Difference between revisions of "Programmed death-ligand 1"
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m (PDL1 immunoexpression does not always predict response to PDL1 blockade) |
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==General== | ==General== | ||
*In theory, positive PD-L1 [[IHC|immunostaining]] predicts response to anti-PD-L1 drugs.<ref name=pmid26970723/> | *In theory, positive PD-L1 [[IHC|immunostaining]] predicts response to anti-PD-L1 drugs.<ref name=pmid26970723/> | ||
**Carcinoma cell is considered "PD-L1 positive" if the cell membrane is partially or completely stained. <ref name="pmid27389313">{{ | **Carcinoma cell is considered "PD-L1 positive" if the cell membrane is partially or completely stained. <ref name="pmid27389313">{{Cite journal | last1 = Scheel | first1 = AH. | last2 = Dietel | first2 = M. | last3 = Heukamp | first3 = LC. | last4 = Jöhrens | first4 = K. | last5 = Kirchner | first5 = T. | last6 = Reu | first6 = S. | last7 = Rüschoff | first7 = J. | last8 = Schildhaus | first8 = HU. | last9 = Schirmacher | first9 = P. | title = Harmonized PD-L1 immunohistochemistry for pulmonary squamous-cell and adenocarcinomas. | journal = Mod Pathol | volume = 29 | issue = 10 | pages = 1165-72 | month = Oct | year = 2016 | doi = 10.1038/modpathol.2016.117 | PMID = 27389313 }}</ref> | ||
*It is, however, more complex than that. Some tumour types are invariably positive, e.g. classical Hodgkin lymphoma, so testing is unhelpful. In contrast, tumors such as malignant melanoma respond regardless of PD-L1 immunoexpression. | *It is, however, more complex than that. Some tumour types are invariably positive, e.g. classical Hodgkin lymphoma, so testing is unhelpful. In contrast, tumors such as malignant melanoma respond regardless of PD-L1 immunoexpression. | ||
*The plethora of companion diagnostics developed for each PD-1/ PD-L1 inhibitor has created challenges, as these assays include different IHC antibody clones, staining protocols and platforms, scoring systems, and cutoffs for defining positivity. | *The plethora of companion diagnostics developed for each PD-1/ PD-L1 inhibitor has created challenges, as these assays include different IHC antibody clones, staining protocols and platforms, scoring systems, and cutoffs for defining positivity. | ||