Safety of AV-MEL-1 With Anti-PD-1 Therapy in Metastatic Melanoma

The sequence is as follows: 1. Patients will provide consent for collection of blood and tumor, willingness to undergo leukapheresis, and intended plan to treat with a standard anti-PD-1 monotherapy regimen, and to treat with their patient-specific AV-MEL-1 once it has been manufactured. 2. Prior to starting anti-PD-1 therapy 1. Surgically resected tumor tissue will be sent to AIVITA Biomedical where it will be processed to establish a short-term cell line of autologous tumor cells. Approximately 1 cm3 of surgically excised tumor is preferred. Whenever possible the tissue should be obtained from a lesion no greater than 2 cm in longest diameter. Part of the sample should be assessed by pathologists to confirm melanoma and to test for PDL-1 expression. 2. Patients will undergo leukapheresis to obtain PBMC that will be converted into dendritic cells (DC). 3. Patients who did not have a PET/CT or CT scan performed within the previous 6 weeks, will undergo a PET/CT or CT to define baseline disease status (measurable disease, non-measurable detectable disease, or no evidence of disease). 3. Patients will initiate anti-PD-1 therapy monotherapy (e.g. pembrolizumab or nivolumab) using standard doses and schedules of administration at week 0. 4. When the vaccine is ready, (approximately week 8 or 9) and the patient has had the opportunity to have received about two months of anti-PD-1 monotherapy, 1. The patient will undergo radiographic assessment (PET/CT or CT) to classify disease status (measurable disease, non-measurable detectable disease, or no evidence of disease) and response (if there was measurable disease at baseline) to the anti-PD-1 therapy. 2. AV-MEL-1 will be given concurrently with continuation of the anti-PD-1 therapy. AV-MEL-1 injections will be given weekly for 3 weeks, (weeks 10-12, then monthly at weeks 16, 20, 24, 28, and 32). Blood will be collected from patients prior to each injection for immune monitoring tests. The timing of AV-MEL-1 injections is not synchronized with the administration of anti-PD-1, but they can be administered on the same day. 5. If anti-PD-1 therapy is discontinued during vaccine treatment, the remaining vaccine doses may still be administered at the discretion of the patient's managing physician.