Itching, or flushing. these are not all the possible side effects. tell your doctor about all your medical conditions, including immune system problems, or if you've had an organ transplant, had or plan to have a stem cell transplant, or have had radiation to your chest area or a nervous system condition. today, keytruda is fda-approved to treat 16 types of advanced cancer, and is being studied in hundreds of clinical trials exploring ways to treat even more types of cancer. it's tru. keytruda from merck. see the different types of cancer keytruda is approved to treat at keytruda.com, and ask ...