mimmunМедицинская иммунологияMedical Immunology (Russia)1563-06252313-741XSPb RAACI10.15789/1563-0625-COL-2352mimmun-2352Research ArticleОРИГИНАЛЬНЫЕ СТАТЬИORIGINAL ARTICLESХарактеристика системного и локального иммунитета и стволовых опухолевых клеток у больных колоректальным раком с различной распространенностью, динамикой и прогнозомCharacteristics of local and system immunity, and features of cancer stem cells in patients with different stage, dynamics and prognosis of colorectal carcinomahttps://orcid.org/0000-0002-1410-122XЗлатникЕ. Ю.ZlatnikE. Yu.

Д.м.н., профессор, главный научный сотрудник лаборатории иммунофенотипирования опухолей

344019, г. Ростов-на-Дону, 14-я линия, 63

Тел.: 8 (961) 272-69-68

PhD, MD (Medicine), Professor, Chief Research Associate, Laboratory of Tumor Immunophenotyping

344019, Rostov-on-Don, 14th line 63

Phone: 7 (961) 272-69-68

elena-zlatnik@mail.ruhttps://orcid.org/0000-0002-6496-9641НовиковаИ. А.NovikovaI. A.

К.м.н., заместитель генерального директора по науке

г. Ростов-на-Дону

PhD (Medicine), Deputy Director for Research

Rostov-on-Don

novikovainna@yahoo.comhttps://orcid.org/0000-0002-8522-1026БондаренкоЕ. С.BondarenkoE. S.

Младший научный сотрудник лаборатории иммунофенотипирования опухолей

г. Ростов-на-Дону

Junior Research Associate, Laboratory of Tumor Immunophenotyping

Rostov-on-Don

lena.lenalen@mail.ruhttps://orcid.org/0000-0001-5226-0152УльяноваЕ. П.UljanovaE. P.

Научный сотрудник лаборатории иммунофенотипирования опухолей

г. Ростов-на-Дону

Research Associate, Laboratory of Tumor Immunophenotyping

Rostov-on-Don

uljanova_elena@lenta.ruhttps://orcid.org/0000-0002-6035-1756СитковскаяА. О.SitkovskayaA. O.

Научный сотрудник лаборатории клеточных технологий, исполняющий обязанности заведующего лабораторией клеточных технологий

г. Ростов-на-Дону

Research Associate, Acting Director, Laboratory of Cell Technologies

Rostov-on-Don

grankina.anastasia@mail.ruФГБУ «Национальный медицинский исследовательский центр онкологии» Министерства здравоохранения РФРоссияNational Medical Research Center of OncologyRussian Federation202210032022241121134Copyright © Златник Е.Ю., Новикова И.А., Бондаренко Е.С., Ульянова Е.П., Ситковская А.О., 20222022Златник Е.Ю., Новикова И.А., Бондаренко Е.С., Ульянова Е.П., Ситковская А.О.Zlatnik E.Y., Novikova I.A., Bondarenko E.S., Uljanova E.P., Sitkovskaya A.O.Данная работа распространяется под лицензией Creative Commons Attribution 4.0.This work is licensed under a Creative Commons Attribution 4.0 License.https://www.mimmun.ru/mimmun/article/view/2352

