Adjuvant immunization of HLA-A2-positive melanoma patients with a modified gp100 peptide induces peptide-specific CD8+ T-cell responses.
OBJECTIVE
To measure the CD8+ T-cell response to a melanoma peptide vaccine and to compare an every-2-weeks with an every-3-weeks vaccination schedule.


METHODS
Thirty HLA-A2-positive patients with resected stage I to III melanoma were randomly assigned to receive vaccinations every 2 weeks (13 vaccines) or every 3 weeks (nine vaccines) for 6 months. The synthetic, modified gp100 peptide, g209-2M, and a control peptide, HPV16 E7, were mixed in incomplete Freund's adjuvant and injected subcutaneously. Peripheral blood mononuclear cells obtained before and after vaccination by leukapheresis were analyzed using a fluorescence-based HLA/peptide-tetramer binding assay and cytokine flow cytometry.


RESULTS
Vaccination induced an increase in peptide-specific T cells in 28 of 29 patients. The median frequency of CD8+ T cells specific for the g209-2M peptide increased markedly from 0.02% before to 0.34% after vaccination (P <.0001). Eight patients (28%) exhibited peptide-specific CD8+ T-cell frequencies greater than 1%, including two patients with frequencies of 4.96% and 8.86%, respectively. Interferon alfa-2b-treated patients also had significant increases in tetramer-binding cells (P <.0001). No difference was observed between the every-2-weeks and the every-3-weeks vaccination schedules (P =.59).


CONCLUSIONS
Flow cytometric analysis of HLA/peptide-tetramer binding cells was a reliable means of quantifying the CD8+ T-cell response to peptide immunization. This assay may be suitable for use in future trials to optimize different vaccination strategies. Concurrent interferon treatment did not inhibit the development of a peptide-specific immune response and vaccination every 2 weeks, and every 3 weeks produced similar results.
Smith
John W
JW
Earle A. Chiles Research Institute, Robert W. Franz Cancer Research Center, Providence Portland Medical Center, 4805 NE Glisan St, 5F40, Portland, OR 97213-2967, USA. josmith@providence.org
Walker
Edwin B
EB
Fox
Bernard A
BA
Haley
Daniel
D
Wisner
Ketura P
KP
Doran
Teri
T
Fisher
Brenda
B
Justice
Lisa
L
Wood
William
W
Vetto
John
J
Maecker
Holden
H
Dols
Annemiek
A
Meijer
Sybren
S
Hu
Hong-Ming
HM
Romero
Pedro
P
Alvord
W Gregory
WG
Urba
Walter J
WJ
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D019496:Cancer Vaccines / Q000008:administration & dosage*; D005260:Female; D005434:Flow Cytometry; D005453:Fluorescence; D005620:Freund's Adjuvant / Q000008:administration & dosage; D015789:HLA-A2 Antigen / Q000032:analysis*; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D007937:Leukapheresis; D008297:Male; D008545:Melanoma / Q000276:immunology*; D008562:Membrane Glycoproteins / Q000008:administration & dosage* / Q000009:adverse effects; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000008:administration & dosage* / Q000009:adverse effects; D010455:Peptides; D010865:Pilot Projects; D012878:Skin Neoplasms / Q000276:immunology*; D016896:Treatment Outcome; D058951:gp100 Melanoma Antigen
D019496:Cancer Vaccines; D015789:HLA-A2 Antigen; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; C548637:PMEL protein, human; D010455:Peptides; C548638:g209-2M melanoma peptide; D058951:gp100 Melanoma Antigen; D007371:Interferon-gamma; D005620:Freund's Adjuvant