RESUMO
BACKGROUND: Cell blocks (CBs) are widely used for biomarker analyses such as immunostaining. Although immunohistochemistry on formalin-fixed paraffin-embedded tissues is standardized, there are multiple preparation methods and fixatives for cytology. Our objective was to investigate the effect of different common fixatives on the immunoreactivity of pleural effusion CBs with metastatic lung adenocarcinomas. METHODS: This prospective study included 24 malignant pleural effusions from different patients with lung adenocarcinoma. From each case, four identical CBs were fixed in 10% neutral buffered formalin, PreservCyt, CytoLyt, and CytoRich Red (only 17 of the cases), respectively. Samples containing <100 malignant cells were excluded. All CBs were stained with thyroid transcription factor 1 (TTF-1; clones 8G7G3/1 and SPT24), napsin A, claudin 4, CEA, CK7, and epithelial cell adhesion molecule (EpCAM; clones BS14, Ber-Ep4, and MOC-31). The fraction and intensity of stained cells were evaluated. RESULTS: Of the investigated markers, a significant difference in staining proportion was seen for TTF-1 clone 8G7G3/1 and EpCAM clone MOC-31, especially with cases being negative in CytoLyt (33.3% and 83.3% positive, respectively) and PreservCyt (62.5% and 83.3%) whereas being positive in CytoRich Red (76.5% and 94.1%) and formalin (both 95.8%). A significantly weaker intensity of staining was seen for all alcohol-based fixatives compared to formalin for TTF-1 clone 8G7G3/1, napsin A, and EpCAM clone MOC-31, whereas EpCAM clone Ber-Ep4 was significantly weaker only in PreservCyt compared with formalin. CONCLUSIONS: Immunocytochemical expression and concordance with formalin-fixed CBs differ depending on the used fixative as well as the antibody and clone, warranting investigation of the reliability of each biomarker for non-formalin-fixed cytology.
RESUMO
BACKGROUND AND PURPOSE: The treatment landscape for patients with advanced non-small cell lung cancer (NSCLC) has evolved significantly since the introduction of immunotherapies. We here describe PD-L1 testing rates, treatment patterns, and real-world outcomes for PD-(L)1 inhibitors in Sweden. MATERIALS AND METHODS: Data were obtained from the Swedish National Lung Cancer Registry for patients with advanced NSCLC and Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0-2 who initiated first-line -systemic treatment from 01 April 2017 to 30 June 2020. PD-L1 testing was available in the registry from 01 January 2018. Kaplan-Meier was used for overall survival (OS) by type treatment and histology. RESULTS: A total of 2,204 patients with pathologically confirmed unresectable stage IIIB/C or IV NSCLC initiated first-line treatment, 1,807 (82%) with nonsquamous (NSQ) and 397 (18%) with SQ. Eighty-six per cent (NSQ) or 85% (SQ) had been tested for PD-L1 expression, a proportion that increased over time. The use of platinum-based therapy as first-line treatment decreased substantially over time while there was an upward trend for PD-(L)1-based therapy. Among patients with PS 0-1 initiating a first-line PD-(L)1 inhibitor monotherapy, the median OS was 18.6 and 13.3 months for NSQ and SQ NSCLC patients, respectively, while for the PD-(L)1 inhibitor and chemotherapy combination regimen, the median OS was 24.0 months for NSQ and not evaluable for SQ patients. INTERPRETATION: The majority of advanced NSCLCs in Sweden were tested for PD-L1 expression. Real-world OS in patients with PS 0-1 receiving first-line PD-(L)1 inhibitor-based regimens was similar to what has been reported in pivotal clinical trials on PD-(L)1 inhibitors.