HER2 Vaccine Research Articles

Cellular immune parameters associated with improved long-term survival in advanced stage breast cancer patients after active immunization with a HER2-specific vaccine

3015 Background: Clinical trials of HER2 vaccines have demonstrated that breast cancer patients can be immunized against HER2 and HER2-specific T cells persist long after vaccination. Immunization with HER2 vaccines is associated with the development of epitope spreading; a broadening of immunity to epitopes throughout the HER2 protein. We evaluated the clinical impact of vaccine induced HER2 specific cellular immunity in breast cancer patients immunized with HER2 vaccines. Methods: 75 subjects from 3 phase I-II vaccine trials were analyzed. T cell responses to HER2 peptides, intracellular (ICD) protein and tetanus toxoid (TT) were assessed by tritiated thymadine incorporation. Subjects were included in the analysis if they had complete baseline labs and received at least three vaccinations. Any SI >2.0 was considered positive. Epitope spreading was defined as a positive post-vaccination response to a non-vaccinating peptide. In addition, the relationship between T cell response and overall survival (OS) was assessed (n=50). Patients were followed a median of 2.7 years. Results: There was a significant difference in level of HER2 ICD immunity after vaccination between stages. There were also significant differences in peptide specific SI (p=0.034) and presence of epitope spreading (p=0.006) between stages. HER2 peptide-specific SI was a significant predictor of epitope spreading (p=0.031). Subjects with epitope spreading had significantly higher peptide responses (mean SI: 11.5) than subjects without epitope spreading (mean SI: 3.3) (p<0.001). Univariate analysis demonstrated patients with epitope spreading had longer OS than patients without epitope spreading (p=0.029, HR=0.50), and increased HER2, but not TT, specific T cell immunity, was associated with improved survival (p=0.025, HR=0.94). Multivariate analysis indicated that HER2, but not TT, specific T cell immunity, was an independent variable (p=0.021, HR=0.86) for prediction of OS in advanced stage subjects. Conclusions: These data suggest that vaccine-induced HER2 specific cellular immune response, with epitope spreading, may have clinical benefit and should be further evaluated in the context of phase II studies. No significant financial relationships to disclose.

Adenovirus-human HER2 vaccine inhibits breast cancer growth and vaccine induced antibodies (VIA) are efficacious against Herceptin-refractory human breast cancer (48.32)

Abstract While HER2/neu specific antibody (Herceptin) therapy has clear efficacy against HER2 overexpressing tumors, most patients who initially respond to Herceptin show disease progression within one year despite continued high expression of HER2. As an alternative to Herceptin, we developed a novel set of adenoviral vectors encoding human HER2 which break tolerance and induce T and B cell responses in human-HER2-transgenic (HuHER2-Tg) mice (kindly provided by W-Z. Wei, Karmanos Cancer Center, MI). Ad-HER2 vaccination results in a high level of HER2-specific T cells and anti-HER2 vaccine induced antibodies (VIA), which significantly inhibits the growth of human HER2 expressing murine 4T1 breast cancer cells (kindly provided by M. Kershaw, Peter MacCallum Cancer Centre, Melbourne, Australia) in HuHER2-Tg mice. Anti-HER2 VIA strongly bound to Herceptin-refractory human breast tumor cells and significantly inhibited their growth in vitro, and mediated complement dependent cytotoxicity. Thus, our findings demonstrate that Ad-HER2 vaccination proved to be efficacious and therapeutically relevant in Herceptin refractory tumor models. Grant support: NIH P50-CA068438 SPORE in Breast Cancer &amp; DOD CTRA BC050221.

A phase I/II study of a HER2/neu (HER2) peptide vaccine plus concurrent trastuzumab

2528 Background: HER2 is a tumor antigen in breast and ovarian cancer. Vaccines targeting both Class I and II epitopes of HER2 can elicit long-lived cellular immunity. Trastuzumab increases the activity of HER2-specific T cells in vitro. This study examines the safety and immunogenicity of a HER2 peptide vaccine given with trastuzumab to augment HER2-specific immune responses in vivo. Methods: 20 HLA-A2+ subjects will be enrolled on this Phase I/II single institution trial. Eligible subjects must have stage IV HER2 overexpressing breast or ovarian cancer, stable or no evident disease on maintenance trastuzumab and a normal baseline MUGA. Subjects must have ECOG performance status 0–1, creat ≤ 2.0, bili &lt; 1.5 × ULN, SGOT &lt; 2 × ULN. The HER2 vaccine used in this study has been previously reported and is composed of 3 HER2 Class II epitopes encompassing Class I epitopes in their natural sequence. (Knutson et al, J Clin Investigation 107:477–484, 2001). Subjects receive 6 vaccinations + GM-CSF at monthly intervals. Primary endpoints are safety and immunogenicity. Results: To date, 14 of 20 subjects have been enrolled. A total of 77 vaccinations have been given. Of 276 reported toxicities, 88% were Grade 1; most common were constitutional symptoms (25%), injection site reactions (14%), and cytopenias (14%). 11% of toxicities were Grade 2; most common were lymphopenia (34%) and headache (19%). There was one Grade 3 toxicity (syncope 5 hours after vaccination) and one Grade 4 toxicity (stroke secondary to brain metastases in long-term follow up). Cardiac toxicity included two Grade 2 asymptomatic decreases in LVEF (54 to 49% and 64 to 45%.) The average decrease in LVEF between baseline and 9 month post-vaccine follow up was 5% ± 5.85 (n = 10). Of the 10 patients who have had immunologic analysis performed at multiple time points, 5 have developed significant T cell immunity to either HER2 overlapping peptide pools and/or HER2 peptides. Complete immunologic analysis will be presented. Conclusions: Subjects with HER2 overexpressing Stage IV cancer can be safely immunized with a HER2 peptide vaccine while receiving concurrent trastuzumab without additional cardiac toxicity. In addition, the approach is immunogenic, generating significant levels of HER2-specific T cells in the peripheral blood. No significant financial relationships to disclose.

