P186 | REAL-WORLD EXPERIENCE ABOUT LENALIDOMIDE MAINTENANCE IN TRANSPLANT-ELIGIBLE NEWLY DIAGNOSED MULTIPLE MYELOMA: A SINGLE-CENTRE RETROSPECTIVE STUDY

Introduction Maintenance therapy with lenalidomide in transplant-eligible patients with newly diagnosed Multiple Myeloma (TE-NDMM) has shown an improvement in PFS and OS, but it is still unknown which is optimal treatment duration. Pivotal trials were conducted administering lenalidomide until progression of disease or toxicity, although a clear benefit about an indefinite duration has not been demonstrated. Methods In our single-centre real-world analysis conducted from 2018 to April 2025, we observed, retrospectively, 80 patients with TE-NDMM who underwent 4-6 cycles of VTD induction, single or double ASCT, and then started maintenance therapy. The main criterion for allowing end of maintenance was the obtainment of a deep and sustained biohumoral complete response after 24-36 months; in selected cases decision was supported by negative radiological findings or bone marrow evaluation. Disease relapse was defined as a reappearance or increase of the serum monoclonal component (M-protein), not requiring immediate treatment. Retreatment was considered in cases of radiological relapse, CRAB symptoms or a rapidly progressive increase in M-protein size. Results Seven patients (8.7%) stopped treatment because of significant haematological toxicity or infective complications; Three (3.7%) discontinued maintenance after a diagnosis of secondary primary malignancy. In eight cases (10%), progression of disease under lenalidomide has been detected. At the end of April 2025, 40 patients are still being treated. We focused on 22 patients (27.5%) that discontinued lenalidomide after a median of 28 months (range 22-42), without significative toxicities. At diagnosis 18% of patients were considered with high-risk cytogenetic features. The median follow-up post discontinuation was 18 months (range 1- 52), during which 5 patients experienced relapse. The median progression-free survival (PFS) for the entire cohort was 40 months, with estimated PFS rates of 66% at 3 years and 44% at 5 years. Among the relapses, just one patient (1.2%) required second-line treatment, after 52 months of follow-up. Thus, treatment-free survival (TFS) exceeded 4 years. Discussion Our experience highlights the unmet need to define optimal duration of lenalidomide: these findings suggest that, in selected patients achieving sustained responses, discontinuation of lenalidomide may be a feasible strategy, with long treatment-free intervals and favourable outcomes.