Comparing AHSCT and alemtuzumab for highly active MS: promising signals, few definitive answers

# What the new analysis found

A systematic review and individual patient data meta-analysis published in September 2026 compared autologous hematopoietic stem cell transplantation (AHSCT) with alemtuzumab for people with highly active multiple sclerosis. Ten studies covering 1,887 patients were pooled.

The pooled estimates showed AHSCT was associated with a higher chance of improving EDSS (hazard ratio 2.12, 95% CI 1.38–3.27) and substantially better relapse-free survival (HR 0.33, 95% CI 0.19–0.58). AHSCT patients also had a higher likelihood of achieving no evidence of disease activity (NEDA) (HR 0.39, 95% CI 0.22–0.67).

No significant differences emerged for long-term disability progression or MRI activity. Safety comparisons did not show statistically significant differences in overall adverse events or mortality, although autoimmune thyroid disease was clearly more frequent after alemtuzumab. Infection-related outcome estimates were imprecise.

# Why the findings are provisional

The authors and commentators label the evidence as very low certainty. Most included studies were observational. That raises risks of selection bias, confounding by indication, and differences in baseline patient characteristics or follow-up intensity. Those limitations mean the pooled associations should be considered hypothesis-generating rather than definitive proof.

# Practical barriers to a definitive randomized trial

A randomized controlled trial (RCT) directly comparing AHSCT and alemtuzumab would be the most reliable way to establish comparative benefit and harm. The blog commentary accompanying the meta-analysis argues such trials are unlikely for several practical reasons:

• Alemtuzumab use has fallen in many settings and is often reserved as a later-line treatment, limiting the pool of patients willing or eligible to be randomized to it.
• Alemtuzumab carries long-term monitoring burdens (monthly blood tests for years) and a known autoimmune risk profile, making trial recruitment harder.

• HSCT trials themselves have shown rapid recruitment where offered, but scaling HSCT centers nationally to offer timely access would be logistically and financially demanding.

# What clinicians and patients can take away now

The meta-analysis suggests AHSCT may deliver stronger control of inflammatory disease activity and greater chances of disability recovery in people with highly active MS. However, the same analysis did not confirm a difference in progression or MRI lesion outcomes, and confidence in the findings is low because of study design limitations.

Decisions about AHSCT versus alemtuzumab therefore remain individualized. Where AHSCT is available, discussion should cover the potential for improved relapse control and EDSS improvement seen in pooled observational data, the different safety profiles (including higher autoimmune thyroid disease with alemtuzumab), and the logistical demands of each approach.

# Where research should go

The most valuable evidence would be a well-designed RCT comparing AHSCT and alemtuzumab with standardized eligibility, endpoints, and safety monitoring. Given the practical barriers outlined, alternative strategies could include carefully planned prospective comparative cohorts with rigorous confounder adjustment, standardized outcome measures like NEDA, and transparent reporting of safety outcomes.