Two cases of severe oral mucositis caused by atezolizumab plus bevacizumab combination therapy for hepatocellular carcinoma.

Atezolizumab is an immune checkpoint inhibitor specific for the programmed death-1 (PD-1) receptor. In this case report, we describe two cases of oral mucositis that developed following the initiation of a systemic chemotherapy regimen comprising atezolizumab and bevacizumab for recurrent hepatocellular carcinoma. After 2 or 3 cycles of treatment, each patient presented with mucosal ulcers in the mouth, oral pain, difficulty in speech and oral intake, and both were admitted to our hospital for management. Following rule out of other conditions such as pharyngeal ulcers, herpetic mucositis, denture or oral trauma, or necrotizing mucositis, both patients were diagnosed with oral mucositis as a severe immune-related adverse event. Oral candidiasis was observed in both cases and should be considered a risk factor for the development of oral mucositis. Chemotherapy was discontinued and treatment with prednisolone was started, along with supportive care. The oral mucositis improved, and prednisolone was gradually reduced; however, in one patient, discontinuation of chemotherapy led to a recurrence of hepatocellular carcinoma. The other patient was lost to follow-up. In patients with risk factors, attention must be paid to the development of oral mucositis during immune checkpoint inhibitor treatment.