Objective: To determine whether linomide (roquinimex) is better than placebo in slowing the time to confirmed clinical worsening in patients with relapsing-remitting (RR) and secondary progressive (SP) MS.

Methods: In this 27-center, randomized, double-blind, placebo-controlled, multiple-dose, phase III trial, 715 patients with active RRMS (n = 90) or SPMS (n = 625) were randomized to receive either linomide (1.0, 2.5, or 7.5 mg orally daily) or placebo. Patients were evaluated at 3-month intervals clinically and with MRI. The planned primary outcome was the time to the development of "confirmed" clinical worsening (increase of >/= 1.0 Expanded Disability Status Scale [EDSS] score for an enrollment EDSS score </= 5.0, or >/= 0.5 point for an enrollment EDSS score of >/= 5.5) not associated with an acute relapse.

Results: The trial was terminated 1 month after it became fully enrolled due to unanticipated serious cardiopulmonary toxicities (pericarditis, pleural effusion, myocardial infarction, and possible pulmonary embolism), pancreatitis, and death. Notable arthralgia, myalgia, bursitis, and facial and peripheral edema were common adverse events. The high dose of linomide (7.5 mg) was not well tolerated. The trial was too brief to determine unequivocal clinical benefits. Trends suggested an unconfirmed early effect on change in EDSS score at 6 months for the medium dose (2.5 mg daily).

Conclusion: MS patients may be more prone to develop important linomide treatment-related adverse events than other previously studied patients. However, linomide may be a potentially more toxic drug than was suspected from observations made in smaller studies for other indications. Phase III trials may identify infrequent and important toxicities that may not be anticipated by phase I and II trials.