Safety and Effect of Doxycycline in Patients With Amyloidosis

In transgenic animal models of disease, the tetracycline antibiotic doxycycline disrupts A beta amyloid fibrils (AB) in Alzheimer's disease, transthyretin (ATTR) amyloid fibrils in familial amyloidotic polyneuropathy, and immunoglobulin light chain (AL) amyloid fibrils. The aim of this single-center, 12-month open label, prospective phase II study was to determine a) the safety and tolerability of prolonged full dose doxycycline in patients with amyloidosis, and b) the effect of doxycycline treatment on amyloid-induced organ dysfunction. We enrolled 25 patients with measurable organ dysfunction caused by amyloid deposition who were not receiving active treatment to control their amyloid production. All 25 subjects received doxycycline 100 mg by both twice daily for up to 12 months depending on their tolerance of the antibiotic. The primary endpoint, defined by the organ most affected by amyloid, was measured at baseline, 6 and 12 months along with safety laboratory values.