Trastuzumab (and biosimilars)
Antineoplastic Agent | Immunological Agent
Black Boxed Warning: Trastuzumab (and biosimilars) carries a black boxed warning for:
- Cardiomyopathy: which includes the risk of cardiac failure. The risk is increased with concurrent anthracycline use.
- Infusion reactions and pulmonary toxicity.
- Embryo-fetal toxicity: Exposure during pregnancy can result in embryo-fetal harm.
- Indications and Efficacy: Trastuzumab is indicated for the treatment of HER2-overexpressing breast cancer and metastatic gastric or gastroesophageal junction adenocarcinoma. Its efficacy and safety profile are intended to mimic that of the original trastuzumab, making it a cost-effective alternative.
- Mechanism of Action: Trastuzumab targets the HER2 receptor, a protein overexpressed in some cancer cells. It inhibits the proliferation of these cells, leading to their destruction.
- Pre-treatment Evaluation: Before initiating treatment, confirm the HER2 positivity of the tumor through validated assays due to variable expression levels and potential diagnostic discrepancies.
- Administration Protocols: Administered via IV infusion, Trastuzumab should be given with careful monitoring, especially during the first infusion, to manage potential reactions. Subsequent infusions might be administered over a shorter duration if well-tolerated.
- Management of Cardiac Risk: Monitor cardiac function prior to and during treatment, especially in patients with pre-existing conditions or those receiving concurrent therapies that may increase the risk of cardiotoxicity. Consider discontinuation of Trastuzumab if significant decrease in cardiac function is observed.
- Infusion Reactions: Patients may experience fever, chills, or more severe symptoms like hypotension during infusions. Pre-medication with antipyretics and antihistamines can reduce these risks. Be prepared to manage severe reactions promptly.
- Pregnancy and Contraception: Advise women of reproductive potential to use effective contraception during treatment and for at least 7 months after the last dose of Trastuzumab. The risks to the fetus from exposure to trastuzumab should be clearly communicated.
- Patient Education: Educate patients about the potential side effects, the importance of reporting symptoms of infusion reactions, and cardiac symptoms immediately. Also, discuss the need for regular cardiac monitoring and follow-up appointments.
- Monitoring for Resistance: Be aware that some patients may develop resistance to trastuzumab; monitoring effectiveness throughout the therapy course is crucial. Consider alternative or additional therapies in patients who show progression.
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