Lenalidomide maintenance after delayed or salvage autologous stem cell transplantation

Lenalidomide (Len) maintenance improves survival after upfront autologous stem cell transplantation (autoHCT) in multiple myeloma (MM), but its role after delayed/salvage autoHCT is less defined. We performed a retrospective study of 163 MM patients who received delayed (n = 102) or salvage (n = 61) autoHCT between 2009 and 2023, followed by Len maintenance. After median follow-up of 50 months, median progression-free survival (PFS) and overall survival (OS) were 23 (95% CI, 20-26) and 62 (95% CI, 50-80) months, respectively. Patients with high-risk cytogenetic abnormalities had inferior outcomes (PFS 8 months; OS 27 months). In multivariable analysis, achieving ≥ complete response post-transplant improved PFS (hazard ratio [HR] 0.49, p = 0.002) and OS (HR 0.44; p = 0.002). Len maintenance ≥5 years was associated with improved PFS (HR 0.19; p < 0.001) and OS (HR 0.15; p = 0.002). Fourteen patients (9%) developed second primary malignancies. In conclusion, extended Len maintenance was associated with prolonged survival after delayed/salvage autoHCT.