A type of cancer, multiple myeloma forms in white blood cells called the plasma cells. These cells help fight infections by making antibodies, and they recognize and attack germs. Multiple myelomas cause cancer cells to accumulate and grow in the bone marrow, crowding out the healthy cells. As a result, cancer cells produce abnormal proteins instead of producing antibodies, causing further complications.

Multiple myeloma usually starts with a benign condition called monoclonal gammopathy of undetermined significance (MGUS).

Standard treatments
The main types of medicinal therapies used for treating multiple myeloma include histone deacetylase, proteasome inhibitors, antibodies, immunomodulatory drugs (IMiDs), steroids, and chemotherapy. Each treatment works in a different way, but the main goal of all these treatment methods is to destroy or inhibit the growth of multiple myeloma cells.

Proteasome inhibitors
These are a staple for multiple myeloma treatment and are used through all the stages of the disease. Proteasomes are protein complexes that help every cell (including cancer cells) in disposing of their old proteins for new proteins. Proteasome inhibitors prevent cancer cells from doing this. As a result, the old proteins pile up, killing the cancer cells. Some examples of proteasome inhibitors are bortezomib, carfilzomib, and ixazomib.

Immunomodulatory drugs (IMiDs)
This class of immunotherapy medicine is a mainstay regime to treat multiple myeloma. They work by regulating certain aspects of the immune system. ImiDs activate certain immune cells inhibiting a certain type of growth signals, directly killing myeloma cells. Some of the prominently used IMiDs to treat multiple myeloma are lenalidomide, pomalidomide, and thalidomide.

Steroids
Another staple for treating multiple myeloma, steroids are also used at every stage of the disease. The optimum dosage of steroids can kill multiple myeloma cells and also decrease the inflammation due to white blood cells overflowing in the disease-affected areas. They are also used to reduce nausea and vomiting due to various treatments. Their side effects may include high blood sugar, weight gain, and sleeping problems.

HDAC inhibitors
Some multiple myeloma cells produce excessive HDAC (histone deacetylase) protein, allowing them to grow quickly and divide. The HDAC inhibitors target this process and kill the cancer cells. HDAC inhibitors are given in combination with other medicines to patients who have received at least two other treatments for the same disease.

Antibodies
These are a type of medicines that consist of monoclonal antibodies that enhance the cancer-fighting abilities of a patient’s own immune system. The antibodies target specific proteins found in the multiple myeloma cells. There are studies being carried out to analyze and increase the strength of checkpoint inhibitors to recognize and stop the growth of multiple myeloma.

Chemotherapy
One of the most prevalent measures taken to treat almost every form of cancer, chemotherapy uses several medicines to kill cancer cells that are in the process of dividing. However, some healthy cells are also affected and damaged in the process, leading to a number of side effects. Some chemotherapy medicines are given orally, others are given intravenously, or they’re both combined to work better at stopping the tumor growth. Chemotherapy treatments are given in cycles, which is usually three to four times a week. A course of treatment usually consists of four to six cycles lasting for about five to six months.

Stem cell transplants
This form of treatment is given in combination with high-dose chemotherapy. This treatment option offers durable remission for people with multiple myeloma. Stem cells provide the body with a new source of healthy cells as chemotherapy attacks all the blood cells in the bone marrow. The stem cell therapy has replaced an older treatment called bone marrow transplants, and there are two types of stem cell therapies:

• Autologous stem cell transplant
  In this type of transplant, the stem cells are taken from the patient’s own blood. All the patients eligible for transplantation are encouraged to preserve their stem cells if they choose to undergo transplantation at some point during the course of the disease. The stem cells are either given with chemotherapy or radiotherapy sessions, and the stored cells are infused back into the patient’s blood. This type of treatment is in the inpatient or outpatient setting, depending on the center and patient’s preference.
• Allogeneic stem cell transplant
  This type of stem cell therapy involves the transfusion of stem cells from a matched donor to a patient, who might be receiving multiple organs, after a session of radiotherapy or chemotherapy. In rare cases, an allogeneic transplant can be curative as it can destroy the remaining multiple myeloma cells, but there are multiple risks involved in using this type of transplant as it can develop graft-versus-host disease (GVHD).