∙ Patients must fulfill all of the following criteria to be eligible for admission to the study. Any exceptions from the protocol-specific selection criteria must be approved by the Principal Investigator and/or the Institutional Review Board (IRB) before enrollment.

• Age \>/= 12 years at the time of informed consent

• Willing and able to provide written informed consent/assent for the trial

• Willing to comply with treatment protocol

• Have a histologically confirmed metastatic and/or locally advanced sarcoma

• Eligible for standard treatment with pembrolizumab

• Eligible for an isolated limb infusion (ILI) as determined by the treating physician

• Have undergone at least one prior line of systemic therapy (e.g. chemotherapy, immunotherapy, targeted or biological therapy) or have declined the standard of care systemic option.

• Have measurable disease (at least one index lesion) as defined by RECIST 1.1 or by clinical measurement for superficial lesions not amenable to radiographic surveillance. Index lesions must not be chosen from a previously irradiated field unless there has been radiographically and/or pathologically documented tumor progression in that lesion prior to enrollment.

• Adequate performance status: ECOG \</= 2 or KPS \>/= 60%

• Adequate organ function determined within 3 weeks of treatment initiation, defined as follows:

‣ Hemoglobin \>/= 8.0 g/dL

⁃ Absolute neutrophil count \>/= 1,000/mm\^3 (1.0 x 10\^9/L)

⁃ Platelet count \>/= 50,000/mm\^3 (50 x 10\^9/L)

⁃ Serum bilirubin \</= 1.5 x upper limit of normal (ULN) OR direct bilirubin \</= ° ° ULN for a patient with total bilirubin level \> 1.5 x ULN Aspartate aminotransferase (AST) \</= 2.5 x ULN OR \</= 5 x ULN for patients with liver metastases

⁃ Alanine aminotransferase (ALT) \</= 2.5 x ULN OR \</= 5 x ULN for patients with liver metastases

⁃ Alkaline phosphatase \< 5 x ULN

⁃ Serum creatinine \</= 1.5 x ULN or a measured or calculated creatinine clearance \>/= 60 mL/min for a patient with creatinine levels \> 1.5 x institutional ULN (Note: Creatinine clearance need not be determined if the baseline serum creatinine is within normal limits. GFR can also be used in place of creatinine or CrCl)

⁃ International normalized ratio (INR) or prothrombin time (PT) \</= 1.5 X ULN unless patient is receiving anticoagulant therapy as long as PT or PTT is within therapeutic range of intended use of anticoagulants

⁃ Activated partial thromboplastin time (aPTT) \</= 1.5 x ULN unless subject is receiving anticoagulant therapy as long as PT and PTT is within therapeutic range of intended use of anticoagulants

∙ Creatinine clearance should be calculated per institutional standard.

∙ For female patients of childbearing potential, negative serum pregnancy test at screening visit and within 72 h prior to the first dose of study medication.