Treatment with imatinib was tolerated by most patients. Adverse events – including edema, nausea, and myalgias – were common (n = 171), although most (98%) were mild to moderate. There were 24 serious adverse events, and 2 were attributed to imatinib.
Steps were taken to improve tolerability. In 83% of patients, the imatinib dose was adjusted due to myalgia; edema and effusions; gastrointestinal complaints; or other illness. About 60% of patients who developed edema were given furosemide, which proved helpful.
These results stand in contrast to those of another group of investigators who set out to do a 6-month, randomized, double-blind, placebo-controlled proof-of-concept pilot study of imatinib in patients with active diffuse cutaneous SSc (Arthritis Rheum. 2011;63:3547-51). A 4:1 randomization strategy was used, stratifying patients according to current use of methotrexate. Imatinib 200 mg was given twice daily. The goal of the study was to enroll 20 patients. However, the study was discontinued after 10 patients were enrolled (9 who received imatinib and 1 placebo) due to poor tolerability and high rates of adverse events. These events were similar to those reported by Dr. Spiera: edema, fluid retention, fatigue, nausea, cramps/myalgias, and diarrhea, but also alopecia and anemia. According to the authors, the side effects occurred even when the imatinib dose was reduced to 200 mg daily. Two patients were hospitalized because of medication side effects.
No differences were found in any measures of efficacy (that is, changes in mRSS, physician’s global assessment, patient’s global assessment, or HAQ scores), but this was attributed to the small number of patients who actually completed the study.
"I think we are going to see more about [TKIs] for systemic sclerosis," said Dr. Spiera. He noted that clinical trials were underway for other TKIs, such as dasatinib and nilotinib. The TKI BIBF 1120 was shown in a phase II, randomized, placebo-controlled trial to slow down the rate of decline of FVC in patients with idiopathic pulmonary fibrosis (N. Engl. J. Med. 2011;365:1079-87).
While Dr. Spiera called for more randomized controlled trials, he also highlighted some of the challenges faced by those conducting clinical trials in scleroderma. These include the difficulty of recruiting patients with such an uncommon disease, the variety in disease phenotypes, the variable natural history, uncertainty as to what are the most relevant and valid outcome measures, and the ethical ramifications of randomizing patients to placebo.
Dr. Spiera listed research support from BMS, Boehringer Ingelheim, Novartis, Roche/Genentech, and United Therapeutics.