Amyloid light-chain (AL) amyloidosis is related to multiple myeloma in that both conditions are caused by the same type of cell. Although the two diseases share some similarities and require some of the same treatments, they also tend to lead to different symptoms and outlooks. For example, multiple myeloma is a type of blood cancer, but experts don’t consider AL amyloidosis to be cancer. AL amyloidosis and multiple myeloma can sometimes occur at the same time.
AL amyloidosis and multiple myeloma develop from plasma cells, a type of white blood cell. Plasma cells are a part of the immune system. They are located in the soft, spongy tissue inside the bones, known as bone marrow. A plasma cell’s main job is to make antibodies (proteins that help fight infection).
In both AL amyloidosis and myeloma, plasma cells grow out of control and make too many abnormal antibody proteins. People with AL amyloidosis have lower levels of plasma cells in their bone marrow than do people with multiple myeloma. AL amyloidosis signs and symptoms are primarily caused by too many proteins building up in the organs. On the other hand, myeloma signs and symptoms are due to too many plasma cells in the bone marrow.
Amyloidosis is a group of diseases caused by abnormal proteins building up within the body. Different types of amyloidosis have different causes. AL amyloidosis, also called light-chain amyloidosis or primary amyloidosis, forms when damaged plasma cells create too much abnormal protein.
Each antibody is made from four smaller proteins: two heavy-chain proteins and two light-chain proteins. In AL amyloidosis, plasma cells make high levels of misshapen light chain. These amyloid proteins clump together and collect in organs, tissues, and nerves, causing damage.
Multiple myeloma develops when plasma cells become cancerous. Myeloma cells duplicate themselves over and over until the plasma cells fill up the bone marrow and crowd out other healthy blood cells. The cancerous cells also make abnormal antibodies called M protein, monoclonal protein, M spike, or paraprotein.
These two conditions cause some of the same sets of signs and symptoms, including kidney damage. However, these signs are caused by slightly different factors. In AL amyloidosis, damage develops when amyloid deposits build up in the kidney. Multiple myeloma results in kidney damage due to too much light chain or high calcium levels.
AL amyloidosis can cause several signs and symptoms that aren’t typically seen in myeloma. These include:
Multiple myeloma may cause additional problems. Symptoms include pain, weakness, or breaks in the bones. These problems develop as myeloma cells fill up the bone marrow. Additionally, high numbers of plasma cells can lead to low numbers of healthy blood cells. People with myeloma may have anemia (low red blood cell counts), leukopenia (low white blood cell counts), and thrombocytopenia (low platelet counts). A lack of normal blood cells, in turn, can cause tiredness, infections, and bleeding problems. Multiple myeloma can also lead to high calcium levels, which can make people feel unusually thirsty, weak, confused, or constipated.
Because abnormal plasma cells are at the root of both AL amyloidosis and multiple myeloma, doctors use therapies that kill plasma cells to treat both conditions. The goal of this type of treatment is to get rid of the root cause of the disease. Doctors also use supportive therapy to treat amyloidosis and myeloma. These treatments aim to reduce symptoms.
Doctors recommend using chemotherapy drugs, such as cyclophosphamide (Cytoxan), to treat both conditions.
Chemotherapy drugs are often paired with targeted therapy medications, which attack specific molecules found on plasma cells. One targeted therapy, daratumumab and hyaluronidase-fihj (Darzalex Faspro), is approved by the U.S. Food and Drug Administration (FDA) to treat both amyloidosis and myeloma. Other myeloma targeted therapies are not yet approved for amyloidosis, but doctors may recommend using them off-label to treat amyloidosis. These drugs include:
Another category of medication called immunomodulatory drugs — which includes lenalidomide (Revlimid) and pomalidomide (Pomalyst) — can help the body fight AL amyloidosis or myeloma. Doctors may also recommend autologous stem cell transplantation. For this procedure, a person’s stem cells (cells that make new blood cells) are replaced — preceded by a high dose of the chemotherapy drug melphalan (Alkeran).
People with multiple myeloma may need additional treatments that are not usually used for amyloidosis. Doctors may use bisphosphonate drugs or radiation therapy to treat signs and symptoms of bone damage. Additionally, chimeric antigen receptor (CAR) T-cell therapy is a treatment that boosts the body’s immune system to more effectively fight cancer. CAR T-cell treatment is approved for myeloma but not amyloidosis.
Supportive care includes treatments that relieve disease symptoms and prevent or manage related health problems. Supportive treatments for AL amyloidosis often include medications or procedures that treat heart failure or kidney failure.
Multiple myeloma often causes low blood cell levels, so people with this condition may need a blood transfusion in which they receive blood from a donor.
About 15 percent of people with myeloma also develop AL amyloidosis. Those who are diagnosed with both conditions may need a different treatment plan. For example, doctors recommend avoiding chemotherapy drugs that may damage the heart, kidneys, or nerves.
People with both AL amyloidosis and myeloma have a worse prognosis than those who have amyloidosis or multiple myeloma alone. According to researchers:
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