P-041: The role of Lenalidomide maintenance and measurable residual disease in a real-life multiple myeloma transplanted population receiving different strategies guided by accessible treatments in Brazil

Background Multiple myeloma (MM) treatment and monitoring with MRD-Next Generation Flow (NGF) has evolved fast in the last decade. Nevertheless, its incorporation by low-middle income countries remains challenging. Despite Lenalidomide maintenance (M-Len) after ASCT improves PFS and OS of MM, and MRD-NGF monitoring can discriminate patients (pts) with better outcomes, there is no data about these approaches in real-world pts in Brazil (BR) and Latin America. Methods Here we evaluated in two cohorts of pts guided by drug access, the benefit in outcomes of M-Len and MRD-NGF monitoring after ASCT. The study enrolled pts from public and private healthcare systems (HS). A total of 53 pts with symptomatic MM receiving up-front CTD n=27 or VCD n=26. All pts had a BM sample at D+100 for MRD-NGF following the EuroFlow SOPs with a limit of detection of 10-6 and a complete protein profile to meet the IMWG response and MRD criteria. Results Residual clonal plasma-cells were detected by MRD-NGF in 60% of all pts and in 44% of those in CR/sCR. MRD+ pts and showed a significant inferior outcome in this setting with median PFS of 26 months vs NR (p=0.05). Since Len was restricted to private HS, we evaluated its impact in a subset of 18 pts (30%), with a median treatment time of 20.5 months. In this group only, 2/18 (11%) cases progressed whereas in those with no M-Len, progression occurred in 19/35 (54%), with median PFS NR vs. 21 months (p=0.001). This benefit extended to OS, since in the M-len group had no deaths, in contrast to 11/35 (31%) (p=0.01) deaths without this drug. Combining the M-Len and MRD-NGF monitoring post ASCT allowed the recognition of distinct group outcomes: M-Len /MRD- (n=7) vs no M-Len/MRD+ (n=21) with median PFS NR vs 16 months (p=0.003). The benefit of maintenance improving disease control was clear among MRD+ pts (n=11) vs MRD+ pts with no M-Len (n=21): median PFS NR vs 16 months (p=0.002) and median OS NR in both groups but with a significant difference in the former (p=0.02). In our cohort, most pts admitted to the public HS had access to CTD without Len maintenance (n=24; 45%), while in the private received bortezomib in induction and M-Len post-transplant (n=15; 28%) with some pts having partial access with VCD/ no M-Len (n=11; 22%) or CTD/M-Len (n=3; 5%). Comparing strategies by drug access CTD/no-M-len in public vs VCD/M-len in private had an impact on both PFS (median of 16 months vs NR; p=0.003) and OS (median NR vs NR; p=0.02). Patients that had access to PI in induction without M-len also had worse outcomes: median PFS NR vs. 21 months for VCD/M-Len vs VCD/no M-Len, respectively (p=0.01), with a trend in OS (p=0.06). Conclusions In real-life, the use of M-Len post-ASCT is associated with better survival outcomes, MRD-NGF was a reproductible and powerful tool to discriminate pts at higher and earlier relapse risk. Inequity of drug access remains a hurdle in countries with constraints, particularly in public HS with a negative impact on survival of MM.