Biomedical subjects

J Schlom

Publications and source records attributed to J Schlom.

At least 55 records · Page 3Linked to original sources

PubMed1999

Comparative studies of a retrovirus versus a poxvirus vector in whole tumor-cell vaccines.

A number of experimental and clinical studies have used retroviral vectors to express transgenes in whole tumor-cell vaccines. Recently, poxvirus vectors such as vaccinia or avipox have been used toward this goal. The studies reported here compare for the first time the use of a retroviral vector versus a poxvirus vector (vaccinia) in whole tumor-cell vaccines. The transgene used was the T-cell costimulatory molecule B7-1, and the tumor was the weakly or nonimmunogenic MC38 murine colon adenocarcinoma. Recombinant retrovirus (R-B7) and the recombinant vaccinia (V-B7) induced equivalent expression of B7 on the surface of the carcinoma cell. Using live whole-tumor cells as vaccine, cells transduced via recombinant retrovirus (MC38/R-B7) and recombinant vaccinia (MC38/V-B7) equally induced protection against challenge by native MC38 cells 14 days later. Upon rechallenge with native MC38 cells 40 days later, however, the MC38/R-B7 vaccine was shown to be less effective than the MC38/V-B7 vaccine. Similar results were obtained when the tumor cells were irradiated prior to administration. When comparative studies were conducted in which X-irradiated tumor-cell vaccines were given to mice bearing experimental lung metastases, the MC38/V-B7 vaccine was shown to be significantly (P = 0.0351) more effective than the MC38/R-B7 vaccine. Additional studies were carried out in mice that had received vaccinia virus previously. Again, the X-irradiated MC38/V-B7 vaccine was statistically (P = 0.024) more effective than the MC38/R-B7 vaccine in the elimination of metastases. When the naïve and vaccinia-immune mice for each vaccination group were combined for meta-analysis (n = 16), the MC38/V-B7 was significantly more effective than the MC38/R-B7 in the treatment of pulmonary metastases (P = 0.0014) in this model. These studies thus demonstrate for the first time that a whole tumor-cell vaccine (either live or X-irradiated) containing a vaccinia transgene is at least as efficient, and sometimes more efficient, in inducing antitumor effects compared with the same vaccine using a retrovirus to express the transgene. The implications for the clinical applications of such approaches are discussed.

Animals↗

PubMed1999

Persistence, immune specificity, and functional ability of murine mutant ras epitope-specific CD4(+) and CD8(+) T lymphocytes following in vivo adoptive transfer.

Adoptive T-cell transfer has been shown to be a potentially effective strategy for cellular immunotherapy in some murine models of disease. However, several issues remain unresolved regarding some of the basic features involved in effective adoptive transfer, such as the influence of specific peptide antigen (Ag) boost after T-cell transfer, the addition of IL-2 post-T-cell transfer, the trafficking of transferred T cells to lymphoid and nonlymphoid tissues, and the functional stability of recoverable CD4(+) and CD8(+) T cells. We investigated several of these parameters, particularly as they relate to the persistence and maintenance of effector functions of murine CD4(+) and/or CD8(+) T lymphocytes after adoptive cellular transfer into partially gamma-irradiated syngeneic hosts. Our laboratory previously identified murine (H-2(d)) immunogenic CD4(+) and CD8(+) T-cell peptide epitopes reflecting codon 12 ras mutations as tumor-specific Ag. Therefore, the model system chosen here employed epitope-specific MHC class II-restricted CD4(+) T cells and MHC class I-restricted CD8(+) T cells produced from previously immunized BALB/c mice. Between 2 and 7 days after T-cell transfer, recipient mice received various combinations of peptide boosts and/or IL-2 treatments. At different times after the T-cell transfer, spleen and lung tissues were analyzed phenotypically to monitor the persistence of the immune T cells and functionally (via proliferation or cytotoxicity assays) to assess the maintenance of peptide specificity. The results showed that immune donor T lymphocytes (uncultured immune T cells or cloned T cells) were recoverable from the spleens and lungs of recipient mice after transfer. The recovery of Ag-specific T-cell responses was greatest from recipient mice that received peptide boosts and IL-2 treatment. However, mice that received a peptide boost without IL-2 treatment responded nearly as well, which suggested that including a peptide boost after T-cell transfer was more obligatory than exogenous IL-2 treatment to sustain adoptively transferred T cells in vivo. Ag-specific T-cell responses were weak in mice that either received IL-2 alone or did not receive the cognate peptide boost after T-cell transfer. The T-cell clones were also monitored by flow cytometry or RT-PCR based on expression of the T-cell receptor Vbeta-chain, which was previously characterized. Ag-specific T cells were recovered from both spleens and lungs of recipient mice, demonstrating that the T-cell clones could localize to both lymphoid and nonlymphoid tissues. This study demonstrates that both uncultured and in vitro-cloned T lymphocytes can migrate to lymphoid tissues and nonlymphoid (e.g., lung) tissues in recipient hosts and that their functional activities can be maintained at these sites after transfer, if they are exposed to peptide Ag in vivo.