Одной из актуальных проблем современной медицины является прогноз течения злокачественных опухолей, оценка которого зависит как от их биологических свойств, так и от состояния иммунной системы больного. Поскольку свойства опухоли и реакции иммунной системы организма на нее тесно взаимосвязаны, в научном и клиническом плане представляется важным использовать их в качестве прогностических маркеров. Целью работы явилось выявление наиболее значимых иммунологических факторов для прогноза течения колоректального рака (КРР) на основе изучения показателей локального и системного иммунитета и некоторых характеристик опухолевых клеток больных с различной распространенностью и динамикой заболевания. У 299 первично выявленных больных КРР I-IV стадии на этапе хирургического лечения изучали состав клеточных и цитокиновых факторов в крови, а также в ткани опухоли, где, кроме того, оценивали количество опухолевых клеток, экспрессирующих маркеры стволовых (ОСК), молекулы главного комплекса гистосовместимости (МНС) и PDL-1. Использованы методы проточной цитометрии, иммуногистохимического (ИГХ) и иммуноферментного анализа (ИФА). Проводили сравнение показателей больных, с различной распространенностью КРР до лечения (наличием/отсутствием регионарных и отдаленных метастазов) и с различной динамикой заболевания (отдаленное метастазирование и летальный исход в период наблюдения). Результаты исследования показали, что при регионарном метастазировании в крови возрастает количество NK и IL-6, снижается уровень СD4+, в ткани возрастает количество ОСК. Исходно генерализованный процесс с отдаленными метастазами характеризуется высоким содержанием в крови IL-6, моноцитов и гранулоцитов, отвечающих на fMLF, в ткани опухоли – количества NKТ и ОСК при более низких уровнях в ней опухолевых клеток, экспрессирующих МНС и PDL-1, а также лимфоцитов, экспрессирующих PD-1/PDL-1. Неблагоприятной динамике КРР в виде развития метастазирования в период наблюдения предшествует повышение в крови количества функционально неактивных NK и IL-10, моноцитов и гранулоцитов, отвечающих на fMLF, а в ткани – повышение уровня ОСК и снижение экспрессии МНС. Летальному исходу предшествовало повышение в крови IL-6 при снижении NK-клеток субпопуляции CD16dimCD56bright, повышение уровня NKТ-клеток и ОСК в ткани опухоли при снижении МНС-экспрессирующих опухолевых клеток.

В качестве прогностических факторов неблагоприятного течения КРР можно рассматривать высокие уровни IL-6 и IL-10, моноцитов и гранулоцитов, отвечающих на fMLF в крови, повышение уровня NKТ-клеток и ОСК при снижении МНС-экспрессирующих опухолевых клеток в ткани. Особого внимания заслуживает снижение экспрессии PD-1/PDL-1 в клетках опухоли и лимфоцитах ее микроокружения при генерализованном КРР.

Clinical prognosis in malignant tumors` is among the most challenging problems of contemporary medicine. It is thought to depend on both biologic properties of tumor cells and patients` immune status. The features of tumor cells and immune reactions are closely interrelated and mutually conditioned. Therefore, possible application of their characteristics as prognostic markers is of great fundamental and clinical importance. The aim of our study is to find out the most significant immune factors for prognosis of colorectal cancer (CRC) based on estimation of local and system immune factors, and some characteristics of tumor cells in the patients at various stages of the disease and different clinical course. Cellular factors of immunity and cytokines were studied in blood and tumor tissue of 299 patients with colorectal cancer (stages I-IV). Malignant cells expressing stem cell markers CSC), MHC and PDL-1 molecules were also counted in the tumor tissue. Blood samples were drawn prior to operation, and tissue samples were taken during surgery being the 1st line of treatment. Flow cytometry techniques (FCM), immunohistochemistry (IHC), and ELISA approach were employed. We have compared data on the patients at different CRC stages (with or without local and distant metastases), as well as cases with different course of the disease (evolving distant metastases and fatal outcome during period of observation). Our results demonstrated increased amounts of NK-cells and IL-6 concentration, along with decreased percentage of blood CD4+ cells in the patients with local metastases, as well as higher CSC numbers in malignant tissue. The initially generalized CRC cases with distant metastases were characterized by high levels of blood IL-6, monocytes and granulocytes responding to fMLF, while in tumor tissue elevated amounts of NKT, CSC and decreased expression of MHC and PDL-1 were observed on tumor cells, like as lower PD-1/ PDL-1 expression on tumor-infiltrating lymhocytes. Unfavorable CRC dynamics, i.e., metastasizing during the observation period was preceded by increased levels of IL-10 in blood, NK cells with poor cytotoxicity, monocytes and granulocytes responding to fMLF. In tumor tissue, overexpression of CSC markers and hypo-expression of MHC on tumor cells were noted. Fatal outcome was preceded by elevation of blood IL-6levels, tissue levels of NKТ and CSC percentages, along with decreased NK cells subset (CD16dimCD56bright) in blood, and decline of MHC-expressing cells in the tumor. Thus, high blood levels of IL-6 and IL-10, fMLF-responding monocytes and granulocytes, as well as elevated amounts of NKT and CSC, hypo-expression of MHC in tumor tissue could be considered prognostic markers of unfavorable course in CRC patients. Decrease of PD-1/PDL-1 expression on tumor cells and lymphocytes from its microenvironment in advanced CRC is of special attention, because checkpoint inhibitors are prescribed in such cases.

