Keytruda (Pembrolizumab) and Opdivo (Nivolumab) have shown excellent responses in melanoma and a certain type of non-small cell lung cancer however; 80% of all cancer patients do not benefit at all.
Researchers determined that excellent responders harbor large numbers of mutated genes, called neoantigens. Neoantigen are closely related to antigens, which in turn cause the body do recognize a substance and then produce antibodies.
http://www.cancer.gov/research/areas/treatment/immunotherapy-using-immune-system
Read up on immunologist Jim Allison and his theory on immunotherapy:
https://www.statnews.com/2015/11/14/jim-allison-cancer-immune-therapy/
and further literature in the Journal of Clinical & Cellular Immunology
http://www.omicsonline.org/open-access/cancer-neoantigens-a-promising-source-of-immunogens-for-cancer-immunotherapy-2155-9899-1000322.php?aid=52360
Targeted Cancer therapy works differently. The purpose of targeted therapy is to identify a particular molecular fault harbored in a person’s tumor. Targeted drugs block tumor cells from rapidly increasing by interfering in growth and survival of cancerous cells.
You may read up more:
http://www.cancer.gov/about-cancer/treatment/types/targeted-therapies/targeted-therapies-fact-sheet
Marion