Amyloidosis

Amyloidosis is a rare disorder that develops when proteins in the body change and become twisted clumps of misshapen proteins that accumulate in organs and tissues. The most common form of amyloidosis consists of light-chain amyloidosis (AL), which arises from plasma cells in the bone marrow. Plasma cells develop when B-lymphocytes, a type of white blood cells, are activated by an infection. In normal circumstances, these plasma cells produce antibodies (also called immunoglobulins) that help the body to attack and kill viruses or bacteria. In patients with AL, abnormal plasma cells produce excess amounts of light chain proteins. These damaged protein fragments can accumulate in tissues throughout the body and damage vital organs such as the heart, or the kidneys. AL can exist on its own, or develop secondary to another condition, such as multiple myeloma (MM).

Other common forms of amyloidosis include amyloid serum A protein (SAA) and amyloid transthyretin protein amyloidosis (ATTR). SAA occurs when there’s too much serum A protein in the body, usually because of a chronic inflammation. ATTR on the other hand is an inherited disorder that is caused by the accumulation of transthyretin protein parts that are produced in the liver. Finally, wild-type, or senile ATTR amyloidosis is a disease that typically occurs in older men and affects the heart. As such, this type of amyloidosis is generally managed by a cardiologist.

Given the fact that amyloidosis symptoms can mimic those of more-common diseases, this disease is often overlooked. Nevertheless, an early diagnosis is important as it can help to prevent further organ damage. When there is a suspicion for amyloidosis, blood and urine samples will be analyzed for the presence of abnormal proteins. In addition to this, a tissue biopsy is taken to look for signs of amyloidosis. These initial tests are usually followed by imaging procedures to evaluate internal organs, such as an echocardiogram, bone scintigraphy, an MRI scan, or an ultrasound of the liver.

For the moment, there is no definitive cure for amyloidosis. However, certain therapies can help to manage disease symptoms and limit the further production of amyloid protein. Of note, if the amyloidosis has been triggered by another condition, such as rheumatoid arthritis, treating the underlying condition can help to reduce the disease burden.

In patients with AL, the treatment targets the abnormal growth of the amyloid producing plasma cells. Currently, the standard first line treatment for these patients consists of a combination of a monoclonal antibody (daratumumab), chemotherapy (cyclophosphamide), a proteasome inhibitor (bortezomib) and the corticosteroid dexamethasone. In addition to this, a stem cell transplantation can be considered for selected patients. Finally, by participating in clinical trials, patients with AL may gain access to alternative treatment options.