Biomedical subjects

Martin A Cheever

Publications and source records attributed to Martin A Cheever.

10 recordsLinked to original sources

PubMed2006

Phase I Trial of sequential administration of recombinant DNA and adenovirus expressing L523S protein in early stage non-small-cell lung cancer.

L523S is an immunogenic lung cancer antigen that has demonstrated preclinical safety when the gene is injected intramuscularly as an expressive plasmid (pVAX/L523S) and when delivered following incorporation into an E1B-deleted adenovirus (Ad/L523S). We performed a phase I clinical trial in 13 stage IB, IIA, and IIB non-small-cell lung cancer patients. pVAX/L523S (8 mg on days 0 and 14 in all cohorts) and Ad/L523S (1, 20, 400 x 10(9) vp on days 28 and 56, cohorts 1, 2, and 3, respectively) were administered to 3 patients in each of three cohorts. No significant toxic effect was identified. All but 1 patient demonstrated greater than or equal to twofold elevation in anti-adenovirus antibodies. One of 10 evaluable patients demonstrated L523S-specific antibody by direct IgG ELISA. Two patients developed disease recurrence and all remain alive after a median of 290 days follow-up. Results suggest a high level of safety but evidence of L523S-directed immune activation was limited, suggesting a need for modification of dose, schedule, and site of vaccination (i.e., intradermal) with further clinical testing.

Adenoviridae↗

PubMed2005

Cancer vaccines and immunotherapies: emerging perspectives.

Research efforts over the last two decades studying immune responses to human carcinomas have demonstrated that antigens expressed by tumor cells can elicit specific cellular and humoral immune responses. Unfortunately, despite the observation that existent immune responses to these antigens are present in some patients with cancer, the tumors continue to progress. Thus, there has been considerable interest to augment these immune responses by immunization. Some of the clinical trials of the first cancer vaccines have provided evidence of clinical benefit thus encouraging the development of other vaccines. Challenges to development of such cancer vaccines include the identification and characterization of the antigen(s) to be targeted, the definition of the desired immune response to be elicited by the vaccine, and the choice of the appropriate vaccine delivery system.

Antibodies, Neoplasm↗

PubMed2004

Effect of dose on immune response in patients vaccinated with an her-2/neu intracellular domain protein--based vaccine.

PURPOSE: To evaluate the safety of an HER-2/neu intracellular domain (ICD) protein vaccine and to estimate whether vaccine dose impacts immunogenicity. PATIENTS AND METHODS: Twenty-nine patients with HER-2/neu-overexpressing breast or ovarian cancer and with no evidence of disease after standard therapy received a low- (25 microg), intermediate- (150 microg), or high-dose (900 microg) HER-2/neu ICD protein vaccine. The vaccine was administered intradermally, monthly for 6 months, with granulocyte-macrophage colony-stimulating factor as an adjuvant. Toxicity and both cellular and humoral HER-2/neu-specific immunity was evaluated. RESULTS: The vaccine was well tolerated. The majority of patients (89%) developed HER-2/neu ICD-specific T-cell immunity. The dose of vaccine did not predict the magnitude of the T-cell response. The majority of patients (82%) also developed HER-2/neu-specific immunoglobulin G antibody immunity. Vaccine dose did not predict magnitude or avidity of the HER-2/neu-specific humoral immune response. Time to development of detectable HER-2/neu-specific immunity, however, was significantly earlier for the high- versus low-dose vaccine group (P =.003). Over half the patients retained HER-2/neu-specific T-cell immunity 9 to 12 months after immunizations had ended. CONCLUSION: The HER-2/neu ICD protein vaccine was well tolerated and effective in eliciting HER-2/neu-specific T-cell and antibody immunity in the majority of breast and ovarian cancer patients who completed the vaccine regimen. Although the dose of vaccine did not impact the magnitude of T-cell or antibody immunity elicited, patients receiving the highest dose developed HER-2/neu-specific immunity more rapidly than those who received the lowest dose.

Adult↗

PubMed2003

Rapid high efficiency sensitization of CD8+ T cells to tumor antigens by dendritic cells leads to enhanced functional avidity and direct tumor recognition through an IL-12-dependent mechanism.

