The Adrenal Gland as a Sanctuary Site of Metastases After Pembrolizumab Treatment: A Case Series.

Therapeutic agents targeting the PD-1/PD-L1 axis have shown durable clinical responses in patients with various cancer types. Although objective responses are common, intrapatient heterogeneous responses have been described, and the mechanism for the different organ responses remains unknown. We present a series of patients in whom a lack of response was noted solely in the adrenal glands. This is the first case series describing 3 patients with heterogeneous patterns of response to pembrolizumab with progression of adrenal metastatic disease despite objective response (complete or partial response) in all other sites of metastatic disease. Two patients, one with melanoma and one with uterine carcinosarcoma, underwent robotic adrenalectomy for enlarging adrenal metastases. An additional patient with melanoma underwent laparotomy with attempted resection, but infiltration of the adrenal tumor into the inferior vena cava prohibited safe excision. This report provides additional insight into the heterogeneous patterns of disease response to anti-PD-1 therapy, highlighting the adrenal gland as a potential sanctuary site for this immunotherapy. These cases display the potential benefit of early surgical resection in this scenario and the pitfalls of delaying referral to a surgeon for assessment of operative intervention.