Y. Sun et al., VACCINATION WITH IL-12 GENE-MODIFIED AUTOLOGOUS MELANOMA-CELLS - PRECLINICAL RESULTS AND A FIRST CLINICAL-PHASE-I STUDY, Gene therapy, 5(4), 1998, pp. 481-490
Citations number
40
Categorie Soggetti
Biothechnology & Applied Migrobiology","Genetics & Heredity",Biology,"Medicine, Research & Experimental
Cytokine gene transfer into tumor cells has been shown to mediate tumo
r regression and antimetastatic effects in several animal models via i
mmunomodulation. Therefore, clinical protocols have been developed to
treat cancer patients with cytokine gene-modified tumor cells, We inse
rted the genes coding for the p35 and p40 chain of interleukin-12 (IL-
12) in two independent eukaryotic expression vectors and transduced me
lanoma cells of 15 different primary tumor cultures with both plasmids
by a ballistic gene transfer approach. Secreted IL-12 demonstrated st
rong bioactivity by inducing interferon-gamma release from peripheral
blood lymphocytes upon coculture with cell culture supernatants after
IL-12 gene transfer which could at least partly be blocked by IL-12-sp
ecific antisera. Further enrichment of transduced tumor cells by magne
tic separation directly after gene transfer increased cytokine secreti
on from a mean of 119 pg in the unsorted to 507 pg IL-12 (24 h/10(6) c
ells) in the magnetically enriched cell fraction. Irradiation of these
cells led to a further elevation of secreted IL-12 (mean 987 pg). Ele
vated IL-12 levels were detected over 7 days after irradiation in vitr
o. In a subsequent first clinical phase I study six patients with meta
static melanoma were vaccinated with autologous, interleukin-12 gene-m
odified tumor cells. Melanoma cells were expanded in vitro from surgic
ally removed metastases, transduced by ballistic gene transfer, irradi
ated and were then injected subcutaneously (s.c.) at weekly intervals.
Clinically, there was no major toxicity except for mild fever. All pa
tients completed more than four s.c. vaccinations over 6 weeks and wer
e eligible for immunological evaluation. Post-vaccination, peripheral
mononuclear cells were found to contain an increased number of tumor-r
eactive proliferative as well as cytolytic cells as determined by a li
miting dilution analysis in two patients. Two patients developed DTH r
eactivity against autologous melanoma cells and one had a minor clinic
al response. Biopsies taken from that patient's metastases revealed a
heavy infiltration of CD4(+) and CD8(-) T lymphocytes. In conclusion,
vaccination induced immunological changes even in a group or advanced,
terminally ill patients. These changes can be interpreted as an incre
ased antitumor immune response.