(ChemotherapyAdvisor) – The largest Phase 2 study in patients with chordoma to date “confirms anecdotal evidence that imatinib has antitumor activity in this orphan disease, and therefore, it is worth further investigation,” according to a study in the Journal of Clinical Oncology published online February 13.

In the study, 56 patients with advanced platelet-derived growth factor-beta (PDGFB)/PDGF receptor beta (PDGFRB)–positive chordomas received imatinib 800mg/day until disease progression. The best response among 50 patients evaluable by RECIST was one partial response obtained at six months (overall tumor response rate, 2%); 35 patients (70%) had stable disease, for a clinical benefit rate of 64%.

A minor dimensional response (<20%) was detected in 9 patients, and a maximum standard uptake value decrease ≥25% was observed in 10 of 26 patients (39%) evaluable for PET response at three months. Median progression-free survival was nine months. No unexpected toxicities were observed. Changes in the Brief Pain Inventory score were consistent with the response assessment.

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“This is a new achievement in an orphan disease devoid of any standard medical therapy,” the authors wrote, adding that lack of response and the potential slow natural course of the disease “do not allow us to affirm that this treatment is effective.”