Six patients will receive IFx-Hu2.0 on an outpatient basis at a single time point in a single lesion, two lesions, or three lesions, as a monotherapy (a maximum of three lesions could be injected). These patients will be assessed for any immediate adverse reactions and at Week 4 (Day 28+/-7 business days for any delayed adverse events.

Six male and/or female adult patients (greater than or equal to 18 years old), of any ethnicity and race, with unresectable stage III or stage IV cutaneous melanoma with accessible lesions, will be eligible for enrollment and treatment with IFx-Hu2.0.

To be eligible for this study, patients with unresectable metastatic disease must have failed, refused or been deemed not candidates for at least one form of systemic anti-PD-1-based immunotherapy as well as BRAF inhibition, if BRAF V600 mutated. Talimogene laherparepvec (IMLYGIC®) is indicated for local treatment of unresectable cutaneous, subcutaneous, and nodal lesions in patients with melanoma recurrent after initial surgery. Therefore, patients with unresectable cutaneous, subcutaneous, and nodal melanoma lesions recurrent after initial surgery must have failed, refused or been deemed not candidates for talimogene laherparepvec to be eligible for this study.

Enrollees will receive IFx-Hu2.0 at a single time point. Depending on the number of accessible lesions, a patient could receive up to three doses across three lesions (one dose per lesion). Forty milliliters of peripheral blood will be collected from these patients prior to treatment administration and at the follow-up visit four weeks later. The target dose will be 100 μg of plasmid DNA per lesion injected at a final dose volume of 200 μL per lesion. To allow for the observation of any acute toxicity in the first subject enrolled and prevent any occurrence of excessive toxicities in subsequent subjects, the first subject enrolled will receive a single dose of IFx-Hu2.0. Subsequent subjects will be administered the product after at least seven days. Beyond the first subject, the maximum number of lesions to be injected at any given time point in the study phase proposed is three lesions. These samples will be used to perform complete blood counts (CBC) and clinical chemistry tests. A urine sample will be obtained for urinalysis for protein and blood at the same frequency. Blood samples will be drawn for immune response evaluation as well. At the end of the study period, a biopsy of the lesion injected and a non-injected lesion (if applicable) will be collected. If the patient has a response to therapy, the patient will have the option of continuing the study at three-week intervals so long as they have not progressed. Optional tumor biopsies and peripheral blood collections may be obtained on subsequent treatment cycles.

Inclusion Criteria:

• Histologically confirmed unresectable stage III or stage IV malignant melanoma, with accessible cutaneous lesions
• Must have measurable disease greater than 3 mm
• At least one injectable lesion and one lesion for biopsy at study conclusion. Lymphocyte count ≥ 500,000 cells/mL
• Eastern Cooperative Oncology Group (ECOG) performance status ≤ 2
• Willing and able to give written, informed consent
• If male or female of childbearing potential must be willing to use a contraceptive during the study and for six months afterward. A woman is considered to be of childbearing potential unless she has had a surgical procedure that would accomplish sterility such a bilateral tubal ligation, hysterectomy or has not had menses for the past 12 months.
• Life expectancy greater than three months
• To be eligible for this study, patients with unresectable metastatic disease must have failed, refused or been deemed not candidates for at least one form of systemic anti-PD-1-based immunotherapy as well as BRAF inhibition, if BRAF V600 mutated.
• Patients with unresectable cutaneous, subcutaneous, and nodal melanoma lesions recurrent after initial surgery must have failed, refused or been deemed not candidates for talimogene laherparepvec to be eligible for this study.
• The entry laboratory criteria for subject eligibility must be less than or equal to grade 1 adverse event levels for the parameters tested as defined by CTCAE v5.0.

Exclusion Criteria:

• Known brain metastases greater than 1 cm at screening.
• Life expectancy of fewer than three months
• Prior systemic anti-cancer treatment within three weeks from start of treatment (Day 0)
• Current treatment with systemic immunosuppressive corticosteroid (greater than 10 mg of daily prednisone) doses or other immunosuppressants such as those needed for solid organ transplants. Medications needed to treat conditions such as reactive airway disease are not excluded.
• Pregnant or lactating women
• Presence of any uncontrolled and significant medical or psychiatric condition which would interfere with trial safety assessments
• Treatment with any investigational product within the three weeks preceding injection
• Immunizations for encapsulated bacteria were not given for patients who have undergone a splenectomy.
• Serious underlying medical or psychiatric conditions, active infections requiring the use of antimicrobial drugs, or active bleeding that would make the subject unsuitable or unable to participate in the study
• Concurrent chemotherapy or biological therapy. Concurrent radiotherapy is allowed as long as it is not the same site as the injected lesion.
• Uncontrolled hepatitis B, hepatitis C, or HIV infection
• History of organ allograft transplantation

Day 0 to 28 days ± 7 business days from the last dose administered.