Cardiac Magnetic Resonance Imaging In A Phase 2 Study Of Rilonacept In Recurrent Pericarditis

Introduction: The magnitude of pericardial delayed hyperenhancement (DHE) by cardiac magnetic resonance imaging (CMR) illustrates the severity of inflammation in pericarditis. We report exploratory CMR data from an open-label Phase 2 study of rilonacept (IL-1α/IL-1β inhibitor) in recurrent pericarditis (RP). Methods: Patients (pts) with idiopathic RP or post-pericardiotomy syndrome (PPS) enrolled in the study. A subset had CMR at baseline (BL) and final visit (FV, 6 mo). Pain (NRS) and inflammation (CRP) were also collected. CMR images were graded (none, mild, moderate, or severe DHE) by a central core lab blinded to clinical data. Results: Of 25 study pts, 11 had CMR at BL and FV; 6 active idiopathic RP, and 5 corticosteroid (CS)-dependent non-active RP (4 idiopathic, 1 PPS). At BL, DHE was severe (3), moderate (2), and none (1) in active RP pts and moderate (1) or mild/none (4) in CS-dependent pts (Figure 1). At FV, DHE was improved (2), resolved (2; one pt example in Figure C/D), or unchanged (2) in active RP pts and was improved (1), resolved (1), unchanged (2) or worsened from none to mild (1) in CS-dependent pts. DHE improvements were associated with decreased pain and CRP and occurred despite discontinuation of CS or reduction in dose level. One pt with severe DHE at baseline and mild DHE at FV experienced a recurrence ~8 weeks after rilonacept discontinuation and enrolled a second time with severe DHE; the patient had reduced CRP and pain NRS during both enrollments and ended the second enrollment with moderate DHE. Conclusions: Serial CMR demonstrated improvement in pericardial DHE after 6 mo of rilonacept treatment, consistent with clinical improvement, while corticosteroids were tapered/discontinued. Recurrence in one pt with incompletely resolved DHE after 6 months of rilonacept treatment could indicate that a longer treatment duration is warranted in patients with unresolved DHE. These preliminary results may inform future CMR-guided treatment studies in RP.