Darzalex (Daratumumab): What It Is and What to Expect

This page is for people with multiple myeloma, and their families, who have been offered daratumumab. It covers how the medicine works, how it is given, what it can do to blood tests, and which side effects to watch for.

Daratumumab is a monoclonal antibody, a lab-made protein that attaches to one target. Its target is CD38, a marker that myeloma cells carry in large amounts. Once it attaches, it calls in the immune system to destroy the cell.

It comes in two forms:

• Darzalex goes into a vein (an IV infusion). The pharmacy works out the amount from your body weight each time.
• Darzalex Faspro is injected under the skin over a few minutes. It mixes daratumumab with an enzyme (a protein that speeds up a chemical change) that lets a larger volume spread into the tissue. It uses a fixed dose.

They are separate products with separate labels, and their approved uses are not the same.

CD38 sits on red blood cells too, in small amounts. That confuses the cross-match test, the check blood banks run before a transfusion to make sure donor blood suits you. The antibody makes the test look positive even when your blood is fine. The label says this can last up to 6 months after the last dose.

The fix is simple as long as people know. Your team can type and screen your blood (record your blood type and antibodies) before treatment starts. The label says to tell blood banks you are on daratumumab. It also helps to tell any hospital and carry a card saying so.

Daratumumab can also confuse the blood and urine tests used to measure myeloma. This is because the drug itself is an antibody and shows up on the same tests. Your team knows to allow for that.

The IV label covers multiple myeloma only, in seven situations:

• Some are for people who are newly diagnosed, split by whether a stem cell transplant is planned.
• Others are for myeloma that has come back or stopped responding after one, two or three earlier lines (rounds) of treatment.

It is nearly always paired with other drugs, such as:

• lenalidomide
• bortezomib
• pomalidomide
• carfilzomib
• dexamethasone

One use is on its own, after at least three prior lines.

The under-the-skin product covers more ground. As well as myeloma, it is approved:

• on its own for high-risk smoldering myeloma (an early form that causes no symptoms yet)
• with bortezomib, cyclophosphamide and dexamethasone for newly diagnosed light chain amyloidosis (a condition where abnormal proteins build up in organs)

The label warns it is not for amyloidosis with the most severe heart involvement outside a trial.

Reactions are common. The IV label says they are most common with the first infusion. They tend to bring a stuffy or runny nose, cough, throat tightness, wheeze, chills or nausea. Medicines are given beforehand to reduce them. You may be sent home with steroids to take the next day. Some reactions start hours or even days later, so tell the team about anything that starts after you leave.

White cells (which fight infection) and platelets (which help blood clot) can drop. Infections, including pneumonia and shingles, are reported. The label says to start antiviral medicine to prevent shingles within a week of starting. It says to keep taking it for 3 months after treatment ends. A fever of 100.4°F (38°C) or higher is an emergency on this treatment. Ring the 24-hour number at once, at any hour. Go to an emergency department if nobody answers quickly.

• Call 911 or go to an emergency department if your throat tightens, your tongue or lips swell, or you wheeze and struggle to breathe after a dose, even hours after you got home, or you have new chest pain. Tell the crew you are on daratumumab. Do not drive yourself.
• Ring the 24-hour myeloma line that same hour if your temperature reaches 100.4°F (38°C) or higher, or chills leave you shaking. If you cannot get through, go to an emergency department and say you are on daratumumab. CDC lists a fever during chemotherapy as a medical emergency. The label warns daratumumab can cause serious and fatal infections (CDC).
• Call your care team right away, at any hour, if you feel chest tightness or chest discomfort after a dose, you have a painful band of blisters on one side of your body, you have a new or worsening cough, or you notice unusual bruising or bleeding, such as new bruises, nosebleeds or bleeding gums. MedlinePlus lists chest discomfort and cough as reactions to tell your doctor or nurse about immediately, and unusual bruising or bleeding as a reason to call your doctor immediately (MedlinePlus).
• Call your care team within a day or two if a stuffy nose alone lingers after a dose. A new or worsening cough is a right-away call, above.

https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=a4d0efe9-5e54-467e-9eb4-56fa7d53b60b

https://www.cancer.gov/about-cancer/treatment/drugs/daratumumab

https://www.cdc.gov/cancer-preventing-infections/patients/fever.html