DETAILED PHENOTYPIC, MOLECULAR AND FUNCTIONAL PROFILING OF MYELOID DERIVED SUPPRESSOR CELLS (MDSCS) IN THE TUMOR IMMUNE MICRO-ENVIRONMENT (TIME) OF MULTIPLE MYELOMA (MM)
Author(s): ,
Cristina Pérez
Affiliations:
Clínica Universidad de Navarra,Pamplona,Spain
,
Cirino Botta
Affiliations:
Magna Graecia University of Catanzaro,Catanzaro,Italy
,
Aintzane Zabaleta
Affiliations:
Clínica Universidad de Navarra,Pamplona,Spain
,
Noemí Puig
Affiliations:
Hospital Universitario de Salamanca,Salamanca,Spain
,
María Teresa Cedena
Affiliations:
Hospital Universitario 12 de Octubre,Madrid,Spain
,
Juana Merino
Affiliations:
Clínica Universidad de Navarra,Pamplona,Spain
,
Diego Alignani
Affiliations:
Clínica Universidad de Navarra,Pamplona,Spain
,
Sonia Garate
Affiliations:
Clínica Universidad de Navarra,Pamplona,Spain
,
Ibai Goicoechea
Affiliations:
Clínica Universidad de Navarra,Pamplona,Spain
,
David Lara-Astiaso
Affiliations:
Clínica Universidad de Navarra,Pamplona,Spain
,
Sarai Sarvide
Affiliations:
Clínica Universidad de Navarra,Pamplona,Spain
,
Joaquín Martínez-López
Affiliations:
Hospital Universitario 12 de Octubre,Madrid,Spain
,
Albert Oriol
Affiliations:
Institut Català d’Oncologia,Barcelona,Spain
,
Rafael Ríos
Affiliations:
Hospital Universitario Virgen de las Nieves de Granada,Granada,Spain
,
Laura Rosiñol
Affiliations:
Hospital Clinic i Provincial,Barcelona,Spain
,
María-Victoria Mateos
Affiliations:
Hospital Universitario de Salamanca,Salamanca,Spain
,
Juan-José Lahuerta
Affiliations:
Hospital Universitario 12 de Octubre,Madrid,Spain
,
Joan Bladé
Affiliations:
Hospital Clinic i Provincial,Barcelona,Spain
,
Jesús F San-Miguel
Affiliations:
Clínica Universidad de Navarra,Pamplona,Spain
Bruno Paiva
Affiliations:
Clínica Universidad de Navarra,Pamplona,Spain
EHA Library. Pérez Ruiz C. Jun 15, 2019; 266965; PS1348
Mrs. Cristina Pérez Ruiz
Mrs. Cristina Pérez Ruiz
Contributions
Abstract

Abstract: PS1348

Type: Poster Presentation

Presentation during EHA24: On Saturday, June 15, 2019 from 17:30 - 19:00

Location: Poster area

Background
Deep understanding of the complexity and diversity of the TIME and its influence on response to therapy is needed to improve the ability to predict, monitor and guide immunotherapeutic responsiveness. Among cells composing the MM-TIME, granulocytic-MDSCs (G-MDSCs) have a prominent role in promoting tumor growth and inducing immunosuppression; however, their phenotype in MM is not well-established.

Aims
To define the phenotype of G-MDSCs based on the integration of phenotypic data, immunosuppressive potential, gene regulatory networks and impact on patients’ outcome of different granulocytic subsets present in the MM-TIME.

Methods
We used multidimensional flow cytometry (MFC) to evaluate the pre-established phenotype of G-MDSCs in bone marrow (BM) samples from healthy donors (HD) (n=4) and MM patients (n=5). We then used principal component analysis (PCA) to unbiasedly identify different granulocytic subsets in the MM-TIME, and FACSorted them for in vitro experiments to analyze their immunosuppressive potential (n=9) and for RNAseq to analyze the molecular profile of G-MDSCs in MM (n=5) vs HD (n=5). The clinical significance of these subsets was determined comparing their numbers at diagnosis within the BM TIME of MM patients (n=71) included in the GEM2012MENOS65 trial.

Results
Human G-MDSCs have been defined as a cell population displaying a CD11b-CD14-CD15+CD33+HLADR- phenotype, representing 1% of total BM nucleated cells in HD and nearly 25% in MM patients. However, we found that the percentage of cells with this phenotype was similar in the BM of HD and MM patients (median of 8% in both, P>.99). Using MFC and according to PCA, 3 granulocyte subsets were unbiasedly identified in the BM of HD and MM, based on homogeneous CD14-CD15+CD33+HLADR- expression but differential reactivity against CD11b, CD13 and CD16: CD11b-CD13lo/-CD16-, CD11b+CD13lo/-CD16- and CD11b+CD13+CD16+. The percentage of all three subsets was similar (P>.5) between HD and MM. Afterwards, we used FACSorting to isolate (1) or deplete (2) individually each of the 3 subsets from MM-BM and determine its immunosuppressive potential in 2 assays. In (1), we noted a significant decrease in T cell proliferation when these were stimulated with CD3/CD28 and in presence of the CD11b+CD13+CD16+ neutrophil subset (0.5-fold, P=.01) but not of the CD11b-CD13lo/-CD16- and CD11b+CD13lo/-CD16- subsets. In (2), we noted that the cytotoxic potential of T cells significantly increased in presence of the BCMAxCD3 bispecific antibody (P=.04) reaching its maximum with the depletion of the CD11b+CD13+CD16+ subset (4-fold, P=.007). Additionally, RNAseq of the 3 subsets in HD and MM patients revealed that genes commonly associated with G-MDSCs (e.g. PTGS2, TGFβ1) were specifically upregulated in the CD11b+CD13+CD16+ granulocytic subset. Finally, we analyzed the distribution of the 3 subsets in the BM of MM patients. Interestingly, we observed that patients with a high number of CD11b+CD13+CD16+ neutrophils at baseline had lower count of T cells and that patients with low ratio between CD11b+CD13+CD16+ and T cells had inferior 3-year rates of progression-free survival as compared to the remaining patients (100% vs 75%, P=.03).

Conclusion
In this comprehensive analysis that integrated molecular, phenotypic, functional and clinical data, we determined a correlation between three well-defined granulocytic subsets and their immunosuppressive potential, thereby providing for the first time, a set of optimal markers (CD11b/CD13/CD16) for monitoring G-MDSCs in MM.

Session topic: 13. Myeloma and other monoclonal gammopathies - Biology & Translational Research

Keyword(s): Granulocyte, Multiple myeloma, Myeloid differentiation, Myeloma

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