Interferon beta tied to spike in thrombotic microangiopathy

(HealthDay)—There has been an unusually high number of cases of thrombotic microangiopathy associated with severe or malignant hypertension in patients with multiple sclerosis who were receiving therapy with recombinant interferon beta, according to a letter to the editor published in the March 27 issue of the New England Journal of Medicine.

David Hunt, Ph.D., from Edinburgh University in the United Kingdom, and colleagues reviewed case histories and pharmacy records to describe an unexpectedly high number of cases of thrombotic microangiopathy associated with severe or malignant hypertension in four patients with multiple sclerosis who were receiving therapy with recombinant interferon beta in South Scotland. All patients presented after years of well-tolerated treatment with interferon beta.

The researchers found no genetic or other causal factor for thrombotic microangiopathy, but did note a significant association with a common manufacturing source of interferon beta (Rebif, Merck). Geographical and temporal distribution of the hemolytic-uremic syndrome and thrombotic thrombocytopenic purpura reports shows that very few cases were reported globally in the first nine years of safety monitoring, but that there has been a recent increase in reports from countries that share the same formulation as that used in the United Kingdom.

"We did not detect such patterns or trends in the safety data from a similar recombinant interferon beta product, suggesting that further investigation of the association with changes in manufacturing may be worthwhile," the authors write.