Targeting Lymphomas Using Non-Engineered, Multi-Antigen Specific T Cells

Immunotherapy is emerging as a potent therapy for a range of hematologic malignancies including lymphomas. Indeed adoptive transfer of T cells genetically engineered to express the CD19 chimeric antigen receptor (CAR) has now received FDA approval for the treatment of patients with refractory diffuse large B cell lymphomas (DLBCL). We have developed a non-engineered T cell-based therapy to treat patients with all types of lymphomas: Hodgkin's (HL) and non-Hodgkin's lymphoma (NHL). The approach uses single T cell lines that simultaneously target a range of tumor-associated antigens (TAAs) that are frequently expressed by these tumors, including PRAME, SSX2, MAGEA4, NY-ESO-1 and Survivin. We can consistently prepare these lines by culturing PBMCs in the presence of a Th1-polarizing/pro-proliferative cytokine cocktail, and adding autologous DCs as APCs that are loaded with pepmixes (15mer peptides overlapping by 11 amino-acids) spanning all 5 target antigens. The use of whole antigen should remove the HLA restriction imposed by the use of transgenic TCRs specific for single peptides, while targeting multiple antigens simultaneously would reduce the risk of tumor immune evasion.

We have generated 42 clinical-grade multiTAA-specific T cell lines, comprising CD3+ T cells (mean 98±1.1%) with a mixture of CD4+ (mean 48±4.3%) and CD8+ (mean 37±4%) T cells, which expressed central and effector memory markers (CD45RO+/CD62L+/CCR7+ -- mean 14±3%; CD45RO+/CD62L+/CCR7- -- 10±2.2%; CD45RO+/CD62L-/CCR7- -- 28.3±3.6%) (n=42). The expanded lines recognized the targeted antigens PRAME, SSX2, MAGEA4, NY-ESO-1 and Survivin (range 0-463, 0-496, 0-330, 0-379 and 0-304 spot forming units (SFU)/2x10⁵ input cells, respectively in IFNg ELIspot, n=34). None of the lines reacted against non-malignant autologous recipient cells (3±3.8% specific lysis; E:T 20:1).

We have treated 33 patients: 13 with HL, 17 with aggressive NHL (diffuse large B-cell, mantle cell, or T cell lymphomas) and 3 with indolent NHLs (FL and marginal zone lymphoma). Patients received 0.5-2x10⁷ multiTAA-T cells/m². Of 18 patients who were infused as adjuvant therapy all but 2 remain in remission (range 3-42 months post-infusion). Fifteen patients have received multiTAA-specific T cells to treat active disease, all of whom had failed a median of 4 lines of prior therapy. Of these, 5 had transient disease stabilization followed by disease progression, 4 have ongoing stable disease, 3-18 months post-multiTAA-specific T cells while the remaining 6 (3 with HL and 3 with DLBCL) have all had complete and durable responses ( 4 to 41 months), as assessed by PET imaging. These clinical responses correlated with the detection of tumor-reactive T cells in patient peripheral blood post-infusion directed against both targeted antigens as well as non-targeted TAAs including MAGEA2B and MAGE C1, indicating induction of antigen/epitope spreading. Notably, no patient, including the complete responders, had infusion-related systemic- or neuro-toxicity. Thus, infusion of autologous multiTAA-targeted T cells directed to PRAME, SSX2, MAGEA4, NY-ESO-1 and Survivin has been safe and provided durable clinical benefit to patients with lymphomas.