Abstract LB-218: Immune response assessment in a phase II trial of AE37 HER2 peptide vaccine

• Published in: Cancer research (Chicago, Ill.) Ill.), 2012-04, Vol.72 (8_Supplement), p.LB-218-LB-218
• Main Authors: Hale, Diane F., Vreeland, Timothy J., Dabney, Raetasha S., Clifton, G Travis, Sears, Alan K., Pappou, Efi, Anastasopoulou, Eleftheria, Ardavanis, Alexandros, Ponniah, Sathibalan, Papamichail, Michael, Perez, Sonia, Shumway, Nathan, Peoples, George E., Mittendorf, Elizabeth
• Format: Article
• Language: English
• ISSN: 0008-5472; 1538-7445
• DOI: 10.1158/1538-7445.AM2012-LB-218

Introduction: AE37 is the Ii-Key hybrid of the HER2 derived peptide AE36 (776-790). A phase I trial administering AE37 with the immunoadjuvant GMCSF demonstrated the vaccine to be safe and capable of stimulating CD4+helper T cells with HER2 specific anti-tumor activity. Here we present an analysis of our immunologic testing of our prospective, randomized, single-blinded, phase II trial of the AE37+GMCSF vs. GMCSF alone for the prevention of breast cancer recurrence. Methods: After completion of indicated standard therapy; disease-free, node positive or high risk node negative breast cancer patients were randomized to receive either AE37+GMCSF (VG) or GMCSF (CG) in 6 monthly intradermal inoculations. Patients were enrolled with any level of HER2 expression (IHC 1+ 2+ or 3+). Specific immunologic responses to both AE36 and AE37 were evaluated. In vitro responses were measured using [3H]-thymidine incorporation assay and in vivo responses using delayed-type hypersensitivity (DTH) reactions. T regulatory cells (Tregs) were measured throughout vaccination series. Data was analyzed using Pearson chi-squared tests. Results: To date 217 patients have enrolled (VG=109, CG=108). HER2 over-expression was present in 54 (49.5%) VG and 51 (47.2%) CG, p=0.783. VG had 59 (51.4%) ER positive and CG had 58 (53.7%, p=0.985). The in vitro proliferation responses with a stimulation index (SI) ≥2 were classified as high responders VG 36 (33.0%) vs CG 8 (7.4%, p