28 NCCN Guidelines for Patients ® : Multiple Myeloma, 2019 3 Myeloma treatments Targeted therapy | Chemotherapy Targeted therapy Targeted therapy is treatment with drugs that target a specific or unique feature of cancer cells. Because these drugs specifically target cancer cells, they may be less likely to harm normal cells throughout your body. Guide 2 lists the targeted therapy drugs and other drugs that are used to treat myeloma. Targeted therapy drugs treat myeloma in different ways. Some block the growth of new blood vessels that feed myeloma cells in the bone marrow. These are called angiogenesis inhibitors . Others block the action of groups of proteins (proteasomes) that allow the myeloma cells to survive. These drugs are called proteasome inhibitors . Another type blocks the action of histone deacetylase enzymes and may cause cell death. These are called HDAC inhibitors . Monoclonal antibodies are another type of targeted therapy. These drugs are man-made antibodies that attach to proteins on cancer cells. An immunomodulator is a type of targeted therapy drug that helps the immune system find and attack cancer cells. Side effects of targeted therapy A side effect is an unhealthy or unpleasant physical or emotional condition caused by treatment. Each treatment for myeloma can cause side effects. The reactions to treatment differ between people. Some people have many side effects. Others have few. Some side effects can be very serious while others can be unpleasant but not serious. Most side effects appear soon after treatment starts and go away after treatment ends. But, other side effects are long-term and may appear years later. The side effects of targeted therapy depend on the drug and dose. Some of the side effects listed are caused by only one targeted drug. Others are caused by many targeted drugs but differ in how likely they are to occur. Some common side effects of targeted therapy drugs used for myeloma are tiredness, weakness, nausea or vomiting, diarrhea, and constipation. These drugs may also cause a low number of red blood cells, white blood cells, or platelets. A low white blood cell count can increase risk of infection. A low platelet count can increase risk of bruising and bleeding. Other common side effects are blood clots, numbness or tingling in the hands or feet, skin rash, and muscle aches. Not all side effects of targeted therapy drugs are listed here. Be sure to ask your treatment team for a complete list of common and rare side effects. If a side effect bothers you, tell your treatment team. There may be ways to help you feel better. There are also ways to prevent some side effects. Chemotherapy Chemotherapy is the use of drugs to kill cancer cells. Many people refer to this treatment as “chemo.” Chemotherapy drugs kill fast-growing cells throughout the body, including cancer cells and normal cells. Some chemotherapy drugs can also cause damage to your bone marrow. Different types of chemotherapy drugs work in different ways to kill cancer cells or stop new ones from being made. Thus, more than one drug is often used. When only one drug is used, it’s called a single agent. A combination regimen is the use of two or more cancer drugs. Chemotherapy is given in cycles of treatment days followed by days of rest. This allows the body to recover before the next treatment cycle. Cycles vary in length depending on which drugs are used. Often, the cycles are 14, 21, or 28 days long. The number of treatment days per cycle and the total number of cycles given also varies based on the regimen used.