Select patients w/ R/R FL based on the presence of EZH2 mutation of codons Y646, A682, or A692 in tumor specimens. Increased risk of developing secondary malignancies. Avoid co-administration w/ strong or moderate CYP3A inhibitors or inducers. No dose adjustment is recommended for patients w/ mild hepatic impairment. Has not been studied in patients w/ moderate or severe hepatic impairment. Can cause fetal harm. Females of reproductive potential should use effective non-hormonal contraception during treatment & for 6 mth after the final dose. Males w/ female partners of reproductive potential should use effective contraception during treatment & for 3 mth after the final dose. Do not breastfeed during treatment & for 1 wk after the final dose. Safety & effectiveness in ped patients <16 yr have not been established.