I took Jerry to the ER Saturday. His O2 was going lower and lower, and his lung volume decreasing drastically. He has pneumonia--the doc is not sure if it is caused by the cancer or side effect of the Keytruda---I don't know if it really matters. The doc is still optimistic that the Keytruda is going to work---they are paid to be optimistic! I am a realist and I see the changes in him daily.