Myeloid-origin dendritic cells (DCs) can develop into IL-12-secreting DC1 or non-IL-12-secreting DC2 depending on signals received during maturation. Through rapid culture techniques that prepared either mature, CD83+ DC1 or DC2 from CD14+ monocytes in only 2 days followed by a single 6-7 day DC-T cell coculture, we sensitized normal donor CD8+ T cells to tumor Ags (HER-2/neu, MART-1, and gp100) such that peptide Ag-specific lymphocytes constituted up to 16% of the total CD8+ population. Both DC1 and DC2 could sensitize CD8+ T cells that recognized peptide-pulsed target cells. However, with DC2, a general decoupling was observed between recognition of peptide-pulsed T2 target cells and recognition of Ag-expressing tumor cells, with peptide-sensitized T cells responding to tumor only about 15% of the time. In contrast, direct recognition of tumor by T cells was dramatically increased (to 85%) when DC1 were used for sensitization. Enhanced tumor recognition was accompanied by 10- to 100-fold increases in peptide sensitivity and elevated expression of CD8beta, characteristic of high functional avidity T cells. Both of these properties were IL-12-dependent. These results demonstrate the utility of rapid DC culture methods for high efficiency in vitro T cell sensitization that achieves robust priming and expansion of Ag-specific populations in 6 days. They also demonstrate a novel function of IL-12, which is enhancement of CD8+ T cell functional avidity. A new approach to DC-based vaccines that emphasizes IL-12 secretion to enhance functional avidity and concomitant tumor recognition by CD8+ T cells is indicated.

Adjuvants, Immunologic↗

PubMed2003

HER2 dendritic cell vaccines.

HER2/neu, a tumor antigen overexpressed by a third of breast cancers, is a potential target for vaccine therapies. A particularly potent immunization strategy to induce T-cell responses against tumor antigens is to use dendritic cells (DCs) loaded with the tumor antigen. We performed two small studies to test the safety, feasibility, and immunologic and clinical responses to immunizations with in vitro-generated DCs loaded with either a human leukocyte antigen A2-restricted peptide fragment of the extracellular domain of the tumor antigen HER2 (E75) or a HER2 intracellular domain (ICD) protein in patients with high-risk resected breast cancer or metastatic cancers expressing HER2. There were no toxicities due to the immunizations in any of the patients. In the study of DCs loaded with the E75 peptide, 1 of 6 patients with metastatic HER2-expressing malignancies who completed all immunizations had stable disease for 6 months; the remainder of the patients had progressive disease. Delayed-type hypersensitivity (DTH) reactivity (2-3 mm of induration) at E75-loaded DC injection sites was observed in 2 of 5 patients evaluated but was similar at the unloaded DC injection sites. In 2 patients, the DTH sites underwent biopsy and a perivascular infiltrate of CD4 and CD8 cells was demonstrated, which was greater in the E75-loaded DC injection sites than in the unloaded DC sites. In the pilot study of ICD-loaded DC in patients with high-risk resected breast cancer, all 3 patients enrolled had no evidence of recurrence at a follow-up of up to 2.5 years. Intracellular domain-specific T-cell responses were detected directly from the peripheral blood by enzyme-linked immunospot and proliferation assay in 2 patients. We conclude that it is feasible and safe to generate and administer HER2-loaded DCs to patients with advanced HER2/neu-expressing malignancies and high-risk breast cancer. The magnitude of the immune responses generated is fairly modest, and more potent DC loading and maturation strategies will be necessary to optimize these vaccines.

Adult↗

PubMed2002

Characterization of KLK4 expression and detection of KLK4-specific antibody in prostate cancer patient sera.

