Prolonged survival and tissue trafficking following adoptive transfer of CD4zeta gene-modified autologous CD4(+) and CD8(+) T cells in human immunodeficiency virus-infected subjects.

We have genetically engineered CD4(+) and CD8(+) T cells with human immunodeficiency virus (HIV) specificity by inserting a gene, CD4zeta, containing the extracellular domain of human CD4 (which binds HIV env) linked to the zeta (zeta) chain of the T-cell receptor (which mediates T-cell activation). Twenty-four HIV-positive subjects received a single infusion of 2 to 3 x 10(10) autologous CD4zeta-modified CD4(+) and CD8(+) T cells administered with (n = 11) or without (n = 13) interleukin-2 (IL-2). Subjects had CD4 counts greater than 50/microL and viral loads of at least 1000 copies/mL at entry. T cells were costimulated ex vivo through CD3 and CD28 and expanded for approximately 2 weeks. CD4zeta was detected in 1% to 3% of blood mononuclear cells at 8 weeks and 0.1% at 1 year after infusion, and survival was not enhanced by IL-2. Trafficking of gene-modified T cells to bulk rectal tissue and/or isolated lamina propria lymphocytes was documented in a subset of 5 of 5 patients at 14 days and 2 of 3 at 1 year. A greater than 0.5 log mean decrease in rectal tissue-associated HIV RNA was observed for at least 14 days, suggesting compartmental antiviral activity of CD4zeta T cells. CD4(+) counts increased by 73/microL at 8 weeks in the group receiving IL-2. There was no significant mean change in plasma HIV RNA or blood proviral DNA in either treatment arm. This sustained, high-level persistence of gene-modified T cells demonstrates the feasibility of ex vivo T-cell gene therapy in HIV-infected adults and suggests the importance of providing HIV-specific T-helper function.

Long-term in vivo survival of receptor-modified syngeneic T cells in patients with human immunodeficiency virus infection.

To study human immunodeficiency virus (HIV)-specific cellular immunity in vivo, we transferred syngeneic lymphocytes after ex vivo expansion and transduction with a chimeric receptor gene (CD4/CD3-zeta) between identical twins discordant for HIV infection. Single and multiple infusions of 10(10) genetically modified CD8(+) T cells resulted in peak fractions in the circulation of approximately 10(4) to 10(5) modified cells/10(6) mononuclear cells at 24 to 48 hours, followed by 2- to 3-log declines by 8 weeks. In an effort to provide longer high-level persistence of the transferred cells and possibly enhance anti-HIV activity, we administered a second series of infusions in which both CD4(+ )and CD8(+) T cells were engineered to express the chimeric receptor and were costimulated ex vivo with beads coated with anti-CD3 and anti-CD28. Sustained fractions of approximately 10(3) to 10(4) modified cells/10(6) total CD4(+) or CD8(+) cells persisted for at least 1 year. Assessment of in vivo trafficking of the transferred cells by lymphoid tissue biopsies revealed the presence of modified cells in proportions equivalent to or below those in the circulation. The cell infusions were well tolerated and were not associated with substantive immunologic or virologic changes. Thus, adoptive transfer of genetically modified HIV-antigen-specific T cells was safe. Sustained survival in the circulation was achieved when modified CD4(+ )and CD8(+) T cells were infused together after ex vivo costimulation, indicating the important role played by antigen-specific CD4(+) T cells in providing "help" to cytotoxic effectors. (Blood. 2000;96:467-474)

T-cell gene therapy.

In the past year, a number of human gene therapy trials involving the adoptive transfer of genetically modified T lymphocytes have been reported. These include trials of adenosine deaminase gene transfer in children with severe combined immunodeficiency syndrome, a gene-marking study of Epstein-Barr virus-specific cytotoxic T cells, and trials of gene-modified T cells expressing suicide or viral resistance genes in patients infected with HIV. Additional strategies for T-cell gene therapy currently being pursued in the clinic involve the engineering of novel T-cell receptors that impart antigen specificity for virally infected or malignant cells.

Systemic T cell-independent tumor immunity after transplantation of universal receptor-modified bone marrow into SCID mice.

Gene modification of hematopoietic stem cells (HSC) with antigen-specific, chimeric, or "universal" immune receptors (URs) is a novel but untested form of targeted immunotherapy. A human immunodeficiency virus (HIV) envelope-specific UR consisting of the extracellular domain of human CD4 linked to the zeta chain of the T cell receptor (CD4 zeta) was introduced ex vivo into murine HSC by retroviral transduction. After transplantation into immunodeficient SCID mice, sustained high level expression of CD4 zeta was observed in circulating myeloid and natural killer cells. CD4 zeta-transplanted mice were protected from challenge with a lethal dose of a disseminated human leukemia expressing HIV envelope. These results demonstrate the ability of chimeric receptors bearing zeta-signaling domains to activate non-T cell effector populations in vivo and thereby mediate systemic immunity.

Comparison of anti-Tac and anti-transferrin receptor-conjugated liposomes for specific drug delivery to adult T-cell leukemia.

Adult T-cell leukemia (ATL) is a rapidly progressive and usually fatal malignancy of mature T cells characterized by the expression of large numbers of interleukin-2 (IL-2) receptors on the cell surface. Anti-Tac, a monoclonal antibody directed against the IL-2 receptor, was conjugated to liposomes and compared with anti-transferrin receptor (anti-TFR) conjugates for specific binding, internalization, and intracellular drug delivery to ATL cells. Two independent assays were used: a fluorimetric assay with liposome encapsulated 1-hydroxypyrene-3,6,8-trisulfonic acid, a pH-sensitive fluorescent dye, and a growth inhibition assay using methotrexate-gamma-aspartate, a liposome-dependent cytotoxic drug. MT-1 and HUT-102 cell lines derived from patients with ATL were compared with Molt-4, a leukemia cell line that does not express IL-2 receptors in an uninduced state. Fluorimetric studies showed specific binding and internalization of anti-Tac-conjugated liposomes by HUT-102 and MT-1 but not by the Tac-negative cell line Molt-4, demonstrating the lack of nonspecific or Fc receptor-mediated uptake. Anti-TFR-conjugated liposomes were effectively bound and internalized by all three cell lines and consistently showed the highest degree of cellular liposome uptake. Drug-containing liposomes conjugated to anti-Tac were more than tenfold more effective in causing growth inhibition of ATL cells than the nonspecific control conjugates. Anti-Tac conjugates caused minimal growth inhibition of Molt-4 cells over the concentration range effective against the ATL cells. Anti-TFR-coupled liposomes gave better growth inhibition of HUT-102 and MT-1 cells (40- to 60-fold) than anti-Tac conjugates. Both anti-Tac-directed and anti-TFR-directed liposomes are effective for intracellular drug delivery to ATL cells and may represent a useful method of treatment in this disease.