Abstract 1408P
Background
ROS1 is the third specific driver gene after EGFR and ALK in NSCLC, and the occurrence frequency is about 1-2%. Compared with traditional FISH and ICH methods, NGS has significant advantages in detecting ROS1 variation. Not only fusion can be detected, but also ascertain fusion partners and fracture sites can be discovered by using NGS. Liquid biopsy based on ctDNA is more and more used in some type of cancers, the use of ctDNA to detect ROS1 variation has become a reliable method for precision treatment of NSCLC. However, the occurrence frequency, common fusion partners and common fracture sites of ROS1 malignant mutation (MUT) in Chinese NSCLC patients are still rarely reported, and the difference in positive rate between tissue and liquid biopsy is still unclear.
Methods
The genetic testing data of Chinese NSCLC patients detected by 3D Medicines (Shanghai, China) with NGS method were retrospectively analyzed. Illumina Neseq-500 sequencing platform was used to detect tissue and peripheral blood samples.
Results
A total of 14971 patients’ samples were analyzed, and 72 (0.48%) were found to carry ROS1 MUT-fusion, including 1 case of squamous cell carcinoma (CD74 - ROS1), and the rest were all adenocarcinoma. Among them, 8515 and 6052 cases were detected with tissue sample or peripheral blood, respectively, 404 cases were detected with both tissue and peripheral blood; 60 (0.67%) detected with tissue sample and 12 (0.19%) detected with peripheral blood were carrying ROS1 MUT-fusion, respectively. The most common fusion partners were CD74 (34, 47.22%), followed by EZR (17, 23.61%), SDC4 (11, 15.28%), TPM3 (3, 4.17%), SLC34A2 (2, 2.78%), NPM1 (1, 1.67%), LRIG3 (1, 1.67%), GRIK2 (1, 1.67%), GOPC (1, 1.67%), and CCDC6 (1, 1.67%). The ROS1 fracture site was located at exon 31-35, among which exon 34 (40, 55.56%), 32 (12, 16, 67%), 33 (12, 16.67%), 35 (6, 8.33%) and 31 (2, 2.78%).
Conclusions
The detection of ROS1 by NGS can clearly distinguish the MUT-fusion from the very likely malignant (VLM) variations and the variants of unknown significance (VOUS). Moreover, ctDNA can be used for the detection of ROS1 fusion, but the positive rate is significantly lower than in tissue detection. The most common fusion partner in Chinese NSCLC patients is CD74, and the most common fracture site is exon 34.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
Depei Huang.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.