Alan K. Sears

Clinical trial results of the HER-2/neu (E75) vaccine to prevent breast cancer recurrence in high-risk patients: from US Military Cancer Institute Clinical Trials Group Study I-01 and I-02.

The authors conducted exploratory phase 1‐2 clinical trials vaccinating breast cancer patients with E75, a human leukocyte antigen (HLA) A2/A3–restricted HER‐2/neu (HER2) peptide, and granulocyte‐macrophage colony‐stimulating factor. The vaccine is given as adjuvant therapy to prevent disease recurrence. They previously reported that the vaccine is safe and effective in stimulating expansion of E75‐specific cytotoxic T cells. Here, they report 24‐month landmark analyses of disease‐free survival (DFS).

AE37: a novel T-cell-eliciting vaccine for breast cancer

Introduction: Immunotherapy, including vaccines targeting the human EGFR2 (HER-2/neu) protein, is an active area of investigation in combatting breast cancer. Several vaccines are currently undergoing clinical trials, most of which are CD8+ T-cell-eliciting vaccines. AE37 is a promising primarily CD4+ T-cell-eliciting HER-2/neu breast cancer vaccine currently in clinical trials. Areas covered: This article reviews preclinical investigations as well as findings from completed and ongoing Phase I and Phase II clinical trials of the AE37 vaccine. Expert opinion: Clinical trials have shown the AE37 vaccine to be safe and capable of generating peptide-specific, durable immune responses. This has been shown in patients with any level of HER-2/neu expression. Early clinical findings suggest there may be benefit to AE37 vaccination in preventing breast cancer recurrence.

Comparison of different HER2/neu vaccines in adjuvant breast cancer trials: implications for dosing of peptide vaccines

We have performed multiple adjuvant clinical trials using immunogenic peptides from the HER2/neu protein (AE37/E75/GP2) plus (GM-CSF) given intradermally to breast cancer patients. Four trials were performed with similar dose-escalation design with increasing doses of peptide (AE37/E75/GP2) and varying amounts of GM-CSF. Dose reductions (DRs) were made for significant local and/or systemic toxicity by decreasing GM-CSF for subsequent inoculations. Ex vivo and in vivo immunologic responses were used to compare groups. Of 132 patients, 39 required DR (30 for robust local reactions [DR-L]). DR patients, particularly DR-L, had greater immune responses both ex vivo and in vivo. Postvaccine delayed-type hypersensitivity in DR-L patients compared with all others was larger for E75 (p = 0.001), AE37 (p = 0.077) and GP2 (p = 0.076). All three peptide vaccines were safe and well-tolerated. These findings have led to a clinically relevant optimal vaccine dosing strategy, which may be applicable to other peptide-based cancer vaccines.

Cancer vaccines: should we be targeting patients with less aggressive disease?

There is enthusiasm for using vaccines to stimulate the immune system to treat cancer. In this article, the authors review the evolution of vaccines evaluated in clinical trials, starting with Phase III trials in metastatic disease and progressing to trials in the adjuvant setting. Data from these trials suggest that cancer vaccines may be more effective in patients with lower volume disease, and data from the E75 peptide vaccine trials suggest that vaccines may be most effective in less aggressive disease.

Circulating regulatory T cells (CD4+CD25+FOXP3+) decrease in breast cancer patients after vaccination with a modified MHC class II HER2/neu (AE37) peptide.

Regulatory T cells (T(Reg)), CD4(+)CD25(+)FOXP3(+), are implicated in suppressing tumor immune responses. We analyzed peripheral blood lymphocytes (PBL) from breast cancer patients receiving a modified HLA class II HER2/neu peptide (AE37) vaccine for T(Reg) cells and correlated their levels with vaccine-specific immune responses. The mean CD4(+)CD25(+)FOXP3(+) T(Reg) cells decreased in patients with vaccination with no significant difference in serum TGF-β levels. IFN-γ ELISPOT and DTH increased after vaccination with a good correlation between T(Reg) cell reduction and size of DTH to AE37. The T(Reg) cell reduction and associated immune response suggest that AE37 may be clinically useful.

Folate receptor α: A storied past and promising future in immunotherapy

Folate receptor alpha (FR α) is a membrane-bound transport protein with several features which make it an attractive target for cancer immunotherapy. FR α is largely shielded from the immune system in normal tissue but exposed while expressed on a variety of malignancies; it is functionally active in cancer pathogenesis; and it is immunogenic. A variety of different immunotherapeutic methods targeting FR α are being explored to treat cancer. Passive immunotherapy includes monoclonal antibodies, antibodies modified to deliver treatments, and modified T cell therapy. Active immunotherapy has focused on using FR α to increase the immunogenicity of cancer or to generate active FR α-directed immunity through a range of vaccination techniques. We will review the rationale behind targeting immunotherapy to FR α and cover the various techniques designed to do this.

