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Biomedical subjects

P Hwu

Publications and source records attributed to P Hwu.

At least 37 records · Page 2Linked to original sources
PubMed1999

Prospective randomized trial of the treatment of patients with metastatic melanoma using chemotherapy with cisplatin, dacarbazine, and tamoxifen alone or in combination with interleukin-2 and interferon alfa-2b.

PURPOSE: The combination of chemotherapy with immunotherapeutic agents such as interleukin-2 and interferon alfa-2b has been reported to provide improved treatment results in patients with metastatic melanoma, compared with the use of chemotherapy alone. We have performed a prospective randomized trial in patients with metastatic melanoma, comparing treatment with chemotherapy to treatment with chemoimmunotherapy. PATIENTS AND METHODS: One hundred two patients with metastatic melanoma were prospectively randomized to receive chemotherapy composed of tamoxifen, cisplatin, and dacarbazine or this same chemotherapy followed by interferon alfa-2b and interleukin-2. Objective responses, survival, and toxicity in the two groups were evaluated at a median potential follow-up of 42 months. RESULTS: In 52 patients randomized to receive chemotherapy, there were 14 objective responses (27%), including four complete responses. In 50 patients randomized to receive chemoimmunotherapy, there were 22 objective responses (44%) (P2 = .071), including three complete responses. In both treatment groups, the duration of partial responses was often short, and there was a trend toward a survival advantage for patients receiving chemotherapy alone (P2 = .052; median survival of 15.8 months compared with 10.7 months). Treatment-related toxicities were greater in patients receiving chemoimmunotherapy. CONCLUSION: With the treatment regimens used in this study, the addition of immunotherapy to combination chemotherapy increased toxicity but did not increase survival. The use of combination chemoimmunotherapy regimens is not recommended in the absence of well-designed, prospective, randomized protocols showing the benefit of this treatment strategy.

Adolescent↗
PubMed1998

Immunizing patients with metastatic melanoma using recombinant adenoviruses encoding MART-1 or gp100 melanoma antigens.

BACKGROUND: The characterization of the genes encoding melanoma-associated antigens MART-1 or gp100, recognized by T cells, has opened new possibilities for the development of immunization strategies for patients with metastatic melanoma. With the use of recombinant adenoviruses expressing either MART-1 or gp100 to immunize patients with metastatic melanoma, we evaluated the safety, immunologic, and potential therapeutic aspects of these immunizations. METHODS: In phase I studies, 54 patients received escalating doses (between 10(7) and 10(11) plaque-forming units) of recombinant adenovirus encoding either MART-1 or gp100 melanoma antigen administered either alone or followed by the administration of interleukin 2 (IL-2). The immunologic impact of these immunizations on the development of cellular and antibody reactivity was assayed. RESULTS: Recombinant adenoviruses expressing MART-1 or gp100 were safely administered. One of 16 patients with metastatic melanoma receiving the recombinant adenovirus MART-1 alone experienced a complete response. Other patients achieved objective responses, but they had received IL-2 along with an adenovirus, and their responses could be attributed to the cytokine. Immunologic assays showed no consistent immunization to the MART-1 or gp100 transgenes expressed by the recombinant adenoviruses. High levels of neutralizing antibody were found in the pretreatment sera of the patients. CONCLUSIONS: High doses of recombinant adenoviruses could be safely administered to cancer patients. High levels of neutralizing antibody present in patients' sera prior to treatment may have impaired the ability of these viruses to immunize patients against melanoma antigens.

Adenoviridae↗
PubMed1998

A T cell-independent antitumor response in mice with bone marrow cells retrovirally transduced with an antibody/Fc-gamma chain chimeric receptor gene recognizing a human ovarian cancer antigen.