The ability to identify prostate tumor or prostate tissue specific genes that are expressed at high levels and use their protein products as targets could greatly aid in the diagnosis and treatment of prostate cancer. Using a polymerase chain reaction (PCR)-based subtraction technique, we have recovered the recently described KLK4 (prostase) gene from human prostate cDNA. In this study, KLK4 gene expression in human prostate tumors was further characterized using cDNA quantitative PCR and immunohistochemistry, demonstrating that the gene is specifically expressed at both the mRNA and protein levels in normal human prostate tissue, and in both primary and metastatic prostate tumor samples. Quantitative mRNA analysis also demonstrated low level expression including adrenal gland, salivary gland and thyroid. Finally, it was demonstrated that prostate cancer patient sera contain antibodies that bind specifically to recombinant KLK4 protein. This antibody has been used to detect KLK4-specific peptides in epitope mapping experiments. The relatively specific expression profile and elevated level of KLK4 mRNA and protein in both tumor and normal prostate tissues, in addition to detectable KLK4-specific antibody in cancer patient sera, supports additional efforts to determine if KLK4 can play a role in the diagnosis of prostate cancer, the monitoring of residual disease, or act as a target for immunotherapy.

Antibodies↗

PubMed2002

Generation of T-cell immunity to the HER-2/neu protein after active immunization with HER-2/neu peptide-based vaccines.

PURPOSE: The HER-2/neu protein is a nonmutated tumor antigen that is overexpressed in a variety of human malignancies, including breast and ovarian cancer. Many tumor antigens, such as MAGE and gp100, are self-proteins; therefore, effective vaccine strategies must circumvent tolerance. We hypothesized that immunizing patients with subdominant peptide epitopes derived from HER-2/neu, using an adjuvant known to recruit professional antigen-presenting cells, granulocyte-macrophage colony-stimulating factor, would result in the generation of T-cell immunity specific for the HER-2/neu protein. PATIENTS AND METHODS: Sixty-four patients with HER-2/neu-overexpressing breast, ovarian, or non-small-cell lung cancers were enrolled. Vaccines were composed of peptides derived from potential T-helper epitopes of the HER-2/neu protein admixed with granulocyte-macrophage colony-stimulating factor and administered intradermally. Peripheral-blood mononuclear cells were evaluated at baseline, before vaccination, and after vaccination for antigen-specific T-cell immunity. Immunologic response data are presented on the 38 subjects who completed six vaccinations. Toxicity data are presented on all 64 patients enrolled. RESULTS: Ninety-two percent of patients developed T-cell immunity to HER-2/neu peptides (stimulation index, 2.1 to 59) and 68% to a HER-2/neu protein domain (stimulation index range, 2 to 31). Epitope spreading was observed in 84% of patients and significantly correlated with the generation of a HER-2/neu protein-specific T-cell immunity (P =.03). At 1-year follow-up, immunity to the HER-2/neu protein persisted in 38% of patients. CONCLUSION: The majority of patients with HER-2/neu-overexpressing cancers can develop immunity to both HER-2/neu peptides and protein. In addition, the generation of protein-specific immunity, after peptide immunization, was associated with epitope spreading, reflecting the initiation of an endogenous immune response. Finally, immunity can persist after active immunizations have ended.

Adult↗

PubMed2002

Designing HER2 vaccines.

HER2/neu is a compelling cancer vaccine candidate because it is overexpressed on some cancer cells relative to normal tissues, it is known to be immunogenic in both animal models and in humans, and it is already known to be targetable by the antibody component of the immune system in the form of monoclonal antibody therapy with trastuzumab. Vaccines offer the theoretical advantage of being able to elicit T-cell responses in addition to antibody responses. HER2 vaccines have been shown to provide benefit in animal models and to be immunogenic in humans. However, the optimal vaccine formulation is not yet known and the therapeutic efficacy of the vaccines in humans has not yet been evaluated. HER2 vaccine approaches currently being tested include peptide-based, DNA plasmid-based, and protein-based vaccines. Our group has developed and started testing a protein-based vaccine composed of both the extracellular domain of HER2 and the carboxyl terminal autophosphorylation portion of the intracellular domain. The extracellular domain was retained to provide for antibody targeting. The kinase domain of the intracellular domain was excluded because of its high degree of homology to other human kinases. The carboxyl terminal autophosphorylation domain was retained because it is the most unique and possibly most immunogenic portion of the HER2 molecule with the least homology to other members of the HER family. The vaccine, termed dHER2, is immunogenic in mice and primates. In animal models it can elicit CD8 and CD4 T-cell responses as well as antibody responses that suppress the growth of HER2-positive cancer cells in vitro and in vivo. Vaccine trials are contemplated in patients with breast cancer that will determine whether the vaccine construct is similarly immunogenic in humans.

