147P - Clinical characteristics and outcomes in non-small cell lung cancer patients harboring rare mutations: A single center real-world data

Background

Lung cancer remains the leading cause of cancer-related mortality. Rare molecular alterations (alt) are those that occur in ≤ 5% of Non-Small Cell Lung Cancer (NSCLC) and include BRAF V600E, MET exon 14 mutation (mut), NTRK rearrangement, RET rearrangement, HER2 exon 20 insertion (ins), ROS1 alterations and EGFR exon 20 ins.

Methods

A retrospective, observational study was conducted in our institution. Patients (pts) with histologically proven NSCLC and a positive molecular study performed between 2018-2021 were included. Our aim was to evaluate the incidence of oncogenic rare alts, compare overall survival (OS) in each subgroup and identify possible prognostic factors.

Results

From 505 pts diagnosed with NSCLC, we found molecular alt in 159 pts (31.5%). Of those 159 pts, median age at diagnosis was 67.0 years-old (38-92), 108 (67.9%) were males and 107 (67.3%) had a performance status (PS) of 0-1. Adenocarcinoma was the most frequent histology (143, 89.9%) with 119 (74.8%) being diagnosed in stage IV and 120 (75.5%) having tobacco exposure. Most common site of metastases was lymph nodes (62, 39.0%) and bone (54, 34.0%). Brain metastasis was seen in 37 (23.3%) pts. The proportion of rare mutations was 26 (5.1% of the population with NSCLC). The most prevalent was MET exon 14 mut (11, 2.2%), followed by BRAF V600E (5, 0.9%), HER2 exon 20 ins (3, 0.6%), RET and ROS1 (each n=2, 0.4%). With 32 pts (20.1%) being alive at time of analysis, median OS was 12.0 months (CI95 8.4-15.6). Although BRAF V600E alts were associated with a longer median OS [17.0 mo (CI95 0-45)], the log-rank test showed no difference in OS between pts with rare alt and other alt (p=0.506). As 1st-line treatment most pts with rare alt received chemotherapy (11, 42.3%) and targeted therapy was primarily given in only 4 pts (2 Dabrafenib+Trametinib and 2 Crizotinib). Liver metastases were identified as an unfavorable prognostic factor for OS (p<0.05) in multivariate Cox regression.

Conclusions

In our cohort, the incidence of rare alt was lower than described in the literature (0.4 to 2.2%), and there was a high prevalence rate of smokers, male and older pts. The median OS for pts with rare alt was comparable to those with more common mutations.

Editorial acknowledgement

Clinical trial identification

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.