Table of Contents

• What is Trastuzumab Deruxtecan?
• Conditions Treated
• How It Works
• Administration
• Efficacy
• Side Effects
• Ongoing Research

What is Trastuzumab Deruxtecan?

Trastuzumab Deruxtecan, also known as T-DXd or Enhertu, is an innovative cancer treatment that belongs to a class of drugs called antibody-drug conjugates^[5]. This medication combines two important components:

1. Trastuzumab: An antibody that targets HER2 proteins on cancer cells
2. Deruxtecan: A powerful anti-cancer drug

By combining these two elements, Trastuzumab Deruxtecan can effectively target and destroy cancer cells while minimizing damage to healthy cells^[9].

Conditions Treated

Trastuzumab Deruxtecan is used to treat various types of cancers, including:

• HER2-positive breast cancer: This type of breast cancer has an excess of HER2 proteins on the surface of cancer cells, making them grow and spread more quickly^[1].
• HER2-low breast cancer: A newly recognized subtype of breast cancer with lower levels of HER2 protein expression^[7].
• Gastric (stomach) cancer: Specifically for advanced HER2-positive gastric or gastroesophageal junction adenocarcinoma^[8].
• Non-small cell lung cancer (NSCLC): For patients with HER2-mutated metastatic NSCLC^[4].

Trastuzumab Deruxtecan is typically used when other treatments have not been effective or when the cancer has spread to other parts of the body (metastasized).

How It Works

Trastuzumab Deruxtecan works in a targeted manner to attack cancer cells:

1. The trastuzumab part of the drug attaches to HER2 proteins on the surface of cancer cells.
2. Once attached, the drug is absorbed into the cancer cell.
3. Inside the cell, the deruxtecan component is released, which is a potent chemotherapy drug.
4. Deruxtecan damages the DNA of the cancer cell, leading to its death^[9].

This targeted approach allows the medication to deliver a strong anti-cancer effect while potentially reducing side effects on healthy cells.

Administration

Trastuzumab Deruxtecan is administered as an intravenous (IV) infusion, typically in a hospital or clinic setting. The dosage and frequency may vary depending on the specific condition being treated and the patient’s response to the medication. Some key points about administration include:

• The infusion is usually given every 3 weeks (21-day cycles)^[5].
• The first infusion typically takes about 90 minutes, while subsequent infusions may be shortened to 30 minutes if well-tolerated^[9].
• The dose is calculated based on the patient’s weight, with common dosages ranging from 5.4 mg/kg to 6.4 mg/kg^[4].
• Treatment continues until disease progression or unacceptable side effects occur.

Efficacy

Clinical trials have shown promising results for Trastuzumab Deruxtecan in various cancer types:

• Breast Cancer: In HER2-positive metastatic breast cancer, the drug has demonstrated significant tumor shrinkage and improved progression-free survival in patients who have received prior treatments^[1].
• Gastric Cancer: For patients with HER2-positive advanced gastric cancer, Trastuzumab Deruxtecan has shown effectiveness in those who have previously received trastuzumab-based treatment^[8].
• Lung Cancer: In HER2-mutated non-small cell lung cancer, the drug has demonstrated promising response rates^[4].

Ongoing studies are further evaluating its effectiveness in various settings and cancer types.

Side Effects

Like all medications, Trastuzumab Deruxtecan can cause side effects. Some of the most common and important side effects to be aware of include:

• Nausea and vomiting: These are common side effects, but can often be managed with anti-nausea medications^[8].
• Fatigue: Feeling tired or weak is a common experience for patients on this treatment.
• Low blood cell counts: The medication can affect the production of blood cells, potentially leading to anemia, increased risk of infection, or bleeding.
• Hair loss: While not as severe as with some other chemotherapies, some patients may experience hair thinning or loss^[1].
• Interstitial lung disease (ILD)/Pneumonitis: This is a rare but serious side effect that requires close monitoring. It involves inflammation in the lungs that can cause breathing difficulties^[5].

Patients should report any new or worsening symptoms to their healthcare team promptly.

Ongoing Research

Trastuzumab Deruxtecan is the subject of numerous ongoing clinical trials aimed at expanding its use and understanding its full potential. Some areas of current research include:

• Earlier stages of breast cancer: Studies are exploring its use in earlier stages of HER2-positive and HER2-low breast cancer^[10].
• Brain metastases: Research is ongoing to evaluate its effectiveness in patients with cancer that has spread to the brain^[5].
• Combination therapies: Trials are investigating how Trastuzumab Deruxtecan works in combination with other cancer treatments.
• Biomarker studies: Researchers are looking at ways to predict which patients will respond best to the treatment^[3].
• Quality of life: Studies are assessing how the treatment affects patients’ overall well-being and daily functioning^[8].

These ongoing studies aim to optimize the use of Trastuzumab Deruxtecan and potentially expand its benefits to more patients with various types of cancer.