The following article features coverage from the Connective Tissue Oncology Society (CTOS) in Maui, Hawaii. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

Patients with a gastrointestinal stromal tumor (GIST) may benefit from BLU-285, which inhibits both KIT and PDGFRα, according to an oral presentation at the Connective Tissue Oncology Society (CTOS) 2017 Annual Meeting.1

The majority of GISTs are driven by KIT or PDGFRa mutations. While imatinib, a tyrosine kinase inhibitor, is an effective treatment for these GISTs, few options are available to patients who acquire imatinib resistance.

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For this 2-part, phase 1 study ( Identifier: NCT02508532), researchers are evaluating whether BLU-285, which is active regardless of resistance-associated mutations, is safe and effective among patients with an imatinib-resistant GIST.

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One hundred and sixteen patients who had received at least 1 prior tyrosine kinase inhibitor — including imatinib — were enrolled to the dose-escalation phase or expansion cohort. The maximum tolerated dose was 400 mg and the recommended phase 2 dose was 300 mg.

Among the 31 patients with PDGFRa D842 resistance mutations, 1 patient had a confirmed complete response, 21 had a confirmed partial response, and 9 had stable disease by RECIST criteria. The estimated 12-month progression-free survival (PFS) was 78%.

Among the 30 patients with KIT mutations, however, only 5 patients had a partial response confirmed by RECIST criteria; stable disease was noted in 18 patients using the same criteria. Patients with KIT mutations treated at higher doses (300 mg or more) had a PFS of 11.5 months.

Grade 3 fatigue, nausea, and anemia were the only grade 3 or worse adverse events noted in at least 5% of patients.

Sixty-seven patients remain on treatment; final results will be presented at an upcoming meeting.

Read more of Cancer Therapy Advisor‘s coverage of the Connective Tissue Oncology Society (CTOS) by visiting the conference page.

Editor’s note: This article has been updated to reflect more recent trial results.


  1. Heinrich M, Jones RL, von Mehren M, et al. Clinical activity of BLU-285 a highly potent and selective KIT/PDGFRα inhibitor designed to treat gastrointestinal stromal tumor (GIST). Oral presentation at: Connective Tissue Oncology Society (CTOS) 2017 Annual Meeting. November 8-11, 2017; Maui, Hawaii.