Early C-reactive protein kinetics predicts immunotherapy response in non-small cell lung cancer in the phase III OAK trial.

Static biomarkers like programmed death-ligand 1 (PD-L1) are insufficient to accurately predict response to immune checkpoint inhibition. Therefore, on-treatment biomarkers, which measure immediate therapy-associated changes, are currently shifting into the focus of immuno-oncology. A prime example of a simple predictive on-treatment biomarker is the early C-reactive protein (CRP) kinetics with its predictive CRP flare-response phenomenon. Here, we were able to confirm the predictive value of CRP flare-response kinetics in the pivotal phase III OAK trial (NCT02008227), which compared atezolizumab with docetaxel in patients with non-small cell lung cancer. Of note, CRP flare-response predicted favorable outcomes only in the immune checkpoint inhibition-treated subgroup, which suggests that it is an immunotherapy-specific phenomenon. In conclusion, we have for the first time validated the high predictive value of early CRP kinetics in a pivotal phase III trial, justifying the broad use of this cost-effective and easy-to-implement on-treatment biomarker to optimize therapy monitoring for patients with non-small cell lung cancer.