a new study has shown.
These latest data were reported by Alasdair J. Coles, MD, University of Cambridge (England), at the Joint European Committee for Treatment and Research in Multiple Sclerosis–Americas Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS–ACTRIMS) 2020, this year known as MSVirtual2020.
Dr. Coles, who led the initial research to develop alemtuzumab in partnership with Genzyme, explained that autoimmune disease is a well-described and common adverse event with the drug, manifesting mainly as autoimmune thyroid events that can occur in up to 40% of patients.
But as postmarketing experience has grown, it has become clear that there is a low frequency of more serious autoimmune disease, he noted. In an effort to understand this better, regulators have suggested that the presence of non–multiple sclerosis (MS) autoimmune disease before alemtuzumab treatment and the emergence of autoimmune disease after alemtuzumab treatment may define a group that is at higher risk of one of the rare but serious autoimmune events for those on the drug.
To investigate if this was the case, Dr. Coles and colleagues analyzed data on 1,216 patients who received alemtuzumab in the clinical development program. Of these, 96 had preexisting non-MS autoimmunity.
Results showed that up to 9 years after alemtuzumab initiation, the percentage of patients with new autoimmune disease was similar in those with (35.4%) versus without (35.3%) preexisting autoimmunity.
Similar percentages of patients with versus without preexisting autoimmunity had two or more new autoimmune events (5.2% vs. 8.2%, respectively). And most patients with thyroid disorders at baseline did not experience new autoimmunity after alemtuzumab.
In addition, treatment-emergent thyroid autoimmunity after the first alemtuzumab course was not associated with subsequent nonthyroid autoimmunity after the second course. Similarly, thyroid autoimmunity after the second course did not predict non-thyroid autoimmunity after the third course.
In another analysis of the incidence of serious autoimmune events from postmarketing data on 25,292 patients treated with alemtuzumab, immune thrombocytopenic purpura was reported in 43 patients, newly identified autoimmune hepatitis in 11 patients, and hemophagocytic lymphohistiocytosis in 9 patients.
There was “no hint at all” that baseline thyroid disorders or postalemtuzumab thyroid disorders are associated with increased risk of these serious autoimmune adverse events, Dr. Coles said.
He calculated that the incidence of serious autoimmune diseases that could be life-threatening after alemtuzumab treatment was 10.7 per 10,000 patients treated for autoimmune hepatitis and 2.7 per 10,000 patients treated for hemophagocytic lymphohistiocytosis.
“From two separate data sources – phase 2/3 trials populations combined and postmarketing data – there is no evidence to support the hypothesis that preexisting non-MS autoimmunity predisposes to the serious but rare autoimmune events that have newly been described, nor does thyroid autoimmunity following the use of alemtuzumab,” Dr. Coles stated.
“In my opinion it is not appropriate to preclude the use of alemtuzumab to patients who have had previous autoimmune disease before treatment or who develop thyroid autoimmunity after alemtuzumab,” he said.
“It remains in my view a reasonable treatment option for patients with active MS to receive this highly effective therapy in the face of well-managed, well-understood thyroid autoimmunity and the very unlikely, rare, but serious autoimmune disease,” he concluded.