Imfinzi (Durvalumab)

Imfinzi (durvalumab) is a PD‑L1 inhibitor used in several advanced solid‑tumor indications.

• Locally advanced or metastatic non‑small cell lung cancer (NSCLC): improves progression‑free survival when given as consolidation therapy after chemoradiation.
• Extensive‑stage small cell lung cancer (SCLC): used as maintenance therapy to extend overall survival.
• Urothelial carcinoma: indicated for patients with locally advanced or metastatic disease who have progressed following platinum‑based chemotherapy.
• Biliary tract cancer: approved for use in adults with unresectable or metastatic disease after prior systemic therapy.

• Durvalumab is a fully human IgG1 monoclonal antibody that binds with high affinity to programmed death‑ligand 1 (PD‑L1) on tumor and immune cells. By blocking the interaction of PD‑L1 with its receptors PD‑1 and CD80, durvalumab prevents the inhibitory signal that dampens T‑cell activation, thereby restoring antitumor immune responses. This reactivation of cytotoxic T‑cells enhances their ability to recognize and destroy malignant cells within the tumor microenvironment.

The safety profile of Imfinzi reflects its immunomodulatory activity and includes both common and less frequent adverse reactions.

Common Side Effects

• Fatigue: feeling of tiredness or lack of energy.
• Nausea: sensation of needing to vomit.
• Diarrhea: loose or watery stools.
• Decreased appetite: reduced desire to eat.
• Rash: mild skin redness or irritation.
• Infusion‑related reactions: transient symptoms such as flushing, chills, or low‑grade fever.

Serious or Rare Side Effects

• Immune‑mediated pneumonitis: inflammation of lung tissue that can impair breathing.
• Hepatitis: liver inflammation presenting with elevated enzymes.
• Endocrinopathies: thyroiditis, adrenal insufficiency, or hypophysitis affecting hormone balance.
• Severe colitis: inflammation of the colon causing abdominal pain and bloody diarrhea.
• Nephritis: kidney inflammation that may reduce renal function.
• Severe infusion reactions: anaphylaxis or hypotension requiring immediate medical attention.

When using Imfinzi, clinicians should observe specific precautions to minimise risks and ensure optimal handling.

• Monitor for immune‑related adverse events: assess organ function regularly and intervene early.
• Evaluate pulmonary status before treatment: baseline imaging helps detect early pneumonitis.
• Check liver enzymes periodically: identify hepatitis or transaminitis promptly.
• Assess endocrine function: screen thyroid and adrenal hormones prior to and during therapy.
• Avoid concurrent use with other immune checkpoint inhibitors unless clinically justified: increased toxicity risk.
• Store at 2‑8 °C: keep refrigerated, protect from light, do not freeze or shake.

Imfinzi may interact with other medicines, primarily through additive immune effects or altered pharmacodynamics.

Major Interactions (Avoid)

• Concurrent use with other PD‑1/PD‑L1 inhibitors: may amplify immune activation and toxicity.
• Live vaccines: increased risk of severe infection; avoid administration during treatment.

Moderate Interactions (Monitor Closely)

• Systemic corticosteroids: may diminish therapeutic efficacy if used at high doses.
• Immunosuppressive agents (e.g., azathioprine, methotrexate): require close monitoring for reduced antitumor response.
• Anticoagulants: monitor for bleeding if severe thrombocytopenia develops.