Kim Ellison

Lymphocyte-activation gene-3, an important immune checkpoint in cancer.

Immunotherapy has recently become widely used in lung cancer. Many oncologists are focused on cytotoxic T lymphocyte antigen‐4 (CTLA‐4), programmed cell death ligand‐1 (PD‐L1) and programmed cell death‐1 (PD‐1). Immunotherapy targeting the PD‐1/PD‐L1 checkpoints has shown promising efficacy in non‐small cell lung cancer (NSCLC), but questions remain to be answered. Among them is whether the simultaneous inhibition of other checkpoints could improve outcomes. Lymphocyte‐activation gene‐3 (LAG‐3) is another vital checkpoint that may have a synergistic interaction with PD‐1/PD‐L1. Here we review the LAG‐3 function in cancer, clinical trials with agents targeting LAG‐3 and the correlation of LAG‐3 with other checkpoints.

ROS1 immunohistochemistry among major genotypes of non-small-cell lung cancer.

Identification of ROS1 rearrangements in patients with lung cancer allows them to benefit from targeted therapy. We compared immunohistochemistry (IHC) with more cumbersome methods such as fluorescence in situ hybridization and reverse transcriptase polymerase chain reaction for identification of ROS1 rearrangements in patients with lung adenocarcinoma (n = 33). Our results showed that IHC is a sensitive (100%) and specific (100%) method to identify ROS1 rearrangements in patients with lung cancer. Background ROS1 gene fusions cause several cancers by constitutively activating the ROS1 tyrosine kinase receptor. ROS1-targeted inhibitor therapy improves survival in the approximately 1% to 2% of patients with lung adenocarcinoma with ROS1 gene fusions. Although fluorescence in situ hybridization (FISH) is the standard diagnostic procedure for detecting ROS1 rearrangements, we studied immunohistochemistry (IHC). Materials and Methods ROS1 IHC was performed on a selected cohort of 33 lung adenocarcinoma whole tissue specimens with alterations in the EGFR (n = 5), KRAS (n = 5), ERBB2 (HER2) (n = 3), ROS1 (n = 6), ALK (n = 5), and RET (n = 3) genes and pan-negative (n = 6) detected by reverse transcriptase-polymerase chain reaction (RT-PCR) and FISH. Results In the cohort of 33 specimens, both ROS1 gene fusion using RT-PCR and high ROS1 protein expression using IHC were detected in 6 specimens. Of these 6 specimens, 5 were also positive by FISH for ROS1 gene rearrangements. All 27 lung cancer specimens that were negative for ROS1 rearrangements by genetic testing had no to low ROS1 protein expression. Conclusion We have optimized ROS1 IHC and scoring to provide high sensitivity and specificity for detecting ROS1 gene rearrangements in whole tissue. ROS1 IHC could be a practical and cost-effective method to screen for ROS1 gene rearrangements.

PD-L1 Expression by Two Complementary Diagnostic Assays and mRNA In Situ Hybridization in Small Cell Lung Cancer

Introduction: Therapeutic antibodies to immune checkpoints show promising results. Programmed death‐ligand 1 (PD‐L1), an immune checkpoint ligand, blocks the cancer immunity cycle by binding the PD‐L1 receptor (programmed death 1). We investigated PD‐L1 protein expression and messenger RNA (mRNA) levels in SCLC. Methods: PD‐L1 protein expression and mRNA levels were determined by immunohistochemistry (IHC) with SP142 and Dako 28‐8 PD‐L1 antibodies and in situ hybridization in primary tumor tissue microarrays in both tumor cells and tumor‐infiltrating immune cells (TIICs) obtained from a limited‐disease SCLC cohort of 98 patients. An additional cohort of 96 tumor specimens from patients with extensive‐disease SCLC was assessed for PD‐L1 protein expression in tumor cells with Dako 28‐8 antibody only. Results: The overall prevalence of PD‐L1 protein expression in tumor cells was 16.5%. In the limited‐disease cohort, the prevalences of PD‐L1 protein expression in tumor cells with SP142 and Dako 28‐8 were 14.7% and 19.4% (tumor proportion score cutoff ≥1%) and PD‐L1 mRNA ISH expression was positive in 15.5% of tumor samples. Increased PD‐L1 protein/mRNA expression was associated with the presence of more TIICs (p < 0.05). The extensive‐disease cohort demonstrated a 14.9% positivity of PD‐L1 protein expression in tumor cells with Dako 28‐8 antibody. Conclusions: A subset of SCLCs is characterized by positive PD‐L1 and/or mRNA expression in tumor cells. Higher PD‐L1 and mRNA expression correlate with more infiltration of TIICs. The prevalence of PD‐L1 in SCLC is lower than that published for NSCLC. The predictive role of PD‐L1 expression in SCLC treatment remains to be established.

