Inclusion Criteria:

        Patient will be eligible for this trial if all the following apply:

          1. Patient has given written informed consent by themselves

          2. Patient aged 20 to 85 years at the time of informed consent

          3. Patient has histologically- or cytologically-confirmed melanoma

          4. Patient with a diagnosis of incurable and unresectable, Stage IIIC, IIID or Stage IV
             advanced melanoma, showing confirmed SD or unconfirmed PD over 12-week treatment with
             an anti-PD-1 antibody such as nivolumab or Pembrolizumab. To be assigned a status of
             SD, changes in tumor measurements must be confirmed by consecutive repeat evaluations
             that should be performed in 4 to 6 weeks after the criteria for response are first met
             over 12-week of an anti-PD-1 antibody treatment.

          5. Patient has a measurable tumor

          6. Patient has life expectancy of at least 12 weeks after the first dose of
             investigational product

          7. Patient has an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
             at screening

          8. Patient has met the following criteria of clinical laboratory tests at screening
             (1)White blood cell (WBC) count over 3,000/μL and neutrophil count over 1,500/μL
             (2)Platelet count over over 75,000/μL (3)Hemoglobin over 8.0 g/dL (4)AST and ALT ≤ 2.5
             × upper limit of normal (ULN) (5)Total bilirubin ≤ 2 × ULN (6)Serum creatinine ≤ 2 ×
             ULN

          9. LDH is not higher than the 2-fold of the upper limit of the institutional reference.

         10. A female patient of childbearing potential (a premenopausal woman, a woman with
             medically or drug-induced amenorrhea, and a woman with no history of sterilization),
             who has agreed to use appropriate contraception, e.g., the barrier method and a total
             abstinence, during the trial treatment until 3 months passed after completion of the
             trial treatment. A male patient who has agreed to use appropriate contraception, e.g.,
             the barrier method and a total abstinence, during the above period.

        Exclusion Criteria:

        Patient will be excluded from participation if any of the following apply:

          1. Patient has brain metastases. Patients with previously treated brain metastases may
             participate provided they are radiologically stable, i.e. without evidence of
             progression for at least 4 weeks by repeat imaging* (note that the repeat imaging
             should be performed during study screening), clinically stable and without requirement
             of steroid treatment for at least 14 days prior to first dose of study treatment.

          2. Patient has showed positive reaction in a prick testing for GEN0101

          3. A patient who has the mutant BRAF gene in a tumor biopsy.

          4. A patient who has current pneumonitis.

          5. Patient concurrently has an active infection requiring systemic therapy.

          6. Patient has received other systemic anticancer therapy than an anti-PD-1 antibody
             therapy such as nivolumab, Pembrolizumab, or local IFN-beta therapy within 3 weeks
             before the time of informed consent (or within 6 weeks before the time of the informed
             consent for a patient who received nitrosourea or mitomycin C)

          7. Patient has received another unapproved drug other than anti-PD-L1 antibody within 4
             weeks before the time of informed consent

          8. Patient has intraocular (uveal) melanoma

          9. Patient has or had another malignant tumor than melanoma. However, this criterion does
             not apply to a patient who has experienced neither recurrence nor metastasis for at
             least 5 years at the time of informed consent.

         10. Patient has received systemic corticosteroid or systemic immunosuppressant within 1
             week before the first dose of investigational product. However, this criterion does
             not apply to a patient who has been on long-term (>6-month) treatment at a low dose
             (equivalent to oral prednisolone under 10 mg/day) or who received prophylactic
             immunosuppressant against contrast media allergy.

         11. Patient has received a live vaccine within 30 days before registration

         12. Patient has enrolled in another clinical trial and received an investigational product
             within 4 months before the first dose of investigational product, or patient has
             intended to be enrolled in another clinical trial in parallel with this clinical trial

         13. A patient who has an active TB infection.

         14. Female patient is pregnant (including one with positive results from a pregnancy test
             at screening), lactating, or intending to become pregnant during participation in this
             trial and before 3 months have passed after completion of this trial. However, this
             criterion does not apply to a patient who will stop lactating (from the date of
             informed consent until 30 days passed after the last treatment). Of note, female
             patients should undergo a beta-HCG test to demonstrate pregnancy status. Male patient
             who does not agree to use appropriate contraception such as the barrier method and a
             total abstinence during this trial until 3 months passed after the completion of this
             trial. (Detailed method is described in 5.7 Contraception)

         15. Patient has psychiatric disease considered to be a potential concern from the
             viewpoints of follow-up and protocol adherence

         16. Patient had given autografting or allografting of organ or tissue (receiving an
             immunosuppressant)

         17. Patient has over 10%-shorter prothrombin time (PT) compared to lower limit of normal
             (LLN) or over 1.5-fold longer activated partial thromboplastin time (APTT) compared to
             ULN at screening

         18. Patient has showed positive reaction to any of HBs antigen, HCV antibody, HIV-1
             antibody, or HIV-2 antibody at screening. However, even if it is positive for HCV
             antibody, it should not be excluded when HCV RNA test is negative.

         19. Patient is considered ineligible for this trial by the investigator or the
             sub-investigators