Drug Discovery
  Molecular Analysis
  Organic and Organometallic Chemistry
  Medicinal Chemistry
  Synthetic Medicinal Chemistry and Chemical Biology
  Identification & validation of novel therapeutic targets - Biological evaluation of bioactive small molecules and drugs
  Structural Biology & Chemistry
  Molecular Endocrinology
  Signal Mediated Gene Expression
  Molecular & Cellular Ageing
  Biomedical Applications
  Holistic Approaches in Health
  Environment and Health
  Metabolic Engineering-Bioinformatics
  Biomarker Discovery & Translational Research
  Enzyme and Synthetic Biotechnology
  Biomimetics & Nanobiotechnology
  Conjugated Polymers for Healthcare, Bioelectronics and Bioimaging


Identification and validation of novel therapeutic targets - Biological evaluation of bioactive small molecules and drugs
Dr. Dimitrios Stellas | Associate Researcher, Group Leader


The team works on in vitro screening, of novel medicinal compounds, novel combinations of already established drugs (repurposing), or novel delivery systems (liposomes, carbon nanohorns etc); mostly using primary cells and cell cancer lines. The goal is to identify novel therapeutic targets and evaluate their toxicity at a cellular level.
The selected drug candidates will be next evaluated in vivo for their efficacy, and/or their toxicity using different mouse systems (immunocompromised or immunocompetent).

Moreover, the team studies the molecular mechanisms and the cellular interactions involved in cancer immunotherapy. Using immunocompetent murine models of breast, colon, and pancreas cancers and trueÒ humanized patient derived models the team will focus on studying the complex interactions between the immune cells and the cancer cells in the primary tumor microenvironment and the metastatic niches. The overall goal is to use beneficial combinations of chemo-immunotherapy providing critical information for direct clinical applications.  


Development of bioactive compounds against selected therapeutic targets and their evaluation in relevant preclinical disease models, aiming at their potential exploitation in innovative approaches for chemo-immunotherapy and treatment using Adoptive Cell Transfer protocols and CAR-NK cell transfers under the prism of personalized medicine.


  • Create a cellular data base using cell lines form different disease types and genetic background and/or mutational burden to provide the most relevant in vitro screening tool.
  • Manipulate primary cells or cell lines (Knock-in or Knock-out gene targets) to express or to completely ablate the protein of interest to validate target specificity.
  • Test the efficacy and the toxicity of novel compounds in vitro and in vivo using the most appropriate mouse models, utilizing different formulations and routes of administration.  


In vivo efficacy/toxicity


Research Overview

Mouse models of Cancer Immunotherapy and Humanized mouse models baring Patient Derived Xenografts

For years, the foundations of cancer treatment were surgery, chemotherapy, and radiation therapy. Over the last two decades, targeted therapies like imatinib (Gleevec®) and trastuzumab (Herceptin®)—drugs that target cancer cells by homing in on specific molecular changes seen primarily in those cells—have also cemented themselves as standard treatments for many cancers. But over the past several years, immunotherapy—therapies that enlist and strengthen the power of a patient’s immune system to attack tumors—has emerged as what many in the cancer community now call the “fifth pillar” of cancer treatment.
One of the most successful attempts in the field of immunotherapy is T Cell Transfer therapy, which is gaining a lot of attention lately due to the indisputable success of Chimeric Antigen Receptor T Cell (CAR-T cells) therapy in B cell lymphomas and Acute Lymphoblastic Leukemia (ALL), in which over 80% of the patients showed complete regression of the disease.
Likewise, Adoptive T cell therapy using ex vivo expanded TILs has also led to complete regression of 20-25 % of patients with metastatic melanoma and other solid tumors. Such remarkable effects were mediated by T cells that specifically target mutant peptides (neoantigens) encoded by genes sharing de novo somatic mutations. Adoptive T cell therapy clinical trials have revolutionized the field of cancer immunotherapy, which now has additional prominent allies, such as monoclonal antibodies against PD1/PDL1 and CTLA 4 that apparently act on the activation of T cells, which recognize and attack cancer cells.
The therapeutic potential of the ACT, which is based on tumor-specific lymphocytes, was first tested by Fefer and Rosenberg about 40 years ago showing only limited efficacy. In recent years, due to the advancement of cellular and molecular biology techniques, such as T cell extraction, expansion and activation ex vivo, and genetic engineering techniques, ACT is becoming a viable therapeutic option for cancer patients who are refractory to conventional therapy. The ACT can also include dendritic cells (DCs) and/or immune effector cells, or combination of both. DCs are often used as vaccine carriers or antigen presenting cells (APCs) to prime naive T cells in vitro or in vivo. Cytotoxic T lymphocytes (CTL) and natural killer cells (NK) are the major effector cells in naturally occurring anti-tumor response and were exploited very early as tool cells for the ACT. An impressive success of ACT has been achieved in several types of cancers during the last two decades, and the most prominent progress was made in B lymphocyte leukemia and lymphoma. Since then, promising results were obtained in a variety of solid tumors, including metastatic melanoma, renal cell carcinoma (RCC), nasopharyngeal cancer, gastric cancer, hepatocellular carcinoma, and lung cancer. ACT with TILs is yet the most effective immunotherapy strategy for patients with metastatic melanoma.

