TEST:

VENTANA ROS1 (SP384) Rabbit Monoclonal Primary Antibody

Given the recent approval of crizotinib in Colombia, public health policies must be oriented toward early detection of driver mutations and prompt treatment. Additionally, future approvals of newly tested tyrosine kinase inhibitors should be anticipated.

The prevalence of ROS1 fusion in an LUAD stage I-III European cohort was relatively low. ROS1 IHC using SP384 clone is useful for exclusion of ROS1 gene fusion negative cases.

Our inhouse panel was associated with rapid TAT and faster initiation of systemic treatment. Approximately 30% of patients would not need tissue sent for NGS based on inhouse detection of a potentially actionable mutation.

No additional ROS1 fusion was identified by FISH or NGS among IHC 0/1+. Thus, this method is useful for preselection of patients with a potential ROS1 fusion, followed by confirmatory FISH and/or NGS.

"The presumably false-positive and uncertain FISH results questions this method for detection of ROS1-rearrangements. Thus, when IHC is used for screening, transcript-based assays are preferable for validation in clinical diagnostics."

Our data indicate that the occurrence of ROS1 fusions is exceedingly low in resected NSCLC. IHC assays are able to detect this fusion, however, the accuracy is variable depending on the used clone. The false positive FISH and several uncertain FISH results neither support the use of FISH as a screening nor as a reference Method to detect ROS1-rearrangement in NSCLC.

Conclusion Both IHC-clones showed a strong and homogenous staining with H-score above 200 in the three cases were both FISH and NGS confirmed the presence of ROS1 fusion. The ROS1 frequency in adenocarcinomas was 0.5%, which is somewhat lower than what has been found in studies including mostly stage IV (1-3 %).

"Introduction: The development of several ROS1 inhibitors means that the importance of accurately identifying ROS1-positive lung cancer patients has never been greater. Therefore, it is crucial that ROS1 testing assays become more standardized.Areas covered: Based on primary literature, combined with personal diagnostic and research experience, this review provide a pragmatic update on the use of the recently released VENTANA ROS1 (SP384) Rabbit Monoclonal Primary Antibody.Expert opinion: This assay provides high sensitivity, so it is an excellent analytical option when screening for ROS1 fusions in patients with advanced non-small cell lung carcinomas."