There is not for the moment a standard test to determine a relevant target population. Preliminary data showed that around 25% of the NSCLC population may have a high PDL1 expression and may have a greater benefit of anti PDL1 therapy. But in fact limited data have been published in European populations on the clinical and pathological characteristics (high PDL1 expression) compared to the weak expression and no expression populations. More over the prognosis rule of a high PDL1 expression in NSCLC is not definitive, with some studies indicating it is a positive prognostic factor while other studies showing that it is a negative prognostic factor.