Cellular immunotherapy study of prostate cancer patients and resulting IgG responses to peptide epitopes predicted from prostate tumor-associated autoantigens - Abstract

The immunogenicity of a cellular immunotherapy using genetically modified vaccines to express α(1,3)galactosyl epitopes (αGal) was evaluated in advanced prostate cancer (PC) patients.

In this dose escalation phase I study, we report safety, feasibility, and immunologic data of an immunotherapy composed of 2 human PC cell lines engineered to express αGal epitopes (HyperAcute-Prostate, HAP, NewLink Genetics). Eight patients received up to 12 biweekly vaccinations with HAP. Enrolled patients (aged range, 53-85 y) had American Joint Committee on Cancer stage IV, any T, any N, M1, Eastern Cooperative Oncology Group PS≤ 2, at least 1 prior hormonal treatment and < 3 prior chemotherapies, adequate bone marrow and organ function, and albumin ≥3.0 g/dL. Serum IgG antibodies to synthetic peptides overexpressed in PC were determined by enzyme-linked immunosorbent assay. Results indicate that HAP immunotherapy induced humoral immune responses to autoantigens in 2 of 8 patients. These patients developed IgG antibody to multiple epitopes overexpressed in PC after immunization. These responding patients received higher doses of the immunotherapy suggesting a dose response. Two immunogenic proteins (prostate-specific membrane antigen, hepsin) belong to the extracellular molecules family participating in malignant cell invasion. Median overall survival for patients was 25.1 months with 1 patient surviving over 70 months with stable PSA and bone metastasis before expiring of other causes. Three of 8 patients showed PSA stabilization (>100 d). In conclusion, HAP immunotherapy induces IgG responses to epitopes from autoantigens overexpressed in PC suggesting dose-dependent effect. HAP represents a viable immunotherapy approach to induce immune responses against tumor cells and may provide clinical benefit with minimal toxicity.

Written by:
Hemstreet GP 3rd, Rossi GR, Pisarev VM, Enke CA, Helfner L, Hauke RJ, Tennant L, Ramsey WJ, Vahanian NN, Link CJ.   Are you the author?
Department of Urology, University of Nebraska Medical Center; Nebraska Cancer Specialists; Veterans Administration Hospital; Department of Surgery, College of Medicine, University of Nebraska Medical Center, Omaha, NE; Tumor Immunology Department; NewLink Genetics, Ames, IA; Research Center for Medical Genetics, Academy of Medical Sciences, Moscow, Russia.

Reference: J Immunother. 2013 Jan;36(1):57-65.
doi: 10.1097/CJI.0b013e3182780abc

PubMed Abstract
PMID: 23211622