Adoptive Transfer↗

PubMed1999

Low-level transforming activity of an activated Ras gene under the control of a vaccinia virus p40 promoter is abrogated by truncation of the Ras cDNA.

Many human cancers have been shown to contain activated forms of the Ras proto-oncogene. Mutations comprising amino acid changes at codons 12, 13 and 61 therefore represent unique targets for cancer immunotherapy. Recombinant Vaccinia viruses encoding point mutated Ras oncogenes have raised issues concerning the safety and transforming ability of these recombinant vaccines. Vaccinia virus, a representative of the orthopox virus genus, is a large DNA virus that is cytopathogenic and that replicates in the cytoplasm of the infected cell. However, it remains unclear whether orthopox viruses are capable of genetic interactions with infected cells. Our studies show that DNA isolated from cells infected with a recombinant Vaccinia virus expressing mutated Ras constituted a poor reagent for transfection into NIH3T3 cells for transformation analysis. Stable integration of a recombinant Vaccinia virus expressing mutant Ras DNA was not detected in recipient cells. This study also demonstrates that the crossover plasmids used to generate the recombinant virus where the activated Ras gene is under the control of a Vaccinia virus early promoter had low but detectable transforming efficiency in the NIH3T3 transformation assay. Analysis of the transfected cells indicated that Ras transcription was initiated upstream of the Vaccinia virus promoter. The introduction of wobble mutations as well as the truncation of the Ras protein removed the transforming capabilities of the crossover vector. This study demonstrates the potential problems and solutions in the use of point mutated oncogenes in live vectors for cancer vaccine development.

3T3 Cells↗

PubMed1999

Anti-tumor immunity elicited by a recombinant vaccinia virus expressing CD70 (CD27L).

CD70, a ligand of the T cell costimulatory receptor CD27, is expressed mainly on activated B cells and has been shown to increase cytotoxic activity and proliferation of preferentially unprimed T cells. Reported herein is the construction of a recombinant vaccinia virus encoding CD70 (designated rV-CD70) and a demonstration of its biological effect on naive T cells in vitro and in vivo. In a whole tumor cell vaccine model, the growth of CD70-negative murine colon adenocarcinoma (MC38) tumor cells infected with rV-CD70 (multiplicity of infection [MOI] of 0.1) and transplanted into syngeneic C57BL/6 mice was inhibited completely while control tumors infected with wild-type vaccinia grew rapidly and killed mice within 3-5 weeks. Tumor-free mice previously immunized with rV-CD70-infected tumors were partially protected against rechallenge with wild-type tumors, demonstrating the induction of systemic anti-tumor immunity. In addition, immunization of C57BL/6 mice with rV-CD70 admixed with vaccinia virus encoding carcinoembryonic antigen (rV-CEA) was superior to treatment with rV-CEA alone in inducing CEA-specific lymphoproliferative T cell responses and reducing growth of murine colon carcinomas transduced with CEA. These studies demonstrate for the first time the potential utility of a recombinant vaccinia virus expressing CD70 to enhance T cell responses and mediate anti-tumor immunity.

