Inclusion Criteria:

          -  Patient has histologically confirmed, unresectable Stage III or Stage IV melanoma as
             defined by the American Joint Committee on Cancer (8th Edition; Gershenwald et al
             2017).

          -  Patient has not received prior systemic treatment for advanced disease. Prior adjuvant
             treatment, defined as treatment following resection of all detectable disease, is
             permitted; last dose must be at least 4 weeks before the first dose of SCIB1.

          -  Patient has been clinically evaluated and pembrolizumab has been determined to be an
             appropriate treatment for their advanced disease.

          -  Patient's BRAF status must be known; patients with BRAF mutation positive disease may
             be enrolled without BRAF inhibitor treatment at the discretion of the Investigator,
             provided that they have no evidence of rapidly progressing disease (LDH above normal
             range, clinically significant tumor-related symptoms).

          -  Patient has at least one measurable lesion per RECIST 1.1 criteria by CT scan or MRI.

          -  Patient has an archival (< 5 years of age) or fresh biopsy sample of tumor available
             for analysis of programmed death-ligand 1 (PD-L1) expression.

          -  Patient is human leukocyte antigen (HLA)-A2 positive.[*]

          -  Patient is positive for HLA-DR4, HLA-DR7, HLA-DR53 or HLA-DQ6.[*]

          -  Patient is at least 18 years of age.

          -  Patient has a life expectancy of more than 3 months.

          -  Patient has an ECOG performance status of 0 or 1.

          -  Patient has adequate organ function as determined by protocol laboratory values.

          -  Patient must be able and willing to provide written Institutional Review
             Board/Research Ethics Committee (IRB/REC) approved informed consent prior to any study
             related procedure. (In the event that the patient is re-screened for study
             participation or if a protocol amendment alters the care of an ongoing patient, a new
             IRB/REC-approved informed consent form must be signed.)

          -  Women of child-bearing potential (including women ≤ 12 months from last menstrual
             period) must have a negative serum pregnancy test during Screening (within the 72
             hours before planned administration of the first dose of study drug on Day 1) and be
             neither breastfeeding nor intending to become pregnant during study participation, and
             shall be warned of potential fetal harm from pembrolizumab. Women of child-bearing
             potential must agree to use highly effective contraceptive methods prior to study
             entry, for the whole duration of study treatment, and for 120 days after
             discontinuation of SCIB1 or pembrolizumab, whichever is last.

          -  Men who are potentially fertile with partners of childbearing potential must agree to
             use highly effective contraceptive methods for the whole duration of study treatment
             and for 120 days after discontinuation of SCIB1 or pembrolizumab, whichever is last.

          -  Patient must be willing and able to comply with scheduled visits, treatment plan,
             laboratory tests and other study procedures.

        [*] HLA testing will be conducted at accredited laboratories by molecular (DNA) typing.

        Exclusion Criteria:

          -  Patient has a diagnosis of uveal or ocular melanoma.

          -  Patient has active central nervous system metastases or carcinomatous meningitis
             (patients with a response to previous treatment for brain metastases are eligible
             provided that they are stable without MRI evidence of progression for at least 4 weeks
             prior to the first dose of study treatment, and systemic steroids have been withdrawn
             for at least 2 weeks).

          -  Patient has previously received a treatment to block cytotoxic T lymphocyte associated
             protein 4, programmed cell death protein 1, PD-L1, or programmed death-ligand 2 with
             the following exception: patients who have received adjuvant treatment with these
             treatments are eligible.

          -  Patient is expected to require any other form of systemic or localized antineoplastic
             therapy while on study.

          -  Patient is taking any systemic steroid therapy within 1 week of the first dose of
             study drug or is receiving any other form of immune suppressant medication.
             Physiological doses of systemic steroids such as those for the management of adrenal
             insufficiency, and topical and inhaled steroids, such as those for the management of
             asthma, are permitted.

          -  Patient is receiving treatment with any investigational product within 28 days (or 5
             half-lives of the treatment concerned) prior to the first dose of study treatment.

          -  Patient has a previous (within 5 years) or current malignancy with the exception of
             melanoma, and curatively treated local tumors such as carcinoma-in-situ of the breast,
             cervix, basal or squamous cell carcinoma of the skin, prostate cancer with Gleason
             grade < 6 and prostate-specific antigen within normal range.

          -  Patient has a concurrent illness which would preclude study conduct and assessment,
             including, but not limited to uncontrolled medical conditions, uncontrolled and active
             infection (considered opportunistic, life threatening, or clinically significant),
             uncontrolled risk of bleeding, or uncontrolled diabetes mellitus, or pulmonary disease
             (including obstructive pulmonary disease, pulmonary fibrosis, and history of
             symptomatic bronchospasm), or alcoholic liver disease, or primary biliary cirrhosis.
             Caution should be used for patients with suspected or diagnosed epilepsy.

          -  Patient has any electronic stimulation device that cannot be removed during the
             administration procedure, such as cardiac demand pacemaker, automatic implantable
             cardiac defibrillator, nerve stimulator or deep brain stimulator.

          -  Patient has a skin-fold measurement of the cutaneous and subcutaneous tissue for all
             eligible injection sites (deltoid or quadriceps muscles with intact lymph drainage)
             that is > 50 mm.

          -  Patient has New York Heart Association class III or IV heart disease, myocardial
             infarction within previous 6 months, a heart rate of ≤ 50 beats per minute, a history
             of significant cardiac abnormality and/or clinically significant abnormal baseline ECG
             reading, active ischemia, or any other uncontrolled cardiac condition such as angina
             pectoris, clinically significant arrhythmia requiring therapy including
             anticoagulants, uncontrolled hypertension (> 140/90 mm Hg), significant
             cerebrovascular disease, or congestive heart failure.

          -  Patient has a history of severe hypersensitivity reaction to treatment with a
             monoclonal antibody.

          -  Patient has an active autoimmune disease or a documented history of autoimmune disease
             or syndrome that requires systemic steroids or immunosuppressive agents (patients with
             vitiligo or resolved childhood asthma/atopy are an exception and are not excluded for
             these conditions). The following patients are not excluded from the study: patients
             who require intermittent use of bronchodilators or local steroid injections, patients
             with hypothyroidism stable on hormone replacement, and patients who receive
             physiological doses of steroids as replacement therapy, such as those for the
             management of adrenal insufficiency. In such cases the recruiting investigator should
             discuss the patients' eligibility with the study Medical Monitor prior to enrolment.

          -  Patient has received a vaccine within the 28 days prior to first dose of study
             treatment.

          -  Patient has a known history of human immunodeficiency virus or has any positive test
             for hepatitis B virus or hepatitis C virus indicating active acute or chronic
             infection.

          -  Patient has a known current or recent history (within the last year) of substance
             abuse including illicit drugs or alcohol.