Efficacy and Tolerability of 5-Year Adjuvant Imatinib Treatment for Patients With Resected Intermediate- or High-Risk Primary Gastrointestinal Stromal Tumor: The PERSIST-5 Clinical Trial

Abstract

Importance: Three years of adjuvant imatinib mesylate therapy is associated with reduced recurrence rates and improved overall survival in patients with high-risk primary gastrointestinal stromal tumor (GIST) compared with patients who receive 1 year of treatment. The impact of a longer duration of therapy is unknown.

Objective: To determine whether adjuvant treatment for primary GIST with imatinib for 5 years is tolerable and efficacious.

Design, setting, and participants: This prospective, single-arm, phase 2 clinical trial (Postresection Evaluation of Recurrence-free Survival for Gastrointestinal Stromal Tumors With 5 Years of Adjuvant Imatinib [PERSIST-5]) included adult patients with primary GIST (expressing KIT) at 21 US institutions who underwent a macroscopically complete resection and were at intermediate or high risk of recurrence, defined as primary GIST at any site measuring 2 cm or larger with 5 or more mitoses per 50 high-power field or nongastric primary GIST measuring 5 cm or larger. Data were collected from August 5, 2009, through December 20, 2016.

Interventions: Imatinib, 400 mg once daily, orally for 5 years or until discontinuation of therapy because of progression or intolerance.

Main outcomes and measures: The primary end point was recurrence-free survival (RFS). The secondary end point was overall survival.

Results: Of the 91 patients enrolled, 48 (53%) were men with a median age of 60 years (range, 30-90 years). Median tumor size was 6.5 cm (range, 2.3-30.0 cm). Median treatment duration was 55.1 months (range, 0.5-60.6 months); 46 patients (51%) completed 5 years of imatinib therapy. Estimated 5-year RFS was 90% (95% CI, 80%-95%), and overall survival was 95% (95% CI, 86%-99%). Recurrence was noted in 7 patients: 1 had disease recur while receiving imatinib (PDGFRA D842V mutation) and died; 6 had disease recur after discontinuation of imatinib therapy. Two additional deaths were unrelated to treatment or tumor progression. Forty-five patients (49%) stopped treatment early because of patient choice (10 [21%]), adverse events (15 [16%]), or other (11 [12%]). All 91 patients experienced at least 1 adverse event, and 17 (19%) experienced grade 3 or 4 adverse events.

Conclusions and relevance: In this first adjuvant trial, to our knowledge, of patients with resected primary GIST who received 5 years of imatinib therapy, no patient with imatinib-sensitive mutations had disease recur during therapy. For patients in whom disease recurred, recurrence was within 2 years of discontinuation of imatinib therapy. Approximately half of the patients discontinued treatment early, most commonly because of patient choice, thus emphasizing the importance of close clinical monitoring to continue imatinib treatment for patients at appropriate risk.

Trial registration: ClinicalTrials.gov identifier: NCT00867113.

Conflict of interest statement

Conflict of Interest Disclosures: Dr Raut reported being an author for the online medical resource UpToDate (Wolters Kluwer). Dr Maki reported being a consultant for AADi, Arcus Ventures, Bayer, Eisai Company, Gem Pharmaceuticals, Immune Design, Karyopharm Therapeutics, Eli Lilly and Company/ImClone, Presage Biosciences, Sarcoma Alliance for Research Through Collaboration, and TRACON Pharma; receiving research funding from Immune Design, Eli Lilly and Company, and TRACON Pharma; and being an author and editor for the online medical resource UpToDate (Wolters Kluwer). Dr Trent reported serving on the advisory board for Bayer and Novartis. Ms Williams reported being an employee of Novartis. Dr Purkayastha reported being an employee of Novartis and having stock and other ownership interests in Novartis. No other disclosures were reported.

Figures

Figure 1.. Trial Flow Diagram

aOne death occurred while the patient had interrupted imatinib treatment for an unrelated medical issue.

Figure 2.. Efficacy of Imatinib Therapy

A, Recurrence-free survival at 5 years (60 months) was 90% (95% CI, 80%-95%). + Indicates censored. B, Disease in 7 patients recurred. One patient’s disease recurred while receiving imatinib mesylate therapy and the patient discontinued imatinib therapy at the time of recurrence. C, Overall survival at 5 years was 95% (95% CI, 86%-99%). + Indicates censored.

Figure 3.. Timing and Reasons for Early Discontinuation of Imatinib Therapy

aBoth deaths were unrelated to tumor recurrence or imatinib mesylate treatment.