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For each patient, a blood sample will be taken at D0 before the CAR-T cells are injected then at D3, D7, D10, D30 after the injection. Flow cytometry analysis will be performed on each sample on the day of collection to determine the level of trogocytosis by effector immune cells (T lymphocytes, NK cells, CAR-T cells) and to define the phenotypic "signature" of trogocytosis.

Flow cytometry analysis to determine the level of trogocytosis by effector immune cells in patients

For each healthy volunteer, a single blood sample will be taken at enrollment. Flow cytometry analysis will be performed on each sample on the day of collection to determine the level of trogocytosis of normal lymphocytes and NK cells.

Flow cytometry analysis to determine the level of trogocytosis by effector immune cells in volunteers

Valérie ROUILLE

Ludovic GABELLIER, MD

Florence GALTIER, MD

CAR-T cell therapy has improved survival in patients with relapsed or refractory diffuse large B-cell lymphoma (DLBCL R/R). However, only 65% of patients achieve a complete metabolic response after this treatment. To date, there is no predictive test for therapeutic response after injection of CAR-T cells. Recent studies have shown that the level of trogocytosis by immune cells correlates with the persistence of tumor cells in patients with hematological malignancies. Our main objective is to identify a phenotypic "signature" of trogocytosis predictive of therapeutic response 6 months after injection of CAR-T cells for DLBCL.

The therapeutic use of CAR-T cells (Chimeric Antigen Receptor T-cells) has significantly improved the survival of patients with relapsed or refractory (R/R) diffuse large B-cell lymphoma (DLBCL). However, only 65% of patients achieve metabolic complete response after this treatment, and one year after CAR-T cells infusion, between 50 and 60% of patients have relapsed or died. Injection of CAR-T cells can also be responsible for serious immunologic and hematologic adverse events. To date, there is no predictive test for the therapeutic response or toxicity following injection of CAR-T cells.

Trogocytosis is a physiological mechanism by which an effector immune cell integrates fragments of the membrane of target cells into its membrane. These aberrant membrane markers can directly modify the functions of the cell that has acquired them. Although the physiological role of trogocytosis remains debated, recent studies have shown that the level of trogocytosis in immune effector cells is correlated with persistent tumor cells in patients with hematological malignancies.

Our main hypothesis is that, in DLBCL, the level of early trogocytosis, assessed by the aberrant expression of tumor markers on the surface of CAR-T cells and other immune effector cells between D0 and D30 after CAR-T cells infusion, correlates with therapeutic response at M6 and/or the occurrence of immunological or severe hematological CAR-T cells side-effects.

Is Trogocytosis a Predictive Marker of CAR-T Cell Response in Diffuse Large B-cell Lymphoma?

La Trogocytose Est-elle un Marqueur prédictif de la réponse Aux Cellules CAR-T Dans Les Lymphomes Diffus à Grandes Cellules B ?

Using flow cytometry to determine the level of trogocytosis, the phenotypic "signature" of trogocytosis will be assessed by the AUC : area under the ROC (Receiver operating characteristic) curve; established on circulating CAR-T cells, T lymphocytes and NK cells of patients, and defined as: the percentage of cells aberrantly expressing different tumor antigens normally expressed on lymphoma cells (CD19, CD20, etc.) at the different analysis times and/or the median florescence intensity (MFI) of the expression of these markers at the different analysis times and/or the evolution of these percentages and the MFI between 2 analysis times.

Failure to obtain a complete metabolic response will be defined by: the absence of a complete metabolic response on the PET scans of D30, D90 and M6 in the absence of implementation of a new therapeutic line; or by the absence of complete metabolic response on all PET scans carried out before the implementation of a new therapeutic line.

Using flow cytometry analysis, the phenotypic "signature" will be assessed by the AUC used to predict the occurrence of immunological side effects (Cytokine Release Syndrome and immune effector cell-associated neurotoxicity syndrome) of grade II or + according to the American Society for Transplantation and Cellular Therapy ASTCT2 criteria. It will be established on circulating CAR-T, T lymphocytes and NK cells of patients, and defined as : the percentage of cells aberrantly expressing different tumor antigens normally expressed on lymphoma cells at the different analysis times,and/or the MFI of the expression of these markers at the different analysis times and/or the evolution of these percentages and the MFI between 2 analysis times.The occurrence of immunological side effects between D0 and D60 will be assessed by clinical and, if necessary, paraclinical examinations (lumbar puncture, brain MRI, etc.). The grade will be evaluated according to the ASTCT2 criteria.

Flow cytometry analysis will be performed to determine the level of trogocytosis by effector cells. The phenotypic "signature" of trogocytosis will be assessed by the AUC used to predict the occurrence of serious hematological side effects (grade III or + cytopenias according to Common Terminology Criteria for Adverse Events CTCAE 5.03 between D30 and M6 after injection of anti-CD19 CAR-T cells .It will be established on circulating CAR-T, T lymphocytes and NK cells of patients, and defined as :the percentage of cells aberrantly expressing different tumor antigens normally expressed on lymphoma cells at the different analysis times, and/or the MFI of the expression of these markers at the different analysis times and/or the evolution of these percentages and the MFI between 2 analysis times. The occurrence of hematological side effects between D30 and M6 will be assessed by blood counts. The grade will be evaluated according to the CTCAE v5.03 criteria.

Flow cytometry analysis will be performed on each sample on the day of collection (at enrollment), to determine the level of trogocytosis which will be evaluated by simple analysis of the trogocytosis phenotype of normal lymphocytes and NK cells in healthy subjects. This result will be considered as a negative control to determine the phenotypic "signature" of trogocytosis of the primary and secondary outcomes above.

Study title	NCT ID	Conditions	Interventions	Eligibility	Organization	Link
Is Trogocytosis a Predictive Marker of CAR-T Cell Response in Diffuse Large B-cell Lymphoma?	NCT06352242	Diffuse Large B...	Flow cytometry ... Flow cytometry ...	18 Years -	University Hospital, Montpellier
Is Trogocytosis a Predictive Marker of CAR-T Cell Response in Diffuse Large B-cell Lymphoma?	NCT06352242	Diffuse Large B...	Flow cytometry ... Flow cytometry ...	18 Years -	University Hospital, Montpellier

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