Recurrent delayed immune-related pneumonitis after immune-checkpoint inhibitor therapy for advanced osteosarcoma.

Introduction: The case of a patient who developed recurrent delayed immune-related pneumonitis (checkpoint inhibitor pneumonitis [CIP]) after immune checkpoint inhibitor (ICI) therapy for advanced osteosarcoma treatment is presented. Case summary: A 25-year-old female patient with metastatic osteosarcoma was treated with atezolizumab. Grade 2 pneumonitis developed three times in the first two years. Treatment was discontinued after recovery from the last episode of pneumonitis, which was complicated with secondary spontaneous pneumothorax. 2 years after discontinuation of immunotherapy, the patient again developed CIP. Pneumonitis symptoms were regressed with oral steroid therapy during follow-up and a stable disease response continued. Conclusion: Immunotherapy can cause recurrent CIP at any time during the treatment period or after discontinuation of treatment.