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Leonor Kremer

Name of the laboratory

CNB-CSIC Protein Tools Unit
Protein Tools Unit & Antibody-Based Agents for Cancer Immunotherapy Group
Department of Immunology and Oncology
Centro Nacional de Biotecnología (CNB)
Spanish National Research Council (CSIC)
Darwin 3, Campus Cantoblanco
28049 Madrid, Spain
(+34) 915 854 614

Members of the laboratory

Unit Leader
Leonor Kremer (PhD) lkremer@cnb.csic.es
Technicians
María Irene Ayuso irene.ayuso@cnb.csic.es
Fernando Gutiérrez del Burgo fernando.gutierrez@cnb.csic.es
Isabel Corraliza Gorjón icorraliza@cnb.csic.es

Laboratory activity

The CNB-CSIC Protein Tools Unit focuses on the design, production, characterization and use of proteins as specific molecular tools. The Unit generates monoclonal antibodies (mAbs), performs studies of the immune response, develops specific immunoassays and analyzes biomolecular interactions. One of our main goals is to generate mAbs not available commercially. The activities, individually or as part of a project, are based on proposals from research groups within the CNB and from private or public research organizations and/or companies. We also help basic research groups with technology transfer from research.

The Unit generated mAbs against more than 60 different antigens, for use in basic and pre-clinical research, drug discovery, and diagnostics. As examples, we produced mAbs to chromatin-associated proteins (Dido, ScoHET), centrosomal proteins (CAP350), immunoglobulins (canine IgE), blood proteins (coagulation factor V, tissue factor, CD5L), neurodegenerative disease-related proteins (tau, beta amyloid peptides), mitochondrial proteins (SCAM3), kinases (P38, PI3K, DGK, GSK3, PKD, SADB), membrane receptors (FOLR1, dectin-1) viral antigens (TEGV RNA polymerase, SARS-CoV-1 envelope, SARS-CoV-2 spike, HIV-1 gp120, IAVs H5N1 nucleoprotein) and other human pathogens (Candida famata, Anisakis sp.).

Research activities

The main objective of our team is the generation and characterization of antibodies directed against tumor cell membrane antigens that have a high potential for use as therapeutic agents for the treatment of cancer.

For several years, our group has been studying the role of chemokines and their receptors in tumor progression and metastasis, focusing on evaluating the potential of chemokine receptors as possible antitumor targets. In this context, we have generated a panel of mouse monoclonal antibodies specific for the chemokine receptors CCR4, CCR6, CCR8 and CCR9, useful also for structure-function studies. We are currently in advanced stages of development of an antibody directed against CCR9, an overexpressed chemokine receptor in the tumor cells of the vast majority of patients with T-cell acute lymphoblastic leukemia (T-ALL). This antibody has been licensed by CSIC to a biotech company as an antitumor agent, and has also been used to functionalize magnetic nanoparticles that specifically recognize human CCR9+ cells for use in magnetic hyperthermia therapy.

Using whole tumor cells as immunogens, we have generated mAbs against other human T-ALL cell surface antigens to be used as part of antibody cocktails capable of synergistically attacking different molecular targets on tumor cells. Among them, we have selected several mAbs that strongly reduce tumor size in orthotopic animal models. Using proteomic techniques and protein arrays, we have identified the cellular antigens recognized by those mAbs that have demonstrated a higher therapeutic activity in in vivo assays, together with a high specificity and subnanomolar affinity level for their respective target antigens.

We are also generating and evaluating mAbs that modulate the immune response in liver fibrosis and cancer (anti CD5L) and that inhibit viral uptake or infection (Ebola, avian influenza virus, HIV-1, SARS-CoV-2).

Techniques available

  • Design of immunization strategies, immunogen production and analysis of immune responses.
  • Poly- and monoclonal antibody production in rabbit, mouse, rat and hamster Immunization with plasmids and transfected cells.
  • Antibody characterization by ELISA, RIA, flow cytometry, immunoprecipitation and Western blot.
  • Purification and labeling of enzymes and antibodies.
  • Development of immunoassays for antigen detection and quantification in biological fluids.
  • Characterization of biomolecular interactions in real time. Determination of kinetic and affinity constants.

