S86 Results from the first phase I clinical study of the novel Ii-Key/HER-2(776–790) hybrid peptide vaccine in patients with prostate cancer

3011 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 IFNγ-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 IFNγ 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. [Table: see text]

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Effect of immunization with the ii-key modified HER2/neu(776-790) (AE37) peptide vaccine on pre-existent immunity to PSA in HLA-A24+ prostate cancer patients: Association with increased AE37-specific immunologic responses.

Journal of Clinical Oncology ◽

10.1200/jco.2012.30.15_suppl.e15125 ◽

2012 ◽

Vol 30 (15_suppl) ◽

pp. e15125-e15125

Author(s):

Sonia A. Perez ◽

Eleftheria Anastasopoulou ◽

Efi Pappou ◽

Nikolaos Fragkiskos Pistamaltzian ◽

Eric von Hofe ◽

...

Keyword(s):

Prostate Cancer ◽

T Cells ◽

Phase I ◽

Cancer Patients ◽

Phase I Study ◽

Peptide Vaccine ◽

Therapeutic Vaccine ◽

Immunological Responses ◽

Her 2 ◽

Mhc Alleles

e15125 Background: In solid tumors such as prostate cancer, novel biomarkers are needed for assessing immunological responses and clinical efficacy. By using dextramers specific for PSA we have retrospectively analyzed CD8+ T cell frequencies in patients with HER-2/neu+ prostate cancer who had received the AE37 vaccine in a phase I study (Perez SA et al Clin. Cancer Res. 2010, 16:3495). AE37 binds to numerous MHC alleles (Perez SA et al Clin. Cancer Res. 2010, 16:3495) (Salazar LG, Clin Cancer Res. 2003, 9:5559) encouraging its use as a therapeutic vaccine for general HER-2/neu+ cancer patients. Methods: CD8+ Dextramer+ T cells were measured, retrospectively, in the blood (which was stored in N2 liquid) of HLA-A24+ (n= 12) and HLA-A2+ (n=12) patients. Blood lymphocytes collected before, during and 6-months post vaccination were all analyzed with the same method involving direct labeling with HLA A24/PSA(153-161)-FITC and PerCP-conjugated anti-CD8 monoclonal antibody. Results: 8 of 12 HLA-A24+ patients had preexistent immunity to PSA as evidenced by the increased percentages of CD8+ HLA-A24/PSA(153-161)+ T cells in pre-vaccination samples. All of these patients had shown increased in vitro (IFNγ-based ELISPOT assay) and in vivo (DTH) immunological responses to the AE37 vaccine in the phase I study (Perez SA et al Clin. Cancer Res. 2010, 16:3495). Importantly, this preexistent immunity was significantly boosted in 5 patients during vaccinations with AE37, was slightly increased in 2 others, whereas in one patient no changes were observed during vaccinations. Conclusions: These results suggest that HLA-A24 expression along with preexistent immunity to PSA(153-164) may represent biomarkers based on which HER-2/neu+ patients can be selected most likely to benefit from vaccination with AE37. A phase II trial is warranted for validating these results. Given the promiscuity of AE37, it would be intriguing to examine if preexistent immunity to other prostate antigens restricted by various MHC alleles exist and to demonstrate an increase in preexistent immunity in association with a positive immunologic response to vaccination with AE37.

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