LAG-3 Protein Expression in Non–Small Cell Lung Cancer and Its Relationship with PD-1/PD-L1 and Tumor-Infiltrating Lymphocytes

Introduction: Immunotherapy targeting the programmed death 1 (PD‐1)/programmed death ligand 1 (PD‐L1) checkpoint has shown promising efficacy in patients with NSCLC. Lymphocyte activating 3 gene (LAG‐3) is another important checkpoint, and its role in NSCLC is still not clear. In this study we investigated lymphocyte activing 3 (LAG‐3) protein expression; its correlation with PD‐1, PD‐L1, and tumor‐infiltrating lymphocytes (TILs); and its association with survival in NSCLC. Methods: The expression of LAG‐3 (EPR4392 [Abcam, Cambridge, MA]) protein was assessed in 55 NSCLC cell lines by immunohistochemistry. LAG‐3, PD‐1 (NAT 105 [Cell Marque, Rocklin, CA]), and PD‐L1 (22C3 [Dako, Carpenteria, CA]) protein expression was evaluated by immunohistochemistry, and TIL abundance was scored in 139 surgically resected specimens from patients with NSCLC. We also verified results in samples from 62 patients with untreated NSCLC and detected a correlation between LAG‐3 expression and EGFR and KRAS mutation and echinoderm microtubule associated protein like 4 gene (EML4)–anaplastic lymphoma receptor tyrosine kinase gene (ALK) rearrangement. Results: LAG‐3 was not expressed on any of the 55 NSCLC cell lines. However, LAG‐3 was expressed on the TILs in 36 patients with NSCLC (25.9%). Sixty patient samples (43.2%) were positive for PD‐1 on the TILs, and 25 (18.0%) were positive for PD‐L1 on tumor cells. Neither LAG‐3 nor PD‐1 was expressed on the tumor cells. LAG‐3 was overexpressed on the TILs in nonadenocarcinoma compared with in adenocarcinoma (p = 0.031). LAG‐3 expression on TILs was significantly correlated with that of PD‐1 on TILs (p < 0.001) and PD‐L1 on tumor cells (p = 0.041) but not with TIL percentage (p = 0.244). With the logistic regression model, the ORs for LAG‐3 were 0.320 (95% confidence interval [CI]: 0.110–0.929) and 4.364 (95% CI: 1.898–10.031) when nonadenocarcinoma was compared with adenocarcinoma and TILs that were negative for PD‐1 were compared with those positive for PD‐1. Recurrence‐free survival was significantly different in patients whose TILs were LAG‐3–negative as opposed to LAG‐3–positive (1.91 years [95% CI: 0.76–3.06] versus 0.87 years [95% CI: 0.27–1.47] [p = 0.025]). Likewise, LAG‐3 status of TILs (negative versus positive) did significantly affect overall survival (OS) (3.04 years [95% CI: 2.76–3.32] versus 1.08 years [95% CI: 0.42–1.74] [p = 0.039]). Using Kaplan‐Meier analysis, we found that patients with both PD‐L1–negative tumor cells and LAG‐3–negative TILs have longer recurrence‐free survival than patients who are either PD‐L1– or LAG‐3–positive or both PD‐L1– and LAG‐3–positive (2.09 years [95% CI: 0.90–3.28] versus 1.42 years [95% CI: 0.46–2.34] versus 0.67 years [95% CI: 0.00–1.45] [p = 0.007]). In the verification stage, high expression of LAG‐3 was also significantly correlated with higher expression of PD‐1 on TILs (p = 0.016) and PD‐L1 on tumor cells (p = 0.014). There was no correlation between LAG‐3 expression and EGFR (p = 0.325) and KRAS mutation (p = 1.000) and ALK fusion (p = 0.562). Conclusions: LAG‐3 is expressed on TILs in tumor tissues of some patients with NSCLC. Its expression was higher in nonadenocarcinoma and correlated with PD‐1/PD‐L1 expression. LAG‐3 positivity or both LAG‐3 and PD‐L1 positivity was correlated with early postoperative recurrence. LAG‐3 was related to poor prognosis.

