Curtis, Allison

Abstract Background Recurrent pericarditis (RP) predominantly shows features consistent with IL-1-mediated chronic autoinflammatory disease (1-4). A recent analysis suggested that supplementing anakinra with colchicine incrementally reduced pericarditis recurrence vs. anakinra alone (5). Rilonacept (a weekly IL-1α and IL-1β cytokine trap with 6-week washout) prevents engagement with IL-1 receptor, inhibiting both IL-1α and IL-1β activity (6). The Phase 3 trial RHAPSODY demonstrated rilonacept efficacy in two independent analyses: Randomized Withdrawal (RW) and Long-Term Extension (LTE) periods (7,8). Purpose Assess long-term recurrence-free persistence with rilonacept as monotherapy in pts with RP during the combined RW and LTE periods of RHAPSODY. Methods Post-hoc analysis. Freedom from recurrence on rilonacept monotherapy was quantified using the Kaplan-Meier (KM) method from RW start (if randomized to rilonacept) or from initiation of bailout rilonacept (if randomized to placebo) until the end of treatment. Prespecified recurrence adjudication criteria were pericarditis pain (numerical rating scale [NRS]) ≥4 plus C-reactive protein (CRP) ≥1 mg/dL. Per RHAPSODY protocol, background therapies were discontinued during the Run-In Period before randomization. In pts treated with rilonacept, concomitant colchicine was not added during the RW period. In the LTE, 6.8% (5/74) of pts added colchicine: one for 2 days of chest pain without CRP elevation, 4 in the absence of chest pain, CRP elevation, or recurrence; these 5 pts were censored in the KM curve at 6 days after last rilonacept dose or at colchicine initiation (whichever was first). One additional pt added colchicine prophylactically before an intentional rilonacept treatment interruption for elective cardiac surgery and experienced a recurrence after this interruption; this pt was not censored from the recurrence-free persistence analysis at colchicine initiation in order to capture this event. Results 74 pts (mean [SD] age 43.9 [15.7] years, 83.8% idiopathic pericarditis, mean [SD] disease duration 2.5 [3.2] years) were analyzed over three years. Rilonacept was well tolerated. Recurrence-free persistence was 95.9% (n=71/74) while receiving rilonacept as monotherapy (Figure 1). The three observed adjudicated recurrences were each associated with temporary interruptions of 1-3 doses of rilonacept. Conclusions Rilonacept as monotherapy provided recurrence-free persistence over the three-year trial duration when used continuously without interruption; pericarditis recurrences occurred only after interruptions. These findings support evidence-based use of rilonacept as monotherapy, minimizing the need for adjunctive treatments and reducing polypharmacy in long-term RP management. Further investigations are warranted to address how to assess pts as candidates for long-term treatment with rilonacept and when to cease rilonacept treatment.

Abstract Background Recurrent pericarditis (RP) is an IL-1-mediated chronic autoinflammatory disease (1,2). The phase 3 trial RHAPSODY demonstrated that rilonacept (IL-1α and IL-1β cytokine trap), the first and only FDA-approved treatment for RP, was effective in treating RP not only as a third-line agent (3L; after corticosteroids) but also as a second-line agent (2L; instead of corticosteroids) and reduced recurrence risk as monotherapy (3). The REgiStry Of the NAtural history of recurreNt periCarditis in pEdiatric and adult patients (RESONANCE) has been collecting long-term combined prospective and retrospective data from US-based pericardial-disease-dedicated programs since 2020 (4). Purpose To assess the efficacy of rilonacept in RP in a real-world setting, extending the clinical trial findings of RHAPSODY. Methods Database cut-off (DCO) was 05 February 2025. Data on RP management were collected and analyzed from pts with ≥2 years of observation in RESONANCE. Disease duration at DCO was defined as time from RP diagnosis to either disease resolution (no disease flares while off all RP treatments for ≥6 months before DCO) or last follow-up (for pts with ongoing treatment at DCO). Pericarditis recurrences (investigator-assessed) were confirmed based on RP symptom data and/or objective findings. Annualized recurrence rates were calculated per RP treatment regimen as total pericarditis recurrences divided by total patient-years (PY) while receiving that treatment. Wilcoxon signed-rank test was utilized to analyze the significance in change of annualized recurrence rates before and after rilonacept initiation. Results At DCO, 81 pts had ≥2 years of follow-up data in RESONANCE; mean (SD) age was 51.0 (16.8) years; most (66.7%) were female; 84% had idiopathic etiology; median (Q1-Q3) disease duration was 3.1 (2.6-3.7) years; and median observation was 2.93 (2.54-3.38) years. Patient-year treatment exposures per treatment were: NSAIDS ± colchicine (n=79; 187.8 PY), corticosteroids (n=30; 61.1 PY), anakinra (n=1; 1.2 PY) and rilonacept (n=35; 72.8 PY). Of the 35 pts treated with rilonacept for any duration (median observation: 3.2 years; median time on rilonacept: 2.08 years), the most common reason for rilonacept initiation was chest pain/recurrence on prior treatment (n=28). The annualized recurrence rate while receiving rilonacept was significantly lower versus all combined prior lines of treatment (4.00 vs. 0.02 events per PY; p=0.002); this outcome was consistent across line of treatment for rilonacept use (2L: 3.73 vs. 0.06 events per PY, p=0.02; 3L: 4.14 vs. 0 events per PY, p<0.001; Table 1). Conclusions This first report of real-world outcomes from RESONANCE shows that rilonacept-containing regimens for RP as 1st, 2nd, or 3rd line therapy reduced recurrence risk over long- term (>2 year) treatment, supporting prolonged management during RP natural history.

