Hidden arm against tumors: microbiota-enabled checkpoint immunotherapy

This week Science published two studies showing how diverse microbiota directly contributes to efficacy of PD-1 checkpoint immunotherapy in several tumors.

First, we need to mention that senior authors from both papers disclosed associations with for-profit pharma/biotech companies (as cofounders, stockholders, paid consultants or advisory board members). Such associations could, in general, be seen as problematic if one promotes therapy lacking particularities.     

Second, data presented do not advance our understanding how microbiota contributes to the effectiveness of checkpoint immunotherapy. The sole conclusion from both papers is that the more diverse cancer patient's microbiota the more benefit it provides during PD-1 immunotherapy. However, when it comes to narrow down beneficial correlation to particular species we find that one paper reported enrichment of Akkermansia muciniphila while other paper reported enrichment of Faecalibacterium and Clostridiales in Responders (as opposed to Non-Responders).

We still don't know much about the role of microbiota in cancer immunotherapy. I think real advance will come when we define how antigens derived from specific microbiota contribute to anti-cancer immunotherapy either by amplifying existing cross-reactive effector T cells or Foxp3+ Tregs. 

posted by David Usharauli