In order to treat common cancers with immunotherapy, chimeric receptors have been developed that combine the tumor specificity of antibodies with T-cell effector functions. Previously, we demonstrated that T cells transduced with a chimeric receptor gene against human ovarian cancer were able to recognize ovarian cancer cells in vitro and in vivo. We now report that recipients of bone marrow cells transduced with these genes exhibited significant antitumor activity in vivo. Moreover, in vivo depletion of T cells in reconstituted mice did not affect antitumor activity, suggesting that other immune cells expressing the chimeric receptor gene may play an important role in tumor rejection.

Animals↗
PubMed1998

Immunologic and therapeutic evaluation of a synthetic peptide vaccine for the treatment of patients with metastatic melanoma.

The cloning of the genes encoding cancer antigens has opened new possibilities for the treatment of patients with cancer. In this study, immunodominant peptides from the gp100 melanoma-associated antigen were identified, and a synthetic peptide, designed to increase binding to HLA-A2 molecules, was used as a cancer vaccine to treat patients with metastatic melanoma. On the basis of immunologic assays, 91% of patients could be successfully immunized with this synthetic peptide, and 13 of 31 patients (42%) receiving the peptide vaccine plus IL-2 had objective cancer responses, and four additional patients had mixed or minor responses. Synthetic peptide vaccines based on the genes encoding cancer antigens hold promise for the development of novel cancer immunotherapies.

Adult↗
PubMed1997

Dendritic cells retrovirally transduced with a model antigen gene are therapeutically effective against established pulmonary metastases.

Dendritic cells (DCs) are bone marrow-derived leukocytes that function as potent antigen presenting cells capable of initiating T cell-dependent responses from quiescent lymphocytes. DC pulsed with tumor-associated antigen (TAA) peptide or protein have recently been demonstrated to elicit antigen-specific protective antitumor immunity in a number of murine models. Transduction of DCs with TAA genes may allow stable, prolonged antigen expression as well as the potential for presentation of multiple, or unidentified, epitopes in association with major histocompatibility complex class I and/or class II molecules. To evaluate the potential efficacy of retrovirally transduced DCs, bone marrow cells harvested from BALB/c mice were transduced with either a model antigen gene encoding beta-galactosidase (beta-gal) or a control gene encoding rat HER-2/neu (Neu) by coculture with irradiated ecotropic retroviral producer lines. Bone marrow cells were differentiated into DC in vitro using granulocyte/macrophage colony-stimulating factor and interleukin-4. After 7 d in culture, cells were 45-78% double positive for DC phenotypic cell surface markers by FACS(R) analysis, and DC transduced with beta-gal were 41-72% positive for beta-gal expression by X-gal staining. In addition, coculture of beta-gal transduced DC with a beta-gal-specific T cell line (CTLx) resulted in the production of large amounts of interferon-gamma, demonstrating that transduced DCs could process and present endogenously expressed beta-gal. DC transduced with beta-gal and control rat HER-2/neu were then used to treat 3-d lung metastases in mice bearing an experimental murine tumor CT26.CL25, expressing the model antigen, beta-gal. Treatment with beta-gal-transduced DC significantly reduced the number of pulmonary metastatic nodules compared with treatment with Hank's balanced salt solution or DCs transduced with rat HER-2/neu. In addition, immunization with beta-gal-transduced DCs resulted in the generation of antigen-specific cytotoxic T lymphocytes (CTLs), which were significantly more reactive against relevant tumor targets than CTLs generated from mice immunized with DCs pulsed with the Ld-restricted beta-gal peptide. The results observed in this rapidly lethal tumor model suggest that DCs transduced with TAA may be a useful treatment modality in tumor immunotherapy.

Animals↗
PubMed1997

Current challenges in cancer gene therapy.

