Selective and Efficient Gene Delivery of CD40-Ligand by a Fiber-Modified Adenovirus Vector with Specific Antibody to Human Leukemia and Myeloma.

The use of adenovirus vector for cancer gene therapy is limited by their low transduction efficiency for lymphoma, leukemia and myeloma. We previously reported that highly efficient gene delivery of CD40-ligand by a modified adenovirus vector with the integrin-binding motif, RGD, in the H1 loop of the fiber knob (AxCAhCD40L-F/RGD) could induce phenotypic alteration followed by T cell immune response to autologous leukemia cells. But the utility of adenovirus with RGD-motif is still limited by their lack of specificity on tumor cells. Recent studies revealed a novel strategy of targeting adenovirus using a bispecific single-chain antibody (scFv) specific for adenovirus and target molecules on tumor cell surface. However, this approach should permit the production of high quantities of active bispecific scFv for in vivo use. To target adenovirus to hematopoietic tumor cells efficiently, we herein constructed a modified adenovirus vector that contained a synthetic immunoglobulin G-binding domain (termed Z33) in H1 loop of the fiber knob. A recombinant adenovirus encoding EGFP, lacZ (as reporter gene; Ax3CAZ3-F/Z33 or Ax3EGFP-F/Z33) or CD40L (as a therapeutic gene; Ax3CD40L-F/Z33) with Z33-modified fiber were tested for gene transfer efficiency into human tumors such as lymphoma, leukemia and myeloma cells. By the treatment with various antibodies specific for CD20 (Rituximab), CD40, CD38, CCR2 or CXCR4 that are expressed on leukemic cells, we achieved 3 to 10-fold enhancement of gene expression in lymphoma/leukemia (Ramos, Daudi or THP-1) and myeloma cells (MM1S, IM-9 or KMS5) compared with control IgG-treated tumors. We also examined specific gene delivery to freshly isolated leukemia B cells from patients that also contains normal lymphocytes. By using antibody to CD20 or CD40, we could selectively deliver CD40L gene with Ax3CD40L-F/Z33 into leukemia B cells (>50% at 300 pu/cell), but not in T and monocytes, followed by the induction of immune costimulatory molecules that are important in anti-leukemia immune response. Overall, our results indicated that combination of Z33-modified adenovirus vector and tumor specific antibody can be used as a modality for the gene therapy of leukemia and myeloma.