системный иммунитетлокальный иммунитетстволовые опухолевые клеткиколоректальный ракраспространенностьдинамикаsystemic immunitylocal immunitystem cellscolorectal cancerstagesprogressionАвторы выражают благодарность доценту кафедры медицинской и биологической физики ФГБОУ ВО «Ростовский государственный медицинский университет» Минздрава РФ, кандидату медицинских наук А.А. Демидовой за проведение статистической обработки данных.ReferencesКит О.И., Новикова И.А., Бахтин А.В., Никипелова Е.А., Шатова Ю.С., Габараева В.М., Нистратова О.В. Первый опыт детекции циркулирующих опухолевых клеток в периферической крови // Международный журнал экспериментального образования, 2013. №. 11-2. С. 37-39.Kit O.I., Novikova I.A., Bakhtin A.V., Nikipelova E.A., Shatova Yu.S., Gabareva V.M., Nistratova O.V. The first experience of detection circulating tumor cells in peripheral blood. Mezhdunarodnyy zhurnal eksperimentalnogo obrazovaniya = Modern Problems of Science and Education, 2013, no. 11-2, pp. 37-39. (In Russ.)Кит О.И., Шапошников А.В., Златник Е.Ю., Никипелова Е.А., Новикова И.А. Местный клеточный иммунитет при аденокарциноме и полипах толстой кишки //Сибирское медицинское обозрение, 2012. Т. 76, №. 4. С. 11-16.Kit O.I., Shaposhnikov A.V., Zlatnik E.Yu., Nikipelova E.A., Novikova I.A. Local cellular immunity in adenocarcinoma and large intestine polyps. Sibirskoe meditsinskoe obozrenie = Siberian Medical Review, 2012, Vol. 76, no. 4, pp. 11-16. (In Russ.)Кжышковска Ю.Г., Стахеева М.Н., Литвяков Н.В., Савельева О.Е., Митрофанова И.В., Степанов И.В., Грачев А.Н., Геращенко Т.С., Завьялова М.В., Чердынцева Н.В. Иммунная система и эффективность противоопухолевого лечения. Томск: Издательство Томcкого университета, 2015. 164 с.Kzhyshkovska Yu.G., Stakheeva М.N., Litviakov N.V., Savelyeva О.Е., Mitrofanova I.V., Stepanov I.V., Gratchev А.N., Gerashchenko Т.S., Zavyalova М.V., Cherdyntseva N.V. Immune system and the efficacy of cancer treatment. Tomsk: Tomsk University Publishing House, 2015. 164 p.Перельмутер В.М., Таширева Л.А., Манских В.Н., Денисов Е.В., Савельева О.Е., Кайгородова Е.В., Завьялова М.В. Иммуновоспалительные реакции в микроокружении гетерогенны, пластичны, определяют противоопухолевый эффект или агрессивное поведение опухоли // Журнал общей биологии. Томск, 2017. Т. 78, № 5. С. 15-36.Perelmuter V.M., Tashireva L.A., Manskikh V.N., Denisov E.V., Savelieva O.E., Kaygorodova E.V., Zavyalova M.V. Heterogeneity and plasticity of immune-inflammatory responses in tumor microenvironment: A role in antitumor effect and tumor aggressiveness. Zhurnal obshchey biologii. Tomsk = Journal of General Biology, Tomsk, 2017, Vol. 78, no. 5, pp. 15-36. (In Russ.)Arnold C.R., Mangesius J., Skvortsova I.I., Ganswindt U. The Role of Cancer Stem Cells in Radiation Resistance. Front. Oncol., 2020, Vol. 10, 164. doi: 10.3389/fonc.2020.00164.Arnold C.R., Mangesius J., Skvortsova I.I., Ganswindt U. The Role of Cancer Stem Cells in Radiation Resistance. Front. Oncol., 2020, Vol. 10, 164. doi: 10.3389/fonc.2020.00164.Athauda A., Segelov E., Ali Z., Chau I. Integrative molecular analysis of colorectal cancer and gastric cancer: What have we