Retrospective analysis of treatment discontinuation in minimal residual disease negative multiple myeloma.

Background: The prognostic significance of minimal residual disease (MRD) negativity in multiple myeloma (MM) is well-established, and MRD negativity serves as a surrogate marker for treatment outcomes. However, in various clinical trials, achieving MRD negativity often leads to treatment continuation until disease progression. In real-world clinical practice, discontinuing treatment could lower healthcare costs and reduce adverse events.

Methods: We retrospectively analyzed patients who reached MRD negativity and discontinued treatment.

Results: A total of 39 multiple MM cases were included (17 eligible and 22 ineligible for autologous stem cell transplantation). The median time to next treatment was 42.4 months. Ten patients (25%) required additional treatment due to paraproteins or clinical relapse. Cumulative incidence of relapse at 12 and 48 months was 11.7% (95% confidence interval [CI], 4.5-28.2%) and 26.4% (95% CI, 12.8-49.6%), respectively. Multivariate analysis revealed that elevated lactate dehydrogenase (LDH) at first visit and t(4;14) were the only baseline factors significantly associated with worse outcomes. Eight patients (20%) with International Staging System (ISS) = I and with no risk factors (history of extramural disease, elevated LDH, high-risk cytogenetics) had no recurrence.

Conclusion: Although treatment discontinuation in high-risk cases is potentially unsafe, low-risk cases demonstrate potential for treatment-free remission.