If you’re being treated for cancer, depending on the type, your doctor may suggest giving you Imfinzi (durvalumab) or Tecentriq (atezolizumab). Both are prescription medications.

Imfinzi and Tecentriq are biologic drugs that work with your immune system to treat specific forms of cancer. A biologic is a complex drug made from parts of living organisms.

These drugs aren’t available in biosimilar forms. (Biosimilars are like generic drugs. But unlike generics, which are made for nonbiologic drugs, biosimilars are made for biologic drugs.)

You may be wondering if Imfinzi or Tecentriq would help your condition. This article highlights how these drugs are alike and different to help you decide which might work better for you.

Note: For more information about each drug, see these in-depth Imfinzi and Tecentriq articles.

Imfinzi contains the active ingredient durvalumab.

Tecentriq contains a different active ingredient, atezolizumab.

Both Imfinzi and Tecentriq belong to a class of drugs called PD-L1 inhibitors. (A drug class is a group of medications that work in a similar way.)

PD-L1 proteins on cells in your body act to shield those cells from attacks by your immune system.

Some cancer cells have lots of these proteins. Drugs such as Imfinzi and Tecentriq attach to PD-L1 proteins on cancer cells and turn them off. This sends a signal to your immune system to come attack the cancer cells.

Imfinzi and Tecentriq work with your immune system to treat specific forms of cancer. Both drugs are used to treat the following types of cancer in adults:

In addition, Tecentriq is used to treat these cancers in adults:

For each of the cancers listed above, additional factors will decide whether Imfinzi or Tecentriq are good treatment options for you. For example, Imfinzi isn’t used for all types and stages of NSCLC.

For more detailed explanations of their uses, read these in-depth Imfinzi and Tecentriq articles.

Imfinzi and Tecentriq are both meant to be long-term treatments. So you may be wondering what their possible side effects are.

Both drugs can cause similar mild or serious side effects. The side effects you may experience will depend on the type of cancer you have and whether you’re taking other treatments with Imfinzi or Tecentriq.

For more information about possible side effects, see these in-depth articles on Imfinzi and Tecentriq.

Mild side effects

Imfinzi and Tecentriq may cause mild side effects in some people. The chart below lists examples of mild side effects that can occur with these drugs.

ImfinziTecentriq
Fatigue (lack of energy)XX
Feeling weakXX
Pain in muscles or bonesXX
ConstipationXX
Decreased appetiteXX
NauseaXX
Swelling in arms or legsXX
Urinary tract infectionXX
CoughXX
Inflamed lungsX
Upper respiratory tract infectionXX
Shortness of breathXX
RashXX
Hair lossXX

This chart may not include all mild side effects of these drugs. More mild side effects may occur if you’re receiving Imfinzi or Tecentriq with other cancer drugs. For more information on the mild side effects of the two drugs, see the Imfinzi medication guide and the Tecentriq medication guide.

Serious side effects

In addition to the mild side effects described above, serious side effects may occur in people using Imfinzi or Tecentriq. See the chart below for a list of serious possible side effects.

ImfinziTecentriq
Allergic reactionXX
Severe immune system reactions*XX
Severe infusion reactionsXX
Serious infections, such as pneumoniaXX

* Severe immune system reactions can occur because Imfinzi and Tecentriq can trigger the immune system to attack your body. The areas most often harmed are the lungs, liver, heart, intestines, and glands that make hormones.

If you have questions about your specific risk for side effects of Imfinzi or Tecentriq, talk with your doctor.

Imfinzi and Tecentriq are both given at a hospital or doctor’s office as intravenous (IV) infusions. (You receive an IV infusion through a needle placed in your vein. Unlike an injection, an infusion “drips in” medication over time.)

You’ll repeat your Imfinzi or Tecentriq infusion every 2, 3, or 4 weeks. Your doctor will discuss your treatment schedule with you. Your schedule depends on your type of cancer and if your treatment plan includes other cancer drugs.

With Imfinzi, each IV infusion will take about an hour.

