Immune-checkpoints inhibitors in metastatic non small cell lung cancer with rare histology.

Abstract

9106 Background: Immune-checkpoints inhibitors (ICIs) have clearly improved prognosis of metastatic lung squamous carcinoma and adenocarcinoma, while their benefit remains uncertain in patients (pts) with rare NSCLC histotypes (RH). The study aim was to evaluate ICIs efficacy in RH. Methods: We retrospectively collected data from consecutive metastatic NSCLC pts treated with ICIs at our Institution from 4/2013 to 12/2018. Objective response rate (ORR) and disease control rate (DCR) were assessed. Fisher’s exact test was used to compare ORR and DCR in RH versus not-RH (NRH). Univariate and multivariate survival analyses were estimated by Kaplan-Meier and Cox progression hazard models. Results: Of 268 pts, 31 (11.6%) had RH: 16 sarcomatoid, 7 pulmonary enteric adenocarcinoma, 4 large cell neuroendocrine carcinoma and 4 adenosquamous carcinoma. In RH group, median age was 67 years old (range 41-81), most were males (71%) and smokers (90.3%); ECOG PS was: 0 (16.1%), 1 (67.8%) and 2 (16.1%). PD-L1 < 1%, 1-49%, ≥50% and unknown expression were reported in 22.6%, 19.3%, 35.5% and 22.6% pts, respectively. Twelve pts received ICIs as first and 19 as second or further-line. ORR was 22.6% in RH, 20.3% in NRH (p = 0.81); DCR was 35.5% in RH, 53.1% in NRH (p = 0.08). After a median follow-up of 20 months (m) (95% CI 4.0 – 36.7 m), median progression-free survival (PFS) was 2.6 m (95% CI 1.9-3.3 m) in RH vs 2.6 m in NRH (95% CI 2.1 – 3.0 m); median overall survival (OS) was 4.6 m (95% CI 0.03-12.0 m) in RH vs 9.2 m (95% CI 7.4 – 10.9 m) in NRH. No statistically significant differences were seen between the two groups (p = 0.729 for PFS, p = 0.601 for OS). At multivariate analyses adjusted for age, sex, smoke, PS, PD-L1 status, line of therapy and histotype (RH vs NRH), only low PS and first line treatment showed better PFS and OS (p < 0.001 and p = 0.003, respectively) in overall population. Conclusions: Our analysis, limited by the small and heterogeneous RH sample size, reported no significant differences between RH and NRH in terms of ORR, DCR and survival. However, looking at OS and DCR data, RH seem to have worse outcome. Correlation between histotype and pts characteristics and survival analyses in a larger cohort of ICIs treated NSCLC pts is ongoing. Specific prospective trials are needed to evaluate ICIs role in RH.