Merck and QualTek, now part of Discovery Life Sciences (DLS), jointly developed the prototype companion diagnostic immunohistochemistry (IHC) assay for measuring PD-L1 expression among patients in clinical trials to predict those who have a higher likelihood of experiencing a response with pembrolizumab.

The prototype IHC assay was utilized prospectively in early MK3475 (pembrolizumab) NSCLC and melanoma patient enrolled trials.

Following early approvals for pembrolizumab, DLS continues to serve as the preferred specialty lab for PD-L1 CDx testing in Merck Investigator Study Protocol (MISP) studies, Merck External Collaborator Studies (MECS) as well as Merck sponsored clinical studies.

In this presentation, data presented is adapted to only IHC experiments from the publication in Archives of Pathology Laboratory Medicine (2016; 140:1259-1266; doi: 10.5858/arpa.2015-0544-OA).