The following article features coverage from the American Society of Clinical Oncology 2020 meeting. Click here to read more of Cancer Therapy Advisor‘s conference coverage.

Binimetinib in combination with imatinib in the frontline setting appeared to improve clinical outcomes for patients with advanced gastrointestinal stromal tumors (GIST), according to the results of a single-institution, single-arm phase 2 trial (ClinicalTrials.gov Identifier: NCT01991379). The trial results were reported at the ASCO20 Virtual Scientific Program.

A total of 39 of 40 patients who received the combination at Memorial Sloan Kettering Cancer Center in New York City were evaluable for analysis. The median age of the patient population was 60 years (range, 29-78 years) and most were male (70%).

The trial met its primary endpoint, showing an overall response rate of 66.7% (26 of 39 patients), which included only confirmed partial responses. (For the trial to be considered positive, at least 24 partial responses were needed.)

Patients who achieved a partial response maintained that response for a median of 30 months.


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“Historically, the objective response rate of imatinib in frontline setting is 45% to 52%,” said study presenter Ping Chi, MD, PhD, department of medicine, Memorial Sloan Kettering Cancer Center.

In addition, 6 of 7 patients with tumors that were previously unresectable had tumors that became resectable after treatment, translating to a resectability conversion rate of 85.7% (95% CI, 42%-100%).

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The median progression-free survival (PFS) for the combination therapy was 29.9 months and the median overall survival had not yet been reached.

For context, Dr Chi said, “Historically, median PFS of imatinib-treated patients in the frontline setting is 18 to 24 months, and the historical median overall survival is 47 to 55 months.”

The most common treatment-associated adverse events were edema, rash, diarrhea, and fatigue. Patients also had grade 3 or 4 anemia (6.8%), neutrophil count decrease (9.1%), hypophosphatemia (13.6%), and creatine phosphokinase elevation (63.6%), which was asymptomatic.

“With these data, we believe the combination strategy is promising and warrants further evaluation in the first-line treatment of advanced GIST,” Dr Chi concluded.

Read more of Cancer Therapy Advisor‘s coverage of the ASCO 2020 meeting by visiting the conference page.

Reference

Chi P, Qin L, Kelly CM, et al. A phase II study of MEK162 (binimetinib [BINI]) in combination with imatinib in patients with untreated advanced gastrointestinal stromal tumor (GIST). Presented at: ASCO20 Virtual Scientific Program. J Clin Oncol. 2020;38(suppl):abstr 11508.