The team will focus on i) identifying and characterizing CD8+ Tumor Infiltrating T Lymphocytes, which have the ability to recognize specific somatic mutations in cancer cells and ii) evaluate the in vivo efficacy of these T cells alone or in combination with immune checkpoint inhibitors. The fresh tumor samples will be provided with patients’ consent under the already existing collaboration between NHRF and the General Hospital of Athens, under the consortium ‘’Medical precision Unit’’. The proposed work plan is depicted below.



Our goal is to provide useful information to the physicians regarding the mutational landscape of the tumor, and the underlying response of the immune system to CANCER NEO-ANTIGENS trying to modify the therapeutic approach towards a personalized therapy, using our in vitro and in vivo data. With the hope that our work will be one of the first attempts to show the lifesaving benefits of ACT and eventually engage our legislative system to incorporate in the near future adoptive cell transfer of modified ex vivo cells to the clinic to completely eradicate some cancer types and expand life expectancy for cancer patients.


Selected Publications

  • Stochastic phenotype switching leads to intratumor heterogeneity in human liver cancer, Matak, A., Lahiri, P., Ford, E., Pabst, D., Kashofer, K., Stellas, D., Thanos, D., and Zatloukal, K., Hepatology 68(3):933-948, 2018
  • Heterodimeric interleukin 15 (hetIL-15) treatment decreases primary breast cancer 4T1 tumors and alleviates the metastatic burden, Stellas, D., Dimas, K., Nagy, B.A., Valentin, A., Felber, B.K., and Pavlakis, G.N., In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018
  • Stellas, D., Karaliota, S., Stravokefalou, V., Nagy, B.A., Felber, B.K., and Pavlakis, G.N., American Association for Cancer Research Annual Meeting, Heterodimeric IL-15 monotherapy results in complete regression of EO771 murine breast tumors through cDC1-lymphocyte interactions and induction of antitumor immunity. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 March 29-3 Apr, Atlanta. Georgia (GA): AACR; Cancer Res 2019
  • Watson, D.C., Yung, B.C., Bergamaschi, C., Chowdhury, B., Bear, J., Stellas, D., Morales-Kastresana, A., Jones, J.C., Felber, B.K., Chen, X., and Pavlakis, G.N.: Scalable, cGMP-compatible purification of extracellular vesicles carrying bioactive human heterodimeric IL-15 / Lactadherin complexes. J Extracell Vesicles. 28;7(1):1442088. 2018
  • Bergamaschi,C., Pandit, H., Nagy,B., Stellas, D., Jensen, S., Bear,J., Cam,M., Valentin,A., Fox,B., Felber, BK., Pavlakis, GN. Heterodimeric IL-15 delays tumor growth and promotes intratumoral CTL and dendritic cell accumulation by a cytokine network involving XCL1, IFN-γ, CXCL9 and CXCL10. J Immunother Cancer. 2020 May;8(1):e000599. doi: 10.1136/jitc-2020-000599


