Gastric but not Renal Amyloid Deposition is Removed by Biologics Therapy in AA Amyloidosis Patients with Rheumatoid Arthritis

Objectives: Several biologics therapy reportedly regress gastric amyloid deposition in AA amyloidosis patients, but it is uncertain whether they can also regress renal amyloid deposition. We carried out serial renal biopsy to clarify the regression of amyloid deposition in kidney by biologics. Methods: After the diagnosis of AA amyloidosis was determined by gastric biopsy to rheumatoid arthritis (RA) patients, renal biopsy was carried out. The patients who had inadequate response by conventional oral medicines for RA were treated with tocilizumab or etanercept for more than two years. After biologics treatment, gastric and renal biopsy was carried out. Results: Six AA amyloidosis patients received biologics and the disease activities of RA were improved significantly. By renal biopsy, four patients were diagnosed with glomerular type and two patients with vascular type. After biologics treatment, amyloid deposition of gastroduodenal tracts was markedly regressed in all six patients. However, amyloid deposition of kidney did not regress significantly in two patients with vascular type whereas four patients with glomerular type could not be carried out renal biopsy due to renal failure. Conclusions: Amyloid deposition of kidney, unlikely to gastric tract, may not regress significantly in AA amyloidosis patients with RA by biologics therapy.