As readers know I am less than enthusiastic about ZAP-70 as a surrogate for IGHV mutations. I came across this conversation on the web which I find interesting.
John C. Byrd, MD:
There is a lot of hype about other biomarkers that were being used as surrogates because IgVH gene mutation status was initially harder to obtain. However, that has changed, and now many good commercial and clinical labs at CLL centers are able to obtain these findings. Other tests, like the 70-kDa zeta-associated protein (ZAP-70), I find very challenging to use in my CLL practice. Patients will bring results from 3 different tests that have 3 different answers. The ZAP-70 is clearly a valuable test in the research setting, but for the purposes of translation into real practice, it has not been easily reproducible across different laboratories.
Jennifer R. Brown, MD, PhD:
I have that exact problem. Frequently, ZAP-70 may be the only prognostic test patients come in with. They have not had cytogenetic analysis by FISH, nor do they know the mutational status of IgVH. They may have put a lot of stock in their ZAP-70 result even though, as you note, it may not be interpretable.