learnt? Cancer Treat. Rev., 2019, Vol. 73, pp. 31-40.Athauda A., Segelov E., Ali Z., Chau I. Integrative molecular analysis of colorectal cancer and gastric cancer: What have we learnt? Cancer Treat. Rev., 2019, Vol. 73, pp. 31-40.Ayob A.Z., Ramasamy T.S. Cancer stem cells as key drivers of tumour progression. J. Biomed.Sci., 2018, Vol. 25, no. 1, pp. 1-18.Ayob A.Z., Ramasamy T.S. Cancer stem cells as key drivers of tumour progression. J. Biomed.Sci., 2018, Vol. 25, no. 1, pp. 1-18.Capp J.P. Cancer stem cells: From historical roots to a new perspective. J. Oncol., 2019, Vol. 2019, 5189232. doi: 10.1155/2019/5189232.Capp J.P. Cancer stem cells: From historical roots to a new perspective. J. Oncol., 2019, Vol. 2019, 5189232. doi: 10.1155/2019/5189232.Coffelt S.B., Marini F.C., Watson K., Zwezdaryk K.J., Dembinski J.L. The pro-inflammatory peptide LL-37 promotes ovarian tumor progression through recruitment of multipotent mesenchymal stromal cells. Proc. Natl Acad. Sci., 2009, Vol. 106, no. 10, pp. 3806-3811.Coffelt S.B., Marini F.C., Watson K., Zwezdaryk K.J., Dembinski J.L. The pro-inflammatory peptide LL-37 promotes ovarian tumor progression through recruitment of multipotent mesenchymal stromal cells. Proc. Natl Acad. Sci., 2009, Vol. 106, no. 10, pp. 3806-3811.Cooley S., Miller J.S. Clinical trials of NK cells for cancer. In: Natural Killer Cells, 2010, pp. 555-570.Cooley S., Miller J.S. Clinical trials of NK cells for cancer. In: Natural Killer Cells, 2010, pp. 555-570.Desai A., Yan Y., Gerson S.L. Concise Reviews: Cancer Stem Cell Targeted Therapies: Toward Clinical Success. Stem Cells Transl. Med., 2019, Vol. 8, no. 1, pp. 75-81.Desai A., Yan Y., Gerson S.L. Concise Reviews: Cancer Stem Cell Targeted Therapies: Toward Clinical Success. Stem Cells Transl. Med., 2019, Vol. 8, no. 1, pp. 75-81.Dunn G.P., Old L.J., Schreiber R.D. The Three Es of Cancer Immunoediting. Annu. Rev. Immunol., 2004, Vol. 22, pp. 329-360.Dunn G.P., Old L.J., Schreiber R.D. The Three Es of Cancer Immunoediting. Annu. Rev. Immunol., 2004, Vol. 22, pp. 329-360.Guo B., Oliver T.G. Partners in Crime: Neutrophil-CTC Collusion in Metastasis. Trends Immunol., 2019, Vol. 40, no. 7, pp. 556-559.Guo B., Oliver T.G. Partners in Crime: Neutrophil-CTC Collusion in Metastasis. Trends Immunol., 2019, Vol. 40, no. 7, pp. 556-559.He H.Q., Ye R.D. The formyl peptide receptors: diversity of ligands and mechanism for recognition. Molecules, 2017, Vol. 22, no. 3, 455. doi: 10.3390/molecules22030455.He H.Q., Ye R.D. The formyl peptide receptors: diversity of ligands and mechanism for recognition. Molecules, 2017, Vol. 22, no. 3, 455. doi: 10.3390/molecules22030455.Heeke S., Mograbi B., Alix-Panabières C., Hofman P. Never travel alone: the crosstalk of circulating tumor cells and the blood microenvironment. Cells, 2019, Vol. 8, no. 7, 714. doi: 10.3390/cells8070714.Heeke S., Mograbi B., Alix-Panabières C., Hofman P. Never travel alone: the crosstalk of circulating tumor cells and the blood microenvironment. Cells, 2019, Vol. 8, no. 7, 714. doi: 10.3390/cells8070714.Huang, Z.L., Liu S., Wang G.N., Zheng S.H., Ding S.R., Tao Y.L., Chen C., Liu S.R., Yang X., Chang