IHC validation in clinical settings; how lab developed assays drive clinical therapies
Langlois, Sarah Elizabeth
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Diagnostic laboratory tests are critical to patient care as they help dictate the most appropriate treatments and procedures. To that end, hospitals and laboratories must ensure their diagnostic assays are optimized so as to afford patients their best chance for recovery. The pathology laboratory at Boston Medical Center, like all testing labs, must validate their IHC protocols yearly according to ASCO/CAP guidelines. Furthermore, BMC has a diverse patient population similar to the Atlanta population-based study published by Lund, et al. in 2010. Based on the results of the yearly ASCO/CAP testing and compared with the results of the Atlanta study, it was found that BMC’s HER2 testing was most likely not capturing all positive cases consistently. This prompted an optimization procedure for HER2 to be implemented. In addition to HER2 testing, BMC is looking at ways to optimize and implement PD-L1 IHC protocols as a way to identify those patients who might benefit from more targeted therapy. METHODS: HER2 IHC was performed with an altered protocol to attempt a higher concordance rate with PhenoPath, a reference lab in Seattle, and the Atlanta study data. ER and PR validation IHC protocols were also performed to ensure adequate concordance with required yearly testing. RESULTS: ER and PR protocols were found to be >95% accurate as compared to reference lab results. The new HER2 protocol yielded more vibrant staining results when compared to known positive reference data and previous BMC testing of the same sample. DISCUSSION: Optimizing lab assays is a critical step in ensuring proper clinical therapies are being utilized. Regular testing of a lab’s IHC output must be continuously verified, and continued data collection of the improved HER2 protocol is needed to make sure appropriate standards are being met. Further testing of PD-L1 IHC protocols will be warranted to maintain maximum efficiency.