Your immune system guards your body like a fortress, sending protective proteins called antibodies to attack invaders like bacteria and viruses. Now, scientists and researchers have found ways to help your immune system fight multiple myeloma, a type of blood cancer.

Bispecific T-cell engagers (BiTEs) are a new type of treatment for relapsed or refractory multiple myeloma (RRMM). Here are six facts about BiTEs you should know if you or a loved one has RRMM.

1. BiTEs Help Your Immune System Fight Cancer

Monoclonal antibodies, also referred to as biologics, are human-made antibodies designed to fight disease. BiTEs are a new form of medication known as bispecific antibodies.

The immune system makes antibodies, which are Y-shaped proteins that attach or bind to a unique molecule of the pathogen called an antigen. Antibodies act as flags for specialized immune cells — known as T cells or T lymphocytes — to recognize and destroy the infected cells or cancer cells.

The prefix “bi” means “two” — and as the term “bispecific” suggests, bispecific T-cell engagers are monoclonal antibodies that can bind to two different proteins. The first is always CD3, which is found on the outside of T cells and plays a key role in T-cell activation. The second protein is on the outside of myeloma cells.

BiTEs act like bridges that connect your immune system and malignant cells. They make it easier for your immune system to destroy your cancer. Scientists are also studying BiTEs as a treatment for other blood cancers like lymphoma and leukemia.

2. BiTEs May Be an Option if Other Treatments Don’t Work

The treatment of multiple myeloma has evolved rapidly over the past few years. Available options for RRMM include:

• Immunomodulatory drugs like lenalidomide (Revlimid) and pomalidomide (Pomalyst)
• Proteasome inhibitors like bortezomib (Boruzu and Velcade) and carfilzomib (Kyprolis)
• Immunotherapies such as daratumumab (Darzalex) and elotuzumab (Empliciti)
• Chimeric antigen receptor T-cell therapy (CAR T-cell therapy)

These drugs may be given alone, as single agents, or in combination regimens.

Although these treatments are often effective at first, most people are eventually diagnosed with RRMM. “Relapsed myeloma” means that the cancer comes back after being destroyed in the first round of treatment. “Refractory myeloma” means that the cancer becomes resistant or stops responding to treatments.

BiTEs work differently from other treatments and may be an option for people with RRMM who’ve tried at least four prior lines of therapy, including:

• A proteasome inhibitor
• An immunomodulatory agent
• An anti-CD38 monoclonal antibody

3. Several BiTEs Have Been Approved for RRMM

The first BiTE approved by the U.S. Food and Drug Administration (FDA) was teclistamab-cqyv (Tecvayli) in 2022. It was followed by elranatamab-bcmm (Elrexfio) and talquetamab-tgvs (Talvey) in 2023 and then linvoseltamab-gcpt (Lynozyfic) in 2025.

BiTE drugs work by binding to a protein on two types of cells — one found on myeloma cells and the other on T cells. Teclistamab, erlanatamab, and linvoseltamab all target a protein called B-cell maturation antigen (BCMA), which is found on myeloma cells. These BiTEs are called BCMA-targeted therapies.

Talquetamab binds to a different type of protein on myeloma cells — G-protein-coupled receptor family C, group 5, member D (GPRC5D). BiTEs that target GPRC5D are called non-BCMA directed therapies.

Currently, BiTE drugs are used for people with multiple myeloma whose cancer came back or doesn’t respond to other treatments. Researchers are looking into whether these drugs may help earlier in the disease or when combined with other treatments.

4. BiTEs Are Given by Injection Under the Skin

Like other biologics used to treat cancer, BiTEs are given as subcutaneous (under the skin) injections, typically in the stomach or thigh. BiTEs can’t be taken by mouth because stomach acid would break them down before the drug has a chance to work.

When you first start treatment, your dose will usually be increased step by step over the first one to two weeks, depending on the BiTE drug. After reaching the full dose, you’ll typically get another injection once every one to four weeks. Your healthcare team will give you the exact dosing schedule for your treatment.

5. BiTE Treatment Can Have Side Effects

Like other medications, BiTEs may cause adverse events (side effects). Side effects have been reported in clinical trials with people who have RRMM.

Common side effects of BiTE drugs include:

• Cytokine release syndrome (an overactive immune response that can cause symptoms ranging from mild and flu-like to severe and life-threatening)
• Low blood cell counts
• Infections
• Fever
• Pain at the injection site
• Fatigue (tiredness that doesn’t improve with rest)
• Cough or shortness of breath
• Nausea
• Headache
• Diarrhea
• Immune effector cell-associated neurotoxicity syndrome (a condition that affects the brain and can cause headache, confusion, agitation, trouble speaking, or — in rare cases — brain swelling)

Talquetamab may also cause side effects such as:

• Nail changes
• Altered taste
• Weight loss
• Rash
• Dry mouth

Your myeloma specialist will help you weigh each treatment’s possible side effects against its potential benefits.

6. Research Shows That BiTEs Help Treat RRMM

The FDA approves new drugs based on clinical trials — large, carefully designed studies in which researchers compare a new drug with the standard treatment. One key measure is called overall response rate (ORR), which is the percentage of people whose cancer shows a partial or total response to treatment.

Although there’s no cure for myeloma, BiTEs have shown promise in improving treatment outcomes and extending life expectancy with RRMM. Below are highlights from clinical trials of BiTE drugs.

Teclistamab-Cqyv Results

• ORR — 61.8 percent
• At nine months, 66.5 percent of people who responded were still in response.

An additional analysis found that people taking teclistamab-cqyv had better progression-free survival (PFS) and overall survival (OS) than those receiving standard therapies. PFS refers to the time until cancer starts growing, and OS is how long people live after starting treatment.

Elranatamab-Bcmm Results

• ORR — 57.7 percent
• About half of responders had a complete response (all signs of cancer disappeared).
• About 82 percent of responders were still in response after nine months of treatment.

Linvoseltamab-Gcpt Results

• ORR — 70 percent
• About 45 percent of responders had a complete response.
• About half of responders had a response within one month, but for some it took up to six months.
• Almost 90 percent of responders were still in response at nine months, and 72 percent still responded after one year.

Talquetamab-tgvs Results

• ORR — About 73 percent
• About 32 percent of responders had a complete response, based on pooled data from different dosing schedules.
• Most responses began in a little more than a month.
• Responses lasted nine months in 85 percent of people, based on pooled results from different dosing schedules.

These trial results show that BiTE drugs are offering new hope for people with relapsed or refractory multiple myeloma. Your doctor or myeloma specialist can help explain what these findings mean for you and how they may guide your treatment choices.

Talk With Others Who Understand

On MyMyelomaTeam, people share their experiences with multiple myeloma, get advice, and find support from others who understand.

Do you have more questions about bispecific T-cell engagers for relapsed/refractory multiple myeloma? Would you consider trying a newly approved treatment for your RRMM? Let others know in the comments below.