Cytological cell blocks for drug screening in advanced lung cancer
2018
Jewish General Hospital, Montreal, Canada
Immunohistochemical analysis (ICH) of the tumor surface protein PD-L1 ("programmed death ligand 1") is of high clinical relevance for the selection of a suitable therapeutic agent in non-small-cell lung cancer (NSCLC). Tumor cells that express PD-L1 are not recognized by the T cells of the body's immune system and elude defence reactions. Clinical studies show that treatment with so-called checkpoint inhibitors, such as pembrolizumab, can strengthen the immune response to the cancer cells again. For a PD-L1-ICH, tumor tissue samples are obtained by small needle biopsies or surgical resection as standard. These invasive procedures are unsuitable for frail patients in the advanced stage and lead to their exclusion from relevant drug studies. In the present study, the PD-L1-ICH of cytological cell blocks was evaluated in several test series and compared with immunohistochemical analyses of small biopsies and surgical tissue samples of the same patients. Based on the Tumor Proportion Score (TPS), the samples were divided into three PD-L1 expression groups (negative, low, and high). Of particular interest was the patient group that was at an advanced stage of NSCLC (high TPS ≥50%), as high expressions are associated with a good response to treatment with checkpoint inhibitors and are associated with higher survival rates. Furthermore, factors such as the type and age of the samples were taken into account in the investigations. Most of the cytological cell blocks were comparable to the small biopsy samples and suitable for PD-L1 testing. PD-L1 expression, as well as the presence of certain predictive biomarkers, was evaluated using statistical methods. Based on the results, the research group evaluates the PD-L1-ICH cytological cell blocks as a suitable and valuable method for the integration of previously unconsidered patient groups into clinical lung cancer studies.
Cytology cell blocks are suitable for immunohistochemical testing for PD-L1 in lung cancer
Hangjun Wang
Added on: 09-08-2022
[1] https://www.annalsofoncology.org/article/S0923-7534(19)34904-X/fulltext
