because of similar drugs david gobin has seen his lung cancer disappear. >> i can do a lot of things i couldn't before. >> reporter: and ken kirkwood's kidney cancer is gone. many researchers believe this is the beginning of one of the most promising eras ever in cancer research. treating, even curing significant numbers of patients in an entirely new way. many similar experimental drugs are being tested and other combinations could work better. the drugs have side effects and will be very expensive there is no doubt they will save many lives. robert bazell, nbc news, new york. >>> when we come back another all american day for a prince. >>> it's going to be closed a long time but at least they have completed the scaffolding all the way to the top of the washington monument. we got a special and not for the faint of heart helmetcam view of the topping off today, 500 feet above the earth. this is all because of the damage from the freak 2011 earthquake. now begins the biggest caulking job in modern history as so many chip, gaps and stress cracks have to be repaired. it is the tallest