Myeloma: a malignant tumor of the bone marrow

Myeloma: a malignant tumor of the bone marrow

Myeloma is also known as Kahler's disease. It also takes the name of multiple myeloma because it almost always affects several areas simultaneously.

Definition of myeloma

There are around 5,000 new cases of myeloma per year in France (125,000 people worldwide). They represent 1% of cancers (30,000 people affected) and they are part of orphan diseases. Myelomas mainly affect people over the age of 60 and slightly more men than women.

Myelomas are malignant cancerous growths that appear in the bone marrow (where our blood is made). They are therefore part of hematological cancers (such as leukemia) since they develop from cells that manage hematopoiesis (manufacture of blood cells). They represent between 15 and 20% of malignant haematological pathologies in the world.




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Development of myeloma

Myelomas grow in bone tissue and are made up of many plasma cells (cells from B lymphocytes responsible for producing antibodies) that have become abnormal. These develop and hyperproduce a specific variety of antibodies: immunoglobulins. The immunoglobulins secreted by plasma cells will gradually destroy bone tissue.

Depending on the myeloma, the plasma cells will produce either immunoglobulin G (in 70% of cases) or immunoglobulin A (30% of cases). They multiply uncontrollably and invade the marrow.

It is therefore a cancer which will destroy the bone and which will set up a vascular network to be able to continue to develop.


Symptoms of multiple myeloma

Although most myelomas are discovered by chance during a routine exam, it is usually done because:

fatigue associated with anemia: plasma cells disrupt the production of red blood cells;
infection: the presence of an excess immunoglobulin inhibits the production of others which can no longer fight against pathogens;
pain generated by bone destruction;
sometimes bone lesions (fractures or even spontaneous fractures in severe cases);
hypercalcemia (excess calcium in the blood);
kidney failure caused by the deposit of antibodies in the kidneys;
neurological disorders (in case of vertebral fracture, compression).
The prognosis of myeloma is quite poor since it alone causes 2% of cancer deaths. The average survival is 5 years but it can drop if the disease is managed at an advanced stage of cancer. In 2015, there were nearly 90,000 deaths from myeloma worldwide.

Myeloma treatment

The most effective treatment for myeloma is immunotherapy. It combines daratumumab with a dual therapy comprising lenalidomide and dexamethasone, a corticosteroid. Daratumumab is a biomedicine that targets the CD38 protein, which is very present in cells in multiple myeloma. This treatment causes rapid destruction of tumor cells by apoptosis (programmed cell death).

Since the end of 2015, the European Medicines Agency has granted European marketing authorization for 4 other new biomedicines: panobinostat (Farydak®), ixazomib, carfilzomib and elotuzumab. "Unfortunately, none of these drugs, yet recognized as effective, is today officially available in France," said the French Association of Patients with Multiple Myeloma (AF3M) in a press release. However, they are available in Belgium, Spain, Italy and Germany.

However, according to the journal Prescrire, panobinostat has not been shown to be effective in prolonging life in refractory or relapsed multiple myeloma. It exposes many side effects often serious and which affect many vital functions, hastening the death of many patients.

New cancer drugs, BH3 mimetics, have also been developed recently. They intervene in the mechanism of apoptosis (programmed cell death which should in principle lead to the destruction of tumors) in order to restore it to normal functioning. This new approach makes it possible to treat 25% of malignant tumors, including multiple myelomas.

This combination reduces the risk of disease progression or death by 63% compared to dual therapy (standard treatment) without additional immunotherapy. However, this treatment is only offered as a second step in patients with multiple myeloma who have already benefited from first-line treatment (for which less than 10% of patients obtain a complete response). With this approach, the mean survival