Abstract
Aims
PD-L1 immunohistochemistry has become a mandatory diagnostic test in the treatment of lung cancer. Several research-initiatives have started to harmonize the five PD-L1 immunohistochemistry assays that have been used in clinical trials. Here we report data on interlaboratory- and interassay-concordance using commercial assays ('assays') and laboratory-developed tests (LDTs) at ten German testing-sites.
Methods and results
To assess interlaboratory-concordance a tissue-microarray containing 21 pulmonary carcinoma specimens was centrally prepared. Pre-cut sections were stained at ten sites using assays 28-8, 22C3, SP263 and SP142 as well as eleven LDTs. Assay-performance was evaluated with a second tissue-microarray containing eleven cell-lines with defined PD-L1 expression.
Quality-control was centrally performed by manual and digital analyses. The assays yielded reproducible IHC stainings at all sites. In agreement with previous studies, 22C3, 28-8 and SP263 showed similar staining patterns while SP142 was distinct. Among the LDTs, six of eleven protocols showed staining patterns similar to assays 22C3 and 28-8. Interlaboratory-concordance of tumor-cell scoring using a 6-step system was moderate (Light's kappa=0.43-0.69) while the clinically approved cut-offs ≥1% and ≥50% showed substantial concordance (kappa=0.73-0.89). Immune-cell scoring using assay SP142 yielded a moderate concordance (kappa=0.42).
Conclusions
The data confirm the previously described staining patterns of the assays and show that they can be reproducibly employed at different sites. LDTs with staining results similar to the assays are implementable yet have to be carefully validated.
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from #ORL-AlexandrosSfakianakis via ola Kala on Inoreader http://ift.tt/2vASpwv
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