CAR-NK cells to the Rescue

Honoring the existing collaboration with NCI / NIH regarding the co-administration of heterodimeric IL-15, anti-mesothelin antibodies and immunotoxins for the treatment of Pancreatic Ductal Adenocarcinoma, the team will now focus on generating, validating and ameliorating the efficacy of CAR-NK cells against mesothelin. Mesothelin (MSLN) is a tumor-differentiated antigen discovered by Kai Chang, Ira Pastan and Mark Willingham at the NCI in 1992. It is a cell-surface glycoprotein with normal expression limited to mesothelial cells lining the pleura, peritoneum, and pericardium but is also highly expressed in many cancers, including malignant mesothelioma, pancreatic cancer, ovarian cancer, lung adenocarcinoma, endometrial cancer, triple negative breast carcinomas, biliary cancer, gastric cancer, and pediatric acute myeloid leukemia. The working scheme is depicted below.


The CAR-NK model will be further expanded to include other cancer specific antigens from other types of solid and blood cancers, and thus create a broader preclinical platform.   

COVID-19 related research

During COVID-19 era, we are trying to study the effects of the neutralization abilities of convalescent plasma. Therefore, with the ongoing collaboration of Dr. Pavlakis’s and Dr.Felber’s Labs at NIH we have generated pseudoviral SARS-COV-2 assays to measure the neutralization ability of human and monkey plasma against SARS-COV-2. We have so far generated an extended variety of pseudoviral assays to evaluate the neutralizing abilities of patient’s plasma against the different SARS-COV-2 variants of concern.


Selected Publications

  • Terpos E, Politou M, Sergentanis TN, Mentis A, Rosati M, Stellas D, Bear J, Hu X, Felber BK, Pappa V, Pagoni M, Grouzi E, Labropoulou S, Charitaki I, Ntanasis-Stathopoulos I, Moschandreou D, Bouhla A, Saridakis S, Korompoki E, Giatra C, Bagratuni T, Pefanis A, Papageorgiou S, Spyridonidis A, Antoniadou A, Kotanidou A, Syrigos K, Stamoulis K, Panayiotakopoulos G, Tsiodras S, Alexopoulos L, Dimopoulos MA, Pavlakis GN. Anti-SARS-CoV-2 Antibody Responses in Convalescent Plasma Donors Are Increased in Hospitalized Patients; Subanalyses of a Phase 2 Clinical Study. Microorganisms. 2020 Nov 28;8(12):1885.
    doi: 10.3390/microorganisms8121885. PMID: 33260775
  • Pappa V, Bouchla A, Terpos E, Thomopoulos TP, Rosati M, Stellas D, Antoniadou A, Mentis A, Papageorgiou SG, Politou M, Kotanidou A, Kalomenidis I, Poulakou G, Jahaj E, Korompoki E, Grigoropoulou S, Hu X, Bear J, Karaliota S, Burns R, Pagoni M, Trontzas I, Grouzi E, Labropoulou S, Stamoulis K, Bamias A, Tsiodras S, Felber BK, Pavlakis GN, Dimopoulos MA. A Phase II Study on the Use of Convalescent Plasma for the Treatment of Severe COVID-19- A Propensity Score-Matched Control Analysis.Microorganisms. 2021 Apr 11;9(4):806.
    doi: 10.3390/microorganisms9040806. PMID: 33920489
  • Terpos E, Stellas D, Rosati M, Sergentanis TN, Hu X, Politou M, Pappa V, Ntanasis-Stathopoulos I, Karaliota S, Bear J, Donohue D, Pagoni M, Grouzi E, Korompoki E, Pavlakis GN, Felber BK, Dimopoulos MA. SARS-CoV-2 antibody kinetics eight months from COVID-19 onset: Persistence of spike antibodies but loss of neutralizing antibodies in 24% of convalescent plasma donors.Eur J Intern Med. 2021 May 18:S0953-6205(21)00161-8.
    doi: 10.1016/j.ejim.2021.05.010.
  • Rosati M., Agarwal M., Hu X., Devasundaram S., Stellas D., Chowdhury B., Bear J., Burns R., Donohue D., Pessaint L., Andersen H., Terpos E., Dimopoulos M.A, Wlodawer A., Mullins I., Venzon D.J, Pavlakis G.N, Felber B.K Control of SARS-CoV-2 infection after Spike DNA or Spike DNA+Protein co-immunization in rhesus macaques.  Plos Pathogens
    doi: /10.1101/2021.06.11.448032
  • Bergamaschi, C., Terpos, E., Rosati, M., Angel, M., Bear, J., Stellas, D., Karaliota, S., Apostolakou, F., Bagratuni, T., Patseas, D., Gumeni, S., Trougakos, I.P., Dimopoulos, M.A., Felber, B.K., and Pavlakis, G.N.: Systemic IL-15, IFN-g, and IP-10/CXCL10 signature associated with effective immune response to SARS-CoV-2 in BNT162b2 mRNA vaccine recipients. Cell Rep. 36: 109504, 2021.
  • Thomopoulos TP, Rosati M, Terpos E, Stellas D, Hu X, Karaliota S, Bouchla A, Katagas I, Antoniadou A, Mentis A, Papageorgiou SG, Politou M, Bear J, Donohue D, Kotanidou A, Kalomenidis I, Korompoki E, Burns R, Pagoni M, Grouzi E, Labropoulou S, Stamoulis K, Bamias A, Tsiodras S, Dimopoulos MA, Pavlakis GN, Pappa V, Felber BK. Kinetics of Nucleocapsid, Spike and Neutralizing Antibodies, and Viral Load in Patients with Severe COVID-19 Treated with Convalescent Plasma. Viruses. 2021 Sep 15;13(9):1844.
    doi:10.3390/v13091844.PMID: 34578426



