studies showed that, despite robust vector DNA detection in the liver and skeletal muscle, ALPK3 (搜索) transgene mRNA was detected at levels an order of magnitude lower than in cardiac tissue, reflecting the cardiac-specific TNNT2 promoter and a liver-specific silencing miR-122a sequence. No evidence of liver or spleen toxicity was observed.
The authors acknowledge study limitations, including that the Alpk3W1538X model does not develop substantial interstitial fibrosis despite disease severity, so future studies will be required to determine whether this level of functional rescue is observed in hearts with pre-existing fibrosis. The studies also used homozygous mice modeling the rare autosomal recessive disease rather than the more common autosomal dominant form.
Globally, around 30 million people are affected by various forms of cardiomyopathy (搜索), and inherited forms are the leading reason for heart transplantation in children. As of early 2026, the number of gene therapy candidates in development worldwide exceeded 2,150, with the United States and China leading the field.