Inclusion Criteria:

   - Able to give informed consent and agree to follow the details of participation as
   outlined in the protocol

   - Male or female subjects aged 12 years or above at the time of consent and who weigh a
   minimum of 40 kg. Only subjects aged 18 years and above will be included in Germany.

   - Clinically confirmed steroid refractory lower GI-aGVHD (MAGIC stage 1-4) prior to
   randomization

   - Have undergone alloSCT from any donor source, any conditioning regimen

   - Treated with SS plus RUX (RUX starts concomitantly to apraglutide or a maximum of 72
   hours before apraglutide initiation)

   - Women of childbearing potential (WOCBP): highly effective method of contraception and
   refrain from donating eggs during the trial and for 4 weeks after the End of Trial
   (EOT) visit

   - Male subjects with partner WOCBP: contraception and abstention from sperm donation
   during the trial and for 2 weeks after the EOT visit

Exclusion Criteria:

   - Treatment with any systemic GVHD therapy other than SS and RUX including methotrexate
   and mycophenolate mofetil at the time of randomization / Day 0

   - Concomitant treatment with Janus kinase inhibitor other than RUX at the time of
   randomization

   - Failed alloSCT due to relapse of underlying malignant disease

   - Presence of SR GI-aGVHD occurring after donor lymphocyte infusion for pre-emptive
   treatment of malignancy recurrence

   - Any use of enteral glutamine or GLP analogs or known ADA, within 6 months prior to
   randomization / Day 0

   - Significant organ system failures (respiratory renal hepatic and cardiac)

   - Presence of relapsed primary malignancy or treatment for relapse after alloHSCT

   - Presence or history of GI tumors (including the hepatobiliary system and pancreas)
   within the last five years before randomization

   - Presence of colonic polyps not removed

   - Active clinically uncontrolled infection or active tuberculosis

   - Known chronic GVHD

   - Known active GI inflammation not related to GI-aGVHD

   - Major abdominal surgery in the last 6-months prior to randomization or history of
   clinically significant intestinal adhesions

   - Abnormal liver function tests