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Recurrent pembrolizumab-induced pneumonitis — SCE Respiratory MCQ

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HardImmunotherapyRecurrent pembrolizumab-induced pneumonitisSCE Respiratory

A 66-year-old man with metastatic squamous non-small-cell lung cancer is receiving pembrolizumab monotherapy. After four cycles, he developed exertional dyspnoea and bilateral peripheral ground-glass opacities. Bronchoalveolar lavage excluded infection and malignant progression, and grade 2 immune-mediated pneumonitis was diagnosed. Pembrolizumab was withheld and prednisolone 1 mg/kg daily was given with a 6-week taper. Symptoms and radiographic abnormalities resolved completely, and pembrolizumab was restarted. After two further cycles, he again develops dry cough and exertional dyspnoea that limit shopping and housework but not self-care. Oxygen saturation is 95% breathing air. CT shows recurrent bilateral organising-pneumonia-pattern opacities. There is no pulmonary embolus or cancer progression. Bronchoscopy demonstrates a lymphocytic alveolitis; bacterial, fungal, mycobacterial and viral investigations are negative. Which management is most appropriate?

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Correct answer: C — Permanently discontinue pembrolizumab and start prednisolone 1–2 mg/kg daily followed by a taper

Explanation lettering: C = shown as B · B = shown as C · E = shown as D · D = shown as E

This is recurrent grade 2 pembrolizumab-associated pneumonitis. The symptoms limit instrumental activities of daily living, but there is no hypoxaemia, oxygen requirement or limitation of self-care to indicate grade 3 disease. The compatible organising-pneumonia pattern, lymphocytic alveolitis and exclusion of infection, embolism and progression support an immune-mediated cause. Pembrolizumab should be permanently discontinued for recurrent grade 2 pneumonitis. Grade 2 or worse pneumonitis also requires corticosteroids, initially prednisolone or equivalent 1–2 mg/kg daily, followed by a taper. A would have been appropriate for the first grade 2 episode, when treatment could be withheld and later restarted after recovery; recurrence removes that rechallenge option. C is appropriate only for an asymptomatic grade 1 abnormality under close surveillance. D applies to severe grade 3–4 or deteriorating disease and introduces unnecessarily intensive immunosuppression in this stable, non-hypoxaemic patient; additional immunosuppression is generally reserved for corticosteroid-refractory toxicity. E is attractive because infection must be excluded before diagnosing immune pneumonitis, but the extensive negative microbiology and recurrent phenotype make empirical antimicrobials an inadequate substitute for corticosteroid treatment and permanent pembrolizumab withdrawal.

Reference: KEYTRUDA 25 mg/mL concentrate for solution for infusion — Summary of Product Characteristics (30 June 2026) — https://www.medicines.org.uk/emc/product/2498/smpc