Safety, Tolerability, Immunogenicity, and Antitumor Activity of GEN-009 Adjuvanted Vaccine

General Inclusion Criteria: * Diagnosis of 1 of the following tumor types: 1. Melanoma (cutaneous). 2. NSCLC. 3. SCCHN (oral, oropharyngeal, hypopharyngeal, or laryngeal). 4. Urothelial carcinoma. 5. Renal cell carcinoma (Part B only). * Understand the study, be willing to comply with all study procedures and sign the informed consent * Adequate tumor tissue available * ECOG performance status of 0 or 1 * Negative pregnancy test (females of childbearing potential) * Agree to use of contraception during the study until at least 90 days after final GEN-009 dose * Adequate hematologic, liver, and kidney function Part A-specific Inclusion: * Have completed or will complete treatment for their disease with curative intent * Have no evidence of disease Part B-specific Inclusion: * Receiving or will initiate treatment with nivolumab or pembrolizumab per disease as listed below: 1. NSCLC: Patients with metastatic non-squamous NSCLC beginning first-line pembrolizumab in combination with pemetrexed and platinum chemotherapy, or metastatic squamous NSCLC beginning first-line pembrolizumab in combination with carboplatin and either paclitaxel or nab-paclitaxel 2. SCCHN: Patients beginning pembrolizumab with recurrent or metastatic SCCHN with disease progression on or after a platinum-based therapy, or beginning first-line pembrolizumab for recurrent or metastatic SCCHN if tumors express PD-L1 with a Combined Positive Score (CPS) ≥ 1. 3. Cutaneous Melanoma: Patients with unresectable or metastatic cutaneous melanoma beginning nivolumab monotherapy or nivolumab in combination with ipilimumab. 4. Urothelial Carcinoma: Patients with locally advanced or metastatic urothelial carcinoma who are beginning pembrolizumab who: 1. Are not eligible for cisplatin-containing chemotherapy, and tumor is PD-L1 positive with CPS ≥ 10, or are not eligible for any platinum-containing chemotherapy, OR 2. Have had disease progression during or following platinum-containing chemotherapy, or within 12 months of neoadjuvant or adjuvant treatment with platinum-containing chemotherapy. 5. Renal Cell Carcinoma: 1. Patients with advanced RCC who have received prior anti-angiogenic therapy, and are beginning nivolumab monotherapy, OR 2. Untreated patients with intermediate or poor risk RCC based on the IMDC score who are beginning nivolumab in combination with ipilimumab. * Disease assessment by CT or MRI * Have at least 1 lesion that is measureable by RECIST 1.1 * Agree to a tumor biopsy 50 days after first GEN-009 vaccination * Participants with hypothyroidism must be on thyroid replacement treatment General Exclusion Criteria: * Received a live vaccine ≤ 28 days, or a non-live vaccine ≤ 14 days, prior to the first dose of GEN-009 * Acute or chronic skin disorders that would interfere with injection * Receiving immunosuppressive therapies or systemic corticosteroids. Note: Use of topical corticosteroids or inhaled corticosteroids is acceptable * Allergy to the vaccine adjuvant Hiltonol (poly-ICLC) * Active hepatitis B or hepatitis C infection * HIV Positive * History of clinically significant cardiac condition * History of leptomeningeal carcinomatosis * Had clinically active immune-mediated disease within 5 years * Received a prior allogeneic stem cell transplant * Has primary immune deficiency * Received a prior solid organ transplant * Has malignant disease, other than the tumor types being treated in this study * Female patient who is pregnant, breastfeeding, or who plans to become pregnant from the signing of the informed consent until ≥ 90 days from last dose of GEN-009 * Any condition that in the judgment of the PI would make the patient inappropriate for enrollment in the study * Patient has received cytotoxic chemotherapy within 4 weeks of the first leukapheresis Part A-specific Exclusion Criteria: * Has received or requires more than 2 adjuvant or neoadjuvant regimens (other than surgical excisions) given with curative intent prior to first GEN-009 vaccination * Has not recovered or stabilized from any clinically significant toxicity associated with any prior procedure or anticancer therapy