H., Wang X.H., Xia Y.F. The prognostic significance of PD-L1 and PD-1 expression in patients with nasopharyngeal carcinoma: a systematic review and meta-analysis. Cancer Сell Int., 2019, Vol. 19, 141. doi: 10.1186/s12935-019-0863-5.Huang, Z.L., Liu S., Wang G.N., Zheng S.H., Ding S.R., Tao Y.L., Chen C., Liu S.R., Yang X., Chang H., Wang X.H., Xia Y.F. The prognostic significance of PD-L1 and PD-1 expression in patients with nasopharyngeal carcinoma: a systematic review and meta-analysis. Cancer Сell Int., 2019, Vol. 19, 141. doi: 10.1186/s12935-019-0863-5.Ito S., Masuda T., Noda M., Hu Q., Shimizu D., Kuroda Y., Eguchi H., Tobo T., Utsunomiya T., Mimori K. Prognostic Significance of PD-1, PD-L1 and CD8 Gene Expression Levels in Gastric Cancer. Oncology, 2020, Vol.98, no. 7, pp. 501-511.Ito S., Masuda T., Noda M., Hu Q., Shimizu D., Kuroda Y., Eguchi H., Tobo T., Utsunomiya T., Mimori K. Prognostic Significance of PD-1, PD-L1 and CD8 Gene Expression Levels in Gastric Cancer. Oncology, 2020, Vol.98, no. 7, pp. 501-511.Iwayama Y., Tsuruma T., Mizuguchi T., Furuhata T., Toyota N., Matsumura M., Torigoe T., Sato N., Hirata K. Prognostic value of HLA class I expression in patients with colorectal cancer. World J. Surg. Oncol., 2015, Vol. 13, no. 1, pp. 1-7.Iwayama Y., Tsuruma T., Mizuguchi T., Furuhata T., Toyota N., Matsumura M., Torigoe T., Sato N., Hirata K. Prognostic value of HLA class I expression in patients with colorectal cancer. World J. Surg. Oncol., 2015, Vol. 13, no. 1, pp. 1-7.Kim R., Cancer immunoediting: from immune surveillance to immune escape. Cancer Immunother., 2007, pp. 9-27.Kim R., Cancer immunoediting: from immune surveillance to immune escape. Cancer Immunother., 2007, pp. 9-27.Krijgsman D., Hokland M., Kuppen P.J.K. The role of natural killer T cells in cancer—a phenotypical and functional approach. Front. Immunol., 2018, Vol. 9, 367. doi: 10.3389/fimmu.2018.00367.Krijgsman D., Hokland M., Kuppen P.J.K. The role of natural killer T cells in cancer—a phenotypical and functional approach. Front. Immunol., 2018, Vol. 9, 367. doi: 10.3389/fimmu.2018.00367.Kuşoğlu A., Avcı Ç. B. Cancer stem cells: A brief review of the current status. Gene, 2019, Vol. 681, pp. 80-85.Kuşoğlu A., Avcı Ç. B. Cancer stem cells: A brief review of the current status. Gene, 2019, Vol. 681, pp. 80-85.Leblanc R., Peyruchaud O. Metastasis: new functional implications of platelets and megakaryocytes. Blood, 2016, Vol. 128, no. 1, pp. 24-31.Leblanc R., Peyruchaud O. Metastasis: new functional implications of platelets and megakaryocytes. Blood, 2016, Vol. 128, no. 1, pp. 24-31.Leone K., Poggiana C., Zamarchi R. The interplay between circulating tumor cells and the immune system: from immune escape to cancer immunotherapy. Diagnostics, 2018, Vol. 8, no. 3, 59. doi: 10.3390/diagnostics8030059.Leone K., Poggiana C., Zamarchi R. The interplay between circulating tumor cells and the immune system: from immune escape to cancer immunotherapy. Diagnostics, 2018, Vol. 8, no. 3, 59. doi: 10.3390/diagnostics8030059.Lin A., Yan W.H. Human leukocyte antigen-G (HLA-G) expression in cancers: roles in immune evasion, metastasis and