Darzalex (generic name daratumumab), a highly effective new medication to treat multiple myeloma, is a laboratory-made monoclonal antibody that targets a specific single protein on the surface of myeloma cells. Of the four therapies for MM approved in 2015 by the U.S. Food and Drug Administration (FDA), only Darzalex has single-agent activity and was approved based on its superiority to existing treatments.
Who Is a Candidate?
In the U.S., Darzalex is indicated:
- In combination with Revlimid and dexamethasone, or Velcade and dexamethasone, for the treatment of patients with myeloma who have received at least one prior therapy, and
- As monotherapy, for the treatment of patients with myeloma who have received at least three prior lines of therapy including a proteasome inhibitor (PI) and an immunomodulatory agent, or who are double-refractory to a PI and an immunomodulatory agent.
How Is Darzalex given?
- The dose of Darzalex, whether alone or in combination with Revlimid and dexamethasone, is 16mg/kg of body weight. It is given weekly for weeks 1–8, every 2 weeks for weeks 9–24, and every 4 weeks for weeks 25 onward until disease progression.
- In combination with Velcade and dexamethasone, Darzalex is given at the standard dose, but is given weekly for weeks 1–9, every 3 weeks for weeks 10–24, and every 4 weeks for weeks 25 onward until disease progression.
- Especially with the first dose, the infusion rate for Darzalex is very slow. The more slowly it is given, the less likely it is that a severe infusion reaction will occur. The first dose is usually given over a period of up to 8 hours. If it is well tolerated, subsequent doses will be given more rapidly, at your doctor’s discretion. Medications are given before and after each Darzalex dose to help prevent an infusion reaction.
Possible Side Effects
Side effects that occurred in 20% or more of the patients in the Darzalex registration clinical trials were infusion reactions, fatigue, nausea, back pain, fever, cough, and upper respiratory tract infection.
Darzalex may cause blood cell counts to drop, with significant numbers of patients experiencing low red blood cell counts (anemia), low platelet counts (thrombocytopenia), and low white blood cell counts (neutropenia and lymphopenia).
Because Darzalex can cause reactivation of the herpes zoster virus (the virus that causes chicken pox, which, when reactivated, causes shingles), all patients should receive preventive treatment with an anti-viral medication.
Darzalex interferes with blood compatibility testing, including antibody screening and cross-matching done prior to blood transfusions. Your doctor should type and screen your blood before you start treatment with Darzalex in case you need a blood transfusion subsequently.
Darzalex may interfere with serum protein electrophoresis (SPEP) and immunofixation electrophoresis (IFE) tests for some patients with IgG kappa myeloma. This can lead to false positive test results for patients with IgG kappa myeloma protein, leading to inaccuracies in detecting complete response and disease progression.
There are no human data to inform a risk with use of Darzalex during pregnancy but, in general, anti-cancer agents and monoclonal antibodies may cause fetal harm. Women of reproductive potential should use effective contraception during treatment and for 3 months after stopping Darzalex treatment.