# A Case of Metastatic Renal Cell Carcinoma Developing Isolated Adrenocorticotropic Hormone (ACTH) Deficiency During Nivolumab Therapy

## TL;DR

A patient with kidney cancer developed a rare hormone deficiency during treatment with nivolumab but still had long-term cancer control after stopping the drug.

## Contribution

Demonstrates long-term tumor response after immune checkpoint inhibitor discontinuation due to isolated ACTH deficiency.

## Key findings

- Isolated ACTH deficiency occurred during nivolumab therapy for metastatic renal cell carcinoma.
- The patient achieved durable partial response for over four years after stopping nivolumab and starting hormone replacement.
- Highlights the need for early recognition of immune-related endocrinopathies in cancer treatment.

## Abstract

We report a case of isolated adrenocorticotropic hormone (ACTH) deficiency that developed after nivolumab therapy for metastatic renal cell carcinoma involving the pancreas and thyroid. The patient presented with nonspecific symptoms that improved promptly after discontinuation of nivolumab and initiation of hydrocortisone replacement therapy. Despite permanently requiring glucocorticoid supplementation, the patient has maintained a durable partial response for more than four years after cessation of nivolumab. This case highlights the importance of early recognition of immune-related endocrinopathies and demonstrates that long-term tumor control may be achieved even after discontinuation of immune checkpoint inhibitors.