Metformin Reduces Tumor Growth in a Murine Flank Schwannoma Model.

HYPOTHESIS: Metformin and aspirin reduce vestibular schwannoma (VS) growth. BACKGROUND: There have been reported associations between patients with VS prescribed metformin and decreased tumor volumetric growth. Aspirin has also been associated with decreased VS growth in animal studies. METHODS: Rat schwannoma cell lines were grown and implanted into 50 athymic nude mice. Tumors were grown to 5 mm, and then mice were injected with either low- or high-dose metformin, aspirin, or saline daily. Tumors were measured until 14 days elapsed or mice demonstrated symptoms such as ulceration, inability to walk, or passed away. RESULTS: There were no significant differences in day 0 tumor sizes between the control and the treatment groups ( p = 0.73). In the low-dose, but not high-dose groups, day 7 volumes were significantly different for both metformin ( p = 0.04) and aspirin ( p = 0.02) compared with placebo. Mean tumor growth rates were 126.6 ± 65.6 mm 3 /day for saline compared with 73.7 ± 29.5 mm 3 /day for low-dose metformin ( p = 0.03) and 68.7 ± 34.8 mm 3 /day for low-dose aspirin ( p = 0.016). There were no significant differences in tumor sizes ( p = 0.59) or growth rates ( p = 0.75) between low-dose metformin and aspirin groups. Low-dose groups had treatment stopped at 14 days, with continued monitoring demonstrating significant increases in tumor growth off treatment for both aspirin ( p = 0.006) and metformin ( p = 0.048). CONCLUSIONS: Metformin treatment significantly reduced VS growth to a similar level as aspirin. Furthermore, when removing both metformin and aspirin treatment, tumor growth significantly increased.

PD-L1 (22C3) Expression Correlates with Clinical and Molecular Features of Lung Adenocarcinomas in Cytological Samples.

INTRODUCTION: PD-L1 expression is the most widely used predictive marker for immune checkpoint inhibitor (ICI) therapy in patients with lung adenocarcinoma. However, the current understanding of the association between PD-L1 expression and treatment response is suboptimal. A significant percentage of patients have only a cytological specimen available for clinical management. Therefore, it is relevant to examine the impact of molecular features on PD-L1 expression in cytological samples and how it might correlate with a therapeutic response. METHODS: We evaluated patients diagnosed with adenocarcinoma of the lung who had both in-house targeted next-generation sequencing analysis and paired PD-L1 (22C3) immunohistochemical staining performed on the same cell blocks. We explored the association between molecular features and PD-L1 expression. In patients who underwent ICIs therapy, we assessed how a specific gene mutation impacted a therapeutic response. RESULTS: 145 patients with lung adenocarcinoma were included in this study. PD-L1-high expression was found to be more common in pleural fluid than in other sample sites. Regional lymph node samples showed a higher proportion of PD-L1-high expression (29%) compared with lung samples (6%). The predictive value of PD-L1 expression was retained in cytological samples. Mutations in KRAS were also associated with a PD-L1-high expression. However, tumors with TP53 or KRAS mutations showed a lower therapy response rate regardless of the PD-L1 expression. CONCLUSION: Cytological samples maintain a predictive value for PD-L1 expression in patients with lung adenocarcinoma as regards the benefit of ICI treatment. Specific molecular alterations additionally impact PD-L1 expression and its predictive value.

The Paris System "atypical urothelial cells" category: can the current criteria be improved?

INTRODUCTION: The Paris System (TPS) for reporting urine cytology was developed for standardization of diagnosis focusing on the detection of high-grade urothelial carcinoma (HGUC). Probably the most challenging task for TPS is to provide criteria for the atypical urothelial cell (AUC) category. The TPS criteria for AUC include increased nuclear/cytoplasmic (N/C) ratio (>0.5) and 1 of the 3 minor criteria including nuclear hyperchromasia (NH), coarse chromatin (CC) and irregular nuclear membrane (INM). We evaluated TPS-AUC diagnostic value and investigated whether other morphologic parameters can improve its criteria. MATERIALS AND METHODS: Urine samples with diagnoses of AUC collected during a 6-month period were re-reviewed. Data captured included N/C ratio >0.5, NH, CC, INM, and 2 additional criteria including enlarged nuclear size (ENS) and the presence of nucleolus (N). ENS was considered when the nucleus was 2 times larger than the urothelial cell or 3 times larger than lymphocyte. RESULTS: By applying the TPS-AUC criteria, the rate of atypia diagnosis reduced in comparison to Pre-TPS (9% versus 13%, P = 0.02). Among the AUC minor criteria, NH was the best criterion with the highest interobserver agreement (IOA) and correlation with HGUC (k = 0.342, r = 0.61, P < 0.001) and strong PPV (93.6%). ENS had the highest PPV (95.8%) and, after NH, had the highest IOA and correlation with HGUC (k = 0.29, r = 0.52, P < 0.001). CONCLUSION: TPS improves the diagnostic value of urine cytology, particularly in cases with atypia. ENS is a strong criterion for increasing the diagnostic value of AUC and potentially can improve TPS performance as a minor criterion.

HPV testing through p16 immunocytochemistry in neck-mass FNA and its correlation with tissue samples.

BACKGROUND: Fine-needle aspiration (FNA) of a neck mass is frequently the initial diagnostic procedure for patients with human papillomavirus-positive head and neck squamous cell carcinoma. By performing a p16 immunocytochemistry (ICC) stain on FNA material, the pathologist can help to direct the treating physician's search for the primary site and to select the proper management for the patient. There is currently no established threshold for the evaluation of p16 ICC in cytology samples. This study was aimed at establishing an optimal threshold for p16 ICC interpretation in cytology samples. METHODS: The pathology databases were searched for all neck-mass FNAs diagnosed as squamous cell carcinoma from January 2010 to March 2019. p16 ICC was performed on cytology smears, and the percentage and intensity of p16-positive cells were assessed. Receiver operating characteristic (ROC) curves were plotted to determine the best cutoff threshold for p16 positivity on cytology smears. RESULTS: p16 ICC was performed on 50 cytology smears. An analysis of 8 different thresholds (combinations of the percentage and intensity of the p16 stain) using ROC curves demonstrated the best threshold to be 50% p16 staining with a sensitivity of 74% and a specificity of 100%. Applying the threshold used for surgical specimens (70%) to cytology samples resulted in a low sensitivity (45%). CONCLUSIONS: p16 ICC on cytology smears shows diminished staining in comparison with surgical samples. Using 50% staining as the cutoff to consider positivity for p16 in cytology smears is proposed to decrease false-negative results while maintaining specificity.