Heterogeneity in Immune Marker Expression after Acquisition of Resistance to EGFR Kinase Inhibitors: Analysis of a Case with Small Cell Lung Cancer Transformation

Introduction: Expression of immune markers is of scientific interest because of their potential roles as predictive biomarkers for immunotherapy. Although the microenvironment of metastatic tumors and/or therapy‐inducible histological transformation may affect the expression of these immune markers, there are few data regarding this context. Methods: A 76‐year‐old never‐smoking female with EGFR‐mutated lung adenocarcinoma (AC) acquired resistance to gefitinib. After her death, an autopsy revealed SCLC transformation and EGFR T790M secondary mutation (T790M) as mutually exclusive resistance mechanisms occurring differently in different metastases; two liver metastases (SCLC versus AC with T790M) and two lymph node metastases (SCLC versus AC with T790M) were analyzed to compare the expression status of immune markers by immunohistochemistry and by an immune oncology gene expression panel. Results: Programmed death ligand 1 (PD‐L1) protein was partially expressed in tumor cells with AC lesions (T790M) but not in tumor cells with SCLC transformation. The liver metastasis with SCLC transformation showed no stromal PD‐L1 expression and scant tumor‐infiltrating lymphocytes, whereas the other lesions demonstrated stromal PD‐L1 staining and infiltration of CD8‐positive T cells. Data generated using an immuno‐oncology gene expression panel indicated a higher level of T‐cell costimulatory molecules and lower expression of type I interferon–regulated genes in lesions with SCLC transformation. Conclusion: These data highlight the heterogeneity of expression of immune markers depending on the metastatic sites and histological transformation and indicate that the biopsy specimen from one lesion may not be representative of immune marker status for all lesions.

Fibroblast Growth Factor Receptor 1 and Related Ligands in Small-Cell Lung Cancer

Introduction: Small-cell lung cancer (SCLC) accounts for 15% of all lung cancers and has been understudied for novel therapies. Signaling through fibroblast growth factors (FGF2, FGF9) and their high-affinity receptor has recently emerged as a contributing factor in the pathogenesis and progression of non–small-cell lung cancer. In this study, we evaluated fibroblast growth factor receptor 1 (FGFR1) and ligand expression in primary SCLC samples. Methods: FGFR1 protein expression, messenger RNA (mRNA) levels, and gene copy number were determined by immunohistochemistry (IHC), mRNA in situ hybridization, and silver in situ hybridization, respectively, in primary tumors from 90 patients with SCLC. Protein and mRNA expression of the FGF2 and FGF9 ligands were determined by IHC and mRNA in situ hybridization, respectively. In addition, a second cohort of 24 SCLC biopsy samples with known FGFR1 amplification by fluorescence in situ hybridization was assessed for FGFR1 protein expression by IHC. Spearman correlation analysis was performed to evaluate associations of FGFR1, FGF2 and FGF9 protein levels, respective mRNA levels, and FGFR1 gene copy number. Results: FGFR1 protein expression by IHC demonstrated a significant correlation with FGFR1 mRNA levels (p < 0.0001) and FGFR1 gene copy number (p = 0.03). The prevalence of FGFR1 mRNA positivity was 19.7%. FGFR1 mRNA expression correlated with both FGF2 (p = 0.0001) and FGF9 (p = 0.002) mRNA levels, as well as with FGF2 (p = 0.01) and FGF9 (p = 0.001) protein levels. There was no significant association between FGFR1 and ligands with clinical characteristics or prognosis. In the second cohort of specimens with known FGFR1 amplification by fluorescence in situ hybridization, 23 of 24 had adequate tumor by IHC, and 73.9% (17 of 23) were positive for FGFR1 protein expression. Conclusions: A subset of SCLCs is characterized by potentially activated FGF/FGFR1 pathways, as evidenced by positive FGF2, FGF9, and FGFR1 protein and/or mRNA expression. FGFR1 protein expression is correlated with FGFR1 mRNA levels and FGFR1 gene copy number. Combined analysis of FGFR1 and ligand expression may allow selection of patients with SCLC to FGFR1 inhibitor therapy.