The ability to transfer novel genes into mammalian cells has allowed us to conceive of novel strategies towards cancer therapy. Since the initial gene-transfer clinical trial in 1989, over 300 cancer patients have been enrolled in gene therapy trials. Despite this, an NIH-sponsored panel concluded that 'clinical efficacy has not been definitively demonstrated at this time in any gene therapy protocol'. However, the first 8 years of gene therapy research have provided us with insights regarding the areas that require further scientific progress. For example, it is now clear that while in vitro assays of gene-modified haemotopoietic progenitor cells suggest high transduction efficiencies, once these cells are infused in vivo, only a small percentage of circulating transduced cells can be detected. While the initial clinical studies have demonstrated that gene transfer in patients can be safe and feasible, they have also indicated that future research is necessary towards the development of improved gene transfer techniques for these approaches to be successful.

Animals↗
PubMed1996

Retroviral transduction of human dendritic cells with a tumor-associated antigen gene.

Dendritic cells (DCs) are potent antigen-presenting cells that can activate quiescent T lymphocytes. When pulsed with tumor-associated antigen (TAA) peptide or protein, murine DCs can provide antitumor immunity. We reasoned that DCs retrovirally transduced with TAA genes might have important advantages over peptide- or protein-pulsed DCs, including long-term TAA presentation in vivo, and presentation of important but undefined epitopes. Therefore, we attempted to retrovirally transduce human DCs with a melanoma TAA gene (MART-1) and determine whether these transduced DCs could raise a specific antitumor response from quiescent autologous T lymphocytes. After retroviral transduction, human CD34+ cells were differentiated into DCs in vitro using granulocyte macrophage colony-stimulating factor, tumor necrosis factor alpha, and stem cell factor. This method consistently yielded a population of DCs as analyzed by morphology, phenotype, and MLR. Flow cytometric analysis revealed that 22-28% of cells expressing the DC phenotype also expressed a transduced marker gene. When DCs were transduced with the gene encoding MART-1, they stimulated much higher levels of cytokine release by MART-1-specific tumor-infiltrating lymphocytes than control DCs transduced with an irrelevant gene. In vitro stimulation using MART-1-transduced DCs but not control-transduced DCs raised specific antitumor CTLs from autologous quiescent T cells. These results provide evidence that human DCs can be retrovirally transduced with a TAA gene and that these transduced cells can raise a specific antitumor immune response in vitro. Transduced DCs may be useful for in vivo immunization against TAA.

Antigens, Neoplasm↗
PubMed1996

Improved gene transfer into human lymphocytes using retroviruses with the gibbon ape leukemia virus envelope.

Gene-modified lymphocytes have a potential role in the therapy of cancer, infectious diseases, and genetic disorders of the immune system. Current gene therapy protocols involving gene transfer into lymphocytes utilize retroviruses with amphotropic envelope proteins. However, transduction efficiencies in lymphocytes using these viruses are relatively low. A potential strategy to improve gene transfer efficiency is the utilization of alternative retroviral envelopes that target unique receptors on the cell surface. One such alternative retroviral envelope, the gibbon ape leukemia virus (GALV) envelope, targets a distinct surface receptor (GLVR-1) that is 60% homologous but not cross-reactive to the amphotropic receptor (GLVR-2/RAM-1). Understanding the relationship between receptor expression and transduction efficiency is important for designing new strategies to improve gene transfer. Therefore, we compared GLVR-1 and GLVR-2 mRNA levels in lymphocytes and found that GLVR-1 was expressed 8- to 19-fold higher than GLVR-2. We then analyzed whether this enhanced expression of GLVR-1 correlated with increased infectivity of lymphocytes by retroviral vectors that utilize the GALV envelope compared to those that use the amphotropic envelope. We evaluated retroviral vectors packaged with either PA317 or PG13, which express the amphotropic and GALV envelopes, respectively. Lymphocyte transduction with PG13-packaged vectors was 4- to 18-fold higher than that with PA317-packaged vectors. These findings suggest that receptor expression level is an important factor in retroviral-target interactions and that gene transfer into human T lymphocytes should be performed with retroviruses that use the GALV envelope as opposed to retroviruses that use the amphotropic envelope.

Cells, Cultured↗
PubMed1996

Costimulation enhances the active immunotherapy effect of recombinant anticancer vaccines.

