Inclusion Criteria:

          -  Willing and able to participate and comply with all trial requirements and able to
             provide signed and dated informed consent prior to initiation of any trial procedures

          -  Male or Female ≥ 18 years of age

          -  Patients with advanced or metastatic non-neurological solid tumors, who have
             progressed on standard therapy or cannot tolerate standard therapy, or for which there
             is no standard therapy preferred to enrolment in a clinical trial

          -  At least one measurable and injectable tumor of ≥ 1 cm in longest diameter (or shorter
             diameter for lymph nodes).

          -  Women of child-bearing potential (WOCBP) must have a negative urine pregnancy test at
             screening and a negative urine pregnancy test prior to administration of each dose of
             RP2 or nivolumab

          -  WOCBP must agree to use adequate birth control throughout their participation and for
             3 months after RP2 alone and 5 months after nivolumab last study treatment

          -  Males with partners of child-bearing potential must agree to use adequate birth
             control throughout their participation and for 3 months for RP2 alone and 7 months
             after nivolumab last study treatment

          -  Have laboratory values (obtained ≤ 28 days prior to first infusion day) in accordance
             with the study protocol

          -  Have an Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0-1

        Combination patients only:

          -  Baseline ECG that does not show abnormalities according to the protocol

          -  Baseline troponin < 0.06 ng/mL

          -  Baseline oxygen saturation levels that do not show abnormalities according to the
             protocol

        Exclusion Criteria:

          -  Prior treatment with an oncolytic therapy

          -  History of viral infections according to the protocol

          -  Systemic infection requiring IV antibiotics within 14 days prior to dosing

          -  Prior complications with herpes infections

          -  Chronic use of anti-virals

          -  Systemic therapies for cancer within 4 weeks of first dose (some others may be
             accepted with shorter time periods)

          -  Conditions that require certain doses of steroids (some doses and types will be
             permitted)

          -  Known active brain metastases - previously treated brain metastases may be permitted

          -  Major surgery ≤ 2 weeks prior to starting study drug

          -  Prior malignancy active with the previous 3 years; except for locally curable cancers
             that have apparently been cured

          -  Female who has a positive urine pregnancy test or is breast-feeding or planning to
             become pregnant during study treatment and 90 days for RP2 alone or 5 months for RP2
             and nivolumab after the last dose of treatment

          -  Participation in another clinical study within 4 weeks prior to the first dose

        Combination patients only:

          -  Participants with history of life-threatening toxicity related to prior immune therapy
             except those that are likely to re-occur with standard countermeasures

          -  Treatment with botanical preparations within 2 weeks prior to treatment

          -  Certain autoimmune diseases, some types will be permitted

          -  Allergy or sensitivity to study drug components

          -  History of interstitial lung disease

          -  Severe hypersensitivity to another monoclonal antibody

          -  Has received radiotherapy within 2 weeks of start of study treatment

          -  Has received a live vaccine within 30 days prior to first dose of study drug

          -  History of non-infectious pneumonitis

          -  History or current evidence of any condition, therapy, or laboratory abnormality that
             might confound the results of the study

          -  Other serious or uncontrolled medical disorders

          -  Known psychiatric or substance abuse disorders that would interfere with cooperating
             with the requirements of the study