Background: The treatment efficacy of immune checkpoint inhibitors (ICIs) is limited, and biomarkers that identify responders are urgently needed. We investigated whether C-reactive protein (CRP) kinetics are associated with the treatment efficacy of ICIs and prognosis in oesophagogastric cancers.
Methods: We analysed 76 gastric cancer patients treated with nivolumab monotherapy. Patients were classified as CRP-spike, CRP-flat or CRP-increase according to CRP kinetics within 6 weeks after nivolumab initiation, and the treatment response and prognosis were compared. We further validated this classification in 71 oesophageal cancer patients with nivolumab monotherapy.
Results: In the gastric cancer cohort, the CRP-spike, CRP-flat, and CRP-increase subgroups included 9, 37 and 30 patients, respectively. The CRP-spike subgroup had higher disease control rates than the CRP-increase subgroup (P = 0.0068) and had significantly better progression-free survival (PFS) (vs. CRP-flat: P = 0.045, CRP-increase: P = 0.0001). Multivariate analysis for PFS identified CRP-spike (HR = 0.38, P = 0.029) as an independent favourable prognostic factor. In the oesophageal cancer cohort, the CRP-spike, CRP-flat, and CRP-increase subgroups included 13, 27 and 31 patients, respectively, and multivariate analysis for PFS also identified CRP-spike (HR = 0.28, P = 0.0044) as an independent favourable prognostic factor.
Conclusions: CRP kinetics may be useful in predicting the long-term outcome of nivolumab treatment in oesophagogastric cancers.
© 2023. The Author(s).