Activation of T lymphocytes in the absence of a costimulatory signal can result in anergy or apoptotic cell death. Two molecules capable of providing a costimulatory signal, B7-1 (CD80) and B7-2 (CD86), have been shown to augment the immunogenicity of whole-tumor cell vaccines. To explore a potential role for costimulation in the design of recombinant anticancer vaccines, we used lacZ-transduced CT26 as an experimental tumor and beta-galactosidase (beta-gal) as the model tumor antigen. Attempts to augment the function of a recombinant vaccinia virus (rVV) expressing beta-gal by admixture with rVV expressing murine B7-1 were unsuccessful. However, a double recombinant vaccinia virus engineered to express both B7-1 and the model antigen beta-gal was capable of significantly reducing the number of pulmonary metastases when administered to mice bearing tumors established for 3 or 6 days. Most important, the double recombinant vaccinia virus prolonged the survival of tumor-bearing mice. These effects were antigen specific. The related costimulatory molecule B7-2 was found to have a similar, although less impressive enhancing effect on the function of a rVV expressing beta-gal. Thus, the addition of B7-1 and, to a lesser extent, B7-2 to a rVV encoding a model antigen significantly enhanced the therapeutic antitumor effects of these poxvirus-based, therapeutic anticancer vaccines.

Animals↗
PubMed1995

In vivo antitumor activity of T cells redirected with chimeric antibody/T-cell receptor genes.

In an effort to broaden the applicability of adoptive cellular immunotherapy toward nonmelanoma cancers, we have designed chimeric antibody/T-cell receptor genes composed of the variable domains from mAbs joined to T-cell receptor-signaling chains. We have demonstrated that T cells retrovirally transduced with these genes can recognize antibody-defined antigens and that this recognition leads to T-cell activation, specific lysis, and cytokine release. In this study, we have examined the in vivo activity of murine T cells transduced with a chimeric receptor gene (MOv-gamma) derived from the mAb MOv18, which binds to a folate-binding protein overexpressed on most human ovarian adenocarcinomas. Nude mice that were given i.p. implants of human ovarian cancer (IGROV) cells were treated 3 days later with i.p. murine tumor-infiltrating lymphocytes (TIL) derived from an unrelated tumor. Mice treated with MOv-gamma-transduced TIL (MOv-TIL) had significantly increased survival compared to mice treated with saline only, nontransduced TIL, or TIL transduced with a control anti-trinitrophenyl chimeric receptor gene (TNP-TIL). In another model, C57BL/6 mice were given i.v. injections of a syngeneic methylcholanthrene-induced sarcoma transduced with the folate-binding protein (FBP) gene. Three days later, mice were treated i.v. with various transduced murine TIL (derived from an unrelated tumor), followed by low-dose systemic interleukin 2. Eleven days after tumor injection, mice were sacrificed, and lung metastases were counted. In multiple experiments, mice receiving MOv-TIL had significantly fewer lung metastases than did mice treated with interleukin 2 alone, nontransduced TIL, or TNP-TIL. These studies indicate that T cells can be gene modified to react in vivo against tumor antigens, defined by mAbs. This approach is potentially applicable to a number of neoplastic and infectious diseases and may allow adoptive immunotherapy against types of cancer not previously amenable to cellular immunotherapy.

Animals↗
PubMed1995

Interleukin-2-transduced lymphocytes grow in an autocrine fashion and remain responsive to antigen.

