P.116 Evaluating 2-3 year responses to disease modifying treatment in adults with spinal muscular atrophy

Abstract

With the wide availability of disease-modifying therapies (DMT) for spinal muscular atrophy (SMA), our knowledge of long-term response arcs grows immensely. The objective of this study is to describe the diverse treatment population and evaluate motor responses after 1-3 years of DMT. We recruited 59 adult participants (mean age=37.2 years, SD=9.3, range=18.0-73.5, outcome measures including RULM, HFMSE, RHS, and 6MWT. All participants had two years of treatment data, while 43 had 3 years. Of patients with 2 years of DMT, most were SMA3 (68.3%), sitters(S) (54.6%), 3 copies of SMN2 (70.2%), without respiratory support (64.2%), treated with nusinersen (57.3%). Of patients that have 3 years of DMT, most were SMA2 (54.2%), non-sitters(NS) (47.3%), 3 copies of SMN2 (83.2%), with respiratory support (52.3%), treated with nusinersen (58.9%). In the 2 year cohort, walkers(W) 6MWT scores showed the most change, with a 13.3% increase in year 1, 11.35% increase into year 2. RULM scores changed the least with 4.8% in year 1, 0.7% increase in year 2. For the S cohort, RULM scores showed highest change (12.4%) and HFMSE showed least change (2.4%). For NS, HFMSE scores changed the most with higher increase over the second year of treatment (8.7%) than the first (7.7%). In the 3 year cohort, similar trends appeared with tapering of increases. W's experienced a 2.3% increase in 6MWT scores, 1.5% increase in HFMSE, and 0.4% increase in RULM. Meanwhile, S's experienced a 3.7% increase in RULM and a 2.3% increase in HFMSE. Finally, NS's saw a 2.3% increase in RULM and a 1.2% increase in HFMSE. For most cohorts, DMTs continue to show changes into the 2nd year of DMT with a plateau into year 3. The 6MWT appears to show the most change for W cohort, RULM for the S cohort and HFMSE for the NS. Future analysis will include annual rates of change alongside other measures such as ATEND and pulmonary function.