PARIS--Nearly 90% of patients with resected Dukes B and C colorectal carcinoma were still alive 3 years after active specific immunization with a new autologous tumor vaccine, researchers from the German Cancer Research Center, Heidelberg, and the University Hospital, Mannheim, Germany, have found.
V. Schirrmacher, PhD, of the Heidelberg center, presented the findings at the Eighth Annual European Cancer Conference (ECCO-8).
To prepare the colorectal cancer vaccine, purified and inactivated cells from the patient's own tumor are incubated with the Newcastle Disease Virus (NDV), a chicken virus with unique antitumor and immune-stimulating properties.
The virus binds almost immediately to the cancer cells and begins replicating within 4 hours, Dr. Schirrmacher said. Transfection of the tumor cells with the virus bolsters their antigen-presenting capacity so that, after inoculation, the patient's immune response is mobilized against his or her own cancer cells.
Noting that immune reactivity, as reflected by delayed hypersensitivity skin reactions, increases after each successive inoculation, he suggested that the strength of this reaction may forecast a more favorable clinical outcome.
After charting the clinical course of 48 patients who received three doses of the NDV vaccine at 2-week intervals, starting 6 to 8 weeks after surgery, the Heidelberg-Mannheim team documented survival rates of 98% at 2 years and 88% at 3 years. Three-year overall survival was 86% in patients with Dukes B colon cancer, 88% in Dukes C colon cancer, 93% in Dukes B rectal cancer, and 88% in Dukes C rectal cancer.
In comparison, Dr. Schirrmacher said, 2-year survival was 74% in a historical control group of more than 600 patients treated with surgery alone, and only 67% in nine patients who received an experimental vaccine made with BCG (Bacillus Calmette Guerin). Side effects of the NDV vaccine were limited to induration and erythema at the inoculation site, in contrast to the persistent ulceration observed after injection of the BCG vaccine.