Avelumab (Bavencio) is a programmed death-ligand 1 (PD-L1) blocking antibody indicated for the treatment of metastatic Merkel cell carcinoma (MCC), locally advanced or metastatic urothelial carcinoma (UC), and advanced renal cell carcinoma (RCC). As an immune checkpoint inhibitor, while activating anti-tumor immune responses, the drug may also induce a series of adverse reactions.

Side Effects of Avelumab (Bavencio)

Metastatic Merkel Cell Carcinoma (MCC)

Incidence ≥20%: Fatigue (47%), musculoskeletal pain (29%), infusion-related reactions (26%), rash (25%), nausea (23%), constipation (22%), cough (22%), and diarrhea (21%).

Laboratory Abnormalities: Lymphopenia (51%, Grade 3-4 in 16%), decreased hemoglobin (40%, Grade 3-4 in 6%), increased AST (31%, Grade 3-4 in 3%), and increased ALT (22%, Grade 3-4 in 3.5%).

Urothelial Carcinoma (UC)

First-Line Maintenance Treatment: Fatigue (35%), musculoskeletal pain (24%), urinary tract infection (20%), rash (20%).

Previously Treated Patients: Fatigue, infusion-related reactions, musculoskeletal pain, nausea, decreased appetite, urinary tract infection (all with incidence ≥20%).

Advanced Renal Cell Carcinoma (RCC)

Combination with Axitinib: Diarrhea (62%), fatigue (53%), hypertension (50%), musculoskeletal pain (40%).

Severe Side Effects of Avelumab (Bavencio)

Immune-Mediated Adverse Reactions

Pneumonitis: Incidence of 1.1%, including fatal cases (0.1%); treatment interruption or permanent discontinuation is required.

Colitis: Incidence of 1.5%, mainly presenting with diarrhea.

Hepatitis: Incidence of 1.1% with monotherapy (including fatal cases 0.1%); hepatotoxicity is enhanced when combined with axitinib, with ALT/AST elevation reaching 9% (Grade 3) and 7% (Grade 4).

Nephritis with Renal Insufficiency: Incidence of 0.1%.

Skin Adverse Reactions: Incidence of 6%, including severe reactions such as Stevens-Johnson syndrome.

Infusion-Related Reactions

Incidence of 26%, including 3 cases (0.2%) of Grade 4 reactions.

Premedication with antihistamines and acetaminophen is recommended before the first 4 infusions.

Precautions for Avelumab (Bavencio)

Dosage Regimens and Adjustments

Standard Dosage: 800 mg intravenously infused over 60 minutes every 2 weeks (for MCC and UC).

Combination Regimen: For RCC, administer in combination with axitinib 5 mg twice daily.

Discontinuation Principles

Treatment Interruption: Grade ≥2 immune-mediated pneumonitis, Grade ≥2 colitis, or specific liver enzyme elevations.

Permanent Discontinuation: Life-threatening (Grade 4) reactions, or recurrent Grade 3 reactions requiring immunosuppressive therapy.

Laboratory Monitoring Requirements

Liver Function: ALT, AST, total bilirubin.

Renal Function: Creatinine.

Thyroid Function.

Electrocardiogram (QT Interval Monitoring).