SYST-20 TARGETED THERAPY MATCHED TO GENOMIC ALTERATIONS (BRAFV600E, NTRK, FGFR, ROS1, PIK3CA, PTEN) IN PATIENTS WITH RECURRENT IDH WILDTYPE GLIOBLASTOMA: A REAL-LIFE COHORT ANALYSIS FROM VENETO INSTITUTE OF ONCOLOGY, PADUA (ITALY)

We retrospectively analyzed 34 patients (pts) [19 males, 15 females, median age 54] with recurrent IDH wildtype glioblastoma treated with target therapy (TT) based on their next-generation sequencing (NGS) profile, between March2020 and December2022 at Veneto Institute of Oncology, Padua (Italy). ECOG PS was 0-1 in 29 pts. All pts received previous radiotherapy and temozolomide. NGS was obtained with FoundationOne®CDx on formalin-fixed paraffin-embedded samples. We identified 6 druggable genomic alterations, classified according to ESCAT (ESMO Scale for Clinical Actionability of molecular Targets): BRAFV600E mutation (IB), NTRK1-2-3 fusions (IC), FGFR1-2-3 alterations (IIB), ROS1 fusions (IIIA), PIK3CA mutations (IIIA) and PTEN loss/mutations (IIIA). The median line of therapy with TT was 3 (range 2-7). TT was dabrafenib/trametinib (9 pts), larotrectinib (2 pts), erdafitinib (4 pts), entrectinib (1 pt), alpelisib (6 pts), ipatasertib+/-atezolizumab (12 pts). At data cut-off (March2023), 19 patients had died. In the entire cohort, median overall survival and progression-free survival (PFS) after starting TT was 8.72 and 2.14 months, respectively. The dabrafenib/trametinib subgroup had the longest median PFS (5.23 months), a disease control rate (DCR) of 77%, an objective response rate of 22%, and a median duration of response of 22.5 months. 7/9 pt had died and 2 pts are continuing dabrafenib/trametinib. The pt with ROS1-GOCP fusion maintained a complete response for 12 months with entrectinib. Among the others, no complete/partial responses were detected. DCR due to stable disease was 50% in larotrectinib and erdafitinib subgroups and 8.3% in ipatasertib+/-atezolizumab subgroup. No toxicities were reported in dabrafenib/trametinib subgroup. Among all patients, no grade 4 drug-related adverse events were observed and in any case TT was interrupted for toxicity. Our results confirm the activity of dabrafenib/trametinib in BRAFV600E mutant glioblastoma pts and might suggest further explorations in targeting ROS1 and FGFR.