P-159 Lenalidomide Maintenance in R2-ISS Stratified Multiple Myeloma Patients - Real World Evidence

Since 2013 the registry is prospective.Four periods were defined: 1 (P1) from 2000 to 2007, in which there was only melphalanprednisone as treatment; Period 2 (P2) from 2008 to 2013, in which thalidomide began to be used for some young patients, in addition to autologous stem cell transplantation (ASCT) in some cases; Period 3 (P3) from 2014 to 2018, in which the protocol to be used was cyclophosphamide-thalidomide-dexamethasone (CTD) and ASCT; Period 4 (P4) from 2019 to 2022, in which triplets based on bortezomib, ASCT and post-transplant maintenance with lenalidomide were used.The indications for ASCT in all periods were restrictive: Only for patients ≤60 years in very good partial response (VGPR) or better.Treatment in the different periods, early mortality (defined as death within the first 6 months of diagnosis), and OS of each group were analyzed.Results: There were 37 patients at P1, 56 at P2, 61 at P3, and 59 at P4.At P1, 65% of patients were treated with a melphalan-prednisone regimen, 8% VAD, and 8% with a thalidomide-based regimen.No ASCT was performed, and early mortality rate was 24%.At P2, 71% were treated with a thalidomide-based regimen (13% CTD, 87% Thaldex), 20% based on melphalan, and 2% based on bortezomib.21% had ASCT performed and 9% received maintenance (Thalidomide-based).Early mortality was 16%.At P3, 90% received a thalidomidebased regimen (82% CTD) and 10% based on bortezomib.33% underwent ASCT, 20% received maintenance (100% thalidomidebased) and early mortality was 16%.At P4, 97% were treated with bortezomib-based triplets.36% were transplanted.Maintenance was administered to 75% of patients, 93% based on lenalidomide.Early mortality was 7%.With a median follow-up of 77.5 months, the median OS for the entire group was 55.1 months.The median OS of P4, P3, P2 and P1 was Not reached, 96, 35 and 25 months, respectively (p< 0.0001).Conclusions: OS has increased in each treatment period.Induction regimens have gone from being melphalan-based, then thalidomide-based, to finally being mostly bortezomib-based.Transplant and maintenance rates have increased over time.Early mortality has decreased, especially in the last period.The median OS of P3 is 8 years, better than expected, as the induction and maintenance regimen was mainly thalidomidebased.P4 showed a trend of an even better OS.Longer follow up is needed.In conclusion, public policies in the Chilean public system have managed to increase OS in our patients.