Results of the first phase I clinical trial of the novel Ii-key hybrid preventive HER2/neu peptide (AE37) vaccine: United States Military Cancer Institute Clinical Trials Group Study I-03

3016 Background: HER2/neu is overexpressed in breast cancer (BCa) and is the source of immunogenic peptides. CD4+ T helper peptides for HER2/neu are being evaluated in vaccine trials. The addition of Ii-Key, a 4-amino-acid LRMK modification, increases vaccine potency when compared to unmodified class II epitopes. We present the results of the first human Phase I trial of the Ii-Key hybrid HER2/neu peptide (AE37) vaccine in disease-free, node-negative BCa patients. Methods: The dose-escalation trial included 5 dose groups, to determine safety and optimal dose of the hybrid peptide (100mcg; 500 mcg; 1,000mcg) and GM-CSF (range 0–250mcg). In the event of significant toxicity, GM-CSF (or peptide in the absence of GM-CSF) was reduced by 50%. Immunologic response was monitored by DTH and 3H-thymidine proliferative assays for both the hybrid AE37 (LRMK + HER2/neu:776–790) and AE36 (unmodified HER2/neu:776–790). Results: All 15 patients completed the trial with no grade 3–5 local or systemic toxicities. Dose redu...