Three-Year Imatinib Regimen Delivers Optimal GIST Treatment

Heikki Joensuu, MD, PhD

According to research unveiled on Sunday at the ASCO conference in Chicago, 3 years of treatment with imatinib (Gleevec) after surgery in patients with high-risk gastrointestinal stromal tumors (GIST) improved overall and recurrence-free survival (RFS) compared with 1 year of treatment.

The phase III trial demonstrated that 3 years of postoperative treatment improved 5-year survival rates compared with a standard 1-year of postoperative treatment with the drug (92.0% vs 81.7%; P = .019), according to lead author Heikki Joensuu, MD, PhD, professor of oncology at Helsinki University Central Hospital in Finland.

He noted that approximately 85% of patients who have advanced GIST respond to imatinib, with partial remission or stable disease lasting a median of 2 years. Joensuu said that imatinib targets the proteins encoded by mutated KITand PDGFR-alpha genes, which are found in approximately 90% of GIST.

Joensuu and colleagues in the Scandinavian Sarcoma Group XVIII/AIO trial studied 400 patients with histologically diagnosed, KIT-positive GIST that met modified Consensus Criteria for high risk of recurrence; the patients were randomized to either 1 or 3 years of imatinib after surgery. Patients were randomized to open-label treatment with 400 mg (4 tablets) of imatinib for either 1 year or 3 years after surgery. After a median follow-up time of 54 months, the investigators found that 5-year RFS was higher in the 3-year group (65.6%) compared with patients treated for 1 year (47.9%).

Although imatinib was generally well tolerated by the patient population, Joensuu noted that adverse events saw 7.7% of the patients in the 1-year group and 13.7% of the patients who received 3 years of adjuvant therapy halt treatment. However, he believes that the 3-year treatment regimen will become the new standard.

“This is the kind of data that does change guidelines,” commented Mark G. Kris, MD, chief of the Thoracic Oncology Service and The William and Joy Ruane Chair in Thoracic Oncology at Memorial Sloan-Kettering Cancer Center in New York City, moderator of the press conference at which the trial results were unveiled. “The entire oncology community was excited when they saw those curves.”

Joensuu H, Eriksson M, Hatrmann J, et al. Twelve versus 36 months of adjuvant imatinib (IM) as treatment of operable GIST with a high risk of recurrence: final results of a randomized trial (SSGXVIII/AIO).J Clin Oncol. 29:2011(suppl; abstract LBA1).