Researchers discovered that mRNA vaccines originally designed to protect against COVID‑19 (i.e., SARS-CoV-2 mRNA vaccines) can also “wake up” the immune system in ways that make certain tumours more responsive to cancer immunotherapy. Specifically:

• In animal models, when tumours that normally don’t respond well to immune checkpoint inhibitors (ICIs) were given an mRNA vaccine plus ICI, the combination suppressed tumour growth more significantly than either treatment alone.

• The vaccine triggered a surge in type I interferon and activated innate immune cells (myeloid cells, dendritic cells) which then helped prime CD8⁺ T cells to recognise tumour-associated antigens.

• In human data from several cohorts of patients with cancers treated with ICIs (such as non-small-cell lung cancer and melanoma), those who had received a SARS-CoV-2 mRNA vaccine within about 100 days before starting ICI therapy had notably better survival outcomes compared to those who had not.

• The study also found that tumours biopsied after recent mRNA vaccination showed increased expression of PD-L1 (a marker often used to predict response to ICI), suggesting the vaccine induced changes in the tumour micro-environment that may make the cancer more “visible” to immunotherapy.

In short

Giving a SARS-CoV-2 mRNA vaccine shortly before or in combination with immune-checkpoint therapy may help “turn on” an immune response in tumours that normally ignore immunotherapy. This finding opens a new avenue: using established mRNA vaccine technology not just for infectious disease, but as a tool to enhance cancer treatment.