T-cells Expressing an Anti-SLAMF7 CAR for Treating Multiple Myeloma

Background:

• Multiple myeloma (MM) is a nearly always incurable malignancy of plasma cells.
• T cells can be genetically modified to express chimeric antigen receptors (CARs) that target malignancy-associated antigens.
• Signaling lymphocytic activation molecule F7 (SLAM7) is highly and uniformly expressed on MM cells but is absent on normal tissues except for some leukocytes, including a subset of cluster of differentiation 8 (CD8)+ T cells, natural killer (NK) cells, B cells, plasma cells and monocytes.
• We have constructed a novel anti-SLAMF7 CAR that can specifically recognize SLAMF7- expressing target cells and eradicate SLAMF7-expressing tumors in mice.
• This protocol will test genetic modification of autologous T cells with genes encoding an inducible caspase 9 (IC9) cell-suicide system plus the anti-SLAMF7 CAR.
• Administration of the dimerizer drug Rimiducid (AP1903) is necessary to activate the inducible caspase 9 (IC9) suicide gene and eliminate CAR T cells.
• In this protocol, the suicide gene system will be used to eliminate CAR-expressing T cells in case of severe toxicities caused by the CAR T cells.
• Possible toxicities include cytokine-associated toxicities such as hypotension, and neurological toxicities. Elimination of NK cells and normal plasma cells could make patients more susceptible to infections. Unknown toxicities are also possible.

Objectives:

Primary

• Determine the safety, feasibility of administering T cells expressing an anti-SLAMF7 CAR plus IC9 cell-suicide system to patients with MM.

Eligibility:

• Greater than or equal to 18 years of age and less than or equal to age 73.
• Patients must have measurable MM defined as a serum M-protein >=0.6 g/dL or a urine M-protein >=200 mg/24 hours or an involved serum free light chain (FLC) level >=10 mg/dL (provided FLC ratio is abnormal) or a biopsy-proven plasmacytoma of 1.5 cm or more in largest dimension, or greater than or equal to 30% bone marrow plasma cells.
• Patients must have previously received at least 3 different treatment regimens for MM.
• Patients must have prior exposure to an immunomodulatory drug (IMiD) such as lenalidomide, and a proteasome inhibitor
• Patients must have a creatinine level of less than or equal to 1.5 mg/dL
• Patients must have a cardiac ejection fraction >= 50%.
• An Eastern Cooperative Oncology Group (ECOG) performance status of 0-2 is required.
• Patients on any anticoagulant medications except aspirin are not eligible.
• No active infections are allowed.
• Absolute neutrophil count >= 1000/microL, platelet count >= 55,000/microL, hemoglobin >= 8g/dL
• Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) less than or equal to 2.5-fold higher than the upper limit of normal.
• At least 14 days must elapse between the time of any prior systemic treatment (including corticosteroids) and the required leukapheresis.
• At least 14 days must elapse between the time of any prior systemic treatment and initiation of protocol treatment. Systemic therapy includes corticosteroids at a dose equivalent to more than 5 mg of prednisone.
• Bone marrow plasma cells must make up less than or equal to 50% of total bone marrow cells less than or equal to 24 days prior to the start of protocol treatment.
• The patient's MM will need to be assessed for SLAMF7 expression by flow cytometry or immunohistochemistry performed at the National Institutes of Health (NIH). The myeloma must express SLAMF7. If unstained, paraffin-embedded bone marrow or plasmacytoma sections are available from prior biopsies, these can be used to determine SLAMF7 expression by immunohistochemistry; otherwise patients will need to come to the NIH for a bone marrow biopsy or other biopsy of a plasmacytoma to determine SLAMF7 expression. The sample for SLAMF7 expression can come from a biopsy obtained at any time before enrollment.

Design:

• This is a phase I dose-escalation trial
• Patients will undergo leukapheresis, and T cells will be modified to express the IC9-anti-SLAMF7 CAR construct.
• The chemotherapy conditioning regimen is cyclophosphamide 300 mg/m^2 daily for 3 days and fludarabine 30 mg/m^2 daily for 3 days. The intent of chemotherapy is to enhance CAR T-cell activity.
• After the chemotherapy ends, the patients will have two days with no treatments and then receive an infusion of CAR T cells.
• The initial dose level will be 0.66x10^6 Anti-SLAMF7-CAR + T cells/kg of recipient bodyweight.
• The cell dose administered will be escalated for up to 4 doses until a maximum tolerated dose is determined.
• Following the T-cell infusion, there will be a mandatory 9-day minimum inpatient hospitalization to monitor for toxicity.
• Outpatient follow-up is planned for 2 weeks, and 1, 2, 3, 4, 6, 9, and 12 months after the CAR T-cell infusion. Afterwards, follow-up will be every six months up to at least 3 years after infusion.