Paraneoplastic tubulointerstitial nephritis exacerbated by immune checkpoint inhibitor

Background: With the expanding indications and thus broader use of immune checkpoint inhibitors, clinicians are faced with a new kind of immune-related adverse events. Because of their immune modulating effects, immune checkpoint inhibitors have the potential to worsen autoimmunity in general. Paraneoplastic syndromes can be caused by tumor-induced autoimmune mechanisms. The use of immune-activating substances such as checkpoint inhibitors might lead to exacerbation of paraneoplastic syndromes causing premature discontinuation of the immunotherapy. Case presentation: We report on a 64-year-old patient with metastasized renal cell carcinoma who developed acute kidney failure after cytoreductive nephrectomy. Work-up revealed a paraneoplastic syndrome that caused tubulointerstitial nephritis (TIN). Glucocorticoid therapy successfully reversed the acute kidney injury. However, adjuvant therapy with Nivolumab provoked a flare-up of the paraneoplastic syndrome on two occasions, eventually leading to a treatment discontinuation. Conclusions: Many cases of Nivolumab-induced TIN have been described lately. However, our case demonstrates therapy failure due to a flare-up of a pre-existing paraneoplastic syndrome of the renal cancer. Against this background, it can only be speculated that some of the TIN cases discussed in prior literature might also have been flare-ups of subclinical autoimmunity.