A systematic review reports that biopsy-proven acute interstitial nephritis (AIN) from immune checkpoint inhibitor therapy frequently presents as severe kidney injury, though many patients achieve recovery after corticosteroid treatment. The review synthesizes evidence on clinical presentation, treatment response, and outcomes to refine expectations for nephritis management. The results underline a recurring clinical reality: kidney immune-related adverse events are not rare and can be life-altering in severity, yet early recognition and steroid-based management can improve recovery chances. For practice, the takeaway is operational rather than theoretical—kidney surveillance and biopsy-confirmation strategies remain central to steering safe continuation or switching of cancer immunotherapy.