A Phase Ib Clinical Study of AC-003 Capsules in Subjects With aGVHD.

Inclusion Criteria: 1. Male or female patients age ≥ 18 years. 2. Patients who have undergone allogeneic hematopoietic stem cell transplantation (HSCT) from any donor source (including matched unrelated donor, haplo-identical). 3. Diagnosis of grade II-IV aGVHD as per MAGIC criteria within 100 days after HSCT. 4. Diagnosis of steroid-refractory or steroid-dependent aGVHD in at least one of the following criteria: 1. Progressive Disease, defined as any target organ worsening, after 3 days of initial treatment with methylprednisolone 1\~2 mg/kg/day (or equivalent corticosteroid) 2. Not partial response after 7 days of initial treatment with methylprednisolone 1\~2 mg/kg/day (or equivalent corticosteroid) 3. Not complete response after 14 days of initial treatment with methylprednisolone 1\~2 mg/kg/day (or equivalent corticosteroid) 4. Relapse of aGVHD when corticosteroid tapering. Exclusion Criteria: 1. Evidence of aGVHD relapsed. 2. Evidence of chronic GVHD or overlap syndrome 3. Receipt of more than one allogeneic HSCT 4. Receipt of more than one systemic treatment for aGVHD in addition to corticosteroid 5. Any corticosteroid therapy for indications other than aGvHD at doses \>= 1 mg/kg/day methylprednisolone (or equivalent corticosteroid) within 7 days prior to enrolment 6. Severe organ dysfunction unrelated to aGVHD 7. Uncontrolled active infection (i.e., bacterial, fungal, or viral)