Real-world advantage and challenge of post-autologous stem cell transplantation MRD negativity in high-risk patients with double-hit multiple myeloma

Abstract Background Autologous stem-cell transplantation (ASCT) remains a beneficial approach for patients with newly diagnosed multiple myeloma (NDMM) in the age of novel therapeutic agents. Nevertheless, limited real-world data is available to establish criteria for identifying high-risk ASCT patients. Methods We analyzed outcomes for 168 NDMM patients who underwent ASCT at our center from December 2015 to December 2022. We investigated the impact of the number of high-risk cytogenetics (HRCA), defined as t(4;14), t(14;16), 1q21 gain/amplification, and del(17p), as well as the post-ASCT minimal residual disease (MRD) status as prognostic indicators. We assessed progression-free survival (PFS) and overall survival (OS), and focused on identifying risk factors. Results The cohort included 42% of patients ( n = 71) with 0 HRCA, 42% ( n = 71) with 1 HRCA, and 16% ( n = 26) with ≥ 2 HRCA. After a median follow-up of 31 months, the median PFS was 53 months (95% CI, 37–69), and OS was not reached for the entire cohort. Despite similar rates of MRD-negativity post-ASCT, patients with ≥ 2 HRCA, termed “double hit” (DH), had a significantly higher risk of progression/mortality than those with 0 or 1 HRCA. Multivariate analysis highlighted DH (HR 4.103, 95% CI, 2.046–8.231) and MRD positivity post-ASCT (HR 6.557, 95% CI, 3.217–13.366) as adverse prognostic factors for PFS, with DH also linked to inferior OS. As anticipated, DH patients with post-ASCT MRD positivity displayed the poorest prognosis, with a median PFS of 7 months post-ASCT. Meanwhile, DH patients with MRD negativity post-ASCT showed improved prognosis, akin to MRD-negative non-DH patients. It is noteworthy to exercise caution, as DH patients who initially achieved MRD negativity experienced a 41% cumulative loss of that status within one year. Conclusions This study strongly advocates integrating DH genetic assessments for eligible ASCT patients and emphasizes the importance of ongoing MRD monitoring, as well as considering MRD-based treatment adaptation for those patients in real-world settings.