KNSA

EX-99.1

2 knsa-20260728xex99d1.htm

EX-99.1

Exhibit 99.1

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Kiniksa Pharmaceuticals Reports Second Quarter 2026 Financial Results and Recent Portfolio Execution

– ARCALYST® (rilonacept) Q2 2026 net product revenue of $243.6 million, representing ~55% year-over-year growth –

– ARCALYST 2026 expected net product revenue increased to $980 - $995 million –

– KPL-387 Phase 2 data demonstrated rapid and sustained reductions in pain and inflammation at 300 mg SC once-monthly, the dose level selected for Phase 3 –

– KPL-387 pivotal Phase 3 trial in recurrent pericarditis now enrolling and dosing patients –

– Conference call and webcast scheduled for 8:30 am ET today –

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London – July 28, 2026 – Kiniksa Pharmaceuticals International, plc (Nasdaq: KNSA) (Kiniksa), a biopharmaceutical company developing and commercializing novel therapies for diseases with unmet need, with a focus on cardiovascular indications, today reported second quarter 2026 financial results and recent portfolio execution.

“In the second quarter, Kiniksa continued to drive growth in new and repeat prescribers of ARCALYST in recurrent pericarditis, which led to a meaningful increase in patients on therapy. As a result, we have raised our 2026 ARCALYST net sales guidance to between $980 and $995 million,” said Sanj K. Patel, Chairman & Chief Executive Officer of Kiniksa. “In our clinical portfolio, KPL-387 Phase 2 data supported initiation of the pivotal Phase 3 trial, PASTORALE, which is now enrolling and dosing patients. We are excited to advance KPL-387 with its target product profile of once-monthly subcutaneous dosing in a liquid formulation. We expect to bring this potential additional treatment option to patients in the 2028/2029 timeframe. Additionally, we continue to develop KPL-1161 with a target profile of once-quarterly dosing and are on track to initiate a Phase 1 trial by the end of this year.”

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Portfolio Execution

ARCALYST (IL-1α and IL-1β cytokine trap)

●ARCALYST net product revenue was $243.6 million for the second quarter of 2026.

●As of the end of the second quarter of 2026, approximately 21% of the 14,000 multiple-recurrence patients were actively on ARCALYST treatment.

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●Since launch, more than 5,000 prescribers have written ARCALYST prescriptions for recurrent pericarditis.

●As of the end of the second quarter of 2026, average total duration of ARCALYST therapy in recurrent pericarditis was approximately 3 years, in line with the median duration of disease.

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KPL-387 (monoclonal antibody IL-1 receptor antagonist)

●Kiniksa today announced data from an interval analysis of the ongoing KPL-387 Phase 2/3 trial in recurrent pericarditis. The Phase 2 dose-focusing portion of the trial is designed to evaluate the dose response and safety of different subcutaneously (SC) administered KPL-387 dose regimens and to support dose selection for the pivotal Phase 3 portion of the trial.

—Participants in the KPL-387 300 mg SC monthly dose group experienced rapid and sustained reductions in Numeric Rating Scale (NRS) pain and inflammation as soon as after the first dose:

—Primary Efficacy Endpoint*

◾Time to Treatment Response1: 4.0 (3.0, 6.0) days.

—Secondary Efficacy Endpoints*

◾Time to Pain Response: 4.0 (3.0, 6.0) days.

◾Time to C-Reactive Protein (CRP) Normalization2: 8.0 (7.0, 9.0) days.

—KPL-387 efficacy was durable throughout the monthly dosing interval.

—KPL-387 was generally well-tolerated, consistent with the well-known safety profile of interleukin-1 (IL-1) pathway inhibition.

●Kiniksa is enrolling and dosing patients in PASTORALE, the pivotal Phase 3 portion of the Phase 2/3 clinical trial.

—PASTORALE is an event-driven, double-blind, placebo controlled, randomized withdrawal (RW) study enrolling up to approximately 85 participants with recurrent pericarditis. PASTORALE is evaluating the efficacy and safety of KPL-387 300 mg SC administered once-monthly in a liquid formulation.

—The primary endpoint is time to first adjudicated pericarditis recurrence during the RW period.

●Kiniksa is also conducting a supplemental Phase 2 Transition to KPL-387 Monotherapy Dosing & Administration Study evaluating the efficacy and safety of dosing regimens used to transition patients from standard therapies to KPL-387 monotherapy.

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KPL-1161 (Fc-modified monoclonal antibody IL-1 receptor antagonist)

●Kiniksa is conducting preclinical development activities with KPL-1161 with a target profile of quarterly SC dosing. The company expects to initiate a Phase 1 first-in-human clinical trial by the end of 2026.

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* Reported as median (95% confidence interval).

1 Treatment Response is defined as Pain Response (NRS score ≤ 2 on the 11-point daily pericarditis pain NRS pain scale) and at least one CRP level ≤ 0.5 mg/dL within 7 days before or after the Pain Response.

2 CRP Normalization is defined as CRP ≤ 0.5 mg/dL.

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Financial Results

●Total revenue for the second quarter of 2026 was $243.6 million, comp

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Kiniksa Pharmaceuticals International, plc_February 24, 2026 0001730430false00017304302026-02-242026-02-24 ​ ​

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

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FORM 8-K

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CURRENT REPORT

Pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 ​ Date of Report (Date of earliest event reported): February 24, 2026 ​ Kiniksa Pharmaceuticals International, plc (Exact name of Registrant as Specified in Its Charter) ​ ​

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England and Wales ​ ​ ​ 001-730430 ​ ​ ​ 98-1795578

(State or other jurisdiction of incorporation or organization) ​ (Commission File Number) ​ (I.R.S. Employer Identification No.)

​ Kiniksa Pharmaceuticals International, plc 105 Piccadilly, Second Floor London, W1J 7NJ England, United Kingdom (781) 431-9100 (Address, zip code and telephone number, including area code of principal executive offices) ​ Kiniksa Pharmaceuticals Corp. 100 Hayden Avenue Lexington, MA, 02421 (781) 431-9100 (Address, zip code and telephone number, including area code of agent for service) ​ N/A (Former Name or Former Address, if Changed Since Last Report) ​ Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions ​ ☐Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425) ​ ☐Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12) ​ ☐Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b)) ​ ☐Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c)) ​ Securities registered pursuant to Section 12(b) of the Act: ​

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Title of each class ​ ​ ​ Trading Symbol(s) ​ ​ ​ Name of each exchange on which registered

Class A Ordinary Shares $0.000273235 nominal value ​

KNSA

​ The Nasdaq Stock Market LLC

​ ​ ​ ​ (Nasdaq Global Select Market)

​ Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter). ​ Emerging growth company ☐ ​ If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐ ​ ​ ​ ​

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Item 2.02. Results of Operations and Financial Condition ​ On February 24, 2026, Kiniksa Pharmaceuticals International, plc issued a press release announcing financial results for the fiscal year ended December 31, 2025. A copy of the press release is furnished with this Current Report on Form 8-K as Exhibit 99.1. ​ Item 9.01. Financial Statements and Exhibits. ​ (d) Exhibits ​ ​

Exhibit No. ​ ​ ​ Description

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99.1 ​ Press Release issued by Kiniksa Pharmaceuticals International, plc, dated February 24, 2026

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104 ​ Cover Page Interactive Data File (embedded within the inline XBRL document)

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. ​ ​

KINIKSA PHARMACEUTICALS INTERNATIONAL, PLC

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Date: February 24, 2026 By: /s/ Douglas Barry

​ ​ Douglas Barry

​ ​ Senior Vice President, Chief Legal Officer and Secretary

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