Most people with myeloma have low blood counts, also called cytopenias, for a period of time after receiving CAR T-cell therapy. This often requires hospital care to support your body while it recovers.

The types of blood cells that can drop include:

• White blood cells. These help fight infection. A low amount of white blood cells is called neutropenia.
• Red blood cells. These carry oxygen to help your body create energy. A low amount of red blood cells is called anemia.
• Platelets. These help stop bleeding. A low amount of platelets is called thrombocytopenia.

CAR-T targets BCMA, a protein found on myeloma cells and healthy plasma cells, a type of white blood cell. You might wonder why other blood cells also drop if BCMA-directed CAR-T isn’t made to remove them. This happens because CAR-T, myeloma cells, and the chemotherapy given before treatment can all cause inflammation in the body. When inflammation is high, your bone marrow may have a harder time making healthy blood cells. 

Doctors may use a tool called the CAR-HEMATOTOX model to help predict if you are at higher risk of low blood counts after CAR-T. This tool looks at how much inflammation is in your body and how well your bone marrow is working. It helps your care team know how closely to monitor you before and after treatment.

Low blood counts can lead to symptoms like:

• Feeling very tired
• Getting infections more easily
• Bruising or bleeding more than usual

It’s important to know what these symptoms feel like so you can contact your care team early.

How are low blood counts managed after CAR-T?

There are several ways your care team will help your blood counts recover: 

• Regular blood tests. These track your white cells, red cells, and platelets to help guide treatment.
• Growth factor shots. If your white cells are very low, you may get a shot like G-CSF (multiple brand names exist) to help your body make more.
• Transfusions. If red cells or platelets are low, you may get a blood transfusion to improve fatigue and lower bleeding risk.
• Corticosteroids. This type of medicine may be used if your immune system attacks red blood cells (a rare side effect).
• IVIG (intravenous immunoglobulin). This type of medicine helps support the immune system if your antibody levels are low.
• Infection prevention. You may get antibiotics or antivirals to prevent infections. Good hygiene is also very important.
• Lifestyle tips. Avoid activities that might cause cuts or injuries if platelets are low. Rest more if you feel tired from anemia.

For most people, low blood counts start to get better within a few weeks to a few months after treatment. In some cases, they may last longer.

Care is tailored to your specific needs so you can feel better and lower the chance of complications.