Evaluation of a recombinant HER2 vaccine: Induction of specific antibodies, T-cells and preliminary activity in metastatic breast cancer patients

631 Background: We designed a vaccine to induce T cells able to recognize epitopes from HER2 and to engender a polyclonal antibody reponse. Methods: The vaccine is a recombinant HER2 protein, including its extra and part of its intra-cellular domains (ECD/ICD), combined with a potent immunologic adjuvant. Cohorts of patients with Stage II/III breast cancer (BC) received 20, 100 or 500 μg in the adjuvant setting. Treatment comprised of six vaccinations over 14 weeks, for the 500-μg dose, recall injections were given on weeks 34 and 38. The trial was extended to include an alternative vaccination schedule: 500 μg on days 0, 28 and 98. In an on-going trial, patients with metastatic BC treated in the first line setting are receiving the 500-μg treatment and being assessed for clinical response. Results: The vaccine was well tolerated, with no symptomatic cardiotoxicity. Antibody (Ab) response against ECD was dose-dependent, with 2/12, 9/14 and 14/15 immune responders in the respective cohorts after four vaccinations. Response was dose-related. Ab isotypes were analyzed in the 500 μg cohort: in 50% of patients, high levels of IgM (30–60%) against ECD were found after four vaccinations. The switch towards IgG was complete in all patients after six vaccinations. The efficacy of booster vaccinations was observed mainly in patients with low IgM after eight weeks. After two vaccinations, Ab titers on the alternative 500 μg vaccination schedule were as high as after four vaccinations utilizing the initial schedule. The anti-ECD antibodies in 11/15 patients (500 μg level) bound HER2-overexpressing breast-cancer cell lines. In sera from 2 patients tested thus far, the gene-expression resembled that of trastuzumab. Assays show that specific T cells were obtained; detailed analysis is continuing. Among metastatic patients, two showed evidence of tumor regression after vaccination. Conclusions: The HER2 vaccine was well tolerated and induced (dose-dependently) anti-ECD Ab that bound the HER2 receptor. Data suggest that the vaccine also induced specific T-cell immunity. The alternative vaccination schedule may increase the Ab titers. This data justifies further evaluation of this vaccine in the phase II/III setting. [Table: see text]

Phase I dose-escalation trial of a recombinant HER2 vaccine in patients with Stage II/III HER2+ breast cancer

2520 Background: Therapy with monoclonal antibodies against HER2 is effective in some patients with HER2+ Stage IV breast cancer. However, many patients do not respond to antibody therapy, and patients who do respond ultimately relapse. The current vaccine is designed to elicit a T-cell response in addition to a polyclonal Ab response and may therefore have a different spectrum of efficacy. Methods: The vaccine formulation contains a truncated recombinant HER2 protein (dHER2) combined with a new potent GSK immunological adjuvant. dHER2 includes the extracellular domain (ECD) and a part of the intracellular domain (ICD) of the HER2 protein. The trial’s objective is to evaluate safety and immunogenicity. Three dose levels of dHER2 protein were tested: 20, 100 and 500 mcg. Three cohorts of 15 patients with Stage II or III breast cancer were enrolled sequentially. Patients received 6 vaccinations over 14 weeks. Results: All patients receiving the 20- and 100-mcg doses have completed the course of 6 vaccinations, and those in the 500-mcg cohort will have done so by March 2005. To date, the vaccine has been well tolerated overall and showed minimal toxicity. Grade 3 fatigue and Grade 3 neutropenia were recorded once each, in different patients who continued treatment. No symptomatic cardiac dysfunction was observed. Ab responses against dHER2, ICD and ECD were elicited. After 4 vaccinations, 2/12 patients in the 20-mcg and 9/14 in the 100-mcg cohort responded to the ECD. Results in the 500 mcg cohort are pending. The function of the anti-ECD antibodies will be assessed by inhibition of growth in vitro of breast-cancer cell lines and by analysis of the HER2 signaling pathways. Conclusions: The dHER2 vaccine appears to be safe in the small number of patients tested. Ab to the ECD and the ICD are induced in a dose-dependent manner, suggesting that the higher-dose vaccine may be required for future Phase II and III studies. Detailed data on antibody and T-cell responses will presented. No significant financial relationships to disclose.

