The virus triggers an immune response that might be harnessed to destroy tumours, researchers say.
Covid infection triggers a subset of immune cells that can attack cancer cells, potentially leading to new treatments for patients left with no other options, researchers say.
In research using mice and the blood of humans infected with covid, researchers found that covid RNA activated signals in the immune system which transformed monocytes into what they called inducible nonclassical monocytes (I-NCMs).
Those cells can move into blood vessels and tissue where tumours grow, which most other immune cells cannot do, the researchers said.
“We found that these populations of nonclassical monocytes perform distinct functions,” the US researchers write in The Journal of Clinical Investigation.
“Nucleotide-binding oligomerization domain-containing protein 2 (NOD2) induced I-NCMs inhibit tumour seeding and induce regression of various tumour colonies more robustly than N-NCM [naturally occurring NCMs].
“Our findings suggest that the induction of I-NCM via NOD2 activation can attenuate tumour metastasis independent of conventional immune pathways necessary for immunotherapies.”
Previous research has shown that a deficiency of the NOD2 protein promotes tumorigenesis and increases tumour metastasis, the researchers say.
“Given that NOD2 agonists have been approved for human use, our findings have potential clinical implications for patients with cancers resistant to current immunotherapies,” they write.
Senior author Dr Ankit Bharat said the team had found that the same cells activated by severe covid could be induced with a drug to fight cancer.
“We specifically saw a response with melanoma, lung, breast and colon cancer in the study,” Dr Bharat, chief of thoracic surgery and director of the Canning Thoracic Institute, said in a statement.
“What makes these cells so special is their dual capability. Typically, immune cells called non-classical monocytes patrol blood vessels, looking for threats. But they can’t enter the tumour site itself due to the lack of specific receptors.
“In contrast, the I-NCMs created during severe covid-19 retain a unique receptor called CCR2, allowing them to travel beyond blood vessels and infiltrate the tumour environment. Once there, they release certain chemicals to recruit body’s natural killer cells.
“These killer cells then swarm the tumour and start attacking the cancer cells directly, helping to shrink the tumour.
Dr Bharat said the study was in preclinical animal models, but the finding “offers hope that we might be able to use this approach to benefit patients with advanced cancers that have not responded to other treatments”.