target for therapy. Mol. Med., 2015, Vol. 21, no. 1, pp. 782-791.Lin A., Yan W.H. Human leukocyte antigen-G (HLA-G) expression in cancers: roles in immune evasion, metastasis and target for therapy. Mol. Med., 2015, Vol. 21, no. 1, pp. 782-791.Mollinedo F. Neutrophil degranulation, plasticity, and cancer metastasis. Trends Immunol., 2019, Vol. 40, no. 3, pp. 228-242.Mollinedo F. Neutrophil degranulation, plasticity, and cancer metastasis. Trends Immunol., 2019, Vol. 40, no. 3, pp. 228-242.Pan Q., Li Q., Liu S., Ning N., Zhang X., Xu Y. Concise review: targeting cancer stem cells using immunologic approaches. Stem Cells, 2015, Vol. 33, no. 7, pp. 2085-2092.Pan Q., Li Q., Liu S., Ning N., Zhang X., Xu Y. Concise review: targeting cancer stem cells using immunologic approaches. Stem Cells, 2015, Vol. 33, no. 7, pp. 2085-2092.Pang R., Law W.L., Chu A.C.Y., Poon J.T., Lam C.S.C., Chow A.K.M., Ng L., Cheung L.W.H., Lan X.R., Lan H.Y., Tan V.P.Y., Yau T.C., Poon R.T., Wong B.C.Y. A subpopulation of CD26+ cancer stem cells with metastatic capacity in human colorectal cancer. Cell Stem Cell, 2010, Vol. 6, no. 6, pp. 603-615.Pang R., Law W.L., Chu A.C.Y., Poon J.T., Lam C.S.C., Chow A.K.M., Ng L., Cheung L.W.H., Lan X.R., Lan H.Y., Tan V.P.Y., Yau T.C., Poon R.T., Wong B.C.Y. A subpopulation of CD26+ cancer stem cells with metastatic capacity in human colorectal cancer. Cell Stem Cell, 2010, Vol. 6, no. 6, pp. 603-615.Phi L.T.H., Sari I.N., Yang Y.G., Lee S.H., Jun N., Kim K.S., Lee Y.K., Kwon Y.H. Cancer stem cells (CSCs) in drug resistance and their therapeutic implications in cancer treatment. Stem Cells Int., 2018, Vol. 2018, 5416923. doi: 10.1155/2018/5416923.Phi L.T.H., Sari I.N., Yang Y.G., Lee S.H., Jun N., Kim K.S., Lee Y.K., Kwon Y.H. Cancer stem cells (CSCs) in drug resistance and their therapeutic implications in cancer treatment. Stem Cells Int., 2018, Vol. 2018, 5416923. doi: 10.1155/2018/5416923.Saunders M., Iveson T. Management of advanced colorectal cancer: state of the art. Br. J. Cancer, 2006, Vol. 95, no. 2, pp. 131-138.Saunders M., Iveson T. Management of advanced colorectal cancer: state of the art. Br. J. Cancer, 2006, Vol. 95, no. 2, pp. 131-138.Shibata M., Hoque M.O. Targeting Cancer Stem Cells: A Strategy for Effective Eradication of Cancer. Cancers, 2019, Vol. 11, no. 5, 732. doi: 10.3390/cancers11050732.Shibata M., Hoque M.O. Targeting Cancer Stem Cells: A Strategy for Effective Eradication of Cancer. Cancers, 2019, Vol. 11, no. 5, 732. doi: 10.3390/cancers11050732.Spillane J.B., Henderson M.A. Cancer stem cells: a review. ANZ J. Surg., 2007, Vol. 77, no. 6, pp. 464-468.Spillane J.B., Henderson M.A. Cancer stem cells: a review. ANZ J. Surg., 2007, Vol. 77, no. 6, pp. 464-468.Steinert G., Schölch S., Niemietz T., Iwata N., García S.A., Behrens B., Voigt A., Kloor M., Benner A., Bork U., Rahbari N.N., Büchler M.W., Stoecklein N.H., Weitz J., Koch M. Immune escape and survival mechanisms in circulating tumor cells of colorectal cancer. Cancer Res., 2014, Vol. 74, no. 6, pp. 1694-1704.Steinert G., Schölch S., Niemietz T., Iwata N., García S.A., Behrens B., Voigt A., Kloor M., Benner A., Bork U., Rahbari