As gene therapy technologies continue to reshape modern medicine, patent law increasingly faces the challenge of distinguishing products of nature from genuine biological engineering. Courts are frequently required to determine whether inventions involving genetic material represent technological innovation or merely the identification of naturally occurring biological features.

This issue was central to the recent United States gene therapy patent dispute between REGENXBIO and Sarepta Therapeutics. On 20 February 2026, the United States Court of Appeals for the Federal Circuit reversed a District Court ruling that REGENXBIO’s claims were directed to a natural phenomenon and therefore not eligible for patent protection. Although decided under US law, this decision offers useful insights for patent practitioners in other jurisdictions, including South Africa.

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The dispute and the ruling

The dispute concerns a patent licensed by REGENXBIO covering recombinant host cells used to manufacture adeno-associated virus (AAV) vectors, which serve as key delivery vehicles for therapeutic genetic material used in gene therapy. Sarepta Therapeutics developed a treatment for Duchenne muscular dystrophy using an AAV-based delivery system. REGENXBIO alleged that Sarepta’s manufacturing process infringed its licensed patent covering the engineered host cells used to produce these vectors.

The United States District Court granted judgment in favour of Sarepta, finding that the patent claims were directed to naturally occurring biological materials and were therefore not eligible for patent protection. The Federal Circuit has now unanimously rejected this reasoning. It decided that the claimed host cells “do not and cannot exist in nature” because they contain modified DNA produced through deliberate human intervention, combining genetic material from different species in a way that does not occur naturally.

In reaching this conclusion, the court drew parallels with the earlier Myriad Genetics case, where it decided that DNA found naturally in an organism is not eligible for patent protection, whereas synthetic DNA created in the laboratory may qualify for patent protection because it does not exist in nature. Thus, this decision reaffirms that human-engineered biological products may be patentable, where they demonstrate meaningful differences from naturally occurring systems.

Implications for South African patent law

Although the REGENXBIO decision was decided under US law, it highlights several structural differences between the United States and South African patent systems that are particularly relevant to biotechnology inventions.

South African patent law, governed by the Patents Act 57 of 1978, does not incorporate the extensive “natural phenomenon” doctrine developed in the United States. While the South African Patents Act excludes discoveries and certain abstract subject matter from patentability, it does not contain a judicial doctrine equivalent to the US restrictions on natural phenomena.

Consequently, inventions involving engineered biological constructs, such as recombinant viral vectors, host cells, or nucleic acid constructs, are generally regarded as patentable subject matter in South Africa, provided they satisfy the traditional requirements of novelty, inventive step and industrial applicability. In practice, this means that inventions similar to those at issue in the REGENXBIO dispute are less likely to encounter patent-eligibility challenges in South Africa.

Another important distinction lies in the procedural framework under which patents are granted. South Africa currently operates a formalities-based, non-substantive examination system, meaning that patent applications are assessed only for compliance with formal requirements prior to grant. As a result, patents relating to recombinant DNA technologies or engineered host cells are not examined for inventive step or patent eligibility prior to grant. These issues typically arise only if a patent is challenged during infringement litigation or revocation proceedings.

However, the REGENXBIO case underscores the extent to which highly technical questions relating to molecular engineering can become central issues in patent disputes. Should similar cases arise in South Africa, our courts would likely need to engage with similar issues when determining whether an invention represents a genuine technological advance rather than a mere discovery.

Lessons for biotechnology innovators

For biotechnology innovators and patent attorneys in South Africa, the REGENXBIO decision offers several practical lessons. Patent specifications should clearly demonstrate that engineered biological inventions possess “markedly different characteristics” from natural systems, by describing the structural modifications and functional differences to natural biological processes. This includes highlighting non-natural combinations of genetic elements that exist in nature, as well as emphasising the role of human intervention in producing the claimed invention.

Additionally, biotechnology innovation operates within a global legal environment, and South African innovators frequently seek patent protection in multiple jurisdictions, including the United States and Europe. As a result, developments in international case law can influence filing strategies, patent claim drafting and freedom-to-operate analyses. Finally, although South Africa currently operates a deposit system, the government has signalled a long-term intention to transition toward substantive examination. Once such reforms are implemented, questions similar to those raised in the REGENXBIO case, may become relevant to local examination practice.

Gene Therapy: what’s next

The Federal Circuit’s decision in REGENXBIO v Sarepta marks a significant development in the evolving landscape of biotechnology patent law. By recognising the patent eligibility of engineered host cells containing modified genetic material, the court reaffirmed that modern genetic engineering can produce inventions fundamentally distinct from the natural biological systems on which they are based.

For South Africa, where many high-value life sciences inventions are protected, the case highlights the importance of drafting robust and technically detailed patent specifications, framing biotechnology inventions as engineered innovations rather than discoveries, and anticipating potential validity challenges during litigation, even within our non-examining patent system. As gene therapy and plant biotechnology continue to expand in importance, cases such as REGENXBIO will increasingly inform how courts and practitioners approach the patentability of complex biological technologies.