Study to Evaluate Imetelstat (JNJ-63935937) in Subjects With International Prognostic Scoring System (IPSS) Low or Intermediate-1 Risk Myelodysplastic Syndrome (MDS)

This is a Phase 2/3, multicenter study of imetelstat that consists of 2 parts. Part 1 is an
open‐label, single-arm design to assess the efficacy and safety of imetelstat. Approximately
55 participants will be enrolled in Part 1, including the expansion cohort, and be
followed-up for safety, hematologic improvement and reduction in transfusion requirement.
Part 2 of the study will be initiated if data from Part 1 are supportive of a satisfactory
benefit/risk profile. Part 2 is a double‐blind, randomized design to compare the efficacy of
imetelstat with placebo. Approximately 170 eligible participants will be randomized in a 2:1
ratio to receive either imetelstat or placebo, respectively. Each part of the study will
consist of 3 phases: a Screening phase (up to 28 days); a treatment phase; and a
post-treatment follow-up phase which will continue until death, lost to follow-up, withdrawal
of consent, or the End of the Study (whichever occurs first). The End of the Study is defined
as 2 years after the study entry of the last participant or anytime the sponsor terminates
the study, whichever comes first.

Inclusion Criteria:

- Man or woman greater than or equal to (>=) 18 years of age

- In Part 1, diagnosis of myelodysplastic syndrome (MDS) according to World Health
Organization (WHO) criteria

- International Prognostic Scoring System (IPSS) low Risk or intermediate-1 risk MDS

- Red blood cell (RBC) transfusion dependent, defined as requiring at least 4 RBC units
transfused over an 8-week period during the 16 weeks prior to Study Entry;
pre-transfusion hemoglobin (Hb) should be less than or equal to 9.0 gram per deciliter
(g/dL) to count towards the 4 units total

- Eastern Cooperative Oncology Group (ECOG) performance status 0, 1 or 2

Exclusion Criteria:

- Participant has known allergies, hypersensitivity, or intolerance to imetelstat or its
excipients

- Participant has received an investigational drug or used an invasive investigational
medical device within 30 days prior to Study Entry or is currently enrolled in an
investigational study

- Prior treatment with imetelstat

- Have received corticosteroids greater than (>) 30 milligram per day (mg/day)
prednisone or equivalent, or growth factor treatment within 4 weeks prior to study
entry

- a) Prior treatment with a hypomethylating agent (example [eg], azacitidine,
decitabine); b) Prior treatment with lenalidomide; c) Has received an
erythropoiesis-stimulating agent (ESA) or any chemotherapy, immunomodulatory, or
immunosuppressive therapy within 4 weeks prior to study entry (8 weeks for long-acting
ESAs)