Immune checkpoint inhibitors, like anti-PD-1 and anti-CTLA-4, are effective against cancer, but not all patients respond
How could the response be improved? Here's an idea from this week's issue of Science
Giampazolias et al. found that feeding mice a diet high in vitamin D enriched the microbiome with a specific bacterium, Bacteroides fragilis
If these vitamin D-enriched microbiomes were transplanted into new mice (via a fecal transplant, FT), they enhanced the activity of anti-CTLA-4 or anti-PD-1 therapy against tumours:
In humans, high levels of genes controlled by vitamin D and its receptor (VDR) correlated with better response to checkpoint inhibition (CPI) by anti-PD-1 and anti-CTLA-4:
What this suggests is that supplementing with vitamin D, a vitamin D-enriched microbiome, or Bacteroides fragilis itself, could enhance the antitumour immunity of checkpoint inhibitors - although this (to my knowledge) is yet to be directly tested in humans
One question that arises: if the activity of anti-PD-1/anti-CTLA-4 against the tumour is increased, are there also more immune-mediated adverse events (e.g., inflammatory or autoimmune)?
Here's the study:
science.org/doi/10.1126/scie…