Early efficacy analysis of the AE37 vaccine in patients with HER2 low-expressing and triple-negative breast cancer.

109 Background: Peptide vaccines comprised of HLA class II epitopes, which elicit CD4+ T cell responses, play a critical role in potentiating immune responses. We are conducting a randomized phase II trial of AE37, a hybrid peptide created by the addition of the Ii-Key moiety (LRMK) to the HER2 helper epitope, AE36 (HER2 aa776-790). Here, we present efficacy data focusing on outcomes in patients with low HER2 (IHC 1+ or 2+) expression and triple negative breast cancer (TNBC). METHODS The trial is enrolling node positive or high risk node negative breast cancer patients with any degree of HER2 expression (IHC 1+, 2+ or 3+ or FISH > 1.2) rendered disease-free following standard of care therapy. Patients are randomized to receive either AE37+GM-CSF or GM-CSF alone in 6 monthly intradermal inoculations followed by booster inoculations administered every 6 months. RESULTS The trial has enrolled 254 patients; 105 in the vaccine group (VG) and 149 in the control group (CG). After a median follow-up of 22.3 months, the disease-free survival (DFS) rate in the VG is 90.3% vs 81.1% in the CG (p=.46), a 49% risk reduction. Evaluating patients with low HER2 expression (IHC 1+ or 2+), there are 53 VG patients and 77 CG patients. The groups are well-matched with respect to the percentage of patients with high grade tumors, tumors > 2cm, the rate of node positivity and ER/PR status (all p>.5). The DFS rate in the VG of low HER2 expressers is 89.8% vs 68.2% in the CG (p=.12), a 68% risk reduction. When limiting analyses to patients with TNBC (ER/PR negative, HER2 1+ or 2+), there are 13 VG patients and 23 CG patients. The groups are again well-matched with the exception of control patients having a larger percentage of tumors > 2 cm (70% vs 31%; p=.02). The DFS rate in the VG of TNBC patients is 83.3% vs 47.6% in the CG (p=.23), a 68% risk reduction. CONCLUSIONS Early analyses suggest clinical benefit to vaccination with AE37, particularly in patients with low HER2-expressing tumors. Importantly, the benefit appears to persist in TNBC patients. Patients will continue to be followed per protocol for 5 years; however, these data suggest that a subsequent phase III trial should evaluate the vaccine in patients with low HER2-expressing disease to include TNBC.

Abstract P5-16-02: Final Results of the Phase I/II Trials of the E75 Adjuvant Breast Cancer Vaccine

Background: We have completed phase I/II clinical trials vaccinating breast cancer patients (pts) with E75, a HLA-A2/A3-restricted HER2/neu (HER2) peptide vaccine. The vaccine was administered in the adjuvant setting to prevent recurrences in high risk patients rendered disease-free with standard of care therapy. We have previously reported preliminary results indicating that the vaccine (including booster inoculations) is safe and effective in stimulating an anti-tumor immune response. Here, we report the final 5 year results from these trials. Methods: The phase I/II trials were performed as dose-escalation/schedule-optimization trials enrolling node positive and high-risk, node negative breast cancer patients with tumors expressing any level of HER2. HLA-A2/A3+ pts were enrolled into the vaccine group (VG) while HLA-A2/A3- pts were followed prospectively as the untreated control group (CG). The VG pts were given 4–6 monthly intradermal inoculations of E75 with GM-CSF during the primary vaccine series (PVS). In addition, a voluntary booster program was initiated during the trial, with booster inoculations being offered every 6 months after completion of the PVS. Patients were monitored for local and systemic toxicity (graded by NCI Common Terminology Criteria for Adverse Events). In vivo immune response was assessed in the VG by delayed type hypersensitivity (DTH) reactions to both E75 and saline, pre- and post-PVS. VG and CG pts were followed for 60 months (mo) and recurrences were documented. Demographic differences were compared with the Fisher9s exact test and disease-free survival was determined using the Kaplan-Meier method and compared by log-rank test. Results: 195 pts were enrolled, 6 withdrew (2 from VG, 4 from CG), 1 was lost to follow-up prior to vaccination, and 1 was found to be ineligible, leaving 187 evaluable pts; 108 in the VG and 79 in the CG. 53 pts volunteered for the booster program and received at least one booster inoculation. The VG and CG were well-matched with the only statistically significant difference being ER−/PR- status (31.1% in VG vs 17.7% in CG, p = 0.04). Vaccination was well tolerated (maximum local toxicity: 73.1% Grade 1, 26.9% Grade 2, 0% Grade 3; maximum systemic toxicity: 72.2% Grade 1, 15.7% Grade 2, and 2.8% Grade 3). In the VG, pre- to post-PVS E75 DTH significantly increased (mean 3.8 ±1.0 vs 14.8±1.4, p Conclusions: The E75 breast cancer vaccine is safe and well–tolerated. It elicits strong immune responses in vaccinated patients. At the end of the 5 year follow-up period, the E75 vaccine shows a strong trend toward preventing breast cancer recurrence in vaccinated patients. To investigate this vaccine (now known as NeuVax) further, the PRESENT trial, a prospective, randomized, double-blind, placebo-controlled, multi-center phase III registration trial has been initiated and is actively enrolling. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-16-02.

