Data Readout

Kiniksa's KPL-387 heads toward first pericarditis data with no IL-1R1 rival

Kiniksa expects Phase 2 dose-finding data on its IL-1R1 antibody KPL-387 in recurrent pericarditis in the second half of 2026, testing a monthly at-home injection against Arcalyst's established biologic-suppression benchmark.

By AppliedXLJuly 13, 2026Trial NCT07010159

Executive Summary

Kiniksa is running a placebo-controlled Phase 2/3 trial of its second IL-1R1 antibody in recurrent pericarditis, aiming to convert its existing biologic franchise into a once-monthly, at-home injection.
No other company has an IL-1R1-targeted program in clinical testing for this indication, leaving KPL-387 to compete against Kiniksa's own approved therapy rather than an external rival.
The sponsor has repeated the same second-half-2026 data window across every disclosure for more than a year, an unusually stable guidance record for a mid-stage cardiovascular trial.
Because the mechanism and disease are already validated by an approved drug, the readout's value lies in whether the new antibody matches that established response and safety profile with a more convenient dosing schedule, not in proving a new biology.

The catalyst

Kiniksa expects Phase 2 dose-finding data from the Phase 2/3 trial of KPL-387 in recurrent pericarditis in the second half of 2026, a window the company first disclosed in February 2025 and has repeated in seven subsequent updates through April 2026. The trial, registered as NCT07010159, enrolls adults weighing at least 40 kg who have recurrent pericarditis despite standard therapy with NSAIDs, colchicine, or glucocorticoids. The Phase 2 portion's primary endpoint is time to treatment response by Week 24; the Phase 3 portion, which the trial rolls into, measures time to pericarditis recurrence against placebo, and the long-term extension tracks the annualized recurrence rate. Kiniksa+1

Probability of Success

Endpoint Met91%

Completes61%

Clinical Significance17%

Regulatory62%

What KPL-387 is

KPL-387 is a fully human IgG2 monoclonal antibody that binds interleukin-1 receptor 1, blocking signaling from both IL-1-alpha and IL-1-beta, and is designed for monthly subcutaneous dosing in a liquid formulation. That target profile sits alongside Kiniksa's approved Arcalyst (rilonacept), an IL-1-alpha/IL-1-beta cytokine trap that generated $417.0 million in 2024 net product revenue and had been prescribed by more than 2,850 physicians for recurrent pericarditis as of that filing. KPL-387 is designed to extend that franchise with a lower dosing frequency rather than introduce a new mechanism into the disease. Kiniksa

The competitive frame

No other industry-sponsored trial targets IL-1R1 in recurrent pericarditis, leaving KPL-387 as the only asset in this target-indication pairing. The nearest indication peer, Cardiol Therapeutics' cannabidiol program (NCT06708299), works through a different mechanism (CB1) and does not compete on target biology. Kiniksa's own second trial of KPL-387, a Phase 2 monotherapy transition study (NCT07288216) enrolling 80 patients, sits alongside this one, meaning the near-term competitive set for this readout is effectively the sponsor's own prior drug and its own second trial, not an external rival.

Operational read

The trial is Recruiting, with an anticipated enrollment of 165 that has not changed since the registry record was first posted, a hold at target the operational model flags as typical rather than a warning sign. Its primary completion date, 2027-12-31, is a year beyond the H2 2026 data window because that date reflects the trial's longer-term extension phase, while the Phase 2 dose-focusing read is a separate, earlier milestone. Registry history shows only one status change, from Not yet recruiting to Recruiting in July 2025, with no protocol amendments to enrollment, endpoints, or eligibility criteria recorded since. NCT07010159

Regulatory context

The FDA granted KPL-387 Orphan Drug Designation for pericarditis in October 2025, a signal of the disease's rare, unmet-need status rather than a marker of expected approval outcome. Kiniksa

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