Inclusion Criteria:

          -  At least 18 years of age

          -  Participants must have histologically or cytologically confirmed renal cell
             carcinoma,urothelial carcinoma, non-small cell lung cancer, squamous cell carcinoma of
             the head and neck or melanoma.

          -  Participants must have recurrent or metastatic disease that is not amenable to local
             therapy with curative intent (surgery or radiation therapy with or without
             chemotherapy).

          -  Must be willing and able to give informed consent and adhere to protocol therapy;
             written informed consent and any locally required authorization must be obtained from
             the participant prior to performing any protocol-related procedures, including
             screening evaluations

          -  Prior exposure to PD-1/PD-L1 inhibitor monotherapy, or prior exposure to CTLA-4
             inhibitor monotherapy is allowed.

          -  Eastern Cooperative Oncology Group (ECOG) performance status 0-2

          -  Adequate normal organ and marrow function

          -  Participants who are receiving therapeutic anti-coagulant therapy are eligible.

          -  Palliative radiation therapy is allowed to non-target lesions at the discretion of the
             treating physician.

          -  Participants must have measurable disease, defined as at least one lesion that can be
             accurately measured in at least one dimension (longest diameter to be recorded) as
             outlined in RECIST version 1.1.

          -  Life expectancy of greater than 3 months.

          -  Female participants of childbearing potential must have a negative serum pregnancy
             test within 7 days prior to treatment.

          -  Body weight must be greater than 66 pounds.

        Exclusion Criteria:

          -  Prior exposure to a combination of IRX-2 regimen, PD-1/PD-L1 inhibitors and CTLA-4
             inhibitors are excluded. Prior exposure to PD-1/PD-L1 inhibitors is allowed.

          -  Radiation therapy with a curable intent within 30 days of first dose of study
             treatment is excluded. However, radiation therapy with a palliative intent is allowed
             to treat after 14 days from the last dose of radiation.

          -  Any medical contraindications or previous therapy that would preclude treatment with
             the IRX-2 Regimen, or nivolumab.

          -  Any unresolved toxicity Grade 2 or greater from previous anticancer therapy with the
             exception of alopecia, vitiligo, and the laboratory values defined in the inclusion
             criteria.

          -  Participants with irreversible toxicity not reasonably expected to be exacerbated by
             treatment with IRX-2, or nivolumab may be included only after consultation with the
             study physician.

          -  Active or prior documented autoimmune or inflammatory disorders

          -  Current or prior use of immunosuppressive medication within 14 days before the first
             dose of study treatment. Some exceptions apply.

          -  Major surgical procedure (as defined by the Investigator) within 28 days prior to the
             first dose of study treatment. Note: Local surgery of isolated lesions for palliative
             intent is acceptable.

          -  History of allogenic organ transplantation.

          -  Symptomatic cardiopulmonary disease, coronary artery disease, serious arrhythmia or
             chronic lung disease. Participants with these conditions who are stable with
             relatively minor symptoms and who are appropriate candidates for systemic treatments
             need not be excluded.

          -  Myocardial infarction within the last 3 months.

          -  Known infection with hepatitis B, hepatitis C, or HIV.

          -  Signs or symptoms of systemic infection (use of antibiotics to treat superficial
             infection or contamination of tumor shall not, by itself, be considered evidence of
             infection).

          -  Clinically significant gastritis or peptic ulcer disease

          -  Stroke or other symptoms of cerebral vascular insufficiency within the last 3 months.

          -  Allergy to ciprofloxacin (or other quinolones).

          -  Previous diagnosis of invasive cancer from which the individual is not disease-free
             AND that has required treatment within the past 3 years, except for superficial skin,
             cervical cancer in-situ, or early stage prostate or bladder cancer (i.e. treatment
             with curative intent and long term disease-free expectations).

          -  History of leptomeningeal carcinomatosis

          -  Known allergy or hypersensitivity to any of the study drugs or any of the study drug
             excipients.

          -  Female participants who are pregnant or breastfeeding or male or female participants
             of reproductive potential who are not willing to employ effective birth control from
             screening to 1 year after the last dose of study treatment.