medwireNews: ROS1 fusions predict a poor outcome in Chinese patients with non-small-cell lung cancer (NSCLC), study findings suggest.
The results showed that the 2.0% of 392 Chinese patients with NSCLC with an ROS1 fusion had significantly shorter median survival than their ROS1-negative counterparts, at 32.2 versus 53.9 months.
Of the eight ROS1-positive patients, five were female, five had never smoked, seven had adenocarcinoma, and one had adenosquamous carcinoma.
However, patients with and without ROS1 fusions did not significantly differ with regard to age, gender, history of smoking, or tumor histology and pathologic stage, say Ke Fei (Tongji University School of Medicine, Shanghai, China) and co-authors in Annals of Oncology.
These findings contradict earlier research suggesting that ROS1-positive patients tend to be young, never smokers with adenocarcinoma, say the authors, who also note that this evidence is weak, owing to the small proportion of NSCLC patients carrying ROS1 fusions.
In multivariate analysis, pathologic stage I/II disease was the most significant predictor for survival (odds ratio [OR]=2.947 vs Stage III/IV), followed by ROS1-negative status (OR=2.569 vs positive status) and age younger than 65 years (OR=1.489 vs older age).
The team says that the slightly higher ROS1 fusion rate in their study compared with previous research may be due to the use of reverse transcription-polymerase chain reaction (RT-PCR) over fluorescent in situ hybridization and other screening techniques.
RT-PCR also allowed for identification of the exact fusion pattern; SLC34A2-ROS1 fusion was identified in four patients, CD74-ROS1 in three patients, and SDC4-ROS1 in one patient. One patient carried two variants of SLC34A2-ROS1, with SCL34A2 exon 13 fused to ROS1 at exon 32 or 34.
The ability to characterize ROS1 fusion may be important in the clinic if, as suspected, tumor sensitivity to ALK/ROS1 inhibitors is shown to differ depending on the exact ROS1 fusion patterns, the researchers comment.
"Given the demonstrated good clinical efficacy of crizotinib in the treatment of NSCLC harboring ROS1 fusions, our study provides new insights into the definition of the NSCLC population most likely to benefit from crizotinib in the absence of a standard diagnostic approach for NSCLC harboring ROS1 fusions at present," Fei et al conclude.
"An expanded study on ROS1 fusions in Chinese NSCLC patients is ongoing," they add.
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