Waldenstroms - reduced dosage Ibrutinib

[dbro1951]

My wife has WM. IGM 2200 - 18 months of Ibrutinib @ 420 per day IGM drops to 145.

All ok until Bilirubin abnormal 6 months ago.

Changed dosage to 280. Bilirubin now normal. All other blood work normal but IGM started to increase now @250.

My question is this. Does this rise in IGM suggest a new normal due to reduced dosage?

Or does this suggest that IBrutinib no longer effective?