Identifying and targeting ROS1 gene fusions in non-small cell lung cancer.
OBJECTIVE
Oncogenic gene fusions involving the 3' region of ROS1 kinase have been identified in various human cancers. In this study, we sought to characterize ROS1 fusion genes in non-small cell lung cancer (NSCLC) and establish the fusion proteins as drug targets.


METHODS
An NSCLC tissue microarray (TMA) panel containing 447 samples was screened for ROS1 rearrangement by FISH. This assay was also used to screen patients with NSCLC. In positive samples, the identity of the fusion partner was determined through inverse PCR and reverse transcriptase PCR. In addition, the clinical efficacy of ROS1 inhibition was assessed by treating a ROS1-positive patient with crizotinib. The HCC78 cell line, which expresses the SLC34A2-ROS1 fusion, was treated with kinase inhibitors that have activity against ROS1. The effects of ROS1 inhibition on proliferation, cell-cycle progression, and cell signaling pathways were analyzed by MTS assay, flow cytometry, and Western blotting.


RESULTS
In the TMA panel, 5 of 428 (1.2%) evaluable samples were found to be positive for ROS1 rearrangement. In addition, 1 of 48 patients tested positive for rearrangement, and this patient showed tumor shrinkage upon treatment with crizotinib. The patient and one TMA sample displayed expression of the recently identified SDC4-ROS1 fusion, whereas two TMA samples expressed the CD74-ROS1 fusion and two others expressed the SLC34A2-ROS1 fusion. In HCC78 cells, treatment with ROS1 inhibitors was antiproliferative and downregulated signaling pathways that are critical for growth and survival.


CONCLUSIONS
ROS1 inhibition may be an effective treatment strategy for the subset of patients with NSCLC whose tumors express ROS1 fusion genes.
Division of Medical Oncology, University of Colorado, MS 8117, 12801 E. 17th Ave, Aurora, CO 80045, USA.
Kurtis D
KD
Davies
Anh T
AT
Le
Mariana F
MF
Theodoro
Margaret C
MC
Skokan
Dara L
DL
Aisner
Eamon M
EM
Berge
Luigi M
LM
Terracciano
Federico
F
Cappuzzo
Matteo
M
Incarbone
Massimo
M
Roncalli
Marco
M
Alloisio
Armando
A
Santoro
D Ross
DR
Camidge
Marileila
M
Varella-Garcia
Robert C
RC
Doebele
D000328:Adult; D000368:Aged; D000944:Antigens, Differentiation, B-Lymphocyte / Q000235:genetics; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics / Q000378:metabolism / Q000473:pathology / Q000628:therapy; D002453:Cell Cycle / Q000187:drug effects / Q000235:genetics; D049109:Cell Proliferation / Q000187:drug effects; D000077547:Crizotinib; D005260:Female; D000949:Histocompatibility Antigens Class II / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D015514:Oncogene Proteins, Fusion / Q000235:genetics / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000008:administration & dosage; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D011720:Pyrazoles / Q000008:administration & dosage; D011725:Pyridines / Q000008:administration & dosage; D050614:Sodium-Phosphate Cotransporter Proteins, Type IIb / Q000235:genetics / Q000378:metabolism; D053671:Syndecan-4 / Q000235:genetics
D000944:Antigens, Differentiation, B-Lymphocyte; D000949:Histocompatibility Antigens Class II; D015514:Oncogene Proteins, Fusion; D047428:Protein Kinase Inhibitors; D011518:Proto-Oncogene Proteins; D011720:Pyrazoles; D011725:Pyridines; C508304:SDC4 protein, human; C493557:SLC34A2 protein, human; D050614:Sodium-Phosphate Cotransporter Proteins, Type IIb; D053671:Syndecan-4; C045084:invariant chain; D000077547:Crizotinib; D011505:Protein-Tyrosine Kinases; C062333:ROS1 protein, human