Pembrolizumab

Background

• Monoclonal antibody to programmed cell death 1 (PD-1)
• Increases anti-tumour T-cell response by blocking interaction between PD-1 on T-cells and PD-L1 on cancer cells
• Indications include melanoma and non-small cell lung cancer

Safety

Adverse Effects

• Immune-related adverse events are common

Immune-Mediated Pneumonitis

• Pneumonitis in a life-threatening side effect occuring in 1-5% of treated patients1
• Slightly more frequent in patients with known asthma or COPD, or who have received chest radiation
• Median time to onset is 2.8 months
• Most cases are mild to moderate, though there has been at least one death
• Pattern on radiography is of ILD (mostly organizing pneumonia, but occasionally NSIP), hypersensitivity pneumonitis, or ground-glass opacities2
• May be managed with prednisone

Infections

• Not particularly immunosuppressive
• Severe infections include mainly bacterial infections (pneumonia, genitourinary infection, SSTI, and bacteremia)
• Possibly occasional viral infections (enterovirus and rhinovirus), rare fungal infections