Immune ablation with autologous hematopoietic stem cell transplantation (AHSCT) was not superior to natalizumab in reducing disability progression or allowing reduction of disability in patients with progressive MS. This was the main result from a non-randomized study comparing pairwise-censored groups.

What is known about the effectiveness of AHSCT in progressive MS mostly comes from results of studies that focused on relapsing-remitting MS. In fact, at ECTRIMS 2022, Dr. Tomas Kalincik (Royal Melbourne Hospital in Australia) presented results of a study comparing AHSCT with 3 high-efficacy DMTs in relapsing-remitting MS. Now Dr. Kalincik explored the effectiveness of AHSCT in progressive MS and compared it with a singly, high-efficacy therapy, namely natalizumab [1]. This comparator was chosen for pragmatic reasons.

Patients with secondary or primary progressive MS from 6 AHSCT MS centers around the world plus patients from the MSBase registry could participate. They were included if they received AHSCT or started natalizumab during progressive MS. A total of 39 patients treated with AHSCT (37 with SPMS, 2 with PPMS) were matched with 139 natalizumab users. The pairwise-censored groups were compared on annualized relapse rates (ARR), freedom from relapses, and cumulative hazards of 6-months confirmed Expanded Disability Status Scale (EDSS) worsening and improvement. Dr. Kalincik stressed that on average, participants had moderately advanced disease, with a mean EDSS of 5.7 and a mean 0.5–0.6 relapses in the preceding year. There was a follow-up of up to 6 years.

Results showed that ARR while on treatment was low in both groups (both 0.08). HR for relapses was 1.04 (95%CI, 0.39 – 2.82; p = 0.92). This result was corroborated by the similar cumulative hazards of having a relapse at year 2 (AHSCT 20%, natalizumab 14%) and at year 5 (31% and 34%, respectively). Confirmed EDSS worsening was relatively prevalent in both groups (HR 1.49; 95% CI 0.70–3.14; P=0.30). HR for improvement, which rarely occurred, was 1.49 (95% CI 0.22–10.28; P=0.67).

In the AHSCT group, 3 patients (7.7%) had febrile neutropenia during mobilization, 9 (23%) had serum sickness, 6 (15%) required ICU admission, and 36 (92%) experienced complications after discharge, including 21 infections. There were no treatment-related deaths.

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