A Novel Peptide Isolated from a Phage Display Peptide Library with Trastuzumab Can Mimic Antigen Epitope of HER-2

Trastuzumab, a humanized antibody to HER-2, has been shown to be effective in the treatment of breast cancer in which HER-2 overexpression and metastasis occurs. In our search for an effective mimic epitope of HER-2 binding with trastuzumab and to develop HER-2 peptide vaccine, we screened a phage display 12-mer peptide library with trastuzumab as the target. A mimetic peptide (mimotope) H98 (LLGPYELWELSH) that could specifically recognize trastuzumab was isolated. The DNA encoding peptide H98 was cloned and expressed as the fusion protein GST-H98 in Escherichia coli BL21. The purified GST-H98 could specifically bind to trastuzumab and block the binding of trastuzumab to HER-2 protein. Moreover, H98 could significantly block the function of trastuzumab inhibiting the growth of cancer cells. Mice that were immunized with GST-H98 made specific antibody to H98 as well as to HER-2. In addition, T-cell proliferation occurred in mice immunized with GST-H98. Although no sequence homology was found between H98 and HER-2, through the use of structure analysis we were able to determine that peptide H98 contributed to a conformational epitope of HER-2. Furthermore, we determined that the last two amino acids at the C terminus, and the third together with the fourth amino acid at the N terminus of peptide H98 are critical to the binding of H98 to trastuzumab. As a result, we conclude that peptide H98 has potential for being developed as a HER-2 vaccine for biotherapy of cancer with HER-2 overexpression.

Human ErbB-2 (Her-2) transgenic mice: a model system for testing Her-2 based vaccines.

Her-2 transgenic (Tg) mice were generated with wild-type human c-ErbB-2 (Her-2) under the whey acidic protein promoter. They are tolerant to Her-2 and appropriate for testing Her-2 vaccines. The expression of transmembrane ErbB-2 from the whey acidic protein-Her-2 cassette and its up-regulation by insulin and hydrocortisone was verified by in vitro transfection. The transgene cassette was microinjected into fertilized eggs from B6C3 (C3H x C57BL/6) females mated with B6C3 males. Transgene-positive mice were backcrossed onto C57BL/6 mice. Human ErbB-2 was expressed in the secretory mammary epithelia during pregnancy and lactation and expressed constitutively in the Bergman glia cells within the molecular layer of the cerebellum. Overt, neoplastic transformation was not detected in any tissue examined. Tolerance to Her-2 was demonstrated by inoculating mice with a syngenic tumor expressing high levels of human ErbB-2. Tumors grew exclusively in Her-2 Tg mice without inducing an Ab response, while the nontransgenic littermates remained tumor free for 10 mo and mounted a robust anti-ErbB-2 Ab response. When immunized five times with plasmid DNA encoding secErbB-2 and GM-CSF, respectively, approximately 33% of the Her-2 Tg mice rejected a lethal challenge of EL-4/E2 tumor cells, whereas all immunized littermates rejected the tumor. Therefore, Her-2 Tg mice express human ErbB-2 in the brain and mammary gland and demonstrated tolerance to ErbB-2 which was partially overcome by DNA vaccination. The breakable tolerance of Her-2 Tg mice resembles that in human and these mice are particularly suited for testing human ErbB-2 based vaccines.

Antitumor vaccination with HER-2-derived recombinant antigens.

Certain types of malignant tumors overexpress HER-2, a transmembrane glycoprotein of the class I receptor tyrosine kinase erbB family. To develop an effective HER-2 vaccine for the selective immunotherapy of these malignancies, we have genetically engineered fusion proteins containing portions of extra- and intracellular HER-2 domains. Activated dendritic cells (DC) cocultured with these novel antigens (Ag) could induce potent responses of Ag-specific T-cell lines in vitro and a protection against HER-2-expressing tumor in vivo. The protective capabilities of HER-2-derived fusion proteins correlated with the efficiency of their presentation to Ag-specific T-cell hybridomas. The most effective Ag contained GM-CSF, the presence of which facilitated their internalization by antigen-presenting cells (APC) in a receptor-mediated manner.

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.

Distinct responses to modified HER-2 vaccines in two different HER-2 transgenic mouse models lessons for the clinic

Distinct responses to modified HER-2 vaccines in two different HER-2 transgenic mouse models lessons for the clinic

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. Semin Oncol 29 (suppl 11):53-61. Copyright 2002, Elsevier Science (USA). All rights reserved.