Assessment of programmed cell death ligand 1 (PD-L1) immunohistochemical staining is used for decision on treatment with programmed cell death 1 and PD-L1 checkpoint inhibitors in lung adenocarcinomas and squamous cell carcinomas. This study aimed to compare the staining properties of tumor cells between the antibody clones 28-8, 22C3, SP142, and SP263 and investigate interrater variation between pathologists to see if these stainings can be safely evaluated in the clinical setting. Using consecutive sections from a tissue microarray with tumor tissue from 55 resected lung cancer cases, staining with five PD-L1 assays (28-8 from two different vendors, 22C3, SP142, and SP263) was performed. Seven pathologists individually evaluated the percentage of positive tumor cells, scoring each sample applying cutoff levels used in clinical studies: <1% positive tumor cells (score 0), 1-4% (score 1), 5-9% (score 2), 10-24% (score 3), 25-49% (score 4), and >50% positive tumor cells (score 5). Pairwise analysis of antibody clones showed weighted kappa values in the range of 0.45-0.91 with the highest values for comparisons with 22C3 and 28-8 and the lowest involving SP142. Excluding SP142 resulted in kappa 0.75-0.91. Weighted kappa for interobserver variation between pathologists was 0.71-0.96. Up to 20% of the cases were differently classified as positive or negative by any pathologist compared with consensus score using ≥1% positive tumor cells as cutoff. A significantly better agreement between pathologists was seen using ≥50% as cutoff (0-5% of cases). In conclusion, the concordance between the PD-L1 antibodies 22C3, 28-8 and SP263 is relatively good when evaluating lung cancers and suggests that any one of these assays may be sufficient as basis for decision on treatment with nivolumab, pembrolizumab, and durvalumab. The scoring of the pathologist presents an intrinsic source of error that should be considered especially at low PD-L1 scores.

The response rate to checkpoint inhibitors for women with high-grade serous carcinoma of the ovary, fallopian tube, and peritoneum (HGSC) is modest, and development of predictive biomarkers is needed. The main focus has been on tumor cell PD-L1 expression, but its assessment alone is insufficient for patient selection in most malignancies. We mapped the presence of macrophages (CD68 and CD163) and lymphocytes (CD3) located within the tumor epithelium, the cell type-specific expression of PD-L1 and PD-1, and their impact on 5-year overall survival (OS) in a consecutive cohort of 130 women diagnosed with advanced HGSC between 2011 and 2015. PD-L1 was expressed mainly by macrophages (not by tumor cells) and PD-1 by lymphocytes. Women with higher CD3, PD-L1, and PD-1 expression had improved OS (P = 0.03, P = 0.007, and P = 0.02, respectively). In the external data set (203 women), high expression of CD274 (encoding PD-L1) was associated with improved OS (P = 0.03), in accordance with our results. Furthermore, higher CD163 expression was associated with better outcome in women with no residual tumor after primary surgery (P = 0.02). Thus, women with greater lymphocyte tumor infiltration had better outcome and PD-L1/PD-1 expression, regardless of PD-1/PD-L1 being markers for immune suppressive pathways, conferred a survival benefit in our cohort. Our results highlight that tumor immunity may be harnessed in subsets of HGSC.

ObjectiveOvarian clear cell carcinomas (OCCCs) constitute a rare ovarian cancer subtype with distinct clinical features, but may nonetheless be difficult to distinguish morphologically from other subtypes. There is limited knowledge of genetic events driving OCCC tumorigenesis beyond ARID1A, which is reportedly mutated in 30–50% of OCCCs. We aimed to further characterize OCCCs by combined global transcriptional profiling and targeted deep sequencing of a panel of well-established cancer genes. Increased knowledge of OCCC-specific genetic aberrations may help in guiding development of targeted treatments and ultimately improve patient outcome.MethodsGene expression profiling of formalin-fixed, paraffin-embedded (FFPE) tissue from a cohort of the major ovarian cancer subtypes (cohort 1; n = 67) was performed using whole-genome cDNA-mediated Annealing, Selection, extension and Ligation (WG-DASL) bead arrays, followed by pathway, gene module score, and gene ontology analyses, respectively. A second FFPE cohort of 10 primary OCCCs was analyzed by targeted DNA sequencing of a panel of 60 cancer-related genes (cohort 2). Non-synonymous and non-sense variants affecting single-nucleotide variations and insertions or deletions were further analyzed. A tissue microarray of 43 OCCCs (cohort 3) was used for validation by immunohistochemistry and chromogenic in situ hybridization.ResultsGene expression analyses revealed a distinct OCCC profile compared to other histological subtypes, with, e.g., ERBB2, TFAP2A, and genes related to cytoskeletal actin regulation being overexpressed in OCCC. ERBB2 was, however, not overexpressed on the protein level and ERBB2 amplification was rare in the validation cohort. Targeted deep sequencing revealed non-synonymous variants or insertions/deletions in 11/60 cancer-related genes. Genes involved in chromatin remodeling, including ARID1A, SPOP, and KMT2D were frequently mutated across OCCC tumors.ConclusionOCCCs appear genetically heterogeneous, but harbor frequent alterations in chromatin remodeling genes. Overexpression of TFAP2A and ERBB2 was observed on the mRNA level in relation to other ovarian cancer subtypes. However, overexpression of ERBB2 was not reflected by HER2 amplification or protein overexpression in the OCCC validation cohort. In addition, Rho GTPase-dependent actin organization may also play a role in OCCC pathogenesis and warrants further investigation. The distinct biological features of OCCC discovered here may provide a basis for novel targeted treatment strategies.

Undifferentiated uterine sarcomas (UUS) are a heterogenous group of high-grade mesenchymal tumors. Although these tumors are highly aggressive, a subset of patients may experience long-term survival. These tumors have previously been divided morphologically into uniform and pleomorphic types. A previous study demonstrated that a mitotic index cutoff of 25 mitoses/10 high-power fields (corresponding to 11.16 mitotic figures/mm) could successfully divide tumors into 2 prognostic groups with significantly different overall survival. The goals of the current study were to (1) validate this mitotic index cutoff in an independent, multicenter cohort and (2) explore the prognostic value of the mitotic index groups in relation to other clinicopathologic variables. Cases were included from 3 independent institutions: The Norwegian Radium Hospital, The Mayo Clinic, and Skåne University Hospital. A total of 40 tumors were included after central review. All cases were negative for the YWHAE-FAM22A/B and JAZF1-JJAZ1 translocations. Survival data were available on all patients. In this study, one-third of patients with UUS survived beyond 5 years. The crude (unadjusted) Cox Proportional Hazards model revealed a number of parameters that significantly impacted overall survival, including mitotic index group, patient age, stage, and the presence of tumor necrosis. Classification into the uniform and pleomorphic types was not prognostic. Combining these parameters into an adjusted model revealed that only the mitotic index group and stage were prognostic. On the basis of these findings, it is proposed that UUS be subdivided into "mitogenic" and "not otherwise specified" types.