Achieving undetectable MRD in CLL means a patient has no detectable cancer cells, at a threshold of <1 detectable CLL cell per 10,000 leukocytes 13

Tumor burden: Decreasing detectable CLL cells in peripheral blood and/or bone marrow.  Arrow pointing down, text at the top reads "High (many CLL cells)" with "Undetectable MRD" and "Low (fewer CLL cells)" at the bottom.  Undetectable MRD means less than 1 detectable CLL cell per 10,000 leukocytes
  • MRD can be measured in the bone marrow and/or peripheral blood 13
  • MRD status at the end of treatment can be used to help assess the response to therapy 11,13
  • MRD negativity may also be referred to as “undetectable minimal residual disease” 11
  • While undetectable MRD and response rates are both measures of disease, it is possible for a patient with a PR to be MRD negative, and for a patient with a CR to be MRD positive 14
  • FDA considers MRD as not yet an established surrogate for clinical outcomes in patients with CLL 15
  • FDA MRD guidance indicates that the therapeutic paradigm with small molecule inhibitors of the B-cell receptor signaling pathway and other novel products is rapidly evolving in this area 15

Updates to the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines®) and iwCLL guidelines, as well as recent guidance from the FDA, indicate that undetectable MRD is emerging as an important measurement of disease. 11,15,16

MRD=minimal residual disease; CLL=chronic lymphocytic leukemia; PR=partial remission; CR=complete remission; FDA=US Food and Drug Administration; NCCN=National Comprehensive Cancer Network; iwCLL=International Workshop on Chronic Lymphocytic Leukemia.