My husband has WM and finished a 6 month course of bendeka/rituxin in November. His IgM was down to 515 and was put on Ibrutinib 2 capsules a day for 1 week, the upped to 3, with a final goal of 4 per day. He did ok on 2 pills but 3 pills gave him horrible diarrhea, constipation and agitated his diverticulosis, so the on-call doctor told him to stop taking the drug. He probably took 17-20 capsules total and then quit cold turkey, never to return because our new oncologist told him his numbers were good (now 325) and he doesn't need the ibrutinub. Since he quit taking the drug he has had excessive chills followed by fevers that range from 100-102, and then profuse sweating. After that he is completely wiped out to where he cant get out of his chair without help. This doesn't happen to the extreme every day, probably 2-3 days a week and milder on the other days. The odd part is that it begins around the same time every day, between 1:00-3:00 PM and can last up to 6 hours before it's all done - except for the sweats, they sometimes linger throughout the night with tshirt changes 2-3 times. And then he is perfectly fine in the mornings. Our new oncologist has ordered a PET scan to make sure the cancer hasn't spread and feels this is not an infection due to the fact that the fever / chills aren't constant throughout the day. I've been reading some articles online that suggest these could be withdrawal symptoms from stopping the Imbruvica. Has anyone else experienced this, and if so please elaborate on what happens to you.