Phesgo
Phesgo is a combination medication containing pertuzumab, trastuzumab, and hyaluronidase or hyaluronidase-zzxf. It's a targeted anticancer treatment for HER2-positive breast cancer that’s either in the early or metastatic stage. Phesgo is an injection that’s given under the skin, and it’s typically used along with other chemotherapy. But people who receive this treatment plan commonly experience hair loss, nausea, and diarrhea.
What is Phesgo?
What is Phesgo used for?
- HER2-positive breast cancers, together with other chemotherapy
How Phesgo works
Phesgo is a combination of three medications.
- Pertuzumab and trastuzumab are monoclonal antibodies that act as a human epidermal growth factor receptor 2 (HER2) inhibitor. It blocks a specific protein in the body that’s important for cell growth called HER2. HER2 is found on both normal and cancer cells. Cancer cells usually have more HER2 proteins than normal cells. This can cause cancer cells to grow more quickly than normal cells. When HER2 is blocked by Phesgo, cancer cells can’t grow and spread as well.
- Hyaluronidase is a protein that helps your body absorb pertuzumab and trastuzumab better when injected under the skin.
Drug facts
Side effects of Phesgo
The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.
Common Side Effects
The following side effects happened in people taking Phesgo together with chemotherapy.
- Hair loss (77%)
- Nausea (60%)
- Diarrhea (60%)
- Physical weakness (31%)
- Tiredness (29%)
- Mouth sores or inflammation (25%)
- Joint or muscle pain (up to 25%)
- Constipation (22%)
- Vomiting (20%)
Less Common Side Effects
- Headache
- Nerve problems (e.g., changes in how you respond to pain or touch, numbness, tingling)
- Change in how things taste
- Lower appetite
- Indigestion
- Gut inflammation
- Dry skin
- Injection site reaction
- Rash
- Cough
- Trouble sleeping
Phesgo serious side effects
Contact your healthcare provider immediately if you experience any of the following.
- Heart problems: chest pain, racing heartbeat, shortness of breath that usually worsens with activity or while lying flat, swelling of your legs or feet, sudden weight gain, fatigue
- Serious allergic reactions: trouble breathing, itching or hives, flushing, swelling, chest pain, fast heartbeat, dizziness
- Lung problems: shortness of breath, trouble breathing
- Serious infections (when receiving together with chemotherapy): repeated fevers, chills, sweating, cough, trouble breathing, severe diarrhea, vomiting, painful or frequent urination
The following Phesgo side effects have also been reported
Side effects that you should report to your care team as soon as possible:
- Allergic reactions or angioedema—skin rash, itching or hives, swelling of the face, eyes, lips, tongue, arms, or legs, trouble swallowing or breathing
- Dry cough, shortness of breath or trouble breathing
- Heart failure—shortness of breath, swelling of the ankles, feet, or hands, sudden weight gain, unusual weakness or fatigue
- Infection—fever, chills, cough, or sore throat
- Infusion reactions—chest pain, shortness of breath or trouble breathing, feeling faint or lightheaded
Side effects that usually do not require medical attention (report these to your care team if they continue or are bothersome):
Pros and cons of Phesgo
Pros
- Preferred first-choice treatment option for HER2-positive advanced breast cancer
- Only one injection that’s given under the skin, rather than two separate infusions of Herceptin (trastuzumab) and Perjeta (pertuzumab) into the vein
- Injection only takes about 5 to 8 minutes to administer
Cons
- Commonly causes diarrhea
- Must use together with additional chemotherapy, so it’s not a single-medication treatment plan for breast cancer
- Requires administration from a healthcare provider
Pharmacist tips for Phesgo
- Stay on track with your Phesgo injections. You can put your appointment dates into your calendar to help you remember when to get your dose. If you miss a dose, contact your provider so they can make changes to your treatment plan if needed. If it’s been at least 6 weeks since your last injection, your provider might need to adjust your dose.
- Phesgo is injected under the skin on the thigh. When you go to get your injection, wear loose shorts or a skirt so your provider can easily inject the medication.
- You might experience a reaction during or shortly after your Phesgo injection. Expect to stay at your provider’s office or infusion center for 15 to 30 minutes after your injection so your care team can watch for reactions. Tell your provider right away if you experience any infusion reactions like fever, chills, headache, or vomiting.
- Diarrhea is a common side effect of Phesgo. To lower your risk, avoid foods that are greasy, fatty, or spicy. It’s also helpful to eat small, frequent meals. Also, be sure to stay hydrated by drinking plenty of clear, noncarbonated drinks.
- You’ll need regular monitoring of your heart while receiving Phesgo and for two years after your last dose. This is because Phesgo can cause heart failure and other heart problems. Make sure to let your provider know if you experience any new or worsening shortness of breath, cough, swelling of your legs or feet, sudden weight gain, racing heartbeat, or dizziness. These can be signs of heart problems, and you might need to stop taking this medication.
- If you’re a female who can get pregnant, you should use birth control while receiving Phesgo and for 7 months after the last dose. This medication can cause harm to an unborn baby. Let your provider know right away if you become pregnant during Phesgo treatment.
