Rationale for Correct Answer

The correct answer is: Associated with increased activity of anti-inflammatory cytokines

Ibudilast is a nonselective phosphodiesterase inhibitor that acts at PDE 3, 4, 10, and 11 receptors. In the central nervous system (CNS), it inhibits production of inflammatory cytokines and increases the release of anti-inflammatory cytokines.1 In a phase 2 trial of progressive MS, the ibudilast group experienced significantly less brain atrophy, the primary endpoint, than the placebo group.2 This difference was due to efficacy in patients with primary progressive MS (PPMS), rather than secondary progressive MS (SPMS).3 The ibudilast group also had significantly less reduction in gray matter relative to placebo.4 In contrast, there was no significant difference in the proportion of patients with new or enlarging T1 or T2 lesions.4

References:
1. Goodman AD et al. Expert Opin Investig Drugs. 2016;25:1231-1237.
2. Fox RJ et al. N Engl J Med. 2018;379:846-855.
3. Goodwin AD et al. Ann Clin Transl Neurol. 2021;8:111-118.
4. Naismith RT. Neurology. 2021;96:e491-e500.