Adenocarcinoma↗

PubMed1999

Induction of anti-tumor immunity elicited by tumor cells expressing a murine LFA-3 analog via a recombinant vaccinia virus.

T cell activation requires binding of the T cell receptor to the major histocompatibility molecule-peptide complex in the presence of adhesion and/or costimulatory molecules such as B7-1 (CD80), B7-2 (CD86), ICAM-1 (CD54), and LFA-3 [corrected]. The major ligand of CD2 is CD48, the murine analog of human leukocyte function-associated antigen 3 (LFA-3). To determine the effect of LFA-3 expression on the immunogenicity of tumor cells, we constructed a recombinant vaccinia virus containing the murine LFA-3 gene (designated rV-LFA-3). rV-LFA-3 was shown to be functional in vitro in terms of expression of LFA-3, T cell proliferation, adhesion, and cytotoxicity. Subcutaneous inoculation of rV-LFA-3-infected murine colon adenocarcinoma tumor cells (MC38) into immunocompetent syngeneic C57BL/6 mice resulted in complete lack of tumor growth. Inoculation of MC38 cells infected with equal doses of control wild-type vaccinia virus resulted in tumor growth in all animals. In addition, partial immunological protection was demonstrated against subsequent challenge with uninfected parental tumor cells up to 56 days after vaccination with rV-LFA-3-infected cells. Anti-tumor memory was also demonstrated by using gamma-irradiated MC38 cells and cells from another carcinoma model (CT26). These studies demonstrate that expression of LFA-3 via a poxvirus vector can be used to induce anti-tumor immunity.

Adenocarcinoma↗

PubMed1999

The use of combination vaccinia vaccines and dual-gene vaccinia vaccines to enhance antigen-specific T-cell immunity via T-cell costimulation.

Several recombinant vaccinia viruses are currently being evaluated to induce antigen-specific immunity to a variety of infectious disease agents and tumor associated antigens. T-cell costimulation is extremely important in enhancing T-cell responses, and recombinant vaccines have now been shown to be effective vectors to express a range of these molecules. Both combination vaccines (an admixture of a recombinant vaccinia virus expressing a specific target antigen and a recombinant vaccinia virus expressing a costimulatory molecule) and dual-gene vaccines expressing both transgenes on the same vector have been shown capable of effectively enhancing antigen-specific responses via T-cell costimulation. In this report, we compare for the first time the use of both types of approaches to enhance antigen-specific T-cell responses, and we demonstrate the importance of route of vaccine administration and vaccine dose in attaining optimal T-cell responses. These studies should have direct bearing on the design of vaccine clinical trials for infectious agents and/or tumor associated antigens, in which T-cell costimulatory molecules will be employed to enhance antigen-specific T-cell responses via the use of either combination or dual-gene vaccinia vaccines.

Adjuvants, Immunologic↗

PubMed1999

Induction of protective host immunity to carcinoembryonic antigen (CEA), a self-antigen in CEA transgenic mice, by immunizing with a recombinant vaccinia-CEA virus.

