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The PD-L1 IHC 22C3 pharmDx is an FDA-approved companion diagnostic to pembrolizumab designed for use on Autostainer Link 48. This study, published in Pathology, compared a 22C3 antibody-based laboratory-developed test (LDT) on BenchMark XT with the FDA-approved PD-L1 IHC 22C3 pharmDx.

Pan-tumor data for this study included samples from a total of 327 patients with esophageal squamous cell carcinoma, head and neck squamous cell carcinoma, and urothelial carcinoma. These samples were stained with the 22C3 antibody, scored using the LDT on BenchMark XT, and compared with PD-L1 IHC 22C3 pharmDx.

Ultimately, it was found that the LDT showed a high concordance with the PD-L1 IHC 22C3 pharmDx, regardless of tumor type. The researchers concluded that this result indicates the possible comparability of PD-L1 IHC 22C3 pharmDx with an LDT based on the 22C3 antibody. However, additional analysis is needed to confirm these findings and pursue future applications [1].


[1] Vainer, G. W., Zatara, G., Huang, L., Emancipator, K., & Nuti, S. (2021). Analytical comparison of a PD-L1 22C3 antibody laboratory-developed test (LDT) protocol on the benchmark XT and PD-L1 IHC 22C3 pharmdx: analysis of pan-tumour and oesophageal cancer samples. Pathology, 53, S47. https://doi.org/10.1016/j.pathol.2021.06.098

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