The Differences Between CAR T-cell Therapy and Bispecific Monoclonal Antibodies 

This week's "Ask Dr. Durie" comes from a patient with questions about the new and exciting immune therapies. Specifically, this patient wants to know what the main differences are between CAR T-cell therapy and bispecific monoclonal antibodies. Well, obviously, this is a very important question. CAR T-cell therapy is what's called cellular therapy, where T cells are harvested from the patient's blood and engineered to attack the myeloma. 

This process takes several weeks, and to treat myeloma, what is called "bridge therapy" is used to try to sustain remission until the CAR T cells are manufactured and ready to be infused, usually after four to six weeks, whenever the product is available. In contrast, bispecific monoclonal antibodies are "off the shelf." 

These are antibodies similar to Darzalex (daratumumab), the anti-CD38 monoclonal antibody that is commercially available. Bispecific antibodies have two arms, one that attacks the myeloma, typically via BCMA, and the other that attaches to T cells via CD3. These are administered by subcutaneous injection and are available when you go to the doctor's office. You can get your subcutaneous shot, and these shots need to be given on an ongoing basis to maintain an excellent response achieved by the bispecific antibody. 

The big difference is that the CAR T-cell product is given on a one-time basis with dramatic benefits, while the bispecific therapy is given as ongoing treatment. The current problem with the CAR T-cell product is that there is limited availability because there have been supply shortages with the materials required to manufacture the CAR T cells. It's been frustrating that CAR T-cell therapy has been hard to come by for many patients who've been on waiting lists for some time. 

Conversely, the bispecifics are available, but the issue with ongoing therapy has been a risk of immune suppression with the development of infections such as pneumonia, which require careful treatment with antibiotics and intravenous immunoglobulin.  

The BOTTOM LINE is that there are very important differences between CAR T-cell therapy and bispecific therapy. 

Both are very exciting and active, but there are many important details to discuss with your doctor to determine what is appropriate and what is available, and to make a joint decision with your doctor.