Immune cells targeting just two cancer-related proteins in melanoma cells largely shrunk the tumors and kept the melanoma at bay for more than 36 weeks post-injection.

As explained by researchers from Germany’s University of Cologne, current cancer-therapy regimens attempt to eliminate all malignant cells of a tumor lesion. This goal is based on an assumption that all cancer cells have equal malignant capacities. To show that selective elimination of a definite, minor tumor cell subpopulation can effectively combat melanoma lesions—which often produce tumors that contain generically diverse types of cells—the researchers targeted a tumor cell subset in human melanomas grafted into mice.

Although the two targeted proteins decorate the surfaces of fewer than 2% of melanoma cells in typical lesions, the immunotherapy strategy “lastingly eradicated melanoma lesions, whereas targeting of any random 10% tumor cell subset was not effective,” noted the investigators in Proceedings of the National Academy of Sciences (2011;108[6]:2474-2479). “Our data challenge the biological therapy and current drug development paradigms in the treatment of cancer.”