Inclusion Criteria:

1. Male or female participants aged ≥18 years at the time of screening
2. Recipient of an hematopoietic stem cell transplantation (HSCT)
3. The disease indication for which the participant required HSCT must be in remission
4. Acute graft-versus-host disease (GvHD), including lower GI involvement (modified International Bone Marrow Transplant Registry (IBMTR) Severity Stage 1 to 4 [>500 mL diarrhea/day]), with or without other organ system involvement Participants should be newly diagnosed. Treatment with methylprednisolone/systemic steroids must have been initiated within 72 hours prior to the first dose of study treatment after enrollment.
5. Evidence of myeloid engraftment (absolute neutrophil count ≥0.5 x 10^9/L)
6. Lower GI GvHD manifested by diarrhea must have other causes of diarrhea ruled out (eg, negative for Clostridium difficile or cytomegalovirus [CMV] infection or oral magnesium administration)
7. Karnofsky Performance Score ≥50%
8. If female of childbearing potential, participant presents with a negative blood pregnancy test
9. Females of childbearing potential with a fertile male sexual partner must agree to employ adequate contraception for the duration of the study.
10. Males must use adequate contraception and must not donate sperm for the duration of the study.
11. Participant is willing and able to comply with the requirements of the protocol

Exclusion Criteria:

1. Participant with manifestations of chronic GvHD
2. Participant with acute/chronic GvHD overlap syndrome
3. Participant whose GvHD developed after donor lymphocyte infusion
4. Participant with myocardial infarction within 6 months prior to enrollment or New York Heart Association Class III or IV heart failure, uncontrolled angina, severe uncontrolled ventricular arrhythmias or electrocardiographic evidence of acute ischemia or active conduction system abnormalities. Prior to the first dose of study treatment, any electrocardiogram (ECG) abnormality at screening must be documented by the investigator as not medically relevant
5. Participant with evidence of recurrent malignancy
6. Participant with veno-occlusive disease (ie, sinusoidal obstruction syndrome)
7. Participant receiving GvHD treatment other than continued prophylaxis (eg, cyclosporine and/or mycophenolate mofetil, etc) or corticosteroid therapy. In addition, a participant who received the first dose of corticosteroid therapy for acute GvHD with lower GI involvement more than 72 hours before the first dose of study treatment is not eligible for the study
8. Participant with severe sepsis involving at least 1 organ failure
9. Participant who is seropositive or positive in the nucleic acid test for human immunodeficiency virus (HIV)
10. Participant with active hepatitis B or C
11. Participant has participated in another clinical study involving an investigational product (IP) or investigational device within 30 days prior to enrollment or is scheduled to participate in another clinical study involving an IP or investigational device during the course of this study
12. If female, participant is pregnant or lactating at the time of enrollment, or has plans to become pregnant during the study
13. Participant with a serious medical or psychiatric illness likely to interfere with participation in the study
14. Participant is a family member or employee of the investigator