Pharmacotherapy to control and destroy myeloma cells

Over the past years, much progress has been made in the treatment of myeloma with various medicines. This has resulted in more effective alleviation of myeloma symptoms. At the same time, those with the disease are living longer.

Today, combinations of several medicines are used, because the agents developed for the treatment of myeloma have different characteristics. In most cases, the first treatment consists of a combination of 2 or 3 medicines. The doctor will choose the most suitable combination for each patient to slow down progression of the disease as effectively as possible. If treatment with one combination is not as effective as anticipated, it will be replaced with another.

Treatment with the new myeloma medicines is often highly specific. The medicines are targeted at
specific cancer genes, proteins or tissues that are essential for the growth and survival of the cancer. This type of treatment prevents the cancer cells from growing and spreading, without harming healthy cells. Modern, targeted pharmaceutical treatments are under constant development.

The groups of medicines used for the treatment of myeloma are listed below.

Immunomodulatory imide drugs (IMiDs)

Oral IMiDs were originally used as hypnotics and sedatives among other uses, but they have proved effective in the treatment of myeloma.

Immunomodulatory medicines

  • prevent tumour cells from developing
  • prevent the growth of blood vessels within tumours
  • stimulate the immune system to destroy tumour cells.

It is not completely understood how IMiDs affect the immune system.

As IMiDs may increase the risk of blood clots, they are often given together with acetylsalicylic
acid or blood-thinning anticoagulants. IMiDs may also cause effects such as decreases in blood cell
counts, numbness and tingling, as well as tiredness and constipation.

Proteasome inhibitors

The cancer medicines known as proteasome inhibitors target specific enzymes in cells:
proteasomes. The role of the proteasome is to break down faulty or unnecessary proteins, which is
important for cell division.

As their name indicates, proteasome inhibitors stop this “protein cutter” from acting. This is a
particularly big problem for myeloma cells, which produce a lot of proteins. When the proteasome
is no longer able to break down the proteins produced by the myeloma cells, these proteins
accumulate in the cells and prevent them from dividing. This eventually results in the death of the
cancer cells and slows down the growth rate of the cancer.

Proteasome inhibition also prevents a problem associated with cancer therapy: the development of
resistance towards cytostatics.

Common adverse effects of proteasome inhibitors include nausea and vomiting, tiredness,
diarrhoea, fever and thrombocytopenia (too few platelets in the blood).

Corticosteroids

Corticosteroids are potent inhibitors of the inflammatory reaction. Of the different corticosteroid
classes, glucocorticoids are often used in the treatment of myeloma.

Corticosteroids are given in high doses together with other agents. Corticosteroids destroy myeloma
cells when given alone, but are more effective when given together with agents such as cytostatics.

The use of corticosteroids may cause increased blood sugar levels, weight gain, trouble sleeping and
mood swings. In long-term use, corticosteroids can increase the risk of infections and make bones
more brittle.

Histone deacetylase (HDAC) inhibitors

HDAC inhibitors are medicines that prevent enzymes called histone deacetylases (HDAC) from
working. HDAC inhibitors may influence which genes are active inside cells, and the aim is to
activate those cells that stop cancer cells from growing.

Common adverse effects of histone deacetylase inhibitors include diarrhoea, vomiting, tiredness,
loss of appetite, swelling of the arms or legs as well as fever and weakness.

Monoclonal antibodies

Monoclonal antibodies activate the immune system to defend the body against pathogens. The
monoclonal antibodies developed for the treatment of myeloma bind to specific proteins in
myeloma cells. This activates the immune system to attack cancer cells, which results in slower
progression of the myeloma.

The adverse effects of monoclonal antibodies may include fever, difficulty in breathing, feeling of
constriction in the throat, flu-like symptoms, dizziness and infections.

Regardless of which myeloma medication you have been prescribed, always tell your doctor if you experience any adverse effects or new symptoms. Before starting the medication, you should also tell your doctor about any other medications and any dietary supplements or herbal remedies you are using.