Endocrine Abstracts

Background: Newer biological drugs such as immune checkpoint inhibitors (ICI) have recently revolutionized cancer therapy. However, hypophysitis and adrenalitis are recognized side-effects of these new therapies. Hypothalamus pituitary adrenal (HPA) axis dysfunction is associated with serious morbidity and mortality. This study aimed to monitor whether the ICI related HPA axis dysfunction recovers.

Materials and Methods: We have conducted a retrospective observational audit of patients on ICI therapy in our centre between 2013 and April 2022. We audited all the patients on ICI therapy under our oncology department, all the patients who have been referred to our endocrinology department with a suspected diagnosis of hypophysitis and all the patients who had a magnetic resonance imaging (MRI) report containing hypophysitis in the differentials. We reviewed their cortisol levels and the therapy received. All the patients who had a low morning cortisol and/or inadequate response to short synacthen test (SST) were classified as having (HPA) axis dysfunction and they had regular follow-up with SST response monitoring.

Results: 661 patients received ICI therapy during the study period, and 28 of them (an incidence of 4.23% over 9 years) developed HPA axis dysfunction. Their mean age was 65 years old and 68% were male. 24 of these 28 patients had pituitary MRI done and 6/24 had radiological features of hypophysitis. One patient was lost to follow-up and all 27 remaining patients were on glucocorticoid replacement therapy (100%), with the majority (19 patients (68%)) taking hydrocortisone. At the end of this retrospective study, 20/27 patients were still alive and there was no HPA recovery during the studied period.

Conclusion: ICI related HPA axis dysfunction is unlikely to show recovery and it will require a life long steroid replacement therapy.