Key takeaways

  • Tecvayli carries FDA boxed warnings for two life threatening reactions: cytokine release syndrome, which happens when the immune system overreacts, and neurologic toxicity that affects the brain and spinal cord.
  • Because of serious safety risks, Tecvayli is only available through a restricted program where trained healthcare professionals give the medication and closely monitor patients for at least 48 hours after the first three doses.
  • Common reactions to Tecvayli include infections, low blood cell counts, and fatigue. The specific side effects vary based on whether the drug is used alone or combined with daratumumab hyaluronidase-fihj.

Tecvayli (teclistamab-cqyv) is a prescription drug used to treat multiple myeloma in adults. It can be used alone or combined with another drug called daratumumab hyaluronidase-fihj.

Keep reading to learn about Tecvayli’s possible side effects.

The side effects you might experience depend on whether you take Tecvayli alone or with other drugs.

Most of these side effects are temporary and easy to manage. If your symptoms don’t go away or interfere with daily life, talk with your doctor. Do not stop Tecvayli treatment unless your doctor recommends it.

Tecvayli alone

The most common side effects when you take Tecvayli on its own are:

Tecvayli with daratumumab hyaluronidase-fihj

The most common side effects when you take Tecvayli with daratumumab hyaluronidase-fihj
include:

  • low antibody levels (hypogammaglobulinemia)
  • upper respiratory infections
  • CRS
  • cough
  • diarrhea
  • muscle and bone pain
  • COVID-19
  • pneumonia
  • injection site reactions
  • tiredness
  • fever
  • headache
  • nausea
  • stomach flu (gastroenteritis)
  • weight loss

Call your doctor right away if you develop serious side effects, or call 911 if they seem life-threatening.

Serious side effects include:

Experiencing side effects? After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you develop a side effect while taking this drug and want to tell the FDA about it, visit MedWatch or call 800-FDA-1088.

Tecvayli has a boxed warning for CRS and neurologic toxicity. A boxed warning is the Food and Drug Administration’s (FDA’s) most serious warning of potential adverse side effects.

If you have symptoms of CRS or neurologic toxicity, tell your doctor right away. If you think you’re experiencing a medical emergency, call 911 or your local emergency number immediately.

Cytokine release syndrome (CRS)

CRS was a common and serious side effect reported in studies of Tecvayli. CRS occurs when your immune system overreacts and releases proteins into your bloodstream. This can cause severe problems, including kidney failure and liver failure, and can be life threatening in rare cases.

Symptoms of CRS may include:

Because of this serious risk, Tecvayli is available only through a risk evaluation and mitigation strategy (REMS) program and is given only by trained healthcare professionals. The FDA requires REMS programs for certain drugs to help make sure they’re given safely.

Your doctor will monitor you closely after your Tecvayli injections. If you have a CRS reaction to the drug, they may recommend going to a hospital for monitoring.

To help prevent CRS, your doctor will gradually increase your Tecvayli dosage. They’ll also likely give you pre-treatment medications, including:

Talk with your doctor to learn more about CRS and your risk of this side effect.

Neurologic toxicity

Tecvayli can cause severe problems affecting your brain and spinal cord, including a condition called immune effector cell-associated neurotoxicity syndrome (ICANS).

Symptoms of ICANS include:

Your doctor will increase your dose of Tecvayli slowly to lower your risk of neurologic toxicity. A healthcare professional will monitor you after you receive each injection.

Your doctor will likely have you stay in the hospital for at least 48 hours after your first three doses of Tecvayli. And they’ll recommend that you don’t drive or operate machinery between your first three doses and for at least 48 hours after you receive your third dose.

Keeping track of side effects

During Tecvayli treatment, consider taking notes on any side effects you’re having so you can share them with your doctor. This is especially helpful when you first start a new drug or combination of treatments.

Your side effect notes can include:

  • what dose of the drug you were receiving when you had the side effect
  • how soon you had the side effect after starting that dose
  • what your symptoms were
  • how your symptoms affected your daily activities
  • what other medications you were taking
  • any other information you feel is important

Before starting Tecvayli, tell your doctor about your health history. Be sure to tell them if any of the following factors apply to you:

  • heart, liver, or kidney problems
  • current infection
  • previous allergic reaction to Tecvayli
  • pregnancy
  • breastfeeding

Tecvayli can harm a fetus, so you must use effective birth control during treatment and for 5 months after your last dose.

All three drugs treat multiple myeloma and share side effects like diarrhea, tiredness, and injection site reactions. They all carry boxed warnings for CRS and neurologic toxicity. However, Talvey (talquetamab-tgvs) and Elrexfio (elranatamab-bcmm) can cause skin issues, which are not common with Tecvayli.

It’s possible. The most serious long-term risks are related to CRS and nervous system problems. Other serious, lasting issues can include liver damage and low blood cell counts.

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Tecvayli is a multiple myeloma medication used alone or in combination with daratumumab hyaluronidase-fihj. It carries severe FDA boxed warnings for Cytokine Release Syndrome (CRS) and neurologic toxicity, including ICANS.

To stay safe, you’ll follow a step-up dosing schedule and be hospitalized or closely monitored for 48 hours following your initial doses.

Tecvayli can cause varying side effects depending on the treatment combination, such as severe infections, low blood cell counts, and musculoskeletal pain. It can also harm a fetus, so people who can become pregnant must use birth control during and after treatment.

Disclaimer: While Healthline strives for factual, comprehensive, and current information, this article is not a substitute for a licensed healthcare professional’s expertise. Always consult a doctor before taking or discontinuing any medication. Drug information is subject to change and may not cover all uses, directions, precautions, warnings, interactions, reactions, or adverse effects. The lack of a warning does not guarantee a drug’s safety, effectiveness, or appropriateness for all patients or specific uses. Learn more about our approach to content integrity.