In this multi-center retrospective centrally reviewed study, we analyzed 18 patients treated with the MEKi trametinib for progressive pLGG...Alterations detected included 8 KIAA1549:BRAF-fusions, three NF1 alterations, one BRAF V600E mutation and one FGFR1 K654Q mutation....We observed 6 partial responses (PR), 2 minor responses (MR), and 10 stable diseases (SD) as best overall responses....Responses were observed in KIAA1549:BRAF- as well as neurofibromatosis type 1 (NF1)-driven tumors. Median treatment time was 12.5 months (range: 2 to 27 months)....