Common questions about Phesgo
There are several situations when Phesgo can be used to treat HER2-positive breast cancer. The medication can help with early-stage breast cancer that hasn’t spread beyond the breast area. In early-stage breast cancer, Phesgo can help shrink the size of the tumor before it’s surgically removed (neoadjuvant therapy). If there’s a high risk that the cancer might come back after surgery, Phesgo can also help get rid of any part of the tumor that might still be there (adjuvant therapy). In addition, Phesgo can help with untreated metastatic breast cancer that has spread to other areas of the body. Discuss with your provider whether Phesgo is an option for your breast cancer.
Maybe. Phesgo injections must be administered by a healthcare provider, typically at an office or infusion center. Sometimes, your provider might let you receive the rest of your Phesgo injections at home after you’ve finished the chemotherapy part of your treatment plan. If your provider thinks it’s safe and a good option for you, they might allow a healthcare provider to come to your home to give you your Phesgo injections. This medication isn’t approved to be given by people other than healthcare providers yet, so you won’t be able to give the injection to yourself. Talk to your provider if you’re interested in having Phesgo given in your home.
No. Chemotherapy medications kill cancer cells in your body. But Phesgo slows cancer cell growth instead of killing the cells. However, people receiving Phesgo will also need to get chemotherapy as part of their breast cancer treatment. Possible chemotherapy agents used with Phesgo include docetaxel (Taxotere) or paclitaxel. Your provider will decide which medications are best for you and your cancer.
The main difference between these two medications is that Phesgo contains two HER2 receptor antagonists (pertuzumab and trastuzumab), whereas Herceptin Hylecta only contains one (trastuzumab only). They’re both injected under the skin and also contain hyaluronidase to help your body absorb medication when injected this way.
Discuss with your provider about the risks and benefits of breastfeeding while getting Phesgo injections. It isn’t known if Phesgo can pass into breast milk, but there’s a risk of serious harm to nursing infants if it does. To be safe, your provider might recommend that you avoid breastfeeding during treatment and for up to 7 months after your last dose. Your provider can help answer any questions you have about breastfeeding or recommend other ways to feed your baby while receiving Phesgo or after treatment.
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Risks and warnings for Phesgo
Phesgo can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Heart failure and other heart problems
- Risk factors: Receiving Phesgo with other heart-damaging anticancer medications
Phesgo can cause new or worsening heart failure and affect how well your heart pumps blood through your body. It can also cause high blood pressure, irregular heartbeats, or in serious cases, death related to a heart problem. Your risk of heart problems is higher if you’re receiving Phesgo with other heart-damaging anticancer medications or if you have other heart problems. Make sure your provider has your full medical history, so they can closely monitor your heart through imaging using an echocardiogram or a MUGA scan. You’ll need to get this scan before starting treatment, about every 3 months while receiving Phesgo, and every 6 months for 2 years after you complete treatment. Let your care team know if you experience any signs and symptoms of heart failure, including shortness of breath, dry cough, irregular heartbeats, chest pain, or weight gain.
Lung problems
- Risk factors: History of lung problems | Cancer tumors in the lung
It’s possible for Phesgo to cause rare, but serious, lung problems, including inflammation of the lungs and fluid buildup in the lungs. Let your provider know if you have difficulty breathing, cough, or fatigue during your treatment.
Harm to unborn baby
Phesgo might cause harm to an unborn baby. If you're a female who’s able to become pregnant, your provider might check to see if you’re pregnant before you start treatment. Use birth control while you’re receiving Phesgo and for at least 7 months after your last dose. Let your provider know right away if you or your partner become pregnant during this time.
Lower white blood cell counts
People receiving Phesgo together with bone marrow-suppressing chemotherapy had lower white blood cell counts compared to those receiving chemotherapy alone. White blood cells help fight off infections, so having low white blood cell levels can raise the risk of developing infections. Let your provider know as soon as possible if you experience fevers, chills, or any sign of infection.
Allergic reaction
- Risk factors: Breathing problems
People receiving Phesgo might experience allergic reactions, which can sometimes be serious. Your provider will observe you for 30 minutes after your first injection to watch out for any symptoms of a reaction. But they’ll only need to observe you for 15 minutes after the rest of your injections. Alert your provider or get medical help right away if you experience any symptom of an allergic reaction. Symptoms include dizziness, nausea, fever, chills, itchy skin, chest pain, and trouble breathing. If a reaction happens, your healthcare provider can slow down or stop the injection. They can also give you certain medication (like antihistamines or anti-fever medications) before your next injections.
Phesgo dosage
Typical dosage for Phesgo
Phesgo is given by a healthcare provider as an injection under the skin on the thigh. After the first dose, it’s given once every 3 weeks.
- For the first dose, you’ll get 1,200 mg of pertuzumab, 600 mg of trastuzumab, and 30,000 units of hyaluronidase.
- For all other doses, you’ll get 600 mg of pertuzumab, 600 mg of trastuzumab, and 20,000 units of hyaluronidase.
