Primary Objectives: Phase 1~--Evaluate the safety and tolerability of valemetostat in combination with R2 in subjects with R/R FL and determine the recommended phase 2 dose (RP2D) for evaluation in phase 2.~Secondary Objectives: Phase 1~Evaluate the efficacy of valemetostat in combination with R2 in R/R FL~Evaluate the pharmacokinetics (PK) of valemetostat in combination with R2~Exploratory Objective: Phase 1~Evaluate pharmacodynamic profile of valemetostat~Evaluate the efficacy of valemetostat in combination with R2 in R/R FL~Primary Objective: Phase 2~--Evaluate the efficacy of valemetostat in combination with R2 in R/R FL~Secondary Objective: Phase 2~Evaluate the ORR~Evaluate the DOR~Evaluate the time to next anti-lymphoma treatment (TTNT)~Evaluate the safety and tolerability~Evaluate the PK of valemetostat in combination with R2~Exploratory Objective: Phase 2~Evaluate the PFS of valemetostat in combination with R2 in R/R FL~Evaluate OS~Evaluate the effect of valemetostat in combination with R2 in R/R FL on epigenetic remodeling and gene expression~Evaluate changes in tumor/immune microenvironment~Evaluate pharmacodynamic profile of valemetostat
To find a recommended dose of valemetostat that can be given in combination with rituximab and lenalidomide to patients with follicular lymphoma. The safety and effects of this drug combination will also be studied