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. Author manuscript; available in PMC: 2019 Jul 1.
Published in final edited form as: Cancer Discov. 2018 May 17;8(7):822–835. doi: 10.1158/2159-8290.CD-18-0099

Figure 3. LKB1 expression by IHC can identify LKB1-deficient LUAC in the absence of STK11/LKB1 alterations.

Figure 3

A. LKB1 IHC expression (H-score) in KRASMUT;STK11/LKB1MUT (KL) and KRASMUT;STK11/LKB1WT LUAC. Quantitative IHC using a commercially available LKB1 rabbit monoclonal antibody (clone D60C5F10, Cell Signaling Technology) is technically robust and can identify LKB1-deficient tumors with intact STK11/LKB1 genomic locus (26). (Left panel) KL LUAC (N=12) exhibit absent or minimal cytoplasmic LKB1 staining, whereas KRASMUT;STK11/LKB1WT LUAC (N=34) display variable LKB1 H-score. LUAC were therefore considered LKB1-proficient if they had intact STK11/LKB1 locus and expressed LKB1 by IHC at any level (LKB1 H-score > 0) and LKB1-deficient if they were STK11/LKB1-altered and/or exhibited LKB1 H-score = 0. Representative images of KL and KP LUAC immuno-stained for LKB1 are included (right panel). Staining was performed as previously described (26). B. Kaplan-Meier estimates of progression-free survival (left panel) and overall survival (right panel) with PD-1 blockade in LKB1-deficient (STK11/LKB1-mutant and/or LKB1 H-score = 0; N=61) and LKB1-proficient (STK11/LKB1-wild-type and LKB1 H-score > 0; N=38) KRAS-mutant LUAC.