Selinexor+Imatinib Combo Found Well Tolerated in IM-Resistant Advanced GIST
Results following the phase Ib portion in the evaluation of imatinib in combination with selinexor displays well tolerability in patients with imatinib (IM)-resistant, advanced GIST, presented at the 2021 ASCO Annual Meeting.
A standard 3+3 dosing schema was applied to determine the recommended phase II dose (RP2D) of this combination. Investigator-assessed response was evaluated every 8 weeks using RECIST 1.1. To note, prior intolerance to imatinib was not permitted.
At data cutoff of Sep 25, 2020, 12 patients were enrolled and received treatment with imatinib (IM) 400 mg and selinexor once weekly at doses of 60 mg, 80 mg) and 100 mg.
Patients, with ages ranging from 46-77, were all evaluable for toxicity response, with no unexpected toxicities observed. The ORR in all patients evaluable for response was 67%, with two patients achieving PR (17%), and 6 patients SD (50%) as the best response.
Additionally, the reported CBR was 42%, with PFS of 3.5 months. Four patients remain on trial following the data cutoff. Common adverse reactions included anemia, neutropenia, vomiting, and fatigue.
To conclude, results demonstrate the combination of IM and selinexor is well-tolerated and has clinical activity in heavily pretreated GIST. The trial is presently continues to study selinexor as single agent in the IM-resistant GIST population. -Alexis Hyams
