Kiniksa Announces Positive Data from Phase 3 Trial of Rilonacept in Recurrent Pericarditis (RHAPSODY) - Primary and all major secondary efficacy endpoints were highly statistically significant - Rilonacept treatment resu

Kiniksa Announces Positive

Data from Phase 3 Trial of Rilonacept in Recurrent Pericarditis (RHAPSODY)

- June 29, 2020 - Kiniksa Pharmaceuticals, Ltd. (Nasdaq: KNSA) ("Kiniksa"), a biopharmaceutical

company focused on discovering, acquiring, developing and commercializing therapeutic medicines for patients with significant

unmet medical need, reported positive data from RHAPSODY, a pivotal Phase 3 trial of rilonacept, a weekly, subcutaneously-injected,

recombinant fusion protein that blocks interleukin-1 alpha (IL-1 ) and interleukin-1 beta (IL-1 ) signaling, in recurrent

pericarditis. RHAPSODY met its prespecified primary and all major secondary efficacy endpoints, showing that rilonacept improved

clinically meaningful outcomes associated with the unmet medical need in recurrent pericarditis, a painful and debilitating autoinflammatory

disease. The U.S. Food and Drug Administration (FDA) granted Breakthrough Therapy designation to rilonacept for the treatment

of recurrent pericarditis in 2019, and Kiniksa expects to submit a Supplemental Biologics License Application (sBLA) later this

"We are pleased to announce that RHAPSODY, our pivotal

Phase 3 trial of rilonacept in recurrent pericarditis, met its primary and all major secondary efficacy endpoints," said Sanj

K. Patel, Chief Executive Officer and Chairman of the Board of Kiniksa. "Combined with a well-tolerated safety

profile and a weekly dosing regimen, these data are an important step forward for patients. We believe rilonacept has the potential

to be the first FDA-approved therapy for recurrent pericarditis. We are committed to submitting an sBLA to the FDA later this

year and look forward to bringing this potential treatment option to patients as soon as possible."

RHAPSODY is a global, randomized withdrawal design, pivotal

Phase 3 clinical trial of rilonacept in recurrent pericarditis. The trial's primary analysis population included 61 actively

symptomatic recurrent pericarditis patients who were failing standard of care treatment, including nonsteroidal anti-inflammatory

drugs (NSAIDs), colchicine, or corticosteroids, initiated rilonacept treatment during a run-in period, discontinued background

medications, and achieved and maintained clinical response (11-point pain Numerical Rating Scale (NRS) 2.0 and C-reactive

protein (CRP) 0.5 mg/dL) on rilonacept monotherapy. Clinical responders were randomized 1:1 to receive continued weekly

rilonacept (n=30) or placebo (n=31) in a blinded manner in the randomized withdrawal period.

The primary efficacy endpoint of time-to-first adjudicated

pericarditis recurrence in the randomized withdrawal period was highly statistically significant.

All major secondary efficacy endpoints in the randomized withdrawal

period were also highly statistically significant.

Rilonacept was well-tolerated in the study, with adverse events

consistent with the FDA-approved label for the treatment of Cryopyrin-Associated Periodic Syndromes (CAPS). The most common adverse

events were injection site reactions.

"The RHAPSODY data provide hope for patients suffering

from recurrent pericarditis," said John F. Paolini, MD, PhD, Chief Medical Officer of Kiniksa. "In fact,

rilonacept patients experienced no or minimal pericarditis pain for nearly 95% of study days through Week 16 compared to less

than half of study days for placebo recipients, which was highly statistically significant. We believe that, by treating and preventing

disease recurrence, rilonacept has the potential to be a transformational therapeutic advancement in the treatment of patients

with recurrent pericarditis and to become the first FDA-approved therapy for this debilitating autoinflammatory disease."

Additional analyses of the RHAPSODY trial results are ongoing,

and Kiniksa plans to present the data at a future medical meeting or in a publication.

Rilonacept was discovered and developed by Regeneron Pharmaceuticals,

Inc. (Regeneron) and is approved by the FDA under the brand name ARCALYST for the treatment of CAPS. Kiniksa licensed rilonacept

from Regeneron in 2017 for evaluation in diseases believed to be mediated by both IL-1 and IL-1 , including recurrent

pericarditis. The FDA granted Breakthrough Therapy designation to rilonacept for recurrent pericarditis in 2019. Based on the

Phase 3 RHAPSODY data announced today, the Biologic License Application (BLA) for CAPS will transfer to Kiniksa, and the company

plans to submit an sBLA with the FDA in recurrent pericarditis later this year. Upon receipt of FDA approval for rilonacept

in recurrent pericarditis, Kiniksa would assume the sales and distribution of rilonacept for the approved indications in the United

States and will evenly split profits on sales with Regeneron.

Conference Call Information

Kiniksa will host a conference call and webcast at 8:30 a.m.

