The Cancer Clue Hidden in Great White Shark DNA

15 July 2026 | White Shark Ocean

Of all the things scientists expected to find when they sequenced the great white shark genome for the first time in 2019, a potential blueprint for fighting human cancer was not high on the list. But that is what the data suggested. The genome of Carcharodon carcharias — at 4.63 billion base pairs, roughly 40% larger than the human genome — turned out to contain some of the most sophisticated DNA protection machinery ever documented in a vertebrate animal.

Great white sharks have the lowest incidence of tumours and cancers of any vertebrate group studied. For an animal that can live 70 years, reach enormous size, and carry billions of cells that could theoretically turn cancerous at any point, this is not an accident. It is the product of 450 million years of evolutionary pressure, and what that pressure built may now have implications for human medicine.

The Problem Large Animals Face

To understand why great white shark cancer resistance is remarkable, it helps to understand a puzzle known as Peto's Paradox. In theory, larger animals should get more cancer than smaller ones. Cancer begins when a single cell mutates and begins dividing uncontrollably — and larger animals have more cells, more cell divisions over a longer lifetime, and therefore more opportunities for something to go wrong. A blue whale has roughly 1,000 times more cells than a human and lives for over a century. By simple probability, it should be riddled with tumours.

It isn't. Neither are great white sharks, elephants, or bowhead whales. Each of these long-lived, large-bodied animals has independently evolved mechanisms to suppress cancer at a rate that defies the arithmetic of cell division. In the case of great white sharks, the 2019 genome gave researchers their first detailed look at exactly how those mechanisms work.

What the Genome Revealed

The sequencing work, published in PNAS in 2019 and led by researchers at Nova Southeastern University and the Save Our Seas Foundation Shark Research Centre, identified several features of the great white genome that distinguish it from other vertebrates.

The first was the abundance of what geneticists call jumping genes, or transposons: sequences of DNA that can copy themselves and insert into different parts of the genome. Transposons are found in many organisms, but in large quantities they cause genomic instability — the very condition that leads to cancer. Great white sharks have an unusually high density of transposons. Under normal evolutionary circumstances, this should be a problem.

Instead, the genome showed something unexpected: a parallel proliferation of stabilising genes that counteract the transposons. The team found that roughly one third of the genes most strongly selected by evolution in great white sharks — the genes that survived and were amplified across millions of years because they conferred survival advantages — produce proteins involved in DNA repair, damage response, and damage tolerance. The genome had essentially built its own error-correction system in direct proportion to the threat posed by its own jumping genes.

Alongside this, the researchers identified specific adaptations in immune-related genes, including modifications in pathways associated with wound healing and tumour suppression. Great white sharks heal from serious injuries — including bites from other great whites — with a speed and completeness that would be remarkable in any animal. The genome suggests this is not incidental but the result of specific evolutionary investment in cellular repair processes.

The VNAR Antibody

The cancer research thread that has attracted the most clinical interest is not the DNA repair machinery itself, but a component of the shark immune system that produces a completely different type of antibody from the ones found in mammals.

Human antibodies are large, Y-shaped molecules built from two heavy protein chains and two light protein chains. They are effective but bulky — their size limits which parts of a target molecule they can physically reach. Sharks produce a second type of antibody alongside their conventional ones: the variable new antigen receptor, or VNAR. VNARs are built from a single heavy chain only, with no light chain at all. This makes them roughly one-tenth the size of a conventional human IgG antibody.

That size difference is medically significant. Tumour cells and pathogens frequently hide their most vulnerable targets in grooves and recesses of their surface proteins — locations that are physically inaccessible to the larger conventional antibody. VNARs are small enough to reach these hidden targets, binding to epitopes that no conventional antibody can get to. They are also exceptionally stable: they maintain their structure and function under temperature extremes, in acidic environments, and after freeze-drying — all conditions that would destroy a conventional antibody.

Research groups have now developed VNAR-based therapies targeting multiple cancer types. A 2025 paper in Frontiers in Immunology reviewed the field comprehensively: VNARs have been engineered to target breast cancer, gastric cancer, lung cancer, colorectal cancer, and liver cancer. One approach uses VNAR-based CAR-T cells — modified immune cells — that target PD-L1, a protein tumours use to hide from the immune system. In preclinical mouse models, these constructs successfully blocked PD-L1 and reduced tumour growth. A separate study demonstrated a VNAR-based immunotoxin targeting TROP-2, a protein overexpressed in multiple solid tumour types.

