Mahoney Kathleen M, Sun Heather, Liao Xiaoyun, Hua Ping, Callea Marcella, Greenfield Edward A, Hodi F Stephen, Sharpe Arlene H, Signoretti Sabina, Rodig Scott J, Freeman Gordon J
Department of Medical Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts. Division of Hematology and Oncology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts.
Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts.
Cancer Immunol Res. 2015 Dec;3(12):1308-15. doi: 10.1158/2326-6066.CIR-15-0116. Epub 2015 Nov 6.
Blocking the programmed death-1 (PD-1) pathway has clinical benefit in metastatic cancer and has led to the approval of the mAbs pembrolizumab and nivolumab to treat melanoma and nivolumab for non-small cell lung cancer. Expression of PD-L1 on the cell surface of either tumor cells or infiltrating immune cells is associated with a higher likelihood of response to PD-1 blockade in multiple studies. Most mAbs to PD-L1 in use are directed to its extracellular domain and immunohistochemically stain tumor tissue with a mixture of cytoplasmic and membrane staining. Cytoplasmic staining obscures the interpretation of a positive reaction on the tumor cell membrane, and thus affects the accuracy of PD-L1 scoring systems. We developed a mAb to the cytoplasmic domain of PD-L1, 405.9A11 (9A11), which is both more selective for membranous PD-L1 and more sensitive in IHC and Western blotting, compared with previous mAbs specific for the PD-L1 extracellular domain. Here, we compare immunohistochemical staining patterns of PD-L1 expression in five types of tumors, using five PD-L1 mAbs: 9A11, 7G11, and three commercially available mAbs. We demonstrate that 9A11, as well as two other cytoplasmic domain-specific mAbs, E1L3N and SP142, can clearly delineate the membrane of PD-L1-positive cells in formalin-fixed paraffin-embedded tissue and facilitate interpretation of staining results.
阻断程序性死亡-1（PD-1）通路在转移性癌症治疗中具有临床益处，这已促使帕博利珠单抗和纳武利尤单抗两种单克隆抗体获批用于治疗黑色素瘤，纳武利尤单抗获批用于治疗非小细胞肺癌。在多项研究中，肿瘤细胞或浸润免疫细胞表面的PD-L1表达与对PD-1阻断产生应答的可能性较高相关。目前使用的大多数针对PD-L1的单克隆抗体均靶向其细胞外结构域，并通过细胞质和膜染色的混合物对肿瘤组织进行免疫组织化学染色。细胞质染色会模糊肿瘤细胞膜上阳性反应的解读，从而影响PD-L1评分系统的准确性。我们开发了一种针对PD-L1细胞质结构域的单克隆抗体405.9A11（9A11），与先前针对PD-L1细胞外结构域的单克隆抗体相比，它对膜性PD-L1的选择性更高，在免疫组织化学和蛋白质印迹法中也更敏感。在此，我们使用五种PD-L1单克隆抗体（9A11、7G11和三种市售单克隆抗体）比较了五种肿瘤类型中PD-L1表达的免疫组织化学染色模式。我们证明，9A11以及另外两种针对细胞质结构域的单克隆抗体E1L3N和SP142，能够在福尔马林固定石蜡包埋组织中清晰勾勒出PD-L1阳性细胞的膜，并有助于染色结果的解读。