The maintenance of T lymphocytes in vivo after adoptive transfer for immunotherapy requires the systemic administration of interleukin-2 (IL-2), but prolonged administration of IL-2 is associated with substantial toxicity. The constitutive production of IL-2 by T cells may be an alternative method to prolong T-cell survival and potentially augment antitumor responses. To study the effects of constitutive production of IL-2 on the growth and antigen reactivity of a murine T cell, the sperm-whale myoglobin (SWM) specific T-cell line 14.1 was retrovirally transduced with the cDNA for IL-2. Cells that were transduced with vectors without an internal promoter were able to proliferate in the absence of exogenously added IL-2, and to grow in an autocrine fashion. These vectors used an internal ribosomal entry site (IRES) to allow translation of the neomycin phosphotransferase (neor) gene. In contrast, the cells transduced with an IL-2 vector in which the neor gene was under the transcriptional control of an internal SV-40 promoter failed to proliferate or grow in the absence of exogenously added IL-2. The proliferation of the cells growing without IL-2 could be inhibited with antibodies to the IL-2 receptor or to human IL-2, indicating that they were still IL-2 dependent. Despite their autocrine growth, no tumor formation was observed in syngeneic mice injected subcutaneously with the transduced cells, and the cells retained their antigen reactivity and specificity. These results suggest that autocrine growth of T cells for therapy will not interfere with effector function.

Animals↗
PubMed1994

Upregulation of tumor necrosis factor-alpha production by retrovirally transduced human tumor-infiltrating lymphocytes using trans-retinoic acid.

The ability of retinoic acid (RA) to upregulate gene expression in human tumor-infiltrating lymphocytes (TIL) transduced with a Moloney murine leukemia virus containing the cDNA encoding tumor necrosis factor (TNF) has been studied. TNF production was increased approximately twofold after treatment with RA. This increase was dose dependent and corresponded to a rise in the level of LTR-driven mRNA measured by Northern analysis. RA did not appreciably increase transcription by the SV40 promoter or increase endogenous TNF production. The effect lasted for 3-6 days following withdrawal of RA. These studies indicate that RA can upregulate LTR-driven gene expression in TIL cells bearing retroviral vectors and may thus be of use in studies of the gene therapy of cancer.

Gene Expression↗
PubMed1994

The genetic modification of T cells for cancer therapy: an overview of laboratory and clinical trials.

Immunotherapies using high doses of interleukin-2 and tumor-infiltrating lymphocytes (TIL) have been developed for the treatment of advanced cancer. Current efforts are aimed at enhancing the therapeutic efficacy of TIL through genetic modification. Initially, we demonstrated that retroviral-mediated gene transfer into TIL using a neomycin resistance marker gene was practical and safe for use in patient therapy. Because TIL have been shown to localize at tumor sites, we are now introducing the TNF gene into TIL in an attempt to increase the local concentrations of TNF in the tumor microenvironment without inducing systemic toxicity. Another gene being studied for insertion into TIL is a chimeric antibody/T-cell receptor gene. For many histologic types of cancer, it is relatively difficult to obtain specific TIL, but many monoclonal antibodies (mAb) exist that bind tumor-associated antigens. In order to combine the effector function of T cells with the antitumor specificity of antibodies, we have constructed chimeric receptor genes containing the variable region domains from mAb linked to T-cell signal-transducing chains. Human TIL retrovirally transduced with a chimeric receptor gene constructed from an anti-ovarian cancer antibody were redirected to recognize and lyse ovarian cancer cell lines specifically. This approach may allow adoptive immunotherapy against histologies not previously amenable to this treatment modality.

Clinical Trials as Topic↗
PubMed1993

Lysis of ovarian cancer cells by human lymphocytes redirected with a chimeric gene composed of an antibody variable region and the Fc receptor gamma chain.

To expand the spectrum of recognition of effector lymphocytes and to redirect them towards predefined targets, we have altered the specificity of human tumor-infiltrating lymphocytes (TIL) through stable modification with chimeric receptor genes consisting of single-chain antibody variable regions linked to the gamma subunit common to the immunoglobulin (Ig)G and IgE Fc receptors. Using either hapten or ovarian carcinoma-specific monoclonal antibodies, we constructed chimeric receptor genes and retrovirally introduced them into CD8+ TIL. Redirected TIL specifically lysed trinitrophenyl-labeled Daudi or a human ovarian carcinoma cell line (IGROV-1), and secreted granulocyte/macrophage colony-stimulating factor upon stimulation with the appropriate antigen. This strategy may allow new approaches towards the adoptive immunotherapy of cancer in humans.

