@dutchw– Good morning and Welcome to Mayo Clinic Connect. Thank you for sharing your story. I am a mentor for Mayo Connect's Lung Cancer and Lung Diseases. I have an unusual lung cancer called Multifocal Adenocarcinoma. I have survived two types of lung cancer for 23+ years and have never had immunotherapy, although I have had chemotherapy. I am sorry if I have given the impression that I have taken this wonderful drug.
@miriam57; @richcolleen– I have found that many people who have finished their two years on Keytruda are followed very closely with CT scans. I am at a loss to tell you that there are other drugs right now that will maintain you. Keytruda is "Humanized antibodies" This means that they are antibodies from non-human species whose protein sequences have been modified to increase their similarity to antibody variants produced naturally in humans. I certainly hope that the positive outcomes for many people who have taken this drug will see many more and maybe even a possibility for a maintenance program. I just don't know of any at this time.
The developers for Keytruda limited the study to two years. There was a lot of competition between several drug makers for the success of such a drug. You can read more of this here: https://en.wikipedia.org/wiki/Pembrolizumab
The reason that I am suggesting that you read Wikipedia about your drug is so that you can see why there was a 2-year limit.