Human carcinoembryonic antigen (CEA) is a well-characterized oncofetal glycoprotein whose overexpression by human carcinomas has been a target for cancer immunotherapy. Transgenic mice that express CEA as a self-antigen with a tissue distribution similar to that of humans have been developed. This study investigates: (a) the responsiveness of the CEA transgenic (CEA.Tg) mice to endogenous CEA or CEA administered as a whole protein in adjuvant; and (b) whether the presentation of CEA as a recombinant vaccinia virus could generate CEA-specific host immunity. By and large, the CEA.Tg mice were unresponsive to CEA, as shown by the lack of detectable CEA-specific serum antibodies and the inability to prime an in vitro splenic T-cell response to CEA. Furthermore, the administration of whole CEA protein in adjuvant to CEA.Tg mice failed to elicit either anti-CEA IgG titers or CEA-specific T-cell responses. Only weak anti-CEA IgM antibody titers were found in those mice. In contrast, CEA.Tg mice immunized with recombinant vaccinia virus expressing CEA generated relatively strong anti-CEA IgG antibody titers and demonstrated evidence of immunoglobulin class switching. These mice also developed T(H)1-type CEA-specific CD4+ responses and CEA peptide-specific cytotoxicity. The ability to generate CEA-specific host immunity correlated with protection of the CEA.Tg mice against a challenge with CEA-expressing tumor cells. Protection against tumor growth was accomplished with no apparent immune response directed at CEA-positive normal tissue. The results demonstrate the ability to generate an effective antitumor immune response to a tumor self-antigen by immunization with a recombinant vaccinia virus. CEA.Tg mice should be an excellent experimental model to study the effects of more aggressive immunization schemes directed at established tumors with the possible development of accompanying autoimmune responses involving normal tissues.

Animals↗

PubMed1999

Anti-tumor activity of human T cells expressing the CC49-zeta chimeric immune receptor.

A chimeric immune receptor consisting of an extracellular antigen-binding domain derived from the CC49 humanized single-chain antibody, linked to the CD3zeta signaling domain of the T cell receptor, was generated (CC49-zeta). This receptor binds to TAG-72, a mucin antigen expressed by most human adenocarcinomas. CC49-zeta was expressed in CD4+ and CD8+ T cells and induced cytokine production on stimulation. Human T cells expressing CC49-zeta recognized and killed tumor cell lines and primary tumor cells expressing TAG-72. CC49-zeta T cells did not mediate bystander killing of TAG-72-negative cells. In addition, CC49-zeta T cells not only killed FasL-positive tumor cells in vitro and in vivo, but also survived in their presence, and were immunoprotective in intraperitoneal and subcutaneous murine tumor xenograft models with TAG-72-positive human tumor cells. Finally, receptor-positive T cells were still effective in killing TAG-72-positive targets in the presence of physiological levels of soluble TAG-72, and did not induce killing of TAG-72-negative cells under the same conditions. This approach is being currently being utilized in a phase I clinical trial for the treatment of colon cancer.

Animals↗

PubMed1999

Construction of phosphorylatable chimeric monoclonal antibody CC49 with a casein kinase I recognition site.

Phosphorylation sites for casein kinase I were introduced into chimeric monoclonal antibody CC49 (MAb-chCC49) by inserting a synthetic fragment (CK1) encoding two casein kinase I phosphorylation sites into an expression vector. The phosphorylation sites were created by incorporating the predicted consensus sequences for phosphorylation by the casein kinase I at the carboxyl terminus of the heavy-chain constant region of the MAb-chCC49. The resultant modified MAb-chCC49 (MAb-chCC49CK1) was expressed and purified. The MAb-chCC49CK1 protein can be phosphorylated by the casein kinase I with [gamma-32P]ATP to high radiospecific activity. The 32P-labeled MAb-chCC49CK1 protein binds to cells expressing TAG-72 antigens. The introduction of phosphorylation sites into MAb provides new reagents for the diagnosis and treatment of cancer. This demonstrates that, as was described for the cAMP-dependent protein kinase site, the casein kinase I recognition site can also be used to introduce phosphorylation sites into proteins.

Amino Acid Sequence↗

PubMed1999

Recombinant vaccinia-PSA (PROSTVAC) can induce a prostate-specific immune response in androgen-modulated human prostate cancer.

