p38 mitogen activated kinase (MAPK) mediates the response to pro-inflammatory cytokines following myocardial infarction (MI) and is inhibited by losmapimod.

LATITUDE-TIMI 60 (ClinicalTrials.gov NCT02145468) randomized patients with MI to losmapimod or placebo for 12 weeks (24 weeks total follow-up). In this pre-specified analysis, we examined outcomes based on MI type [ST-segment elevation MI (STEMI) (865, 25%) and non-STEMI (2624, 75%)].

In patients with STEMI, inflammation, measured by hs-CRP, was significantly attenuated with losmapimod at 48 hours (P <0.001) and week 12 (P = 0.01). Losmapimod lowered NT-proBNP in patients with STEMI at 48 hours (P = 0.04) and week 12 (P = 0.02). The effects of losmapimod on CV death (CVD), MI, or severe recurrent ischemia requiring urgent coronary artery revascularization at 24 weeks [MACE] differed in patients with STEMI (7.0% vs 10.8%; HR 0.65, 95%CI 0.41 – 1.03; P= 0.06) and NSTEMI (11.4% vs 8.5%; HR 1.30, 95%CI 1.02 – 1.66; P = 0.04; p[int] = 0.009). CVD or HHF among patients with STEMI were 5.6% (losmapimod) and 8.3% (placebo) (HR 0.66; 95%CI 0.40 – 1.11; P = 0.12) and in NSTEMI were 4.8% (losmapimod) and 4.4% (placebo) (HR 1.09; 95%CI 0.76 – 1.56) in patients with NSTEMI.

Patients with STEMI treated with losmapimod had an attenuated inflammatory response. Our collective findings raise the hypothesis that mitigating the inflammatory response may result in different outcomes in patients with STEMI and NSTEMI. While the difference in outcomes is exploratory, these findings do support separate examination of patients with STEMI and NSTEMI and increased emphasis on heart failure in future investigation of modulators of inflammation in MI.