Early negative minimal residual disease in bone marrow after immunotherapy is less predictive of late or non-marrow relapse among patients with high-risk stage 4 neuroblastoma.

Molecular detection of minimal residual disease (MRD) measured by quantitative reverse transcription-polymerase chain reaction using a four-marker panel in the bone marrow (BM) after only two treatment cycles of anti-GD2 immunotherapy was a strong independent outcome predictor among high-risk patients with stage 4 neuroblastoma in first remission. While 32 of 46 MRD-negative patients relapsed within 2 years from immunotherapy, only four had marrow relapse; in three of these four patients, MRD turned positive in the subsequent BM. We conclude that negative MRD in the post-cycle two BM was rarely associated with BM relapse, but it did not exclude recurrences at other sites.