Ask the Lab Scientist Q3 2020: MRD Edition

MRD-specific questions submitted by readers and answered by the CLL Society Medical Advisory Board

Remember that we cannot give medical advice and any suggestions should be reviewed with your treating doctors.

By Susan Leclair, PhD, CLS (NCA)

Would you kindly help me understand an MRD test report?  It was for MRD 1 per 10,000
and I am confused because I was naively seeking a readout of a simple number per 10,000. 

Test B-Cell Clonality
Result: Detected
Comments:
Dominate Clone V3-30, MUTATED
% of Dominate Clone: 73.85%
Dominate Clone Mutation Rate: 9.8%
Kappa Clonality: DETECTED
% of Kappa Clone Detected: 81.9%
Additional VH family (Minor Clone) NA
% of Minor Clone: NA
Minor Clone Mutation Rate: NA

I do understand the Clinical Significance comments and the PCR methodology explanation.  This was my first MRD test and I requested it because things were looking so positive: my trisomy 12 which two years ago was found in 84% of cells analyzed was down to zero, deletions of DLEU1, DLEU2 on the long arm of chromosome 13 at q14 (9.0% of cells) and homozygous deletion of DLEU, DLEU2 on the long arm of chromosome 13 at q14 (5.5% of cells) were all also down to zero.  My ALC and WBC and other blood counts were now in the normal range and I was excited.  After 16 months of Ibrutinib treatment followed by Venetoclax treatment, I wanted a gauge.  I just am not able to figure out from this report how close or how far from 1 in 10,000 I was.

 

Here is the answer from lab scientist, Dr. Susan Leclair:

You are not in a molecular remission because there are clonal cells present.  Of those clonal cells, 3 out of 4 contain V3-30 mutation.

Most of these cells (81.9% of the 73.85% that are mutated or 60.5% of all the cells which were seen) were capable of making kappa chains.  There are no additional mutation noted.

You are correct that there are no population numbers identified.  One possible explanation is that since this test is used to determine if a patient is in a molecular remission, the exact number was assumed to be less important than yes/no.  I would suggest that you ask your physician to find out if a quantitative assay was performed (not reported for a number of possible reasons) and what was the result.   If this was taken from a bone marrow sample, then it is up to you to decide if the absolute value is worth another collection.  If it was from the peripheral blood, you can insist on a quantitative assay.

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Susan Leclair, PhD, CLS (NCA) is Chancellor Projessor Emerita at the University of Massachusetts Dartmouth; Senior Scientist, at Forensic DNA Associates; and Moderator and Speaker, PatientPower.info – an electronic resource for patients and health care providers.