I am trying to query metadata from the Genomic Data Commons (GDC) Data Portal and used the sample code from its website: 

    import requests
    import json

    cases_endpt = 'https://api.gdc.cancer.gov/cases'

    # The 'fields' parameter is passed as a comma-separated string of single names.
    fields = ["submitter_id",
              "case_id",
              "primary_site",
              "disease_type",
              "diagnoses.vital_status"
             ]

    fields = ','.join(fields)

    params = {"fields": fields,
              "format": "TSV",
              "size": "100"
             }

    response = requests.get(cases_endpt, params = params)

    print(response.content)

However, I am not getting a tsv file in return. I am ultimately getting an FPKM instead. Any help is appreciated!