Failure of Tafamidis to Halt Progression of Ala36Pro TTR Oculomeningovascular Amyloidosis

Oculomeningovascular amyloidosis is a variant of transthyretin (TTR) amyloidotic polyneuropathy, which is associated with blindness and brain ischemia, microhemorrages, and siderosis due to prominent production of the abnormal TTR in the eye and in the choroid plexuses. Tafamidis is a TTR stabilizer that is orally administered and, by interfering with amyloid fibril formation and deposition, is capable of slowing progression of TTR polyneuropathy and of early-stage cardiomyopathy. However, the ocular manifestations of amyloid deposition progressed despite tafamidis therapy in Val30Met TTR amyloidosis, and the effects of tafamidis on meningovascular amyloidosis are unknown. We observed failure of tafamidis to halt progression of oculomeningovascular amyloid deposition in a patient with familial Ala36Pro TTR amyloidosis. She received molecular diagnosis at age 24 and presented at age 26 with paresthesias of the lower limbs and bowel dysfunction. Echography showed minimal amyloid opacities in the corpus vitreum. Treatment with tafamidis meglumine was started. Sixteen months later, she complained of severe headache followed by left hemiparesthesias and numbness lasting 20 minutes. Magnetic resonance imaging showed multiple focal and diffuse hemosiderin deposits compatible with microbleeds and early siderosis. Echography showed a marked increase of “vitreal opacities.” Our observation confirms that tafamidis fails in halting increase of vitreal amyloid deposits and indicates that it is presumably ineffective in preventing clinical onset due to progression of meningovascular amyloidosis. These failures may be due to the incapability of tafamidis to cross the blood–retina and blood–brain barriers. Therapeutic options targeting oculomeningovascular TTR amyloidoses in humans are required.