Darzalex (daratumumab) is a biologic medicine used to treat multiple myeloma, a type of cancer that affects plasma cells in the bone marrow. It is a monoclonal antibody that targets a protein called CD38, which is found in high amounts on the surface of myeloma cells.

Darzalex is used in various settings:

• Newly diagnosed multiple myeloma, both in people who are eligible for stem cell transplant and those who are not
• Relapsed or refractory multiple myeloma (cancer that has come back or stopped responding to other treatments)

It is typically used in combination with other myeloma medicines, such as bortezomib, lenalidomide, thalidomide, or dexamethasone.

How it works:

CD38 is a protein expressed heavily on myeloma cells. Daratumumab binds to CD38 and triggers multiple mechanisms to destroy the myeloma cells, including activating the immune system against them. By targeting CD38 directly, Darzalex kills cancer cells while sparing most healthy cells.

Your dose and schedule:

Darzalex is administered by a healthcare professional, either as a subcutaneous (SC) injection under the skin of the abdomen, or as an intravenous (IV) infusion. The schedule depends on the treatment phase and the combination regimen being used. Early in treatment, it may be given weekly, then fortnightly, then monthly. Your oncologist will outline the full schedule for you.

Before you start:

• Tell your haematologist and care team about all medicines, vitamins, and supplements you take
• You will receive pre-medications (antihistamines, corticosteroids, and fever medicine) before each infusion to reduce the risk of infusion-related reactions
• Darzalex can interfere with blood type testing (blood banking). Make sure any healthcare provider is aware you are on Darzalex before any surgery or transfusion, as it can cause false positive results on certain blood tests
• Tell your doctor if you have any history of respiratory conditions such as COPD or asthma

Darzalex is given by a healthcare team, so a missed dose means a missed appointment.

If you need to reschedule:

• Contact your haematology team as soon as possible to rebook
• Try not to delay doses for long, as consistent treatment is important for effectiveness

Infusion-related reactions are the most common concern during or shortly after Darzalex infusion.

These can include:

• Runny nose, cough, or throat tightness
• Nausea or vomiting
• Shortness of breath or wheezing
• Chills, fever, or flushing

These reactions usually happen during or within a few hours of the first infusion and become less common with subsequent treatments. Your care team will monitor you closely and pre-medicate you to reduce this risk. Tell your nurse immediately if you notice any of these symptoms.

Darzalex is stored and prepared by your hospital or clinic.

If you are ever given a supply to bring to an appointment:

• Store in the fridge at 2°C to 8°C
• Do not freeze or shake
• Keep in the original packaging to protect from light
• Keep out of reach of children and pets

Side effects depend on the dose, schedule, and other medicines taken alongside Darzalex.

Common ones include:

• Infusion or injection site reactions: Particularly with the first dose. Pre-medications help reduce this risk
• Infections: Including upper respiratory tract infections, pneumonia, and urinary tract infections. Report fever or signs of infection to your care team promptly
• Fatigue: Very common. Let your care team know if it significantly affects your daily life
• Low blood counts: Anaemia, neutropenia (low white blood cells), and thrombocytopenia (low platelets) are common with Darzalex combinations. Regular blood tests monitor for this
• Nausea: Usually mild. Let your care team know if it is difficult to manage
• Back or joint pain: Some people report musculoskeletal discomfort

Contact your haematology team if any side effect concerns you.

Tell your haematologist and pharmacist everything you are taking.

Key points include:

• Blood banking interference: Daratumumab coats red blood cells and can cause false positive results in blood compatibility tests. Inform all healthcare providers and blood banks that you are taking Darzalex
• Live vaccines: Avoid live vaccines during treatment. Discuss any vaccinations with your haematologist

Never start, stop, or change any medicine without speaking to your doctor first.

What is multiple myeloma?

Multiple myeloma is a cancer of plasma cells, which are a type of white blood cell that normally produces antibodies. In myeloma, cancerous plasma cells accumulate in the bone marrow, crowding out healthy blood cells and producing abnormal proteins. It can cause bone pain, anaemia, kidney problems, and increased susceptibility to infection.

Why does Darzalex interfere with blood tests?

Daratumumab binds to CD38, which is also present on red blood cells in small amounts. This causes a positive result in certain blood compatibility tests, which can make it difficult for the lab to match blood for a transfusion. It is important to tell your care team and any hospital you visit that you are taking Darzalex so they can use special techniques to get accurate results.

Is the subcutaneous injection easier than the infusion?

Yes. The subcutaneous formulation of Darzalex (given as a small injection under the skin of the abdomen) takes only a few minutes to administer and was developed to reduce the burden of lengthy IV infusions. Your haematologist will advise which formulation is available and most suitable for you.

Ace provides accurate and independent information medically reviewed on prescription medications. This material is provided for educational purposes only and is not intended for medical advice, diagnosis or treatment.