Publications (2021-present)

  • Egea-Benavente D, Corraliza-Gorjón I, van Zanten TS, Morales MDP, Kremer L, Barber DF. Enhancing Magnetic Hyperthermia at the Cell Membrane by Anchoring 92R-Functionalized Magnetic Nanoparticles to Low-Endocytic CCR9 Surface Receptors. Adv Healthc Mater. 2026;15:e03501. doi: 10.1002/adhm.202503501.
  • Cebrián-Sastre E, Ruiz-Enamorado Á, Castañeda-García A, Gola S, García-Bravo P, Kremer L, Blázquez J. Regulation of the Expression of nucS, a Key Component of the Mismatch Repair System in Mycobacteria. Antibiotics (Basel). 2025;14:1065. doi: 10.3390/antibiotics14111065.
  • Sanchez-Moral L, Paul T, Martori C, Font-Díaz J, Sanjurjo L, Aran G, Téllez E, Blanco J, Carrillo J, Ito M, Tuttolomondo M, Ditzel HJ, Fumagalli C, Tapia G, Sidorova J, Masnou H, Fernández-Sanmartín MA, Lozano JJ, Vilaplana C, Rodriguez-Cortés A, Armengol C, Valledor AF, Kremer L, Sarrias MR. Macrophage CD5L is a target for cancer immunotherapy. EBioMedicine. 2023;91:104555. doi: 10.1016/j.ebiom.2023.104555.
  • Labat-de-Hoz L, Comas L, Rubio-Ramos A, Casares-Arias J, Fernández-Martín L, Pantoja-Uceda D, Martín MT, Kremer L, Jiménez MA, Correas I, Alonso MA. Structure and function of the N-terminal extension of the formin INF2. Cell Mol Life Sci. 2022;79:571. doi: 10.1007/s00018-022-04581-y.
  • Santamaria S, Delgado M, Botas M, Castellano E, Corraliza-Gorjon I, Lafuente P, Muñoz-Calleja C, Toribio ML, Kremer L, Garcia-Sanz JA. Therapeutic potential of an anti-CCR9 mAb evidenced in xenografts of human CCR9+ tumors. Front Immunol. 2022;13:825635. doi: 10.3389/fimmu.2022.825635.
  • Rubio-Ramos A, Bernabé-Rubio M, Labat-de-Hoz L, Casares-Arias J, Kremer L, Correas I, Alonso MA. MALL, a membrane-tetra-spanning proteolipid overexpressed in cancer, is present in membraneless nuclear biomolecular condensates. Cell Mol Life Sci. 2022;79:236. doi: 10.1007/s00018-022-04270-w.
  • Cacho-Navas C, Reglero-Real N, Colás-Algora N, Barroso S, de Rivas G, Stamatakis K, Feito J, Andrés G, Fresno M, Kremer L, Correas I, Alonso MA, Millán J. Plasmolipin regulates basolateral-to-apical transcytosis of ICAM-1 and leukocyte adhesion in polarized hepatic epithelial cells. Cell Mol Life Sci. 2022;79:61. doi: 10.1007/s00018-021-04095-z.
  • Ferrero DS, Busnadiego I, Garriga D, Guerra P, Martín MT, Kremer L, Usón I, Rodriguez JF, Verdaguer N. Structure and dsRNA-binding activity of the Birnavirus Drosophila X Virus VP3 protein. J Virol. 2021;95:e02166-20. doi: 10.1128/JVI.02166-20.

Patents

  • Title: Combination Therapy Comprising Anti-CCR9 Antibody and Vincristine for Cancer. Patent Application: WO2023EP52720. Priority date: 03.02.2022. Owner: SunRock Biopharma SL and CSIC. Inventors: S Santamaría García-Minguillán, M Delgado Álvarez, JA García Sanz, L Kremer Barón, L Simón Buela, P Garrido Cuesta, A Pérez Díaz.
  • Title: Antibodies against CCR9 and methods of use thereof. Application granted: US9884915B2. Status: Active. Owner: CSIC. Inventors: S Chamorro Pérez, A Franco Villanueva, JA García Sanz, L Kremer Barón, CMartínez Alonso, M Vela Cuenca, L Carramolino Fitera.