N.N., Büchler M.W., Stoecklein N.H., Weitz J., Koch M. Immune escape and survival mechanisms in circulating tumor cells of colorectal cancer. Cancer Res., 2014, Vol. 74, no. 6, pp. 1694-1704.Vrankar M., Kern I., Stanic K. Prognostic value of PD-L1 expression in patients with unresectable stage III non-small cell lung cancer treated with chemoradiotherapy. Radiation Oncol., 2020, Vol. 15, no. 1, pp. 1-12.Vrankar M., Kern I., Stanic K. Prognostic value of PD-L1 expression in patients with unresectable stage III non-small cell lung cancer treated with chemoradiotherapy. Radiation Oncol., 2020, Vol. 15, no. 1, pp. 1-12.Walcher L., Kistenmacher A.K., Suo H., Kitte R. Cancer Stem Cells – Origins and Biomarkers: Perspectives for Targeted Personalized Therapies. Front. Immunol., 2020, Vol. 11, 1280. doi: 10.3389/fimmu.2020.01280.Walcher L., Kistenmacher A.K., Suo H., Kitte R. Cancer Stem Cells – Origins and Biomarkers: Perspectives for Targeted Personalized Therapies. Front. Immunol., 2020, Vol. 11, 1280. doi: 10.3389/fimmu.2020.01280.Wang X., Sun Q., Liu Q., Wang C., Yao R., Wang Y. CTC immune escape mediated by PD-L1. Med. Hypotheses, 2016, Vol. 93, pp. 138-139.Wang X., Sun Q., Liu Q., Wang C., Yao R., Wang Y. CTC immune escape mediated by PD-L1. Med. Hypotheses, 2016, Vol. 93, pp. 138-139.Zahran A.M., Rayan A., Fakhry H., Attia A.M., Ashmawy A.M., Soliman A., Elkady A., Hetta H.F. Pretreatment detection of circulating and tissue CD133+ CD44+ cancer stem cells as a prognostic factor affecting the outcomes in Egyptian patients with colorectal cancer. Cancer Manag. Res., 2019, Vol. 11, pp. 1237-1248.Zahran A.M., Rayan A., Fakhry H., Attia A.M., Ashmawy A.M., Soliman A., Elkady A., Hetta H.F. Pretreatment detection of circulating and tissue CD133+ CD44+ cancer stem cells as a prognostic factor affecting the outcomes in Egyptian patients with colorectal cancer. Cancer Manag. Res., 2019, Vol. 11, pp. 1237-1248.Zeuner A., Todaro M., Stassi G., De Maria R. Colorectal cancer stem cells: from the crypt to the clinic. Cell Stem Cell, 2014, Vol. 15, no. 6, pp. 692-705.Zeuner A., Todaro M., Stassi G., De Maria R. Colorectal cancer stem cells: from the crypt to the clinic. Cell Stem Cell, 2014, Vol. 15, no. 6, pp. 692-705.Zhang Y., Kang S., Shen J., He J., Jiang L. Prognostic significance of programmed cell death 1 (PD-1) or PD-1 ligand 1 (PD-L1) Expression in epithelial-originated cancer: a meta-analysis. Medicine, 2015, Vol. 94, no. 6, e515. doi:10.1097/MD.0000000000000515.Zhang Y., Kang S., Shen J., He J., Jiang L. Prognostic significance of programmed cell death 1 (PD-1) or PD-1 ligand 1 (PD-L1) Expression in epithelial-originated cancer: a meta-analysis. Medicine, 2015, Vol. 94, no. 6, e515. doi:10.1097/MD.0000000000000515.Zhang D., Tang D.G., Rycaj K. Cancer stem cells: regulation programs, immunological properties and immunotherapy. Semin. Cancer Biol., 2018, Vol. 52, Pt 2, pp. 94-106.Zhang D., Tang D.G., Rycaj K. Cancer stem cells: regulation programs, immunological properties and immunotherapy. Semin. Cancer Biol., 2018, Vol. 52, Pt 2, pp. 94-106.

The authors declare that there are no conflicts of interest present.