Researchers analyzing prospective data from two consecutive clinical trials have demonstrated that patients with Philadelphia-positive (Ph+) acute lymphoblastic leukemia (ALL) with measurable pre-transplant levels of minimal residual disease (MRD) have a significantly higher risk of relapse. However, by administering post-transplantation tyrosine kinase inhibitors (TKIs), 5-year disease-free survival and overall survival were comparable in MRD-positive and -negative patients.
The researchers analyzed transplant outcomes of 65 Ph+ ALL patients in first complete remission treated with chemotherapy and imatinib. Twenty-four patients (37%) achieved a complete or major molecular response at time of conditioning, and 41 (63%) remained MRD positive.
Based on pre-transplant measurement, MRD-negative patients had significantly lower rates of relapse compared with MRD-positive patients: 8% vs. 39%, respectively (p=0.007). However, at 5-years post-transplant and with the use of TKIs, no differences in disease-free survival (58% vs. 41%,p=0.17) and overall survival (58% vs. 49%, p=0.55) were found for MRD-negative compared with MRD-positive patients.
The researchers concluded that achieving a complete molecular remission before transplantation “reduces the risk of leukemia relapse even though TKIs may still rescue some patients relapsing after transplantation.”