Kiniksa Reports Fourth Quarter and Full-Year 2020 Financial Results and Corporate and Pipeline Activity - Strong execution across pipeline of immune-modulating assets throughout 2020 enables multiple milestones in 2021 -

Kiniksa Reports Fourth Quarter and Full-Year

2020 Financial Results and

Corporate and Pipeline Activity

- Strong execution across pipeline of

immune-modulating assets throughout 2020

enables multiple milestones in 2021 -

- Rilonacept in recurrent pericarditis

granted priority review, with PDUFA goal date

- Clinical data expected in 1H 2021

from KPL-404 (anti-CD40) Phase 1 clinical trial

and mavrilimumab Phase 2 clinical trial in severe COVID-19 -

- Year-end 2020 cash reserves of approximately

- February 23, 2021 - Kiniksa Pharmaceuticals, Ltd. (Nasdaq: KNSA) ("Kiniksa"),

a biopharmaceutical company with a pipeline of assets designed to modulate immunological pathways across a spectrum of diseases,

today reported fourth quarter and full-year 2020 financial results and corporate and pipeline activity.

"Kiniksa delivered outstanding performance in 2020, with

encouraging clinical data across our pipeline as well as Breakthrough Therapy designation or Orphan Drug designation for rilonacept,

mavrilimumab and vixarelimab," said Sanj K. Patel, Chief Executive Officer and Chairman of the Board of Kiniksa. "Building

on this momentum, we expect to launch rilonacept in recurrent pericarditis, pending FDA approval, in the first half of 2021. We

also anticipate final Phase 1 data for KPL-404, our anti-CD40 program, in which data generated to-date support the best-in-class

potential of this molecule and the opportunity for its evaluation in multiple devastating autoimmune diseases. Further, we expect

data from the fully-enrolled mavrilimumab Phase 2 clinical trial in severe COVID-19 in the first half of this year. With these

significant advances, it is important to highlight we are well capitalized with cash reserves of approximately $323 million."

Rilonacept (IL-1 and IL-1 cytokine trap)

Mavrilimumab (monoclonal antibody inhibitor targeting GM-CSFR )

Vixarelimab (monoclonal antibody inhibitor of signaling through

KPL-404 (monoclonal antibody inhibitor of signaling between

Kiniksa is a biopharmaceutical company focused on discovering,

acquiring, developing and commercializing therapeutic medicines for patients suffering from debilitating diseases with significant

unmet medical need. Kiniksa's product candidates, rilonacept, mavrilimumab, vixarelimab and KPL-404, are based on strong

biologic rationale or validated mechanisms, target underserved conditions, and offer the potential for differentiation. These

pipeline assets are designed to modulate immunological pathways across a spectrum of diseases. For more information, please visit

is a weekly, subcutaneously-injected, recombinant dimeric fusion protein that blocks interleukin-1 alpha (IL-1 ) and interleukin-1

beta (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, specifically Familial Cold Autoinflammatory Syndrome and Muckle-Wells

Syndrome, and DIRA. Rilonacept in recurrent pericarditis is an investigational drug. The FDA granted Breakthrough Therapy designation

to rilonacept for the treatment of recurrent pericarditis in 2019 and Orphan Drug designation to rilonacept for the treatment

of pericarditis in 2020.

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 ARCALYST were injection site reaction and upper respiratory tract infection. Patients

should be monitored for changes in their lipid profiles and provided with medical treatment if warranted. Treatment with immunosuppressants,

including ARCALYST, may result in an increase in risk of malignancies. Hypersensitivity reactions associated with ARCALYST administration

in clinical studies have been rare. If a hypersensitivity reaction occurs, administration of ARCALYST should be discontinued and

appropriate therapy initiated.

Mavrilimumab is an investigational fully-human monoclonal antibody

that targets granulocyte macrophage colony stimulating factor receptor alpha (GM-CSFR ). Mavrilimumab achieved prospectively-defined

primary endpoints of efficacy and safety in over 550 patients with rheumatoid arthritis through Phase 2b clinical studies in Europe.

