Abstract 1323P
Background
Immunotherapy has improved survival for patients with incurable non-small cell lung cancer (NSCLC). The only validated biomarker is tumour PD-L1 expression. The aim of the present study was to evaluate NK cell activity as a prognostic biomarker in patients with NSCLC treated with PD-1/PD-L1 inhibitors.
Methods
Enrolled patients were eligible for PD-1/PD-L1 inhibitor treatment (any line). NK cell activity was estimated using 1 ml of blood. Blood was sampled into special tubes (NK Vue® tubes) and placed in an incubator at 37°C within 15 minutes of sampling. Following 24 hours of stimulation the level of interferon gamma (IFNγ) in the plasma was measured by ELISA (NK Vue® ELISA) as a surrogate for NK cell activity. Cutpoint between high and low NK cell activity was set at IFNγ 200 pg/ml per the manufacturer’s recommendation.
Results
Blood samples were available from 78 patients before, and 73 patients after, the first cycle of treatment. There was no significant difference in IFNγ between baseline (median 158 pg/ml, interquartile range [IQR] 32.5-424 pg/ml) and after the first treatment cycle (median 154 pg/ml, IQR 32.5-500 pg/ml, p=0.697, Wilcoxon signed-rank test). In patients with high NK cell activity (IFNγ >= 200 pg/ml) after the first cycle of treatment, 21% had progressive disease at the first evaluation. This was 34% for patients with low NK cell activity (IFNγ < 200 pg/ml), but the difference did not reach statistical significance (p=0.061, Fisher’s exact test). There was no statistically significant difference in overall survival (OS) when grouping patients into high vs low NK cell activity at baseline. However, high NK cell activity after one cycle of PD-1/PD-L1 inhibitor was a favourable prognostic factor with a median overall survival (OS) of 436 days (IQR 234-597 days) compared to patients with low NK cell activity (median 216 days, IQR 143-492 days, p=0.004, Logrank test).
Conclusions
High NK cell activity after the first cycle of PD-1/PD-L1 inhibitor is a favourable prognostic factor in patients with NSCLC.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
NKMax America provided NK Vue test kits free of charge for use in the study. The Danish Foundation for Cancer Research (non-profit foundation). The Department of Oncology, Vejle Hospital.
Disclosure
A. Jakobsen: Non-remunerated activity/ies, Received NK Vue test kits free of charge: NKMax America. All other authors have declared no conflicts of interest.