OBJECTIVES: Prostate cancer recurrence, evidenced by rising prostate-specific antigen (PSA) levels after radical prostatectomy, is an increasingly prevalent clinical problem in need of new treatment options. Preclinical studies have suggested that for tumors in general, settings of minimal cancer volume may be uniquely suitable for recombinant vaccine therapy targeting tumor-associated antigens. A clinical study was undertaken to evaluate the safety and biologic effects of vaccinia-PSA (PROSTVAC) administered to subjects with postprostatectomy recurrence of prostate cancer and to assess the feasibility of interrupted androgen deprivation as a tool for modulating expression of the vaccine target antigen, as well as detecting vaccine bioactivity in vivo. METHODS: A limited Phase I clinical trial was conducted to evaluate the safety and biologic effects of vaccinia-PSA administered in 6 patients with androgen-modulated recurrence of prostate cancer after radical prostatectomy. End points included toxicity, serum PSA rise related to serum testosterone restoration, and immunologic effects measured by Western blot analysis for anti-PSA antibody induction. RESULTS: Toxicity was minimal, and dose-limiting toxicity was not observed. Noteworthy variability in time required for testosterone restoration (after interruption of androgen deprivation therapy) was observed. One subject showed continued undetectable serum PSA (less than 0.2 ng/mL) for over 8 months after testosterone restoration, an interval longer than those reported in previous androgen deprivation interruption studies. Primary anti-PSA IgG antibody activity was induced after vaccinia-PSA immunization in 1 subject, although such antibodies were detectable in several subjects at baseline. CONCLUSIONS: Interrupted androgen deprivation may be a useful tool for modulating prostate cancer bioactivity in clinical trials developing novel biologic therapies. Immune responses against PSA may be present among some patients with prostate cancer at baseline and may be induced in others through vaccinia-PSA immunization.

Androgen Antagonists↗

PubMed1999

Generation and characterization of a novel single-gene-encoded single-chain immunoglobulin molecule with antigen binding activity and effector functions.

Monoclonal antibody (MAb) CC49 is a murine IgG1 that reacts with tumor-associated glycoprotein (TAG)-72, a pancarcinoma antigen. Clinical trials using radiolabeled CC49 for diagnostic imaging have demonstrated specific localization of more than 90% of carcinomas. The feasibility of adopting in vivo gene inoculation methods for antibody-based immunotherapy requires introduction and expression of two genes, encoding immunoglobulin (Ig) heavy and light chains, in a single cell to generate a functional antibody. To circumvent the problems inherent in this approach, we have constructed a single-gene encoding a single-chain immunoglobulin (SCIg) that, unlike previously developed SCIgs, contains all IgG domains. To construct the novel SCIg, the carboxyl end of the constant region of the chimeric (c) CC49 kappa chain is joined, via a 30 residue Gly-Ser linker peptide, to the amino terminus of the CC49 heavy chain. To our knowledge, neither a linker peptide this long nor a linkage between the constant light (C(L)) and variable heavy domains has been reported previously. Transfectomas developed by introducing the expression construct of the amplifiable gene in dihydrofolate reductase-deficient Chinese hamster ovary (CHO dhfr-) cells secrete a 160 kDa homodimeric molecule, SCIgcCC49. The in vitro antigen binding properties of SCIgcCC49 are comparable to those of cCC49 and SCIgcCC49deltaC(H)1, a single-chain Ig deficient in constant heavy chain-1 (C(H)1) and C(L) domains. The antibody-dependent cellular cytotoxicity (ADCC) of SCIgcCC49 and cCC49 were also comparable. This single-gene approach for generating an immunoglobulin molecule may facilitate in vivo gene inoculation as well as ex vivo transfection of patients' cultured tumor-infiltrating lymphocytes for immunotherapy protocols for a variety of diseases, including cancer.

Animals↗

PubMed1999

In vivo comparison of CHX-DTPA ligand isomers in athymic mice bearing carcinoma xenografts.

