[Autoimmune-related bleeding occurring during combined immunotherapy for lung cancer - Case report]. / Complication hémorragique inattendue pour un cancer bronchique sous double immunothérapie.

INTRODUCTION: Specific immune-related adverse events in lung cancer treatment are rare and it is important that they are identified as they may have important adverse consequences. We report such a case here. CASE REPORT: A Caucasian female diagnosed with KRAS mutant advanced adenocarcinoma of the lung was enrolled in a phase Ib trial assessing the combination of an anti cytotoxic T-lymphocyte- associated protein 4 antibody and a programmed death-Ligand 1 inhibitor. For several years, she had also been taking warfarin for recurrent pulmonary embolism. At day 15 of treatment, she presented with grade 1 haematomas and signs of grade 2 hyperthyroidism. Blood tests revealed a normal number of platelets but an INR increased to 6.5. Thyroid function tests and auto antibodies confirmed the presence of an autoimmune thyroitidis. The study treatment was then stopped and the patient received 1mg/kg of prednisone and 40mg of propranolol. At day 28, the thyroid function and symptoms were normalized. No direct interactions exist between immunotherapy and vitamin K antagonists (VKA) but hyperthyroidism, through pharmacokinetic and metabolic mechanisms, can boost VKA plasma levels and increase INR, leading to hemorrhagic complications. CONCLUSIONS: This case emphasizes that special consideration should be given to patients with VKA treatment planned to receive immunotherapy.