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