The 22 October issue of Nature featured a paper titled “SARS-CoV-2 mRNA vaccines sensitize tumours to immune checkpoint blockade” and a summary article titled “Tumours might be sensitized to immune therapy by COVID mRNA vaccines.” Because Nature uses British rather than American English, “tumour” is spelled with a “u” instead of the American “tumor.” When I was in my first year of junior high school, our English textbook followed British usage, but from the second year onward it switched to American English. So I understand the difference between the two English systems, but I still can’t help feeling a bit of discomfort when I see the contrast.
Returning to the main topic: for cancer patients treated with immune-checkpoint antibodies, those who received an mRNA vaccine against SARS-CoV-2 within 100 days of starting ICI therapy showed better treatment outcomes of ICI. This enhancement was not observed with the influenza vaccine, suggesting that the effect is likely to be specific to mRNA vaccines.
Looking at 30-month overall survival in stage IV non–small cell lung cancer (NSCLC) and melanoma, the differences are striking. For NSCLC, survival was about 60% in the vaccinated group vs. about 30% in the unvaccinated group, roughly a two-fold difference. For melanoma, survival was around 75% for the vaccine group vs. slightly under 50% for non-vaccinated patients, again a substantial gap. Statistical analysis also showed solid significance, with p = 0.0002 for lung cancer and p = 0.0048 for melanoma.
How mRNA vaccines enhance the efficacy of immune-checkpoint antibodies remains partly mysterious. It is still unclear whether the effect comes from the RNA itself or from immune activation triggered by its delivery system. If the vaccine and checkpoint therapy were administered at the same time, the difference might be even greater. Advances in technology often bring unexpected phenomena.
Perhaps surprising effects could also emerge from combining immune-checkpoint antibodies with the Maruyama vaccine. And if we further combine these with neoantigen-based approaches, we might even move closer to truly curing cancer.