With Tecentriq, your first IV infusion will take about an hour. If you don’t have any infusion-related side effects, future infusions may each take about 30 minutes.

Each drug comes in vials of a solution that a healthcare professional will use to prepare your IV infusion.

The Imfinzi solution comes in one strength: 50 milligrams (mg) per milliliter (mL). Imfinzi vials come in two sizes:

  • 2.4 mL, which contains 120 mg of Imfinzi
  • 10 mL, which contains 500 mg of Imfinzi

The Tecentriq solution also comes in one strength: 60 mg/mL. Tecentriq vials come in two sizes:

  • 14 mL, which contains 840 mg of Tecentriq
  • 20 mL, which contains 1,200 mg of Tecentriq

How long do Imfinzi and Tecentriq stay in your system?

Both Imfinzi and Tecentriq stay in your system for months after your last dose. During this time, your body slowly breaks down the drug.

After receiving a dose of Imfinzi, the drug stays in your system for about 3 months.

A dose of Tecentriq stays in your system longer, about 5 months.

You may wonder why these drugs are given every 2 to 4 weeks if they last for months in the body. This is to ensure that there’s enough medication in your system every day during your treatment period to be effective.

You may wonder whether Imfinzi and Tecentriq are effective at treating your condition.

Imfinzi and Tecentriq were shown to be effective in studies for treating certain types of cancer. If you’d like to read more about how each drug performed in studies, see the prescribing information for Imfinzi and Tecentriq.

Whether you have health insurance or not, cost may be a factor when you’re considering these drugs.

To see cost estimates for Imfinzi and Tecentriq based on where you live, visit WellRx.com. But keep in mind that what you’ll pay for either drug depends on your treatment plan, your health insurance, and the pharmacy you use.

Imfinzi and Tecentriq are both biologic drugs. These drugs aren’t available in biosimilar forms. (Biosimilars are like generic drugs. But unlike generics, which are made for nonbiologic drugs, biosimilars are made for biologic drugs.)

Imfinzi or Tecentriq may not be right for you if you have certain medical conditions or other factors that affect your health. Talk with your doctor about your health history before you start either drug.

Before starting Imfinzi or Tecentriq, talk with your doctor if you have any of the following conditions or health factors.

  • autoimmune disease
  • infection
  • liver problems
  • breathing problems
  • organ transplant
  • stem cell transplant
  • pregnancy
  • breastfeeding
  • nervous system conditions

For more information about these warnings, read these in-depth Imfinzi and Tecentriq articles.

The short answer: It’s not likely.

Details: Imfinzi and Tecentriq both stay in your system for several months after your last dose. Switching from one to the other could expose your body to both drugs. It’s important to avoid having both drugs in your system at the same time, as this could raise your risk for harmful side effects.

If you need to stop Imfinzi or Tecentriq, your doctor may advise switching to a different kind of medication. This may be a better option than waiting 3 to 5 months for your system to clear Imfinzi or Tecentriq. This approach depends on your condition. Be sure to discuss any concerns with your doctor.

If you’ve had a serious immune system reaction as a side effect of Imfinzi, your doctor isn’t likely to recommend switching to Tecentriq, and vice versa. Since these drugs work in a similar way, they have similar risks of serious immune system reactions.

Talk with your doctor about your options if you’re interested in switching your medication.

Reminder: You shouldn’t switch drugs or stop your current treatment unless your doctor recommends it.

Imfinzi and Tecentriq work in a similar way to treat several types of cancer. There are also key differences between these drugs in terms of the types of cancers that they treat, their dosages, and their side effects.

If you’re deciding between Imfinzi and Tecentriq to treat your cancer, ask your doctor any questions you have. This should help you choose the better option for you. Here are some suggestions, if you’re not sure where to start:

  • Is there a reason why Imfinzi might be better for me than Tecentriq?
  • Would Imfinzi or Tecentriq interact with any medications I’m taking?
  • Could Imfinzi or Tecentriq cure my type of cancer?
  • What would my treatment schedule be like for each drug?
  • Is it safe for me to take herbal supplements with Imfinzi or Tecentriq?

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.