Monoclonal antibodies (MAbs) labeled with radiometallonuclides via metal chelators are being investigated in the laboratory for use in clinical trials. The biodistribution of 111In- and 88Y-labeled antibody (MAb B72.3) using two isomeric forms (CHX-A and CHX-B) of the 2-(p-isothiocyanatobenzyl)-cyclohexyl-DTPA was compared in athymic mice bearing LS-174T tumors, human colon carcinoma xenografts. CHX-(A or B)-125I-DTPA-B72.3 was co-injected in all athymic mice to assess if the chelate conjugation altered the properties of MAb B72.3. In vitro studies demonstrated maintenance of integrity and immunoreactivity for both radioimmunoconjugates. The in vivo analysis, however, indicated major differences between the two isomer forms. In fact, the 88Y-CHX-A-DTPA radioimmunoconjugate demonstrated over the 7-day study period, a more efficient and stable tumor localization as well as a slower blood clearance rate than the CHX-B-DTPA chelate conjugate, suggesting a greater in vivo stability. Differences were also evident in critical normal organ uptake: no significant increase in liver- and spleen- or bone-to-blood ratios was observed when the CHX-A-DTPA chelate was labeled with indium or yttrium. The results described here demonstrate that the CHX-A-DTPA chelate conjugate can be considered more suitable than the CHX-B-DTPA isomer form when radiometallonuclides are coupled to an MAb.

Animals↗

PubMed1999

A phase I vaccine trial with peptides reflecting ras oncogene mutations of solid tumors.

Mutations in the ras genes occur in 20% of all human cancers. These genes, in turn, produce mutated proteins that are unique to cancer cells, rendering them distinguishable from normal cells by the immune system. Thus, mutated Ras proteins may form potential targets for immune therapy. We conducted a phase I/pilot clinical trial in patients with advanced cancers to test the toxicity and the ability to induce an immune response by vaccination with 13-mer mutated Ras peptides reflecting codon 12 mutations. These peptides corresponded to each of the patient's own tumor Ras mutation. Patients were vaccinated monthly x3 subcutaneously with the specific Ras peptide along with Detox adjuvant (RiBi ImmunoChem Research, Inc., Hamilton, MT, U.S.A.) at one of five different peptide dose levels (100, 500, 1,000, 1,500, and 5,000 micrograms). Three out of 10 evaluable patients generated a mutant Ras specific CD4+ and/or CD8+ T-cell immune response. The CD8+ cytotoxic cells specific for Gly to Val mutation at codon 12 were capable of lysing an HLA-A2-matched tumor cell line carrying the corresponding mutant but not the wild-type ras gene. The treatment has been well tolerated with no evidence of serious acute or delayed systemic side effects on any of the five dose levels. We demonstrated that we can generate in cancer patients specific T-lymphocyte responses that detect single amino acid differences in Ras oncoproteins. Neither the immune responses nor the minor side effects seen were found to be dose dependent. This approach may provide a unique opportunity for generating a tumor-directed therapy. Also, in vitro stimulation of these cells with the corresponding peptide generated specific T-cell lines that could be used for adoptive immune therapy.

Adult↗

PubMed1999

The diversity of T-cell co-stimulation in the induction of antitumor immunity.

T-cell activation has now been shown to require at least two signals. The first signal is antigen-specific, is delivered through the T-cell receptor (TCR) via the peptide/major histocompatibility complex (MHC), and causes the T cell to enter the cell cycle. The second, or co-stimulatory, signal is required for cytokine production and proliferation, and is mediated through ligand interaction on the surface of the T cell. This chapter deals with: 1) comparative studies on the use of a dual-gene construct of a recombinant vaccinia (rV) vector containing a tumor-associated antigen (TAA) gene and a co-stimulatory molecule gene vs the use of admixtures of rV-TAA and rV containing the co-stimulatory molecule to induce anti-tumor immunity; 2) the use of an admixture of vaccinia viruses containing a TAA gene and the B7-1 co-stimulatory molecule gene to induce a therapeutic response in a lung metastasis tumor model; 3) the antitumor efficacy of whole-tumor-cell vaccines in which the B7-1 co-stimulatory molecule is expressed in a tumor-cell vaccine via a vaccinia vs a retroviral vector; 4) the use of recombinant poxviruses containing the genes for the co-stimulatory molecules ICAM-1 or LFA-3 to induce antitumor immunity; and 5) the use of poxvirus vectors containing a triad of co-stimulatory molecules (B7-1, ICAM-1 and LFA-3) that synergize to enhance both CD4+ and CD8+ T-cell responses to a new threshold.