Eastern Time on Monday, June 29, 2020 to discuss top-line pivotal Phase 3 data for rilonacept in recurrent pericarditis. Individuals

interested in participating in the call should dial (866) 614-0636 (U.S. and Canada) or (409) 231-2053 (international) using conference

ID number 2089128. To access the webcast, please visit the Investors and Media section of Kiniksa's website at www.kiniksa.com.

The archived webcast will be available on Kiniksa's website for 14 days beginning approximately one hour after the call

RHAPSODY is the global, randomized withdrawal design, pivotal

Phase 3 clinical trial of rilonacept in recurrent pericarditis. Eligible patients presented at screening with at least a third

pericarditis episode, defined as at least 1 day with pericarditis pain of 4 on the 11-point NRS and a CRP value

1 mg/dL within the 7-day period prior to first study drug administration. Patients could be receiving concomitant NSAIDs and/or

colchicine and/or oral corticosteroid treatment in any combination. The study was comprised of 4 periods: a screening period;

a single-blind run-in period during which patients received a loading dose of rilonacept 320 mg injected subcutaneously (SC) followed

by 160 mg SC weekly while background pericarditis medications were tapered and discontinued; a double-blind, placebo-controlled

randomized withdrawal period during which clinical responders to rilonacept were randomized 1:1 and received 160 mg SC weekly

rilonacept or placebo; and a long-term extension treatment period with up to 24 months of open-label rilonacept 160 mg SC weekly.

The primary efficacy endpoint was time-to-first pericarditis-recurrence in the randomized withdrawal period. The Clinical Endpoint

Committee adjudicated all suspected pericarditis recurrences for inclusion in the primary efficacy endpoint analysis. The co-principal

investigators are Dr. Allan Klein of Cleveland Clinic and Dr. Massimo Imazio of the University of Torino, Italy. For more information,

refer to ClinicalTrials.gov Identifier:

About Recurrent Pericarditis

Recurrent pericarditis is a painful and debilitating autoinflammatory

cardiovascular disease that typically presents with chest pain and is often associated with changes in electrical conduction and

sometimes buildup of fluid around the heart, called pericardial effusion. Patients with pericarditis are deemed recurrent if they

have an additional episode after a symptom-free period of 4-6 weeks, and chronic if symptoms from any one episode last longer

than three months. Recurrent pericarditis symptoms impair qualify of life, limit physical activities, and lead to frequent emergency

department visits and hospitalizations. There are currently no FDA-approved treatments for recurrent pericarditis.

About the Rilonacept License Agreement with Regeneron

In 2017, Regeneron granted Kiniksa an exclusive license to

develop and commercialize rilonacept worldwide, aside from Israel, Egypt, Turkey and select countries in the Middle East and North

Africa. In the United States and Japan, Kiniksa's license is initially for all indications other than those involving local

administration to the eye or ear, oncology, deficiency of the interleukin 1 receptor antagonist (DIRA) and CAPS. If Kiniksa

is successful in receiving marketing approval for rilonacept in the United States for a new indication, the scope of the license

granted to Kiniksa will automatically expand to include DIRA and CAPS in the United States and Japan, and Kiniksa will assume

the sales and distribution of rilonacept in these additional indications. Outside the United States and Japan, Kiniksa's

license is for all indications other than local application to the eye or ear, oncology, CAPS, DIRA and certain periodic fever

syndromes. Kiniksa made an upfront payment of $5.0 million to Regeneron and is obligated to make regulatory milestone payments

of up to $27.5 million in the aggregate. Thereafter, Kiniksa and Regeneron will evenly split profits on sales of rilonacept after

deducting certain commercialization expenses subject to specified limits.

Rilonacept is a weekly, subcutaneously-injected, recombinant

fusion protein that blocks IL-1 and IL-1 signaling. Rilonacept was discovered and developed by Regeneron and is approved

by the FDA under the brand name ARCALYST for the treatment of CAPS, which includes Familial Cold Autoinflammatory

Syndrome and Muckle-Wells Syndrome. Rilonacept for the treatment of DIRA is currently pending FDA approval following the submission

of a supplemental BLA in June 2020. Rilonacept in recurrent pericarditis is an investigational drug. The FDA has granted Breakthrough

Therapy designation to rilonacept for recurrent pericarditis.

Important information about ARCALYST (rilonacept) Injection

IL-1 blockade may interfere with immune response to infections.

Serious, life-threatening infections have been reported in patients taking ARCALYST. ARCALYST should be discontinued if a patient

develops a serious infection. Taking ARCALYST with TNF inhibitors is not recommended because this may increase the risk of serious

Patients should not receive a live vaccine while taking ARCALYST.

It is recommended that prior to initiation of therapy with ARCALYST patients receive all recommended vaccinations, as appropriate,

including pneumococcal vaccine and inactivated influenza vaccine. In the initial development program for ARCALYST, six serious

adverse reactions were reported by four patients: Mycobacterium intracellular infection, gastrointestinal bleeding and colitis,

sinusitis and bronchitis and Streptococcus pneumoniae meningitis. The most commonly reported adverse reactions associated with