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Evidence suggests that the quantity of cytotoxic lymphocytes influences the likelihood for a successful application of immune checkpoint inhibitors. To compare the density of CD8+lymphocytes across various different tumor types, a tissue microarray (TMA) composed of up to 50 tumor samples each from 85 different cancer types and subtypes was analyzed. A total of 2652 cancers and 608 normal tissues were successfully analyzed by CD8 immunohistochemistry followed by automated image analysis of digitized slides. The median number of CD8+lymphocytes ranged from 6 cells/mm2in pleomorphic adenoma up to 1573 cells/mm2in Hodgkin’s lymphoma. CD8 counts were generally lower in normal tissues. Blood vessels of the spleen was the only non-lymphatic tissue staining for CD8.In solid tumors, highest CD8 densities (cells/mm2) were found in seminoma (median: 424), Warthin’s tumor (median: 425), squamous cell cervical cancer (median 468), medullary breast cancer (median: 657) and thymoma (median: 889).Tumor types approved for therapy with checkpoint inhibitors such malignant melanoma (median: 81), muscle invasive urothelial carcinomas (median: 119), small cell lung cancer (median: 120), clear cell kidney cancer (median: 153), squamous cell cancer (median: 189) and adenocarcinoma of the lung (median: 328) as well as Hodgkin’s lymphoma (median:1573) were all ranking among the upper half of our list. Comparably high CD8 densities (cells/mm2) were also found for several rare and aggressive cancer types including Merkel cell carcinoma (median: 70), angiosarcoma (median: 95), anaplastic thyroid cancer (median: 156), anal carcinoma (median: 104), squamous cell carcinoma of the vagina (median: 128) and embryonal carcinoma of the testis (median: 186). The CD8 cell count was highly variable within tumor types. In 73 of 84 analyzed cancer types, the CD8 count at least occasionally exceeded the average CD8 count of tumors for which checkpoint inhibitors have been approved.These data support the concept, that in most tumor types at least some individual cancers may benefit from treatment with immune checkpoint inhibitors. Citation Format: Niclas C. Blessin, Florian Lutz, Patrick Spriesterbach, Wenchao Li, Tim Mandelkow, Vera Nickelsen, Ronald Simon, Claudia Hube-Magg, Florian Viehweger, Maximillian Lennartz, Christoph Fraune, Kristine Fischer, Katharina Möller, Stefan Steurer, Jacob R. Izbicki, Guido Sauter, Sarah Minner, Frank Jacobsen, Andreas M. Luebke, Franziska Büscheck, Doris Höflmayer, Waldemar Wilczak, Eike Burandt, Andrea Hinsch. Distribution of CD8+cytotoxic lymphocytes in human neoplasms [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4567.

Since several decades, prostate specific antigen (PSA) is regarded as a specific marker for healthy and neoplastic prostate tissues, and PSA level changes in blood and tissue are discussed as prognostic markers of prostate cancer. Using a custom-made mouse monoclonal anti-PSA antibody, we studied expression of PSA in a tissue microarray (TMAs) comprising 17,456 prostate cancers with long-term follow-up data. PSA staining was typically present in the cytoplasm and pronounced at the apical cell pole. PSA expression was often reduced (15%) or even completely lost (1%). Reduction of PSA expression was significantly linked to adverse features of prostate cancer, including advanced stage, high classical and quantitative Gleason grade, presence of lymph node metastasis, a positive surgical margin, increased cell proliferation, and reduced time to recurrence (p Citation Format: Ronald Simon, Martina Kluth, Kristine Fischer, Sarah Bonk, Claudia Hube-Magg, Doris Höflmayer, Maximilian Lennartz, Florian Lutz, Guido Sauter, Franziska Büscheck, Ria Uhlig, David Dum, Andreas M. Luebke, Corinna Wittmer, Frank Jacobsen, Eike Burandt, Stefan Steurer, Waldemar Wilczak, Sarah Minner. Prostate specific antigen (PSA) as a diagnostic and prognostic marker of prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 430.