None of these therapies are yet approved for clinical use in humans. But the pipeline is active, the science is well-founded, and the starting point is the immune system of an animal that has been running its own cancer suppression programme for nearly half a billion years.

Why Sharks and Not Something Else

It is worth asking why shark-derived antibodies, rather than antibodies from other cancer-resistant animals, are attracting such concentrated research interest. The answer is partly the unique single-chain structure of VNARs — which has no equivalent in any mammal — and partly the evolutionary depth of the shark immune system itself.

Sharks diverged from the lineage that would produce all bony vertebrates, including every mammal, approximately 450 million years ago. That is 450 million years of independent immune system evolution, solving the problems of infection, cancer, and cellular damage in a completely different way from anything that lives on land. The solutions sharks arrived at are genuinely distinct from anything in the mammalian toolkit — which is exactly why they are interesting. If mammalian immune systems had all the answers, we would already have solved cancer. What sharks offer is a different set of answers, arrived at independently, that we have not yet fully read.

What This Means Beyond Medicine

The cancer resistance finding sits alongside the other remarkable features of the great white genome — the genome stability machinery, the wound healing adaptations, the immune modifications — as evidence of what 450 million years of selection pressure actually builds. Each of these features exists not because evolution was planning ahead or designing for human benefit, but because the sharks that had better DNA repair, faster healing, and more robust immune responses survived longer and produced more offspring.

The great white shark alive today is not the shark that existed 450 million years ago. It is the product of an unbroken chain of survivors, each slightly better than the one before at solving the problems of staying alive in a demanding ocean. The cancer resistance is one solution to one of those problems. The fact that it may also solve some of our problems is a by-product of that survival record.

White Shark Ocean operates cage diving and surface encounters in Mossel Bay, South Africa. Every encounter supports the conservation of animals that may one day contribute to human medicine. Book at whitesharkocean.com.

Frequently Asked Questions

Do great white sharks get cancer?

Great white sharks have the lowest incidence of tumours and cancers of any vertebrate group studied. While it is not accurate to say they are completely immune — tumours have been documented in some shark species — the rate is exceptionally low given their size, cell count, and lifespan. The 2019 sequencing of the great white genome identified specific mechanisms responsible for this resistance: a proliferation of DNA repair and stabilising genes that counteract genomic instability, and immune system adaptations that support rapid wound healing and tumour suppression.

What did the great white shark genome sequencing find?

The great white shark genome, sequenced in 2019 by researchers at Nova Southeastern University and the Save Our Seas Foundation Shark Research Centre, revealed a genome 40% larger than the human genome at 4.63 billion base pairs. Key findings included an unusually high density of jumping genes (transposons) alongside a parallel proliferation of stabilising genes — roughly one third of the most evolutionarily selected genes code for DNA repair proteins. The genome also showed specific modifications in immune and wound-healing pathways, and the structural basis of the shark's unique single-chain VNAR antibodies.

What is a VNAR antibody and why does it matter for cancer treatment?

VNAR (variable new antigen receptor) antibodies are a type of antibody unique to sharks and their relatives. Unlike conventional antibodies, which are built from two heavy chains and two light chains, VNARs consist of a single heavy chain only — making them approximately one-tenth the size of a standard human IgG antibody. This small size allows VNARs to reach hidden targets on the surface of cancer cells and pathogens that are physically inaccessible to conventional antibodies. They are also exceptionally stable under extreme conditions. Researchers have developed VNAR-based therapies targeting breast, gastric, lung, colorectal, and liver cancers, as well as VNAR-based CAR-T cells that block the PD-L1 protein tumours use to evade the immune system.

What is Peto's Paradox?

Peto's Paradox refers to the observation that cancer rates do not scale with body size and lifespan the way simple probability would predict. Larger animals have more cells and longer lives, which should mathematically increase their cancer risk — yet blue whales, elephants, great white sharks, and bowhead whales all have remarkably low cancer rates. Each of these species has independently evolved specific biological mechanisms to suppress cancer, despite having vastly more cells and cell divisions than smaller, shorter-lived animals. Understanding how they do it has become a significant area of cancer biology research.

Could shark cartilage supplements prevent cancer?

No. The idea that consuming shark cartilage protects against cancer is a myth with no credible scientific support. The cancer resistance properties of sharks are located in specific genetic and immunological systems — their DNA repair machinery, genome stability mechanisms, and VNAR antibodies — none of which survive digestion or are in any way present in cartilage supplements. Shark cartilage products have been tested in clinical trials and found to be ineffective against cancer. The myth has caused significant harm to shark populations through demand for cartilage products, while providing no benefit to the people who consume them.