Results from the first phase I clinical study of the novel Ii-Key/HER2/neu(776–790) hybrid peptide vaccine in patients with prostate cancer S. A. Perez, S. Bisias, N. L. Kallinteris, A. Ardavanis, K. G. Georgakopoulou, N. Apostolikas, A. Thanos, M. Papamichail, E. von Hofe and C. N. Baxevanis Saint Savas Cancer Hospital, Athens, Greece; Antigen Express, Inc., Worcester, MA
Background: HER-2/neu(776–790) represents an immunogenic epitope from the HER-2/neu oncoprotein whose immunogenicity is highly potentiated upon linkage with the Ii-Key moiety (LRMK) from the MHC class II invariant chain. Herein, we present the results of the first phase I clinical trial of the Ii-Key/HER-2/neu(776–790) (AE37) vaccine in patients (pts) with prostate cancer.
Methods: Androgen-dependent (AD) and androgen-independent (AI) pts with HER-2/neu+ (IHC: 1–3) prostate adenocarcinomas were eligible. Concomitant medication with bicatulamide and LHRH or docitaxel was allowed. All pts received 6 monthly vaccinations with the AE37 vaccine (500 µg of AE37 plus 125 µg of GM-CSF) administered in two doses intradermally 5cm apart in the same extremity for each vaccination cycle. Immunologic responses were measured monthly in vitro by the IFN-based ELISPOT assay using pts’ PBMC and in vivo at the beginning and end of immunizations using DTH. Local dermal reactions were also measured after each vaccination.
Results: Eligible pts [AD (n=18), AI (n=10)] were at stages T1–3N0M0, GS: 3–7 (n=18); T1–3N+M0, GS: 6–7 (n=2); T1–3N0M+, GS: 6–9 (n=4) and T1–3N+M+, GS: 6–9 (n=4). All pts had standard treatment prior to vaccinations, including surgery (S) (n=9); hormonal treatment (HT) (n=4); S+HT (n=6); S+HT+radiotherapy (RT); (n=2); S+chemotherapy (CH) (n=2); HT+RT (n=2); CH (n=3) and S+HT+CH (n=2). During vaccinations, 11 pts were free of any treatment, while 5 pts who had progressive disease received additional chemotherapy; the remainder received HT alone or combined with RT. 25 pts completed all vaccinations. Toxicity and side effects beyond grade-2 were not observed. GM-CSF was reduced by 50% for subsequent vaccinations when a local reaction of 100mm or greater was observed. DTH reactions to the parent HER-2/neu(776–790) peptide were increased (compared to pre-vaccination) for all pts, while approximately half the pts responded with significantly increased IFN responses to AE37 and/or parent HER-2/neu(776–790) peptide in at least 2 sequential vaccination cycles.
Conclusions: <<<<<The AE37 vaccine is safe and well tolerated. AE37 is also capable of eliciting potent and specific immunologic responses in prostate cancer pts.>>>>>
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