A Study Evaluating Venetoclax Alone and in Combination With Azacitidine in Subjects With Relapsed/Refractory Myelodysplastic Syndromes (MDS)

Inclusion Criteria:

- Subjects who have relapsed or refractory MDS.

- Subject enrolled in venetoclax monotherapy must have documented failure of prior
therapy with a hypomethylating agent (HMA). HMA-failure is defined as:

1. Relapse after initial complete or partial response or hematological improvement
after at least 4 cycles of azacitidine or at least 4 cycles of decitabine within
the last 5 years, OR

2. Failure to achieve complete or partial response or hematological improvement
after at least 4 cycles of azacitidine or at least 4 cycles of decitabine within
the last 5 years

- Subjects must have presence of < 20% bone marrow blasts per bone marrow
biopsy/aspirate at screening.

- Subject is not a candidate to undergo allogenic hematopoietic stem cell
transplantation (HSCT).

- Subject must have an Eastern Cooperative Oncology Group (ECOG) performance score of
≤2.

- Subject must have adequate hematologic, renal, and hepatic function.

Exclusion Criteria:

- Subject has received prior therapy with a BH3 mimetic.

- Subject has MDS evolving from a pre-existing myeloproliferative neoplasm (MPN).

- Subject has MDS/MPN including chronic myelomonocytic leukemia (CMML), atypical chronic
myeloid leukemia (CML), juvenile myelomonocytic leukemia (JMML) and unclassifiable
MDS/MPN.

- Subject has received allogeneic HSCT or solid organ transplantation.

- Subject has received a live attenuated vaccine within 4 weeks prior to the first dose
of study drug.

- Subject is pregnant or breastfeeding.