Animals↗

PubMed1999

Phase I study in cancer patients of a replication-defective avipox recombinant vaccine that expresses human carcinoembryonic antigen.

PURPOSE: A phase I clinical trial in patients with advanced carcinoma was conducted, using a replication-defective avipox vaccine containing the gene for the human carcinoembryonic antigen (CEA). The canarypox vector, designated ALVAC, has the ability to infect human cells but cannot replicate. PATIENTS AND METHODS: The recombinant vaccine, designated ALVAC-CEA, was administered intramuscularly three times at 28-day intervals. Each cohort of six patients received three doses of either 2.5 x 10(5), 2.5 x 10(6), or 2.5 x 10(7) plaque-forming units of vaccine. RESULTS: The vaccine was well tolerated at all dose levels and no significant toxicity was attributed to the treatment. No objective antitumor response was observed during the trial in patients with measurable disease. Studies were conducted to assess whether ALVAC-CEA had the ability to induce cytolytic T-lymphocyte (CTL) responses in patients with advanced cancer. Peripheral blood mononuclear cells (PBMCs) from patients with the MHC class I A2 allele were obtained before vaccine administration and 1 month after the third vaccination. Peripheral blood mononuclear cells were incubated with the CEA immunodominant CTL epitope carcinoembryonic antigen peptide-1 and interleukin 2 and quantitated using CTL precursor frequency analysis. In seven of nine patients evaluated, statistically significant increases in CTL precursors specific for CEA were observed in PBMCs after vaccination, compared with before vaccination. CONCLUSION: These studies constitute the first phase I trial of an avipox recombinant in cancer patients. The recombinant vaccine ALVAC-CEA seems to be safe and has been demonstrated to elicit CEA-specific CTL responses. These studies thus form the basis for the further clinical exploration of the ALVAC-CEA recombinant vaccine in phase I/II studies in protocols designed to enhance the generation of human T-cell responses to CEA.

Adult↗

PubMed1999

A Phase I study of active immunotherapy with carcinoembryonic antigen peptide (CAP-1)-pulsed, autologous human cultured dendritic cells in patients with metastatic malignancies expressing carcinoembryonic antigen.

Dendritic cells (DCs), antigen-presenting cells capable of priming naive T cells to specific antigens in an HLA-restricted fashion, have been demonstrated to induce protective T cell-mediated immunity in tumor-bearing animals. We performed this study to test the safety, feasibility, and clinical response of immunizations with in vitro-generated DCs, loaded with an HLA-A2-restricted peptide fragment of the tumor antigen carcinoembryonic antigen (CEA), for the treatment of patients with advanced CEA-expressing malignancies. Cell preparations enriched for autologous DCs were generated from the patients' plastic adherent peripheral blood mononuclear cells in serum-free media supplemented with granulocyte macrophage colony-stimulating factor and interleukin-4. Within the cell preparation, 66% of the cells expressed the phenotype typical for DCs (CD86high, HLA-DRhigh, and CD14low). The DCs were loaded with the CEA peptide CAP-1 and cryopreserved. Groups of three to six patients received four weekly or biweekly i.v. infusions of the CAP-1-loaded DC in escalating dose levels of 1 x 10(7), 3 x 10(7), and 1 x 10(8) cells/dose. A subset of the patients in the last group also received intradermal injections of 1 x 10(6) DCs. There were no toxicities directly referable to the treatments. One patient had a minor response, and one had stable disease. Skin punch biopsy at DC injection sites demonstrated pleomorphic infiltrates in the three patients evaluated. We conclude that it is feasible and safe to generate and administer large numbers of previously cryopreserved DCs loaded with CAP-1 peptide to patients with advanced malignancies.

