Search

Fibroepithelial lesions (FL) of the breast, in particular, phyllodes tumors (PT) and fibroadenomas, pose a significant diagnostic challenge. There are no generally accepted criteria that distinguish benign, borderline, malignant PT and fibroadenomas. Combined genome-wide DNA methylation and copy number variant (CNV) profiling is an emerging strategy to classify tumors. We compiled a series of patient-derived archival biopsy specimens reflecting the FL spectrum and histological mimickers including clinical follow-up data. DNA methylation and CNVs were determined by well-established microarrays. Comparison of the patterns with a pan-cancer dataset assembled from public resources including “The Cancer Genome Atlas” (TCGA) and “Gene Expression Omnibus” (GEO) suggests that FLs form a methylation class distinct from both control breast tissue as well as common breast cancers. Complex CNVs were enriched in clinically aggressive FLs. Subsequent fluorescence in situ hybridization (FISH) analysis detected respective aberrations in the neoplastic mesenchymal component of FLs only, confirming that the epithelial component is non-neoplastic. Of note, our approach could lead to the elimination of the diagnostically problematic category of borderline PT and allow for optimized prognostic patient stratification. Furthermore, the identified recurrent genomic aberrations such as 1q gains (including MDM4), CDKN2a/b deletions, and EGFR amplifications may inform therapeutic decision-making.

Primary Liver Cancers - Hepatocellular Carcinoma and Cholangiocarcinoma

Background: Hepatocellular carcinoma (HCC) accounts for 75-85% of all primary liver malignancies. HCC represents an attractive target for immune checkpoint inhibitors (ICI) and tumor microenvironment (TME) agents. The development and success of ICI therapies requires a comprehensive model to study interactions of immune networks in the TME. Patient-derived organoids (PDO) have emerged as promising individualized models for ex vivo drug testing. While PDO are superior to previous models, due to their inherent heterogeneity and their enhanced capacity to capture tumor characteristics, the lack of mesenchymal and immune components limit their use for testing drug classes such as ICI or study tumor-TME interaction. Here, we developed and characterized a perfusion-based cultivated ex vivo HCC tissue model that preserves the tumor tissue architecture and maintains the pathophysiological microenvironment of human tissue for testing of TME-related treatments. Materials and methods: Fresh tumor tissue was obtained from surgical specimens of six patients undergoing liver resection for HCC. Tissue fragments of 2x2x2 mm were installed between two discs of collagen type 1 porous scaffold and placed in a perfusion-based bioreactor (U-shaped Culture Under Perfusion; U-CUP) for tissue engineering or cultured in static condition. At different time points, cultured tissue fragments were formalin-fixed and paraffin-embedded for downstream analysis. Cell viability and morphology was monitored on day 0, 5 and 7 by using hematoxylin and eosin staining. The changes in TME composition were monitored by immunohistochemistry using cell-type specific antibodies like CD34 for endothelial cells, CD3 for T-cells, alpha-smooth muscle actin (a-SMA) for fibroblasts and arginase-L for urea cycle. Results: Microscopic analysis revealed that, compare to static culture, the morphology and the viability of the cells were preserved during the culture period in the U-CUP. Tissue histology as well as the immunophenotypic pattern observed in the original tissue was maintained. Similarly, the presence of endothelial cells (CD34+) and fibroblasts (a-SMA+) were detected in the U-CUP cultured samples in a similar proportion to the original tumor samples. The presence of T-cells (CD3+) was stable at all time points. Compared to the samples cultured under static conditions, the U-CUP tended to show less necrosis during the seven-day course. Conclusion: Compared to PDO, U-CUP bioreactor tumor culture seems to preserve mesenchymal and immune components. This enables further investigation and assessment of TME-related treatments, such as ICI. Citation Format: Gabriel Fridolin Hess, Manuele Giuseppe Muraro, Mairene Coto-Llerena, Silvio Däster, Caner Ercan, Simone Muenst, Otto Kollmar, Salvatore Piscuoglio, Savas Deniz Soysal. Perfusion-based bioreactor preserves microenvironment of hepatocellular carcinoma ex vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6041.

Background: Hepatocellular carcinoma (HCC) is the most common primary liver malignancy. Curative treatments in early-stage HCC are hampered by high recurrence rates, and targeted therapies against HCC are rare. Little is known about the impact of tumor microenvironment (TME) in this tumor. Manipulation of the immune system by tumors leads to compromised antigen recognition and an immunosuppressive microenvironment. One immunomodulatory strategy employed by malignant tumors is the expression of the programmed cell death receptor 1 ligand (PD-L1), whose receptor is expressed on activated T cells (PD-1). The use of immune checkpoint inhibitors (ICI) has shown antitumor activity and unprecedented rates of durable clinical responses in various cancer types. In HCC, nivolumab and pembrolizumab are described as possible second line therapies. Expression of PD-1 and PD-L1 in the TME has prognostic importance and can predict response to ICI. The aim of our study was to investigate the impact of PD-1 and PD-L1 expression on HCC recurrence and the relation to their cancer-immune phenotypes. Materials and methods: Immunohistochemical staining was performed on archival tissue from 91 HCC, primary and recurrence, using the following antibodies: NAT105 (PD-1) and Ventana SP263 (PD-L1). On the basis of protein expression, tumors were classified as immunologically active, excluded or deserted. PD-1 and PD-L1 immunoreactivity was evaluated as the proportion of positive staining of the total number of immune cells (0%, 1%). Results: Basic tumor characteristics were not related to recurrence of HCC. However, the immune-excluded subclass showed significant association with recurrence in HCC. The majority of non-recurrent HCC showed PD-1 expression >1% (78%; 38/49), also statistically significant. Conversely, recurrent HCC showed low PD-1 expression (0% or 1%) (77%; 49/64). An association between HCC recurrence and PD-L1 expression on tumor cells was not found. Conclusion: In concordance with previous reports, we found an association between low frequency of PD-1 expression and increased HCC recurrence, as well as the lack of impact of PD-L1 expression on HCC recurrence. Furthermore, our results suggest that HCC recurrence may be more frequent in immune-exclusive tumors. Pembrolizumab as adjuvant instead of 2nd line therapy should be further investigated. Citation Format: Gabriel Fridolin Hess, Mairene Coto-Llerena, Jasmin Zeindler, Silvio Däster, Simone Muenst, Jürg Vosbeck, Caner Ercan, Otto Kollmar, Salavtore Piscuoglio, Savas Deniz Soysal. PD1 expression and immune-active lymphocytes can predict recurrence of hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6146.