Prognosis of immunotherapy for non-small cell lung cancer with CDKN2A loss of function

Background: Immunotherapy has been widely used to treat non-small cell lung cancer (NSCLC) but is only effective in 20% of patients. Cyclin-dependent kinase inhibitor 2A (CDKN2A) is an important tumor suppressor gene, and its loss of function (LOF) is quite common in NSCLC. Pre-clinical studies suggest CDKN2A LOF promotes immune evasion; however, the results in relation to NSCLC are controversial, and debate continues as to the effect of CDKN2A LOF on immunotherapy.

Methods: In this study, we collected the data of 49 CDKN2A LOF and 173 CDKN2A wild-type NSCLC consecutive patients treated by any line of immunotherapy. Through immunohistochemical (IHC) and immunofluorescent (IF) staining, we analyzed the CDKN2A predominant transcription protein p16^INK4A in the CDKN2A LOF and CDKN2A wild-type NSCLC patients. Using Kaplan-Meier curves, we also examined the relationship between CDKN2A LOF and immunotherapy.

Results: The IHC and IF staining results showed that most CDKN2A LOF patients were p16^INK4A negative, while most CDKN2A wild-type patients were p16^INK4A positive. In the LOF group, five patients had partial responses, 35 had stable disease, and nine had progressive disease after the first evaluation of immunotherapy. The LOF group had a median progression-free survival (PFS) time of 4.67 months, while the wild-type group had a median PFS time of 8.63 months [hazard ratio (HR): 0.54; 95% confidence interval (CI): 0.38-0.77; P<0.001]. The LOF group had a median overall survival (OS) time of 9.07 months, while the wild-type group had a median OS time of 21.37 months (HR: 0.42; 95% CI: 0.29-0.61; P<0.001).

Conclusions: Our study revealed that CDKN2A LOF NSCLC patients treated with immune checkpoint inhibitor (ICI) mono-therapy or combined therapy had a worse prognosis than those with CDKN2A wild-type NSCLC. However, our study also suggested that ICI could work quite effectively in selective CDKN2A LOF patients.