Efficacy and Tolerability of Entospletinib in Combination With Systemic Corticosteroids as First-Line Therapy in Adults With Chronic Graft Versus Host Disease (cGVHD)

Key Inclusion Criteria:

- Willing and able to provide written informed consent

- Male or non-pregnant, non-lactating, females

- Newly diagnosed cGVHD defined by:

- At least 100 days after receiving any allogeneic hematopoietic stem cell
transplant AND

- Receiving a new course of systemic corticosteroids (≥ 0.5 mg/kg/day) as
first-line cGVHD therapy at least 1 day and no more than 21 days prior to first
dose of ENTO/Placebo AND

- Moderate to severe cGVHD as assessed by NIH cGVHD Diagnosis and Staging Criteria
(NCDSC) with at least three organ systems involved OR one organ system with a
score of 2 OR lung organ score = 1

- Individuals who have undergone transplant for hematologic malignancy are required to
be in complete remission.

- Have either a normal ECG or one with abnormalities that are considered clinically
insignificant by the investigator in consultation with the Sponsor

Key Exclusion Criteria:

- Inability to begin systemic corticosteroids therapy at a dose of ≥ 0.5 mg/kg/day (or
equivalent)

- Uncontrolled infection within 4 weeks prior to randomization

- History of the following therapies in the post-transplant period:

- B cell depleting biologic agents

- CD19 CAR-T cells based therapies

- BTK/SYK/JAK/PI3K inhibitors

- Phototherapy-unless administered for acute GVHD

- Treatment of cGVHD with anti-thymocyte globulins (ATG), or campath within 60 days of
screening visit unless used for treatment of acute GVHD

- Severe organ dysfunction manifested during screening period:

- Requiring supplemental oxygen at more than 2 L/min

- Uncontrolled arrhythmia or heart failure

Note: Other protocol defined Inclusion/Exclusion criteria may apply.