Minimal residual disease (MRD) quantification results in improved progression-free survival (PFS) prediction in patients who achieve partial response (PR) and those who achieve complete remission (CR) after completion of chemotherapy or immunotherapy to treat chronic lymphocytic leukemia (CLL), according to combined results from two phase III studies.
Researchers determined MRD status, measured clinical response, and assessed PFS and overall survival in 554 patients enrolled in two randomized trials of the German CLL Study Group. They found that PFS did not differ significantly between MRD-negative CR and MRD-negative PR. However, PFS was longer for MRD-negative PR than for MRD-positive CR (p=0.048) and for MRD-positive CR compared with MRD-positive PR (p=0.002).
Compared with MRD-negative CR, only patients with MRD-positive PR had a significantly shorter overall survival (not reached vs. 72 months; p=0.001), whereas there was no detectable difference for patients with MRD-negative PR or MRD-positive CR (p=0.612 and p=0.853, respectively).
The authors conclude that “MRD quantification allows for improved PFS prediction in both patients who achieve PR and CR, which thus supports its application in all responders.”
In an accompanying editorial, Dr. William Wierda notes that determining MRD status in patients with CLL has great clinical value because it may lead to an earlier determination of more effective therapy.