Short summary

The purpose of this study is to increase our understanding of why chimeric antigen receptor (CAR) T cells formed from white blood cells (WBCs) of patients with chronic lymphatic leukemia (CLL), multiple myeloma (MM) and non-Hodgkin lymphoma (NHL) are less effective in killing cancer cells than CAR T cells formed from WBCs of healthy individuals and patients with acute lymphoblastic leukemia (ALL). Furthermore, the aim is to find methods to improve the T cells of cancer patients in the laboratory to enable them to form more effective CAR T cells.

Rationale

Blood cancer can be divided into malignant lymphoma, MM, and leukemia. These diseases can be further divided according to the types of blood cells affected. Often, the B cell line is involved. CLL and MM are common types of hematological cancers in the Western world. B cell CLL is characterized by the accumulation of a clone of mature B cells in bone marrow (BM), blood, and secondary lymphoid tissue. MM is characterized by the malignant transformation of plasma cells in the BM. Current treatments for CLL and MM are not curative, and only for CLL is there a curative potential with allogeneic stem cell transplantation, which, however, is a highly toxic treatment that can only be offered to a small subset of patients. Therefore, CLL and MM is considered incurable diseases and there is a need for the development of new therapies. B cell NHL is  a heterogeneous group of malignant tumors of the lymphoid tissue characterized by the clonal expansion of B cells. Although many patients are cured with current treatments, there are still a lot of patients with poor prognosis in need of new treatment options. 

Since B cells are not vital, new treatment methods that affect the cancerous B cells and the healthy B cells simultaneously have emerged. Typically, antibodies are used, but in recent years, T cells from the patient genetically modified to express a CAR directed against CD19 have shown tremendous potential as treatment for CD19+ malignancies leading to FDA approval of several products. In lymphoma and CLL, complete responses have been observed in about 40% of patients. Although promising, these data do not compare to the 90% complete response rates reported for patients diagnosed with ALL.

CAR T cell based strategies for B cell malignancies

Traditionally, a CAR consists of an extracellular antibody-derived single chain variable fragment connected via a transmembrane domain and a hinge region to the intracellular domain of CD3zeta (1st generation CAR). The CD3zeta domain alone is not sufficient to drive optimal T cell proliferation and cytokine production. Incorporation of co-stimulatory domains (e.g. 4-1BB, CD28) in 2nd and 3rd generation CARs has increased persistence and efficiency.

Characteristics of the development of blood cancer are defects in the mechanisms of apoptosis combined with an enhanced response to survival signals from the tumor microenvironment. Significant to this, are signals that the cancer cell receives through B cell membrane proteins belonging to the tumor necrosis factor receptor (TNFR) superfamily, including B cell activation factor receptor (BAFF-R) and transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI). These molecules are therefore potential targets for CAR T cell therapy.

T-cell exhaustion

Exhaustion of T cells is a well known consequence of cancer. Cardinal features include reduced proliferation, cytotoxicity, cytokine production and T cell survival. Exhaustion is previously described for T cells from CLL patients with upregulation of several inhibitory receptors including programmed death 1 (PD-1), natural killer cell receptor 2B4 (CD244) and CD160. Phenotypic analysis of CLL T cell subsets also show a reduction in the number of naive and central memory T cells. This constitutes a potential problem for CAR T cell therapy against CLL, as these subsets have been shown to display better expansion, persistence and antitumor activity in vivo.

Although, clinical trials investigating CD19 CAR T cells for the treatment of CLL and lymphoma have shown less efficacy compared to the treatment of ALL, a study, using the ITK inhibitor, Ibrutinib, demonstrated restoration of T cell function combined with enhanced CAR T cell efficacy in CLL-patients. This gives hope that exhausted T cells can be counteracted by appropriate treatment before inserting the CAR into the T cells.

In this study, we hypothesize that the lower efficacy of CAR T cells in CLL is caused by the exhaustion of the autologous T cell product with upregulation of several inhibitory receptors and reduction of the T cell subsets that exhibit better expansion, persistence and antitumor activity. It is also assumed that similar conditions may occur in other B-cell derived malignancies. Therefore, biobank samples from patients with NHL and MM will also be used.

Description of the cohort

Patients with a primary diagnosis and/or relapse within the hematological diagnoses CLL, non-Hodgkin's lymphoma and multiple myeloma, whose samples have been submitted to the Danish Cancer Biobank (DCB) from a laboratory in the Region of Southern Denmark.

Data and biological material

Cryopreserved PBMCs, extracted data from patient records, register data from DCB.

Collaborating researchers and departments

Department of Clinical Immunology, Odense University Hospital

• Professor Torben Barington, D.M.Sc.

Department of Hematology, Odense University Hospital

• Professor Niels Abildgaard, D.M.Sc.