TAT 2018: Predicting response to immunotherapy

Speaker: Ignacio Melero

Ignacio Melero explains that because we have very imperfect predictive biomarkers, we are achieving very meaningful clinical efficacy in about 20% of our patients depending on type of disease, and we see marginal benefit in another fraction of patients. Several other parameters helping to predict the response to immunotherapy were elaborated. 

We have seen that having T-lymphocytes in the tumour microenvironment is a good predictive factor and is reflected by the fact that tumour cells are trying to escape by expressing immuno regulatory molecules including PD-L1.
There is some interesting correlative science in the antigenicity of the tumour reflected by the number of non-synonymous mutations that are encoded in the genome of the tumour cells.  
At TAT 2018 Congress, there was a session devoted to the effect that gut microflora exerts on the efficacy of immunotherapy.  
Another simpler parameter in peripheral blood could be the level of some circulating cytokines which might be predictive in PD1 and CTLA-4 targeted therapies.
There is a lot of research going on and it’s highly likely that very soon we will see some stratification based on tumour mutation burden estimated with a precision medicine sequencing data. Regarding other biomarkers such as interferon gamma signatures in the tumour or T-cell infiltration, we will probably have to wait a little bit more.
A take-home message is that some biomarkers are already a clinical reality and many more are coming.