AAV Manufacturing Partnership Supports Gene Therapy for CLN2 Batten Disease

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US-based Andelyn Biosciences, a cell and gene therapy contract development and manufacturing organization, and Tern Therapeutics, a privately held biotechnology company also based in the United States, have entered into a collaboration to perform late-stage process performance qualification (PPQ) manufacturing of Tern’s investigational gene therapy, TTX-381. The therapy is designed to address vision loss in children affected by neuronal ceroid lipofuscinosis 2 (CLN2) Batten disease, a rare and fatal pediatric neurodegenerative disorder with no available treatments for its ocular symptoms (1).

CLN2 disease results from a deficiency in the TPP1 protein, with an estimated incidence of 0.5 per 100,000 live births. Symptoms typically appear between ages two and four, beginning with seizures and developmental decline. Progressive vision loss follows soon after and can lead to complete blindness as early as age seven. This rapid disease trajectory underscores the urgency for therapeutic development (2,3).

“Partnering with Tern Therapeutics on this transformative program underscores Andelyn’s commitment to enabling breakthrough therapies for rare and devastating diseases,” said Matt Niloff, chief commercial officer, Andelyn, in a Sept. 3, 2025 press release (1). “Our deep experience in AAV [adeno-associated virus] process development and manufacturing, coupled with regulatory alignment and proven execution of PPQ batches, positions us to help bring this therapy to patients as efficiently and safely as possible.”

What challenges arise in gene therapy design and manufacturing?

TTX-381 is a one-time, subretinal AAV gene therapy. It is engineered to deliver a functional copy of the TPP1 gene directly to retinal cells, restoring enzyme activity to slow or prevent vision loss. The late-stage PPQ manufacturing milestone is crucial for the cell and gene therapy sector as it gives validation to the production processes being consistent, reproducible, and able to meet regulatory requirements for potential commercial launch.

Andelyn’s involvement centers on its expertise in AAV vector manufacturing and its record of PPQ batch production, capabilities that are essential as gene therapies move toward market readiness. Late-stage process validation remains one of the most challenging phases of gene therapy development, requiring both technical rigor and alignment with regulatory expectations.

What industry implications present themselves around gene therapy development?

This partnership highlights the role of specialized manufacturers in advancing therapies for rare diseases. For drug developers, the collaboration demonstrates how external expertise in complex biologics manufacturing can accelerate the path from preclinical development to potential commercial approval.

Tern’s focus is on advancing treatments for rare diseases with an urgency shaped by patient needs. The company emphasized the importance of manufacturing strength in executing on that mission. “We’re excited to partner with Andelyn and leverage their long history with AAV technologies, strong late-stage manufacturing capability, and a shared dedication to rare disease patients,” said Alex Bailey, chief executive officer, Tern, in the release. “Together, we aim to deliver a therapy that has the potential to change the lives of children and families facing CLN2 Batten disease, providing hope where today there are no effective treatment options.”

By reaching this stage, the TTX-381 program not only progresses toward clinical and regulatory milestones but also illustrates the maturing infrastructure supporting gene therapy commercialization. For pharmaceutical manufacturing and development experts, the collaboration underscores the increasing importance of process validation, scalability, and regulatory alignment in delivering next-generation therapies.

References

1. Andelyn Biosciences. Andelyn Biosciences and Tern Therapeutics Partner for Late-Stage Process Performance Qualification (PPQ) Manufacturing of AAV Gene Therapy for the Treatment of CLN2 Batten Disease. Press Release. Sept. 3, 2025.
2. Nickel, M.; Simonati, A.; Jacoby, D.; et al. Disease Characteristics and Progression in Patients with Late-Infantile Neuronal Ceroid Lipofuscinosis Type 2 (CLN2) Disease: An Observational Cohort Study. Lancet Child Adolesc. Health. 2018, 2 (8), 582–590. DOI: 10.1016/S2352-4642(18)30179-2.
3. Soangra, R.; Grant-Beuttler, M.; Chang, H.; Wang, R. Y. Two-Year Follow-Up of Gait and Postural Control Following Initiation of Recombinant Human Tripeptidyl Intracerebroventricular Enzyme Replacement Therapy in Two Atypical CLN2 Patients. Sci Rep 2025, 15, 1042. DOI: 10.1038/s41598-024-82157-5