PD-L1 assessment in cytology samples predicts treatment response to checkpoint inhibitors in NSCLC.

BACKGROUND: Testing for tumor programmed death ligand-1 (PD-L1) expression was initially developed with histology specimens in non-small cell lung cancer (NSCLC). However, cytology specimens are widely used for primary diagnosis and biomarker studies in clinical practice. Limited clinical data exist on the predictiveness of cytology-derived PD-L1 scores for response to immune checkpoint inhibitor (ICI) therapy. METHODS: We reviewed all NSCLC specimens clinically tested at the University Health Network (UHN) for PD-L1 with 22C3pharmDx, from 01/2013 to 04/2021. Treatment outcomes in patients treated with single agent ICI therapy were reviewed and compared according to cytology- and histology-derived PD-L1 scores. RESULTS: We identified 494 and 1942 unique patients with cytology- and histology-derived tumor proportion scores, respectively, during the study period. Informative testing rates were 95 % vs 98 % for cytology and histology, respectively. Clinical data were available for 152 patients treated with single agent ICI: 61 cytology and 91 histology. Overall response rates (ORR) were similar for cytology and histology (36 % vs 34 %; p = 0.23), as well as median progression free survival (PFS) (4.9 vs 4.2 months; p = 0.99) and overall survival (23.4 vs 19.7 months; p = 0.99). The results remained similar even after adjusting for PD-L1 expression levels and line of ICI treatment (PFS HR 1.15; 95 %CI 0.78-1.70; p = 0.47). CONCLUSIONS: Treatment outcomes to single agent ICI based on cytology-derived PD-L1 scores were comparable to histology controls. Our results support PD-L1 biomarker testing on both cytology and histology specimens.

Impact of touch preparations on core needle biopsies.

BACKGROUND: Touch preparations (TPs) can be performed for on-site adequacy assessment of core needle biopsies (CNBs). Although TPs can play a role in decreasing the number of nondiagnostic core biopsies, the impact of TPs on CNB has not been extensively evaluated. METHODS: Computerized tomography-guided CNBs performed in a tertiary cancer center were retrospectively identified. On-site adequacy assessment was performed in all cases. The matching TPs and CNBs were evaluated for diagnostic accuracy of the TP. The relation between the site of biopsy and the cellularity of the CNB was also analyzed. RESULTS: A total of 1100 CNB cases with associated TPs were identified over a 6-month period. Eighty-four cases (8%) showed marked differences in cellularity between CNB and TP, and 43 of these 84 cases (4.3%) showed the presence of diagnostic cells in either CNB or TP, but not in both. Lung was the biopsy site where CNB was most affected by loss of diagnostic cells. CONCLUSIONS: TP and CNB findings must be integrated to prevent a misdiagnosis. Lung CNBs were more frequently affected by performing TPs.