Abstract Aims In the Phase 3 trial, RHAPSODY, rilonacept effectively resolved active pericarditis recurrences, and long-term treatment led to sustained pericarditis recurrence risk reduction. Prior analysis suggested association between higher late gadolinium enhancement (LGE) at baseline and more rapid recurrence upon rilonacept suspension after 12 weeks of treatment. This subgroup analysis assessed the utility of longitudinal serial cardiac magnetic resonance (CMR) imaging for tracking clinical improvement and predicting post-treatment cessation outcomes to help guide clinical decision-making. Methods and results At an 18-month decision milestone (18MDM) in the RHAPSODY long-term extension, investigators decided if patients would continue rilonacept, suspend rilonacept for off-treatment observation, or discontinue the study. Pericardial thickness, pericardial oedema (T2-short tau inversion recovery, T2-STIR), and LGE were determined at baseline and 18MDM by an imaging core lab blinded to clinical data, and pericarditis recurrence was investigator-assessed. CMR results in patients with data at both baseline and 18MDM (n = 13) showed that pericardial thickness, T2-STIR, and LGE were reduced during rilonacept treatment. Among patients with CMR data who suspended rilonacept at the 18MDM (n = 7), five (71%) had a pericarditis recurrence within 1–4 months of rilonacept suspension, despite all having had none/trace LGE (n = 7) and negative T2-STIR (n = 7) at the 18MDM and two having received prophylactic colchicine. Conclusion Continued clinical improvement during prolonged rilonacept treatment corresponded with improvement on CMR, including reduced pericardial thickness, resolution of pericardial oedema, and resolution of LGE. However, none/trace LGE at 18MDM while on treatment did not predict absence of pericarditis recurrence upon subsequent rilonacept suspension in this size-limited subgroup.

Introduction: Rilonacept treatment in RHAPSODY resolved active pericarditis recurrences, and long-term treatment led to sustained risk reduction. Prior analysis linked greater baseline Late Gadolinium Enhancement (LGE), with more rapid recurrence upon rilonacept suspension after 12 weeks of treatment. Serial cardiac magnetic resonance (CMR) imaging (T2-STIR, LGE) enabled longitudinal assessment for tracking clinical improvement, guiding decision-making, and predicting patient outcomes after treatment cessation. Methods: At the long-term extension (LTE) 18-month decision milestone (18MDM), investigators chose, based on clinical status, to continue rilonacept, suspend rilonacept/observe, or discontinue the LTE. An imaging core lab blinded to clinical data measured pericardial thickness and graded pericardial edema (T2-STIR) and LGE at baseline and 18MDM. Pericarditis recurrence was assessed clinically following rilonacept suspension. Results: Baseline and 18MDM CMRs were available for 13 patients. Reductions in pericardial thickness, T2-STIR, and LGE from baseline to 18MDM while on treatment are provided in Figure . CMRs were obtained in 7/8 patients suspending rilonacept at 18MDM: LGE was none/trace, and T2-STIR was negative; yet, 5/7 (71%) had pericarditis recurrence within 1-4 months of rilonacept suspension despite prophylactic colchicine (n=2). Conclusions: Continued clinical improvement during prolonged rilonacept treatment corresponded with improvement on CMR, including reduced pericardial thickness, resolution of pericardial edema on T2-STIR, and resolution of LGE. Negative/trace LGE at 18MDM while on treatment did not predict absence of pericarditis recurrence upon subsequent rilonacept suspension in this size-limited subgroup. Larger prospective studies examining CMR parameters in guiding RP treatment duration decisions and informing associated clinical outcomes are warranted.