A Multi-Center Phase 2 Study to Evaluate Efficacy and Safety of Oral Abexinostat as Monotherapy in Patients With Relapsed or Refractory Follicular Lymphoma

Inclusion Criteria: 1. Life expectancy ≥ 3 months 2. Histologically confirmed grade 1, 2, or 3a follicular lymphoma (FL) 3. Have received at least two prior standard therapy lines including anti- cluster of differentiation antigen (anti-CD20) antibody and cytotoxic therapy for follicular lymphoma (FL) 4. Confirmed to be unresponsive to the last line of therapy (have stable disease or disease progression during treatment),or have disease progression following the last line of therapy 5. Have at least one radiologically measurable lymph node or extranodal lymphoid malignant lesion as assessed by computed tomography (CT) or magnetic resonance imaging (MRI); 6. Eastern Cooperative Oncology Group (ECOG) performance status of 0 to 2 7. Meet various hematological, liver function and renal function lab parameters Exclusion Criteria: 1. Histologically confirmed grade 3b follicular lymphoma, or transformed diffuse large B-cell lymphoma (DLBCL) 2. Current or history of central nervous system (CNS) lymphoma; 3. Toxicity not yet recovered from previous anti-tumor therapies 4. Uncontrolled systemic infections or infections requiring intravenous antibiotics 5. Have previously treated by abexinostat or other histone deacetylase (HDAC) inhibitors; 6. Have received steroid hormone within 7 days, chemotherapy, targeted therapy within 28 days, radiotherapy within 14 days, anti-cancer antibody therapies within 28 days 7. Unable to swallow tablets, or presence of significant functional gastrointestinal disorders that may affect the oral administration and absorption of the study drug 8. Have received autologous stem cell transplant within 3 months before the first dose, or allogeneic stem cell transplant within 6 months before the first dose 9. Presence of active graft-versus-host disease 10. Have undergone a major surgery within 28 days 11. Evidence of possible human immunodeficiency virus (HIV) infection or hepatitis C virus (HCV) infection 12. Have cardiac impairment as defined per protocol 13. Have prior history of malignancies other than follicular lymphoma