Scientists at the Stanford University School of Medicine in the US are starting a clinical trial using human patients this month, as a combination of a tiny segment of DNA and a specific antibody injected into a solid tumour has been shown to remove not only the target tumour but also others in the body in mice, Science Translational Medicine journal reported.
The combination therapy prompts the body’s own immune system to tackle tumors.
“When we use these two agents together, we see the elimination of tumours all over the body,” says oncologist Ronald Levy, one of the authors of the study.
“This approach bypasses the need to identify tumour-specific immune targets and doesn’t require wholesale activation of the immune system or customisation of a patient’s immune cells.”
Levy and his colleagues found a way to reactivate the moribund T cells. To do this, they inject a target tumour with a couple of micrograms of a short stretch of DNA called a CpG oligonucleotide. This works with nearby immune cells to activate a receptor called OX40 on the surface of the T cells.
CpG oligonucleotide is already used to bolster several types of cancer treatment.
“Our approach uses a one-time application of very small amounts of two agents to stimulate the immune cells only within the tumour itself,” explains Levy.
“In the mice, we saw amazing, body-wide effects, including the elimination of tumours all over the animal.”
Mice carrying breast, colon and melanoma tumours were also treated successfully. Trials were also conducted on mice genetically engineered to develop multiple breast cancers. In many cases treating the first tumour to appear prevented others arising.
While the treatment is effective against a range of cancers, each application conditions T cells to fight only one. Tests on mice with two types of tumour found that only the type treated went into remission, leaving the other unaffected.
“This is a very targeted approach,” Levy says. “Only the tumour that shares the protein targets displayed by the treated site is affected. We’re attacking specific targets without having to identify exactly what proteins the T-cells are recognising.”
An initial human trial will get underway soon, with the researchers looking to recruit about 15 patients with low-grade lymphoma.