A 67-year-old man comes to the office after he noticed several nodules in his left axilla. He has a history of malignant melanoma on his upper back, which was treated with wide surgical excision 4 years ago. The patient undergoes biopsy of an axillary lesion, and histopathology reveals melanoma recurrence. Subsequent whole-body positron emission scan shows diffuse metastatic disease involving the lungs, liver, and left axillary nodes. Checkpoint inhibitor therapy with pembrolizumab is initiated, which leads to significant reduction in the size of the axillary nodules and metastatic lesions. Which of the following best correlates with the treatment response in this patient?

Question

A 67-year-old man comes to the office after he noticed several nodules in his left axilla.  He has a history of malignant melanoma on his upper back, which was treated with wide surgical excision 4 years ago.  The patient undergoes biopsy of an axillary lesion, and histopathology reveals melanoma recurrence.  Subsequent whole-body positron emission scan shows diffuse metastatic disease involving the lungs, liver, and left axillary nodes.  Checkpoint inhibitor therapy with pembrolizumab is initiated, which leads to significant reduction in the size of the axillary nodules and metastatic lesions.  Which of the following best correlates with the treatment response in this patient?

Quizplus · Accepted Answer

Eductional Objective: Programmed-death receptor 1 (PD-1) is a checkpoint inhibitor that downregulates the cytotoxic T-cell response.  Neoplastic cells often exploit this receptor via the overexpression of PD-1 ligand.  PD-1 receptor inhibitors (eg, Pembrolizumab) restore the T-cell response, allowing cytotoxic T cells to invade the tumor and induce apoptosis of neoplastic cells.

A 67-Year-Old Man Comes to the Office After He Noticed