The Effect of Diflunisal on Familial Amyloidosis

The purpose of this study is to determine if diflunisal can prevent progressive lower leg nerve damage in patients with familial amyloidosis polyneuropathy. Funding Source - FDA Office of Orphan Products Development (OOPD); National Institute of Neurological Disorders and Stroke (NINDS)

Familial amyloidosis polyneuropathy (FAP) is a rare, lethal, autosomal dominant, neurodegenerative disease characterized by misfolding of variant transthyretin tetramer (TTR) - a transport protein produced by the liver. The disease causes TTR to become unstable, triggering amyloid fibrils to form and leading to peripheral and autonomic nerve dysfunction. Currently, the only treatment for FAP is a liver transplant, which is expensive and risk-filled. Medicines are needed to treat this disease. Previous in vitro (in a test tube) studies have shown that a common anti-inflammatory drug called diflunisal stabilizes TTR, preventing the formation of amyloid fibrils. The goal of this 2-year randomized, double-blind, placebo-controlled research study is to establish whether diflunisal can stop the nerve damage, or peripheral neuropathy, resulting from amyloid production in patients with FAP. Scientists already know that diflunisal prevents formation of amyloid in the test tube. This study will determine if the drug can block amyloid production in FAP patients. Participants will be randomly chosen to receive either diflunisal or an inactive (placebo) pill twice daily for 24 months. Participants will be carefully monitored through 7 follow-up visits, either at the study center or with individual primary care physicians. Participating in the study does not preclude patients from being listed for liver transplantation.

familial amyloid polyneuropathy, familial amyloidosis, diflunisal, amyloidosis, transthyretin, peripheral neuropathy, autonomic neuropathy, amyloid cardiomyopathy

The primary endpoint, the difference in polyneuropathy progression between treatments, was measured by the Neuropathy Impairment Score plus 7 nerve tests (NIS+7) which ranges from 0 (no neurologic deficits) to 270 points (no detectable peripheral nerve function).

Change from baseline of the Kumamoto Score (0-102 points, increasing with disease severity), a clinical neurologic scale of motor, sensory, and autonomic function combined with heart and kidney end organ measures developed to track disease progression in Familial Amyloid Polyneuropathy (ATTR-FAP)

The 36 item short-form health survey (SF-36) was used to assess the difference between treatment groups for change of physical component scores over 2 years treatment. Range 0-100; lower scores reflect lower quality-of-life.

The 36 item short-form health survey (SF-36) was used to assess the difference between treatment groups for change of mental component scores over 2 years treatment. Range 0-100; lower scores reflect lower quality-of-life.

Inclusion Criteria: Age 18 to 75 years Biopsy proven amyloidosis Genotyping of variant transthyretin Signs of peripheral or autonomic neuropathy Exclusion Criteria: Use of other non-steroidal anti-inflammatory drugs Other causes of sensorimotor polyneuropathy Anticipated survival <2 years or liver transplantation in <1 yr Liver transplantation Profound nerve, heart or kidney impairment Pregnancy or unwillingness to use contraception by women of childbearing age Active or recent gastrointestinal bleeding Non-steroidal or aspirin drug allergy/hypersensitivity

A manuscript analyzing cardiac outcomes is being prepared. We will consider IPD after the manuscript is complete and accepted.

Berk JL, Suhr OB, Obici L, Sekijima Y, Zeldenrust SR, Yamashita T, Heneghan MA, Gorevic PD, Litchy WJ, Wiesman JF, Nordh E, Corato M, Lozza A, Cortese A, Robinson-Papp J, Colton T, Rybin DV, Bisbee AB, Ando Y, Ikeda S, Seldin DC, Merlini G, Skinner M, Kelly JW, Dyck PJ; Diflunisal Trial Consortium. Repurposing diflunisal for familial amyloid polyneuropathy: a randomized clinical trial. JAMA. 2013 Dec 25;310(24):2658-67. doi: 10.1001/jama.2013.283815.