Assessment of alemtuzumab third dose for resumed MS activity; two North-East England centres experience

<h3>Background</h3> In previous trials, ATZ demonstrated sustained efficacy in 62% of MS patients over a 5-year period. This observation presents real-world data from two MS centers in the North East of England (Royal Victoria Infirmary and Sunderland Royal Hospital) to evaluate the incidence of patients requiring a third dose of ATZ. <h3>Results</h3> Between April 2014 and September 2023, 196 MS patients received ATZ, with eight excluded for various reasons. Of these patients, 71% were treatment-naïve, while 29% had prior exposure to disease-modifying therapies (DMTs). The median follow-up post ATZ second course ranged from 3 to 9 years. Among 189 patients, 78.3% and 92.3% demonstrated no evidence of disease activity (NEDA) at ≥3 years, and ≥ 5 years following ATZ second course, respectively. Conversely, 21.6% required additional therapy, with 20.1% opting for a third ATZ course and 1.6% choosing an alternative DMT. Among those receiving a third ATZ course, 26.3% later required an alternative DMT due to resumed disease activity. Immune secondary phenomena were observed in 39.7% of patients, with thyroid disorders being the most prevalent ATZ-related side effect (38%). <h3>Conclusion</h3> ATZ exhibited a significantly higher durable efficacy at ≥ 5 years follow-up, than the clinical trials. Thyroid disease is the predominant immune-related phenomenon.