Recombinant fowlpox viruses encoding the anchor-modified gp100 melanoma antigen can generate antitumor immune responses in patients with metastatic melanoma.
OBJECTIVE
The purpose of this study was to evaluate the immunological responses and therapeutic effectiveness of immunization with fowlpox vaccines encoding the gp100 melanoma antigen in patients with metastatic melanoma.


METHODS
In three consecutive clinical trials, patients were immunized with recombinant fowlpox viruses encoding three different forms of the melanoma/melanocyte-associated antigen gp100: (a) the native, full-length gp100 molecule; (b) the gp100 molecule with two amino acids modified to increase binding to HLA-A*0201 molecules; and (c) a "minigene" construct encoding a single, modified epitope gp100:209-217(210M) targeted to the endoplasmic reticulum. The immunogenicity of these constructs was studied using peripheral blood mononuclear cells to measure epitope-specific release of IFN-gamma.


RESULTS
Reactivity against gp100 was not seen in any patient before receiving fowlpox immunization. Whereas just one of seven patients developed reactivity after receiving fowlpox encoding native gp100, 10 of 14 patients who received fowlpox encoding the anchor modified full-length gp100 exhibited reactivity against the native gp100 molecule, and 12 of 16 patients were successfully immunized after inoculation with the modified minigene construct (p2 = 0.02). There was no difference in the latter group between those randomized to vaccination by i.v. or i.m. routes. There was one partial cancer regression in the group of 46 patients receiving virus in the absence of interleukin (IL)-2. Once patients showed evidence of progressive disease, they were eligible for "cross-over" treatment to IL-2 alone or with the fowlpox virus. None of the 13 patients receiving the full-length or modified full-length forms of gp100 responded when receiving IL-2, whereas 6 of 12 patients who received the fowlpox containing the minigene construct and then received IL-2 showed objective cancer regressions, including three patients with complete regression.


CONCLUSIONS
These data underscore the importance of modifying anchor residues of nonmutated self-antigen peptides to generate cellular immune responses after immunization and support the further investigation of recombinant fowlpox viruses encoding modified epitopes administered in combination with IL-2.
Rosenberg
Steven A
SA
Center for Cancer Research, Surgery Branch, National Cancer Institute, NIH, Bethesda, Maryland 20892, USA. sar@mail.nih.gov
Yang
James C
JC
Schwartzentruber
Douglas J
DJ
Hwu
Patrick
P
Topalian
Suzanne L
SL
Sherry
Richard M
RM
Restifo
Nicholas P
NP
Wunderlich
John R
JR
Seipp
Claudia A
CA
Rogers-Freezer
Linda
L
Morton
Kathleen E
KE
Mavroukakis
Sharon A
SA
Gritz
Linda
L
Panicali
Dennis L
DL
White
Donald E
DE
D000328:Adult; D000368:Aged; D000951:Antigens, Neoplasm / Q000737:chemistry; D018414:CD8-Positive T-Lymphocytes / Q000378:metabolism; D019496:Cancer Vaccines; D045744:Cell Line, Tumor; D000939:Epitopes / Q000737:chemistry; D005260:Female; D005587:Fowlpox virus / Q000737:chemistry*; D015234:HLA-A Antigens / Q000235:genetics; D015789:HLA-A2 Antigen; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry; D007371:Interferon-gamma / Q000378:metabolism; D007376:Interleukin-2 / Q000378:metabolism; D008297:Male; D008545:Melanoma / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000378:metabolism; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000737:chemistry* / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D014612:Vaccines / Q000737:chemistry; D014616:Vaccinia virus / Q000378:metabolism; D058951:gp100 Melanoma Antigen
D000951:Antigens, Neoplasm; D019496:Cancer Vaccines; D000939:Epitopes; D015234:HLA-A Antigens; C435939:HLA-A*02:01 antigen; D015789:HLA-A2 Antigen; D007074:Immunoglobulin G; D007376:Interleukin-2; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; C548637:PMEL protein, human; D010455:Peptides; D014612:Vaccines; D058951:gp100 Melanoma Antigen; D007371:Interferon-gamma