All pts were identified as BRAF or NF1 alterations (BRAF V600E 12/23, 52.2%, KIAA1549-BRAF fusion 8/23, 34.8% and NF1 mut 3/23, 13.0%). At a median follow-up of 7.79 months, 22 pts were evaluated for efficacy: 6 partial response (PR, 27.3%, unconfirmed PR 3), 9 minor response (MR, 40.9%, unconfirmed MR 2), and 7 stable disease (SD, 31.8%)...The preliminary study results showed that treatment of FCN-159 was remarkably efficacious for pLGG pts. FCN-159 is well tolerated and easily manageable, without new safety signal observed.