Animals↗

PubMed2002

Immunization of cancer patients with a HER-2/neu, HLA-A2 peptide, p369-377, results in short-lived peptide-specific immunity.

Ideally, vaccines should be designed to elicit long-lived immunity. The goal of this study was to determine whether HER-2/neu peptide-specific CD8+ T-cell immunity could be elicited using an immunodominant HER-2/neu-derived HLA-A2 peptide alone in the absence of exogenous help. Granulocyte macrophage colony-stimulating factor (GM-CSF) was used as adjuvant. Six HLA-A2 patients with HER-2/neu-overexpressing cancers received 6 monthly vaccinations with a vaccine preparation consisting of 500 microg of HER-2/neu peptide, p369-377, admixed with 100 microg of GM-CSF. The patients had either stage III or IV breast or ovarian cancer. Immune responses to the p369-377 were examined using an IFN-gamma enzyme-linked immunosorbent spot assay. Before vaccination, the median precursor frequency (range), defined as precursors per 10(6) peripheral blood mononuclear cell, to p369-377 was 0 (no range). After vaccination, the median precursor frequency to p369-377 in four evaluable patients was 0 (0-116). Overall, HER-2/neu peptide-specific precursors developed to p369-377 in two of four evaluable subjects. The responses were short-lived and not detectable at 5 months after the final vaccination. Immunocompetence was evident, because patients had detectable enzyme-linked immunosorbent spot responses to tetanus toxoid and influenza. These results demonstrate that HER-2/neu MHC class I epitopes can induce HER-2/neu peptide-specific IFN-gamma-producing CD8+ T cells. However, the magnitude of the responses were low, as well as short-lived, suggesting that CD4+ T-cell help is required for lasting immunity to this epitope.

Aged↗

PubMed2002

Toxicity, immunogenicity, and induction of E75-specific tumor-lytic CTLs by HER-2 peptide E75 (369-377) combined with granulocyte macrophage colony-stimulating factor in HLA-A2+ patients with metastatic breast and ovarian cancer.

To determine the toxicity and immunogenicity of the HER-2/neu, HLA-A2-restricted peptide E75 in patients with metastatic breast and ovarian cancer, 14 patients were vaccinated with escalating amounts of E75 (100, 500, and 1000 microg) mixed with 250 microg granulocyte macrophage colony-stimulating factor as adjuvant. Each vaccine dose was administered in a total volume of 1.5 ml divided into four intradermal injections and administered weekly for 4 weeks, followed by monthly boosts for a total of 10 injections. Vaccinations were well tolerated without significant toxicity. Blood was drawn before, at 8 weeks, and up to 13-16 months after vaccination for measurement of cellular immunity. Seven of 8 patients tested had significant delayed type hypersensitivity to E75 defined as >5 mm induration. Peripheral blood mononuclear cells from 5 of 9 patients tested proliferated to E75 with a stimulation index of > or = 2.0. Of 8 vaccinated patients tested for induction of a CTL response, 4 responded to stimulation by autologous dendritic cells plus cytokines by eliciting E75-specific lytic activity consistent with the presence of activated/memory cells, 2 others after in vitro stimulation with E75 + interleukin-12 +/- anti-CD152(33KD), whereas 2 others did not respond. Four patients with E75-specific CTLs present specifically recognized E75 on indicator tumors as demonstrated by cold-target inhibition of tumor lysis. These 4 patients showed E75-specific IFN-gamma production. peripheral blood mononuclear cell from 3 of these patients proliferated to E75, but stimulation indices were higher in the prevaccine samples. All 4 of the patients showed DTH responses to E75. These results demonstrate that vaccination with E75+ granulocyte macrophage colony-stimulating factor can induce both peptide-specific IFN-gamma and epitope specific CTLs, which lyse HER-2/neu+ tumors in stage IV patients.

Abatacept↗