Monocytes were cultured in the presence of interleukin (IL)-4 (500 U/mL) granulocyte- macrophage colony-stimulating factor (800 U/mL) and control antigen keyhole limpet hemocyanin (10 mg/mL). Dendritic cells were matured with autologous monocyte-conditioned medium (30%, v/v) supplemented with prostaglandin E2 (10 mg/mL) and 10 ng/mL tumor necrosis factor-α for 48 hours. Plasmacytoid dendritic cells and myeloid dendritic cells were isolated directly from leukapheresis products using the fully closed immunomagnetic CliniMACS isolation system. Plasmacytoid and myeloid dendritic cells were cultured overnight at a concentration of 106 cells/mL in X-VIVO-15 containing 2% pooled human serum supplemented with 10 ng/mL recombinant human IL-3 (plasmacytoid dendritic cells) or 800 U/mL granulocyte- macrophage colony-stimulating factor and 10 μg/mL control antigen (myeloid dendritic cells). The plasmacytoid dendritic cells were activated subsequently for 6 hours by addition of FSME- IMMUN (1:10 v/v).
Dendritic cells were pulsed with the human leukocyte antigen (HLA) class I gp100-derived peptides, and the tyrosinase-derived peptide tyrosinase. In one protocol, dendritic cells from HLA-DRB*01:04–positive patients also were pulsed with HLA-DRB*01:04–binding peptides of both gp100 and tyrosinase. In protocols IV, V, and VIII, mature dendritic cells were electroporated with mRNA encoding gp100 or tyrosinase and cells were resuspended in 0.1 mL for injection.
All patients were vaccinated with autologous dendritic cells loaded with tumor-associated antigens of gp100 and tyrosinase according to a schedule of 3 biweekly vaccinations. In absence of disease progression, patients received a maximum of 2 maintenance cycles at 6-month intervals.
Peripheral blood mononuclear cells collected after each vaccination were analyzed for the presence of control antigen-specific T cells. Almost all patients (12 of 14) showed a cellular response to control antigen in the first cycle. In 7 of 13 patients tested, control antigen-specific IgG antibodies were detected after vaccination. These results indicate that the vaccine induced de novo immune responses.
All patients received at least 3 vaccinations (1 cycle), and 1 patient did not have a skin test because of rapid progressive disease. Ten patients showed stable disease at the first evaluation point, 3 months after start of vaccination, but 7 patients progressed before a second cycle was started after 6 months according to protocol. One patient received a second cycle of vaccinations, and 2 patients received all 3 vaccination cycles and had stable disease up to 28 months. Seven (50%) patients survived more than 2 years after start of dendritic cell vaccination for metastatic uveal melanoma. Thus far, 12 patients have died of melanoma-related disease and 2 patients are still alive with metastases. Patients showed a median overall survival of 29 months for M1a, 22.5 months for M1b, and 6 months for M1c.
No severe toxicity (grade 3 or 4) occurred. The vaccine-related side effects observed in the vaccinated patients were grade 1 fatigue (5 patients), flu-like symptoms (8 patients), and erythema at the intradermal injection site (6 patients).
This data show that dendritic cell vaccination is feasible and safe in metastatic uveal melanoma. Our data suggest the potential of dendritic cell-based immunotherapy to enhance the host’s antitumor immunity and that it may be associated with longer than average overall survival times in metastatic uveal melanoma.
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Scientific article publishing date : 7/14/2017
Immucura identifier :BSC21_158EN