"There is continued interest in developing new therapies for melanoma patients with recurrent or distant metastatic disease at the time of diagnosis because there are no systemic therapies that can be relied upon to cure them. Patients with metastatic melanoma are at high risk for additional metastases and death," said Dr. Robert O. Dillman, executive medical and scientific director at the Hoag Cancer Center and lead investigator for the study.
For the study, 54 patients with regionally recurrent or distant metastatic melanoma were injected with a vaccine that included each patient's own immune cells (dendritic cells) and 500 micrograms of granulocyte-colony stimulating factor (GM-CSF), an immune stimulator, three times a week and then monthly for five months for a total of up to eight injections.
The researchers then obtained patient's dendritic cells from their peripheral blood, and mixed them with a cell culture of the patient's own melanoma cells that had been self-renewing and proliferating in the laboratory.
The patient-specific vaccine is designed to stimulate the patient's immune system to react against tumour stem cells or early progenitor cells that can create new depots of cancer throughout the body.
Data showed that the projected five-year survival rate was 54 percent at a median follow up of 4.5 years (range 2.4 to 7.4) for the 30 surviving patients.
The results were found to be superior to those observed following vaccination with irradiated tumour cells in 48 melanoma patients in a previous trial.
Eight patients in the dendritic cell vaccine study experienced remarkable long-term, progression-free survival after completing the vaccine therapy, even though they had widely metastatic disease and/or repeated appearance of new metastases despite various therapies.
The vaccine treatment was well tolerated, with most patients experiencing mild skin irritation and redness at the injection site.
"The one-year and projected five-year survival rates of 85% and 54%, respectively, are remarkable for melanoma patients with documented metastatic disease. This study is extremely encouraging and shows the potential these types of personalized cancer vaccines have for patients diagnosed with metastatic melanoma," said Dillman.
The study has been published in Cancer Biotherapy and Radiopharmaceuticals.