A Phase 1 Study to Evaluate SNDX- 6352 in Subjects With Active cGVHD

This is dose escalation study in patients with active chronic graft versus host disease who
have received at least 2 lines of prior therapy including ibrutinib.

Inclusion Criteria:

1. Subject must be 18 years of age or older, at the time of signing the informed consent.

2. Subjects who are allogeneic HSCT recipients with cGVHD requiring systemic immune
suppression.

3. Subjects with active cGVHD whose disease is unresponsive to ibrutinib in at least the
second line setting (due to progression of disease, intolerability or toxicity).

a. Active cGVHD is defined as the presence of signs and symptoms of cGVHD per 2014 NIH
Consensus Development Project on Criteria for Clinical trials in cGVHD.

4. Subjects may have persistent active acute and cGVHD manifestations (overlap syndrome),
as defined by 2014 NIH Consensus Development Project on Criteria for Clinical trials
in cGVHD.

5. Karnofsky Performance Scale of ≥60 with a life expectancy of at least 3 months.

6. Adequate organ and bone marrow functions.

7. Contraceptive use by men or women should be consistent with local regulations
regarding the methods of contraception for those participating in clinical studies.

8. Capable of giving signed informed consent which includes compliance with the
requirements and restrictions listed in the informed consent form (ICF) and in the
study protocol.

Exclusion Criteria:

1. Has acute GVHD without manifestations of cGVHD.

2. Any evidence (histologic, cytogenetic, molecular, hematologic, or mixed) of relapse of
the underlying cancer or post-transplant lymphoproliferative disease at the time of
screening.

3. History or other evidence of severe illness, uncontrolled infection or any other
conditions that would make the subject, in the opinion of the Investigator, unsuitable
for the study.

4. Known history of human immunodeficiency virus (HIV) or active hepatitis C virus (HCV)
or hepatitis B virus (HBV).

5. Diagnosed with another malignancy (other than malignancy for which transplant was
performed) within 3 years of enrollment, unless previously treated with curative
intent and must be approved by Sponsor medical monitor (e.g., completely resected
basal cell or squamous cell carcinoma of the skin, resected in situ cervical
malignancy, resected breast ductal carcinoma in situ, or low-risk prostate cancer
after curative resection).

6. Female subjects who is pregnant or breastfeeding.

7. Previous exposure to study intervention or known allergy/sensitivity to study
intervention.

8. Taking agents other than a corticosteroid and one calcineurin inhibitor (CNI) for
treatment of cGVHD (This does not include agents being prescribed expressly for the
treatment of acute GVHD).

9. Receiving an investigational treatment within 28 days of study entry.