We carried out a retrospective cohort study on patients with metastatic non-small cell lung cancer (mNSCLC) to identify the peripheral blood count parameters associated with response to immune checkpoint inhibitors (ICIs). There were 17 males and 15 females. Their median age was 64.5 years (range 20-84). History of smoking was present in 25/32 (78%) patients. Twelve patients received pembrolizumab, 19 patients nivolumab, and one patient nivolumab followed by pembrolizumab. Responses were observed in 19/32 (59%) patients, all partial responses. There was no difference in the distribution of sex, age, and smoking status between responders and non-responders. The median time to response (TTR) was 12 weeks (range 6-24) and the median duration of response (DoR) was 24 weeks (range 7-112). Higher pre-therapy absolute monocyte counts (AMCs) correlated to shorter TTR (p = 0.03), but not to response rate or DoR. Within the group of responders, those with AMCs > 700/mm3 had a significantly shorter median TTR than those with AMCs ≤ 700/mm3 (8 weeks vs 12 weeks; p = 0.048). Although baseline absolute neutrophil counts (ANCs) did not have any prognostic value, ANCs after first dose predicted response to ICI (p = 0.02). Patients with ANCs ≤ 4200/mm3 after first dose were more likely to respond than those with ANCs > 4200/mm3 (OR = 6.8; 95% CI 1.1-41.8; p = 0.05). Analysis of AMC and ANC before and during therapy may, therefore, provide an easy method to identify those mNSCLC patients most likely to benefit from ICI therapy.
Keywords: Absolute monocytes; Absolute neutrophils; Immune checkpoint inhibitors; Non-small cell lung cancer.