Inclusion Criteria:

          1. Obtained written informed consent

          2. Patients must have histologically confirmed peripheral T-cell lymphoma according to
             the 2016 revision of the World Health Organization classification of lymphoid
             neoplasms. Tumor samples are required for central pathology review to confirm the
             diagnosis.

          3. Patients must have measurable disease according to the Lugano criteria.

          4. Patients should be transplant-ineligible upon their entry into this study, and must
             have relapsed after or been refractory/intolerant to ≥ 1 (but not > 3) prior systemic
             therapy(ies) for PTCL.

          5. Adequate bone marrow reserve and organ system functions.

        Exclusion Criteria:

          1. Any unsolved toxicity > Common Terminology Criteria for Adverse Events (CTCAE) grade 1
             from previous anti-cancer therapy (except alopecia).

          2. Active infections, active or latent tuberculosis.

          3. Patients with severely decreased lung function.

          4. History of heart failure or QT interval prolongation.

          5. Central nervous system (CNS) or leptomeningeal lymphoma.

          6. History of treatment with Janus kinase (JAK) or signal transducer and activator of
             transcription 3 (STAT3) inhibitor.

          7. Patient has undergone an allogeneic stem cell transplant. Patient had autologous stem
             cell transplant within 6 months.