Group Structure and Personnel

Dr. Dimitrios Stellas, Associate Researcher, Group Leader


Experience & Expertise

The team supports fit for purpose to full compliance.
The team advises on study design from preliminary in vitro cytotoxicity or in vitro efficacy to a full-fledged preclinical trial using in vivo immunocompetent, or immunodeficient mice and Patient Derived Xenografts. 


Selected publications

  • Stellas, D., Szabolcs, M., Koul, S., Li, Z., Polyzos, A., Anagnostopoulos, C., Cournia, Z., Tamvakopoulos, C., Klinakis, A., and Efstratiadis, A.: Therapeutic effects of an anti-myc drug on mouse pancreatic cancer. J. Natl. Cancer Inst. 106:dju320 doi:10.1093/jnci/dju320, 2014.
  • Truillet, C., Bouziotis, P., Brugiere, J., Martini, M., Sancey, L., Lux, F., Denat, F., Boschetti, F., Stellas, D., Anagnostopoulos, C., Koutoulidis, V., Moulopoulos, L., Perriat, P., and Tillement, O.: Ultrasmall particles fo Gd-MRI and 68Ga-PET dual imaging. Contrast Media Mol. Imaging 10: 309-319, 2014.
  • Galani, A., Tsitsias, V., Stellas, D., Psycharis, V., Raptopoulou, C., and Karaliota, A.: Two novel compounds of vanadium and molybdenum with carnitine exhibiting potential pharmacological use. J. Inorg. Biochem. 142: 109-117, 2015
  • Pippa, N., Stellas, D., Skandalis, A., Pispas, S., Demetzos, C., Libera, M., Marcinkowski, A., and Trzebicka, B.: Chimeric lipid/block copolymer nanovesicles: physico-chemical and bio-compatibility evaluation. Eur. J. Pharm. Biopharm. 107: 295-309, 2016.
  • Naziris, N., Pippa, N., Stellas, D., Chrysostomou V., Libera, M., Trzebicka,B., Pispas,S., and Demetzos, C. Development and Evaluation of Stimuli-responsive Chimeric  Nanostructures. AAPS PharmSciTech. 2018 Oct;19(7):2971-2989
  • Pippa, N., Naziris, N., Stellas, D., Massala, C., Zouliati, K., Pispas, S., Demetzos, C., Forys, A., Marcinkowski, A., Trzebicka, B. PEO-b-PCL grafted niosomes: the cooperativilty of amphiphilic components and their properties in vitro and in vivo. Colloids and Surfaces B: Biointerfaces 2019 May (177):338-345





© National Hellenic Research Foundation (NHRF), 48 Vassileos Constantinou Ave., 11635 Athens, Greece, Tel. +302107273700, Fax. +302107246618