PD-1, PD-L1 Protein Expression in Non-Small Cell Lung Cancer and Their Relationship with Tumor-Infiltrating Lymphocytes

Background Immunotherapy targeting the programmed death-1 (PD-1)/programmed death ligand-1 (PD-L1) checkpoint has shown the good outcomes in non-small cell lung cancer (NSCLC). We investigated PD-1 and PD-L1 protein expression and their correlation with tumor-infiltrating lymphocytes (TILs), and association with survival in NSCLC. Material/Methods The expression of PD-1 (NAT105, Cell Marque) and PD-L1 (28-8, Dako) protein was assessed in 55 NSCLC cell lines by immunohistochemistry (IHC). PD-1 (NAT105, Cell Marque) and PD-L1 (22C3, Dako) protein expression was evaluated by IHC, and TIL percentage was scored, in 139 surgically resected specimens from patients with NSCLC. Results PD-1 was not expressed on NSCLC cell lines. PD-L1 was expressed on 20 NSCLC cell lines (36.4%). A total of 60 patient samples (43.2%) were positive for PD-1 on the TILs, and 25 (18.0%) were positive for PD-L1 on tumor cells. High expression of PD-1 on tumor cells was significantly correlated with higher expression of PD-L1 (P=0.026) and a higher percentage of TILs (P<0.001). In the Cox regression model, the odds ratio for PD-1 was 2.828 (95% CI: 1.325–11.165; P=0.013) and 8.579 (95% CI: 4.148–22.676; P<0.001) when PD-L1 and TILs were positive. Patients whose tumor cells were PD-L1 negative had a tendency for longer relapse-free survival (RFS) than patients who were PD-L1 positive (1.85 years, 95% CI: 0.77–2.93 vs. 0.97 years, 95% CI: 0.71–1.23; P=0.054). Conclusions PD-1 was expressed on TILs in tumor tissues in NSCLC patients. PD-L1 was expressed on both TILs and tumor tissues. PD-1 expression was correlated with PD-L1 on tumor cells and TILs. Patients who were PD-L1 positive tended to experience progression after surgery.

Therapy-induced E-cadherin downregulation alters expression of programmed death ligand-1 in lung cancer cells

OBJECTIVES Immunotherapy that targets the programmed death-1/programmed death-ligand 1 (PD-L1) axis has been approved for treatment of non-small cell lung cancer (NSCLC) patients in many countries. However, our current understanding of the role of immunotherapies on NSCLC patients with epidermal growth factor receptor (EGFR) mutation, following acquisition of resistance to EGFR tyrosine kinase inhibitors (TKIs), is so far unclear. Especially, there is little data on if each acquired resistance mechanism to EGFR-TKIs alters PD-L1 expression status which is employed as an important predictive biomarker for PD-1/PD-L1 targeting agents. MATERIALS AND METHODS Lung cancer cell lines (HCC827, HCC4006, PC9, H1975, H358, SW900, and H647) and their daughter cells that acquired resistance to EGFR-TKIs or cytotoxic drugs (cisplatin or vinorelbine) were examined. PD-L1 expression was analyzed by immunohistochemistry, immunoblotting, and/or fluorescent imaging. Published microarray data were also employed to evaluate our findings. RESULTS AND CONCLUSION We found correlations between therapy-induced E-cadherin downregulation and decreased PD-L1 expression using our cell lines and published microarray data. ShRNA mediated E-cadherin knockdown decreased PD-L1 expression in parental cells, and dual immunofluorescent staining of E-cadherin and PD-L1 suggests co-localization of both molecules. We also observed marked downregulation of PD-L1 in cells with E-cadherin downregulation after chronic treatment with vinorelbine. These results indicate a correlation between therapy-induced E-cadherin downregulation and decreased PD-L1 expression, highlighting the importance of re-biopsy after acquisition of resistance to EGFR-TKIs, not only for the evaluation of resistance mechanisms but also for the determination of PD-L1 expression status.