Cloning, Molecular↗
PubMed1993

Characterization of human tumor cell lines transduced with the cDNA encoding either tumor necrosis factor alpha (TNF-a) or interleukin-2 (IL-2).

Tumor cell lines were generated from cancer patients, 17 with metastatic melanoma and one with colon adenocarcinoma. The lines were characterized as tumor cells by the presence of tumor associated antigens demonstrated by indirect immunofluorescence and analysing using a fluorescence activated cell sorter (FACS). The tumor cell lines were transduced using retroviruses encoding neomycin phosphotransferase and either human tumor necrosis factor alpha (TNF-alpha) or interleukin-2 (IL-2). Following transduction, cells were selected and grown in the neomycin analogue G418. Fibroblasts overgrew tumor cells in 6/18 cases following selection in G418 and 1/18 lines did not grow at all after selection. In the remaining 11 lines the expression of tumor associated antigens, growth, and susceptibility to lysis by LAK cells was similar between the selected transduced tumor cell lines and the nontransduced controls. Of the lines tested, all were positive for the presence of the cytokine gene by Southern blot or PCR analysis. In addition, no replication competent retrovirus was detected in the cell lines following transduction using an extended mink S+L- focus assay. The amount of specific cytokine produced per 10(5) transduced tumor cells in 24 h ranged from 0.2 ng to 5.8 ng of TNF-alpha for the TNF transduced lines and from 0.1 ng to 3.6 ng of IL-2 for the IL-2 transduced tumor cell lines. One transduced tumor cell line examined maintained consistent levels of cytokine production when studied at 15 different time intervals over a period of 198 days. Additionally, 40,000 rads of gamma irradiation did not stop cytokine production from two transduced tumor cell lines when studied over 6 days. This study demonstrates the feasibility of growing human tumor cell lines from surgical biopsies and genetically modifying those lines to produce a cytokine of choice for possible use as a tumor cell vaccine.

Adenocarcinoma↗
PubMed1993

Functional and molecular characterization of tumor-infiltrating lymphocytes transduced with tumor necrosis factor-alpha cDNA for the gene therapy of cancer in humans.

TNF is effective in causing the regression of selected murine tumors when administered at high concentrations. Therapeutic levels in humans cannot be obtained systemically, however, because of dose-limiting toxicity. The development of immunotherapy with IL-2 and tumor-infiltrating lymphocytes (TIL), which can accumulate at tumor sites in some patients, and of efficient retroviral techniques for gene transfer into eukaryotic cells has allowed new therapeutic approaches using TNF. We have retrovirally transduced human TIL with the gene for TNF in an attempt to deliver high concentrations of TNF to the tumor site without dose-limiting systemic toxicity. Successful gene insertion was confirmed by Southern hybridization in 16 of 16 transduced and selected TIL cultures from 15 different patients, with an estimated 28 to 93% transduced cells within each culture. Transduced selected TIL cultures produced greater amounts of TNF, compared with nontransduced controls, in 11 of 16 cultures evaluated. However, overall production of TNF was > 30-fold lower, compared with a transduced and highly selected tumor cell line control (MEL-TNF). In addition, steady state levels of vector-derived transcript in nine of 10 transduced selected TIL cultures were < 14% of the amount seen in the MEL-TNF control line. In an attempt to increase TNF production, TIL were transduced with a mutated form of TNF containing the IFN-gamma signal peptide in place of the transmembranous region, to enhance secretion into the endoplasmic reticulum. By using this vector, TNF production increased by an average of fivefold. These studies demonstrate that TIL can be genetically modified to express and secrete a protein for use in targeted cancer therapy but that partial expression blockades exist that prevent maximal cytokine production by introduced genes in TIL.

DNA↗