Chronic lymphocytic leukemia (CLL) cells can be made to express recombinant CD40-ligand (CD154) by transduction with a replication-defective adenovirus vector (Ad-CD154). Ad-CD154–transduced and bystander leukemia cells become highly effective antigen-presenting cells that can induce CLL-specific autologous cytotoxic T lymphocytes in vitro. This study investigated the immunologic and clinical responses to infusion of autologous Ad-CD154-CLL cells in patients with CLL. After a one-time bolus infusion of autologous Ad-CD154–transduced leukemia cells, there was increased or de novo expression of immune accessory molecules on bystander, noninfected CLL cells in vivo. Treated patients also developed high plasma levels of interleukin-12 and interferon-γ, the magnitudes of which corresponded to absolute blood CD4+T-cell counts before therapy. On average, patients experienced a greater than 240% increase in absolute blood T-cell counts within 1 to 4 weeks of treatment. Moreover, treatment increased the numbers of leukemia-specific T cells, demonstrated by autologous ELISPOT assay and mixed lymphocyte reactions. These biologic effects were associated with reductions in leukemia cell counts and lymph node size. Treatment did not induce autoimmune thrombocytopenia or hemolytic anemia and no dose-limiting toxicity was observed. This approach may provide a novel and effective form of gene therapy for patients with this disease.

Immunotherapy against infectious agents and malignant tumors requires efficient priming of effector cells through direct expression and/or efficient cross-presentation of antigens by antigen-presenting cells. Electroporation is a new procedure aimed at transiently increasing cell membrane permeability and direct delivery of antigen or antigen-encoding nucleic acids inside targeted cells. We evaluated the tolerability including compliance with repeated electroporation treatments using MedPulser DDS in 24 healthy adults. Pain severity was evaluated at time of electroporation treatment, and at 1, 5, 10, and 20 minutes, and 24 hours thereafter, using two clinically validated questionnaires: McGill Pain Questionnaire (MPQ) (Present Pain Intensity) and Brief Pain Inventory (BPI). Electroporation treatments were generally well tolerated. Twenty-two out of 24 subjects returned for the second electroporation treatment 14 days after first treatment. Only two subjects reported a treatment-related systemic adverse experience following either electroporation application. For both pain assessment tools, maximum pain and/or discomfort were mostly reported immediately (within 5 minutes) after electroporation; Furthermore, no difference was observed when comparing peak-pain scores after first and second electroporation treatments. This study supports the clinical application of MedPulser DDS for the improvement of antigen-induced immune responses for prophylactic or therapeutic vaccines, especially in gene-based therapies for cancer.

Chronic lymphocytic leukemia (CLL) cells can be made to express recombinant CD40-ligand (CD154) by transduction with a replication-defective adenovirus vector (Ad-CD154). Ad-CD154–transduced and bystander leukemia cells become highly effective antigen-presenting cells that can induce CLL-specific autologous cytotoxic T lymphocytes in vitro. This study investigated the immunologic and clinical responses to infusion of autologous Ad-CD154-CLL cells in patients with CLL. After a one-time bolus infusion of autologous Ad-CD154–transduced leukemia cells, there was increased or de novo expression of immune accessory molecules on bystander, noninfected CLL cells in vivo. Treated patients also developed high plasma levels of interleukin-12 and interferon-γ, the magnitudes of which corresponded to absolute blood CD4+T-cell counts before therapy. On average, patients experienced a greater than 240% increase in absolute blood T-cell counts within 1 to 4 weeks of treatment. Moreover, treatment increased the numbers of leukemia-specific T cells, demonstrated by autologous ELISPOT assay and mixed lymphocyte reactions. These biologic effects were associated with reductions in leukemia cell counts and lymph node size. Treatment did not induce autoimmune thrombocytopenia or hemolytic anemia and no dose-limiting toxicity was observed. This approach may provide a novel and effective form of gene therapy for patients with this disease.