Heterogeneity of EGFR Aberrations and Correlation with Histological Structures: Analyses of Therapy-Naive Isogenic Lung Cancer Lesions with EGFR Mutation

Introduction: EGFR gene somatic mutation is reportedly homogeneous. However, there are few data regarding the heterogeneity of expression of mutant EGFR protein and EGFR gene copy number, especially in extrathoracic lesions. These types of data may enhance our understanding of the biology of EGFR‐mutated lung cancer and our understanding of the heterogeneous response patterns to EGFR TKIs. Methods: An 81‐year‐old never‐smoking female with lung adenocarcinoma could not receive any systemic therapy because of her poor performance status. After her death, 15 tumor specimens from different sites were obtained by autopsy. Expression of mutant EGFR protein and EGFR gene copy numbers were assessed by immunohistochemical analysis and by silver in situ hybridization, respectively. Heterogeneity in these EGFR aberrations was compared between metastatic sites (distant versus lymph node) or histological structures (micropapillary versus nonmicropapillary). Results: All lesions showed positive staining for mutant EGFR protein, except for 40% of the papillary component in one of the pulmonary metastases (weak staining below the 1+ threshold). Expression of mutant‐specific EGFR protein, evaluated by H‐score, was significantly higher in the micropapillary components than in the nonmicropapillary components (Mann‐Whitney U test, p = 0.014). EGFR gene copy number was quite different between lesions but not correlated with histological structure or metastatic form. However, EGFR gene copy numbers were similar between histological structures in each lesion. Conclusion: These data indicate that expression of EGFR mutant protein and EGFR gene copy number do not change as a consequence of tumor progression. This also justifies using the biopsy specimens from metastases as a surrogate for primary tumors.

CD44 facilitates epithelial to mesenchymal transition phenotypic change at acquisition of resistance to EGFR kinase inhibitors in lung cancer

Epithelial-to-mesenchymal transition (EMT) is one of the acquired resistance mechanisms to EGFR tyrosine kinase inhibitors (TKI) in lung cancers. Because EMT is related to tumor invasion, metastases, and resistance to various treatments, it is important to prevent the emergence of EMT. However, molecular mechanism(s) underlying EMT phenotypic changes, as well as biomarker(s) that predict the emergence of EMT in EGFR-mutated lung cancers, are unclear to date. Through the comparison of expression data between isogenic lung cancer cell lines that acquired resistance to EGFR-TKI(s), we identified that high CD44 expression is related to a mesenchymal phenotype and that shRNA-mediated knockdown of CD44 reversed the EMT change. High membranous CD44 expression was identified in lesions with mesenchymal phenotype that were obtained from lung cancer patients who developed acquired resistance to gefitinib or afatinib, whereas isogenic lesions without EMT change showed negative/weak staining for CD44. Immunohistochemistry for treatment-naïve lung cancer cell lines with EGFR mutations found those that acquire resistance to EGFR-TKIs via EMT (HCC4006 and H1975 cells) had strong membranous CD44 expression compared with non–EMT-transforming lines which demonstrated negative or weak staining (Fisher exact test P value = 0.036). shRNA-mediated CD44 knockdown in HCC4006 cells prevented the emergence of EMT after chronic exposure to osimertinib. These results suggest that upregulation of CD44 facilitates EMT-phenotypic change in lung cancers with EGFR mutations when treated with EGFR-TKIs. In addition, our results suggest that CD44 can be a useful biomarker to predict the emergence of EMT upon EGFR-TKI monotherapy. Mol Cancer Ther; 17(10); 2257–65. ©2018 AACR.