ERK1/2 Inhibitor Ulixertinib in Pan-cancer Patients with BRAF Fusions or Non-V600E/K Mutations: Results from the NCI-MATCH ECOG-ACRIN Trial (EAY131) Subprotocol Z1L
Vivek Subbiah, Fengmin Zhao, Ragini R. Kudchadkar, Ryan J. Sullivan, Helen X. Chen, Robert J. Gray, Victoria Wang, Lisa M. McShane, Larry V. Rubinstein, David Patton, P. Mickey Williams, Stanley R. Hamilton, Tilak K. Sundaresan, Barbara A. Conley, James V. Tricoli, Carlos L. Arteaga, John J. Wright, Lyndsay N. Harris, Peter J. O'Dwyer, Alice P. Chen, Keith T. FlahertyAbstract
Purpose: Mutations in BRAF at codons other than V600 (non-V600) and BRAF fusions confer dependence on RAF-MEK-ERK pathway. Subprotocol Z1L (EAY131-Z1L) investigated the clinical activity of ulixertinib (ERK1/2 inhibitor) in patients with tumors harboring these alterations. Patients and Methods: In this single-arm study, patients with BRAF non-V600 mutation or BRAF fusion were given ulixertinib orally, at a dose of 600 mg twice daily, continuously for each 28-day cycle until progression or intolerability. The primary endpoint was objective response rate (ORR). Secondary endpoints included progression-free survival (PFS), 6-month PFS, and overall survival (OS). Results: Among 34 eligible patients, median age was 66.5; 50% were female, 88% were white, 9% black, 3% Asian. ECOG PS 1 in 74% of patients. Median number of prior therapies was 4. Tumor types included multiple gastrointestinal malignancies (n = 16), lung cancer, melanoma (n = 3 each), among others. No patients achieved CR or PR, resulting in ORR = 0%. Stable disease was the best response in 7/26 centrally confirmed cases. Median PFS was 1.7 months (90% CI: 1.1, 2.2), 6-month PFS rate was 5% (90% CI: 0.6%, 17.7%), and median OS was 3.5 months (90% CI: 1.9, 5.4). Twenty patients (57%) had grade 3 toxicities, and one patient (3%) had grade 4 toxicity as their worst toxicity; there were no grade 5 toxicities. Conclusion: Ulixertinib had no demonstrable evidence of clinical activity in this small, heavily pretreated population of patients with tumors harboring BRAF fusions, or with non-V600E, non-V600K BRAF mutations.