A Trial of Doxycycline vs. Standard Supportive Therapy in Newly-diagnosed Cardiac AL Amyloidosis Patients Undergoing Bortezomib-based Therapy

Systemic amyloidoses are rare diseases affecting approximately 1 in 100,000 persons each year. In systemic amyloidoses abnormal proteins deposit in bodily organs and severely impair their function, causing death if not treated effectively. Light chain (AL) amyloidosis is caused by a usually small population of plasma cells (the cells that produce antibodies). These cells produce part of antibodies, the light chains (LC) that form amyloid deposits. Almost every organ, with the exception of the brain, can be affected by AL amyloidosis. The heart is involved in three fourths of patients and is responsible for almost all the deaths occurring in the first 6 months after diagnosis. Current therapy of AL amyloidosis is based on drugs targeting the plasma cells producing the amyloid-forming LC. At present, most patients receive a powerful anti-plasma cell drug, bortezomib, as part of their initial treatment. However, bortezomib-based therapy, can improve heart involvement only in less than one third of patients with AL amyloidosis, and many patients (approximately one third) still die within 12 months from diagnosis. Early cardiac deaths remain an acute unmet need and the major determinant of overall outcome in this disease. Thus, there is the need of alternative means to treat heart involvement in AL amyloidosis. Doxycycline is a widely used, well tolerated, antibiotic that has been marketed for decades and used to treat a number of different infectious diseases caused by bacteria. This molecule has been extensively studied in the laboratory, in animal models and, more recently, in small studies involving patients, for its potential of improving cardiac damage in amyloidosis. These studies showed that doxycycline disrupts amyloid deposits, reduces the amyloid load in a mouse model, and counteracts the toxicity exerted by amyloid-forming LCs on C. elegans, a worm whose pharynx is used as a model resembling human heart. In a small clinical study, doxycycline was given to pa