Adult↗

PubMed1999

Phase I trial of a recombinant vaccinia virus encoding carcinoembryonic antigen in metastatic adenocarcinoma: comparison of intradermal versus subcutaneous administration.

The principal objectives of this trial were twofold: (a) to examine the safety and relative efficacy of intradermal needle injection versus s.c. jet administration of a carcinoembryonic antigen (CEA)-encoding recombinant vaccinia virus (rV-CEA) over a limited dose range and (b) to evaluate CEA-specific immune responses or antitumor effects induced by rV-CEA vaccination. Patients were randomly assigned to one of two groups, depending upon the technique of vaccine administration. All 20 patients received two doses of 10(7) or 10(8) pfu of rV-CEA at a 4-week interval. Toxicity was limited to modest local inflammation at the inoculation site as well as low-grade fever and increased fatigue, each affecting fewer than 20% of the patients. No evidence of CEA-specific lymphoproliferation, interleukin 2 release, delayed-type hypersensitivity, or antibody response was observed. Thus, the efficacy comparison between the two administration techniques was based upon the induction of immune responses to the vaccinia virus vector. Both techniques induced vaccinia-specific lymphoproliferation, interleukin 2 release, and antibody responses of comparable magnitude and frequency as well as protected 80% of patients against pustule formation following vaccinia scarification. Thus, there is no compelling reason to recommend one administration technique over the other based upon toxicity or efficacy. We have selected s.c. jet injection for subsequent trials of rV-CEA based on the ability to accommodate larger injection volumes, enhanced standardization between clinicians, and avoidance of needles that could transmit the vaccine or blood-borne pathogens to health care workers. We recommend use of 10(8) pfu doses for subsequent trials of recombinant vaccinia virus vaccines based upon the favorable toxicity profile and more consistent local pustule formation indicative of an adequate inoculation of live virus. No objective clinical responses to the rV-CEA vaccine were observed among this population of patients with widely metastatic adenocarcinoma.

Adenocarcinoma↗

PubMed1999

Generation and characterization of a single gene-encoded single-chain-tetravalent antitumor antibody.

Monoclonal antibody (mAb) CC49, a murine IgG1, reacts with the tumor-associated glycoprotein-72 expressed on a variety of carcinomas. In clinical trials, radiolabeled CC49 has shown excellent tumor localization to a variety of carcinomas. To minimize the immunogenicity of CC49 mAb in patients, a humanized CC49 (HuCC49) was generated by complementarity-determining region (CDR) grafting. The relative affinity of HuCC49 was 2-3-fold less than that of the murine mAb. With the aim of improving tumor targeting, attempts have been made to enhance the avidity of the HuCC49 mAb. Previous research has yielded a single gene-encoded immunoglobulin, SCIgcCC49deltaCH1, which is a dimer of a single chain consisting of CC49 single-chain Fv linked to the NH2 terminus of the human gamma1 Fc through the hinge region. This molecule is comparable to the mouse-human chimeric CC49 in terms of in vitro antigen binding properties, cytolytic activity, and rate of plasma clearance in athymic mice bearing human tumor xenografts. Recently, a single gene encoding a single-chain immunoglobulin consisting of a HuCC49 diabody attached to human gamma1 Fc via the hinge region was constructed. The diabody, a bivalent antigen-binding structure, is made up of variable heavy (V(H))/variable light (V(L)) domains and V(L)/V(H) domains. In each of the variable domain pairs, the V(H) and V(L) domains are linked through a short linker peptide. Meanwhile, the two pairs are linked via a 30-residue Gly-Ser linker peptide to yield two antigen-binding sites by lateral and noncovalent association of the V(L) of one pair with the V(H) of the other. Transfectomas expressing the single-gene immunoglobulin secrete a homodimer of about Mr 160,000 that reacts to tumor-associated glycoprotein-72. This tetravalent humanized antitumor immunoglobulin molecule may potentially be an efficacious therapeutic and diagnostic reagent against a wide range of human carcinomas.

Animals↗