In 17 pts with V600 mutated tumors (excluding CRC) treated with prior MAPKi, 3 (18%) had PR and 5 (29%) had SD. In V600 mutated tumors, PRs occurred in 6 (55%) gliomas, 3 (100%) ovarian cancers, and 1 each in CRC (7%), small bowel (50%), papillary thyroid (13%) and anaplastic thyroid (25%) cancers....As single agent anticancer therapy, FORE8394 had antitumor activity in various tumors with BRAF alterations, including pts previously treated with MAPKi and pts with BRAF fusions.

48 pts were V600+ (mITT), including 14 (29%) with colorectal cancer (CRC, 1 confirmed partial response [cPR]); 4/48 V600 K/M (0 cPR). 19 pts with no prior BRAFi/MAPKi (excluding CRC) included: 6 papillary thyroid cancer (PTC), 4 anaplastic thyroid cancer (ATC), 3 high grade glioma (HGG), and others; 2/19 V600K/M (ATC, pancreas). cPR = 31.6% (6/19), CBR = 63.2% (12/19), median response time = 12.1 wks; median response duration = 13.5 mo. Objective response rate (ORR) = 20.8%; clinical benefit rate (CBR) = 35.4% at 24 weeks….FORE8394 achieved clinically relevant exposures, low rate of symptomatic AEs, and high ORR & durable PFS in BRAFi/MAPKi naïve pts with BRAFV600 solid & CNS tumors.

PLX8394 and cobicistat demonstrated a favorable safety profile and encouraging activity in patients with advanced cancers with BRAF class I and II alterations. Dynamic changes in ctDNA were predictive of clinical outcomes.