Enhertu

Enhertu can only be obtained with a prescription. It should be prescribed by a doctor and given under the supervision of a healthcare professional who has experience in the use of cancer medicines.

It is given by infusion (drip) into a vein over 90 minutes once every three weeks. Patients who tolerate the first 90‑minute infusion can receive subsequent infusions over 30 minutes. Treatment may be continued for as long as it remains effective. The dose depends on the patient’s body weight and the type of cancer that is being treated.

The infusion may cause allergic reactions, so the patient should be monitored during and after the infusion for signs such as fever and chills. If the patient develops side effects, the doctor may reduce the dose or stop treatment temporarily or permanently.

For more information about using Enhertu, see the package leaflet or contact your doctor or pharmacist.

The active substance in Enhertu, trastuzumab deruxtecan, is made up of two active components which are linked together:

• trastuzumab is a monoclonal antibody (a type of protein) that has been designed to attach to HER2. By attaching to HER2, trastuzumab activates cells of the immune system, which then kill the cancer cells. Trastuzumab also stops HER2 from stimulating the growth of cancer cells. HER2 is produced at high levels in about a fifth of gastric cancers and a quarter of breast cancers, and at lower levels in about half of the remaining breast cancers.
• deruxtecan is a toxic substance that kills cells when they attempt to divide and grow. It becomes active once the trastuzumab component has attached to HER2 and enters the cancer cell. Deruxtecan blocks an enzyme called topoisomerase I which is involved in copying cell DNA needed to make new cells. By blocking topoisomerase I, cancer cells are prevented from multiplying and eventually die.

Breast cancer

An ongoing main study showed that Enhertu was effective at shrinking the tumour in patients with metastatic breast cancer or breast cancer that could not be removed by surgery. All patients had received two or more HER2-targeted treatments. The tumour shrank in around 61% of 184 patients treated with the recommended dose of Enhertu.

An additional study involved 524 patients previously treated with a HER2-targeted treatment (trastuzumab) and a taxane for HER2-positive breast cancer that was metastatic or could not be removed by surgery. The study showed that patients treated with Enhertu lived for at least 18.5 months without their disease getting worse compared with at least 5.6 months for patients treated with trastuzumab emtansine.

Another main study found that Enhertu increased the time patients with HER2-low breast cancer lived without their disease getting worse. The study involved 557 patients with breast cancer that was metastatic or could not be removed by surgery and who had been previously treated with another cancer medicine. The study found that patients who received Enhertu lived for an average of 9.9 months without their disease getting worse compared with 5.1 months for those who received another cancer medicine chosen by the doctor.

Gastric cancer and gastro-oesophageal junction cancer

The benefits of Enhertu in gastric and gastro-oesophageal cancer were investigated in one main study involving 79 patients whose cancer had worsened following HER2-targeted treatment consisting of trastuzumab. The study did not compare Enhertu with any other medicines or placebo (dummy treatment). In 42% (33 out of 79) of patients the cancer responded to treatment, as observed by shrinkage in the size of the cancer, which lasted on average for 8 months.

The most common side effects with Enhertu (which may affect more than 1 in 5 people) are nausea (feeling sick), tiredness, vomiting, alopecia (hair loss), constipation, decreased appetite, anaemia (low levels of red blood cells), neutropenia (low levels of neutrophils, a type of white blood cell that fights infection), diarrhoea, muscle and bone pain, increased levels of certain liver enzymes (transaminases), thrombocytopenia (low levels of blood platelets which can lead to bleeding and bruising) and leucopenia (low levels of white blood cells).

The most common serious side effects are neutropenia, anaemia, nausea, tiredness, leucopenia, lymphopenia, vomiting, thrombocytopenia, hypokalaemia (low blood potassium levels which can cause weakness, muscle cramps, tingling and heart rhythm disturbance), diarrhoea, pneumonia, neutropenia with fever, dyspnoea (difficulty breathing), decreased appetite, increased levels of certain liver enzymes, increased blood levels of the enzyme alkaline phosphatase, dyspnoea (difficulty breathing), weight loss, reduced ejection fraction (a measure of how well the heart pumps blood) and interstitial lung disease (disorders causing scarring in the lungs).

The frequency and seriousness of side effects that can occur with Enhertu depend on the type of cancer that is being treated.

For the full list of side effects and restrictions of Enhertu, see the package leaflet.

Enhertu was effective at treating HER2-positive breast cancer in patients who had received one or more HER2-targeted treatments. In addition, it was effective at treating HER2-low breast cancer in patients who had previously received another cancer medicine. The side effects of Enhertu are considered manageable and similar to those of other trastuzumab-containing medicines, although the risk of lung disease may be higher with Enhertu. These side effects, including those affecting the lungs, are mostly reversible and can be managed by changing the dose and closely monitoring the patient.

Treatment with Enhertu also showed benefits in a group of patients with gastric and gastro-oesophageal cancer who had previously received treatment including trastuzumab and had few treatment options. It was therefore considered to address an unmet medical need in these patients, although the lack of a comparison group in the main study limited the evaluation of the benefits and risks associated with its use.

Enhertu has been given ‘conditional authorisation’. This means that the European Medicines Agency decided that the benefits of Enhertu are greater than its risks, but the company will have to provide additional evidence after authorisation.

Conditional authorisation is granted on the basis of less comprehensive data than are normally required. It is granted for medicines that fulfil an unmet medical need to treat serious diseases and when the benefits of having them available earlier outweigh any risks associated with using the medicines while waiting for further evidence. Every year, the Agency will review any new information that becomes available until data become comprehensive and this overview will be updated as necessary.

Since Enhertu has been given conditional authorisation, the company that markets Enhertu will provide results from a study comparing Enhertu with treatment of the doctor’s choice in patients with metastatic breast cancer or breast cancer that cannot be removed by surgery. The study will provide information about whether patients given Enhertu live longer and how long the patients live without their disease getting worse. The company will also provide results from a study to evaluate the safety and effectiveness of Enhertu in patients with gastric or gastro-oesophageal junction cancer that is metastatic or cannot be removed by surgery and has worsened following treatment with a trastuzumab-based regimen. The study will compare Enhertu with ramucirumab given in combination with paclitaxel.

The company that markets Enhertu will provide educational material to healthcare professionals to inform them that Enhertu can cause lung disease and what symptoms to watch out for. In addition, because of a potential risk of confusion between Enhertu and other trastuzumab-containing medicines, including Kadcyla, due to their similar sounding active substances (trastuzumab deruxtecan, trastuzumab emtansine and trastuzumab), the educational material will include information to alert healthcare professionals not to use these medicines interchangeably and to inform them on how to avoid medication errors.

A patient alert card including this information will also be provided to patients who are prescribed Enhertu.

Recommendations and precautions to be followed by healthcare professionals and patients for the safe and effective use of Enhertu have also been included in the summary of product characteristics and the package leaflet.

As for all medicines, data on the use of Enhertu are continuously monitored. Side effects reported with Enhertu are carefully evaluated and any necessary action taken to protect patients.

Enhertu received a conditional marketing authorisation valid throughout the EU on 18 January 2021.