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ABSTRACT: Purpose
This phase Ib trial was designed to evaluate the safety and early efficacy signal of the combination of imatinib and binimetinib in patients with imatinib-resistant advanced gastrointestinal stromal tumors (GISTs).Patients and methods
This trial used a standard 3 + 3 design to determine the recommended phase II dose (RP2D). Additional patients were enrolled on an expansion cohort at the RP2D enriching for succinate dehydrogenase (SDH)-deficient GISTs to explore potential efficacy.Results
The trial enrolled nine patients in the dose-escalation cohort and 14 in the dose-expansion cohort including six with SDH-deficient GISTs. Imatinib 400 mg daily with binimetinib 45 mg twice daily was established as the RP2D. Dose-limiting toxicity (DLT) was asymptomatic grade 4 creatinine phosphokinase (CPK) elevation. The most common non-DLT grade 3/4 toxicity was asymptomatic CPK elevation (69.6%). Other common ≥grade 2 toxicities included peripheral edema (17.4%), acneiform rash (21.7%), anemia (30.4%), hypophosphatemia (39.1%), and aspartate aminotransferase (AST) increase (17.4%). Two serious adverse events occurred (grade 2 dropped head syndrome and grade 3 central retinal vein occlusion). No unexpected toxicities were observed. Limited clinical activity was observed in KIT-mutant GIST. For SDH-deficient GISTs, one of five had confirmed RECIST1.1 partial response (PR). The median progression-free survival (mPFS) in patients with SDH-deficient GIST was 45.1 months [95% confidence interval (CI), 15.8-not estimable (NE)]; the median overall survival (mOS) was not reached (95% CI, 31.6 months-NE). One patient with a refractory metastatic SDH-deficient GIST had an exceptional pathologic response and durable clinical benefit.Conclusions
The combination of imatinib and binimetinib is safe with manageable toxicity and has encouraging activity in SDH-deficient but not imatinib-refractory KIT/PDGFRA-mutant GISTs. The observed clinical benefits provide a motivation for a larger trial of the combination strategy in SDH-deficient GISTs.
SUBMITTER: Chi P
PROVIDER: S-EPMC9012681 | biostudies-literature | 2022 Apr
REPOSITORIES: biostudies-literature

Chi Ping P Qin Li-Xuan LX Camacho Niedzica N Kelly Ciara M CM D'Angelo Sandra P SP Dickson Mark A MA Gounder Mrinal M MM Keohan Mary L ML Movva Sujana S Nacev Benjamin A BA Rosenbaum Evan E Thornton Katherine A KA Crago Aimee M AM Francis Jasmine H JH Martindale Moriah M Phelan Haley T HT Biniakewitz Matthew D MD Lee Cindy J CJ Singer Samuel S Hwang Sinchun S Berger Michael F MF Chen Yu Y Antonescu Cristina R CR Tap William D WD
Clinical cancer research : an official journal of the American Association for Cancer Research 20220401 8
<h4>Purpose</h4>This phase Ib trial was designed to evaluate the safety and early efficacy signal of the combination of imatinib and binimetinib in patients with imatinib-resistant advanced gastrointestinal stromal tumors (GISTs).<h4>Patients and methods</h4>This trial used a standard 3 + 3 design to determine the recommended phase II dose (RP2D). Additional patients were enrolled on an expansion cohort at the RP2D enriching for succinate dehydrogenase (SDH)-deficient GISTs to explore potential ...[more]