A CD8 Positron Emission Tomography With Computed Tomography (PET/CT) Study Using ⁸⁹Zr Df-IAB22M2C in Patients With Metastatic Melanoma Receiving Bempegaldesleukin (NKTR-214) and Nivolumab

NKTR-214 is a cytokine (Investigational Agent), a protein which is found to expand certain immune cells (known as CD8+ T Cells and Natural Killer Cells) to promote their anti-tumor effects. Nivolumab is a full human monoclonal antibody that binds to a molecule called PD-1 (programmed cell death protein 1) on immune cells and promotes anti-tumor effects. ⁸⁹Zr Df-IAB22M2C is an experimental injected molecule containing a radioactive atom; this molecule attaches to CD8+ T cells and allows those T cells to be seen on PET/CT scans. Part 1: A total of 4 eligible patients will be enrolled into part 1. During Cycle 1, patients will receive single agent NKTR-214, 3 injections ⁸⁹Zr Df-IAB22M2C , and 6 PET/CT scans. Starting with Cycle 2, patients will receive NKTR-214 in combination with nivolumab q3w for the remainder of the study. Once the PET/CT imaging data from Part 1 have been reviewed, Part 2 will open for enrollment. Part 2: A total of 20 eligible patient will be enrolled into part 2. During Cycle 1, patients will receive single agent NKTR-214 or nivolumab, 2 injections of ⁸⁹Zr Df-IAB22M2C , and 3 PET/CT scans. In Cycle 2 and beyond, patients will receive NKTR-214 in combination with nivolumab q3w for the remainder of the study. During Cycle 2, patients will receive 1 injection of ⁸⁹Zr Df-IAB22M2C and 1 PET/CT scan. All patients enrolled in the study will be closely monitored to determine if there is response to the treatment as well as for any side effects that may occur. The efficacy of the combination will be assessed using objective response rate (ORR). Exploratory immunological biomarkers in plasma and tumor samples will evaluate immune activation.