Kiniksa's lead indication for mavrilimumab is GCA, a rare inflammatory disease of medium-to-large arteries. Kiniksa is also

evaluating mavrilimumab in COVID-19 pneumonia and hyperinflammation. The FDA granted Orphan Drug designation to mavrilimumab for

the treatment of GCA in 2020.

is an investigational fully-human monoclonal antibody that targets oncostatin M receptor beta (OSMR ),

which mediates signaling of interleukin-31 (IL-31) and oncostatin M (OSM), two key cytokines implicated in pruritus, inflammation

and fibrosis. Kiniksa believes vixarelimab to be the only monoclonal antibody in development that targets both pathways simultaneously.

Kiniksa's lead indication for vixarelimab is prurigo nodularis, a chronic inflammatory skin condition characterized by severely

pruritic skin nodules. The FDA granted Breakthrough Therapy designation to vixarelimab for the treatment of pruritus associated

with prurigo nodularis in 2020.

is an investigational humanized monoclonal antibody that is designed to inhibit CD40-CD40L interaction,

a key T-cell co-stimulatory signal critical for B-cell maturation and immunoglobulin class switching and Type 1 immune responses.

Kiniksa believes disrupting the CD40-CD40L interaction is an attractive approach for multiple autoimmune disease pathologies such

as rheumatoid arthritis, Sjogren's syndrome, Graves' disease, systemic lupus erythematosus and solid organ transplant.

Kiniksa owns or controls the intellectual property related to KPL-404.

Forward-Looking Statements

This press release contains forward-looking statements within

the meaning of the Private Securities Litigation Reform Act of 1995. In some cases, you can identify forward looking statements

by terms such as "may," "will," "should," "expect," "plan," "anticipate,"

"could," "intend," "target," "project," "contemplate," "believe,"

"estimate," "predict," "potential" or "continue" or the negative of these terms

or other similar expressions, although not all forward-looking statements contain these identifying words. All statements

contained in this press release that do not relate to matters of historical fact should be considered forward-looking statements,

including without limitation, statements regarding: our belief that clinical data across our pipeline along with breakthrough therapy

and/or orphan drug designations drove our performance in 2020; the potential commercial launch of rilonacept in recurrent pericarditis

in the first half of the year, if approved by the FDA, and our plans to commence sales and distribution of rilonacept for all other

approved indications in the United States at that time; expected timing of data from clinical trials, including expected data from

the Phase 2 portion of the Phase 2/3 clinical trial of mavrilimumab in severe COVID-19 pneumonia and hyperinflammation in the first

half of 2021 and final data and safety follow-up from all cohorts of the single-ascending-dose Phase 1 clinical trial of KPL-404

in healthy volunteers in the first half of 2021; expected timing of next steps for mavrilimumab, including for giant cell arteritis

(GCA), in the first half of 2021; our belief that KPL-404 has the potential to address a broad range of autoimmune diseases; our

beliefs about the mechanisms of action of our product candidates and potential impact of their approach, including our beliefs

that vixarelimab is the only monoclonal antibody in development that targets both interleukin-31

(IL-31) and oncostatin M (OSM) pathways simultaneously and KPL-404 potentially being a best-in-class monoclonal antibody

inhibitor; our belief that KPL-404's disruption of the CD40-CD40L interaction

is an attractive approach for multiple autoimmune disease pathologies; our belief that all of our product candidates offer the

potential for differentiation; and expectation about our cash reserves funding our current operating plan into 2023.

forward-looking statements are based on management's current expectations. These statements are neither promises nor guarantees,

but involve known and unknown risks, uncertainties and other important factors that may cause our actual results, performance

or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking

statements, including without limitation, the following: delays or difficulty in enrollment of patients in, and activation or

continuation of sites for, our clinical trials; amendments to our clinical trial protocols initiated by us or required by regulatory

authorities; delays or difficulty in completing our clinical trials, including as a result of the COVID-19 pandemic; potential

for changes between final data and any preliminary, interim, top-line or other data from clinical trials conducted by us or third