A protein that evolved long before animals developed circulatory systems appears to influence whether cancer immunotherapy works, but only when tumors manufacture it themselves. The same protein circulating in the bloodstream showed no relationship to treatment response.
Researchers at Nagoya University in Japan report that complement C3, produced locally by cancer-associated fibroblasts inside tumors, restricts the infiltration of immunosuppressive myeloid cells and improves the effectiveness of anti-PD-1 immunotherapy. Liver-derived C3 traveling through the blood had little impact, according to the work published in Nature Communications.