Vaccine-specific T-cell proliferation in response to a dual peptide cancer vaccine in breast and ovarian cancer patients

Meeting abstracts HER2 is a commonly expressed tumor-associated antigen in breast (BrCa) and, therefore, an attractive target for immunotherapy. We have investigated HER2-derived peptides as vaccines mixed with GM-CSF to include GP2 (a HLA-A2 and HLA-A3 restricted, CD8+ eliciting epitope) and AE37

P1-13-02: Long-Term Clinical Benefit of Adjuvant Breast Cancer Vaccine: 5 Year Efficacy of E75 with Multiple Booster Inoculations.

Background: We are conducting phase I/II clinical trials vaccinating breast cancer patients with E75, an HLA-A2/A3 restricted HER2/neu (HER2) peptide mixed with GM-CSF. The vaccine has been studied in the adjuvant setting to prevent recurrences in clinically disease-free patients after completion of standard therapy. We have previously reported that the vaccine is safe, effectively stimulates HER2−specific immunity, and appears to improve disease-free survival at 24 months. Here, we report long-term data at a median follow-up of 60 months. Methods: The phase I/II trials were performed as dose escalation/schedule optimization trials enrolling node positive and high-risk, node-negative patients with tumors expressing any level of HER2. Vaccinated patients were given 4–6 monthly inoculations of E75 with GM-CSF immunoadjuvant. Due to waning immunity, a voluntary booster program was initiated, with inoculations every 6 months after completion of the primary vaccine series (PVS). Patients were monitored for local and systemic toxicities, which were graded by the NCI9s Common Terminology Criteria for Adverse Events. Vaccinated patients and controls were followed for 60 months and recurrences were documented. Demographic differences were compared with the Fisher9s exact test and survival was analyzed by the log-rank test. Results: 187 patients were enrolled; 108 in the vaccine group (VG) and 79 in the unvaccinated control group (CG). The vaccine and control groups were well-matched with the only statistically significant difference being ER-/PR- status (31.1% in VG vs 17.7% in CG, p=0.04). Vaccination was well tolerated with primarily grade 1 and grade 2 toxicity in the PVS (Local Toxicity: 85% Grade 1, 15% Grade 2, 0% Grade 3; systemic toxicity: 71% Grade 1, 14% Grade 2, and 3% Grade 3). Fifty-three of the VG patients received at least one booster, with 34 receiving a second booster, 25 a third, 22 a fourth, 12 a fifth, and 9 receiving at least six boosters. Booster inoculations were well-tolerated with only grade 1 and 2 local and systemic toxicities. There were delayed urticarial reactions in 7/53(13%) of the boosted patients occurring at a median of 9 days (5-21 days) after inoculation; these were grade 2 reactions and well-tolerated. After a median follow-up of 60 months, there has been a nonsignificant decrease in recurrences observed in the VG compared to the CG (10.6% vs 20.3%, p=0.098). The hazard ratio is 0.52 in the VG. In patients with immunity maintained with voluntary boosters, there have been even fewer (3.8%) recurrences (p=0.03). Conclusions: The E75 breast cancer vaccine is safe and well-tolerated. With long-term follow-up at 60 months, the E75 vaccine continues to show a strong trend toward preventing breast cancer recurrence in vaccinated patients particularly in patients whose immunity is maintained with booster inoculations. To investigate this further, a phase III trial with prospective boosting is being initiated. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-13-02.