Kiniksa Pharmaceuticals Reports Fourth Quarter and Full-Year 2022 Financial Results and Recent Portfolio Execution - ARCALYST (rilonacept) Q4 2022 and full-year 2022 net product revenue of $39.9 million and $122.5 millio

Kiniksa Pharmaceuticals Reports Fourth Quarter

and Full-Year 2022 Financial Results and Recent Portfolio Execution

- ARCALYST (rilonacept)

Q4 2022 and full-year 2022 net product revenue of $39.9 million and $122.5 million, respectively -

- ARCALYST full-year 2023 net product

revenue expected to be $190 - $205 million, representing >60% year-over-year growth at the midpoint -

average total duration of therapy as of the end of Q4 2022 was ~18 months after accounting for patient restarts -

- Cash reserves expected to fund operations

into at least 2025 -

- February 28, 2023 - Kiniksa Pharmaceuticals, Ltd. (Nasdaq: KNSA) (Kiniksa), a biopharmaceutical company

with a pipeline of immune-modulating assets designed to target a spectrum of cardiovascular and autoimmune diseases, today reported fourth

quarter and full-year 2022 financial results and recent portfolio execution.

"Kiniksa executed across its cardiovascular and emerging autoimmune

franchises in 2022," said Sanj K. Patel, Chairman and Chief Executive Officer of Kiniksa. "Within the cardiovascular franchise,

we are focused on increasing brand awareness of ARCALYST, the only FDA-approved treatment for recurrent pericarditis, and pursuing collaborative

study agreements for mavrilimumab in rare cardiovascular diseases. In our emerging autoimmune franchise, we believe KPL-404, our CD40

antagonist, has significant potential for differentiation in targeting chronic autoimmune diseases. We are advancing the Phase 2 trial

of KPL-404 in rheumatoid arthritis into the efficacy portion and expect data in the first half of 2024. Additionally, our profitable ARCALYST

collaboration, non-dilutive capital from strategic out-licensing transactions, and continued financial discipline support these efforts

while providing cash runway into at least 2025."

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

KPL-404 (monoclonal antibody inhibitor of CD40-CD154 interaction)

Mavrilimumab (monoclonal antibody inhibitor targeting GM-CSFR )

Conference Call Information

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 portfolio of immune-modulating assets, ARCALYST, KPL-404, and mavrilimumab, are based on strong biologic rationale

or validated mechanisms, target a spectrum of underserved cardiovascular and autoimmune conditions, and offer the potential for differentiation.

For more information, please visit www.kiniksa.com.

ARCALYST is a weekly, subcutaneously injected recombinant dimeric fusion protein that blocks interleukin-1

alpha (IL-1 ) and interleukin-1 beta (IL-1 ) signaling. ARCALYST was discovered by Regeneron and is approved by the U.S. Food

and Drug Administration (FDA) for recurrent pericarditis, cryopyrin-associated periodic syndromes (CAPS), including Familial Cold Autoinflammatory

Syndrome and Muckle-Wells Syndrome, and deficiency of IL-1 receptor antagonist (DIRA). The FDA granted Breakthrough Therapy designation

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

in 2020. The European Commission granted Orphan Drug Designation to ARCALYST for the treatment of idiopathic pericarditis in 2021.

IMPORTANT SAFETY INFORMATION

For more information

about ARCALYST, talk to your doctor and see the Product Information.

KPL-404 is an investigational

humanized monoclonal antibody that is designed to inhibit CD40-CD154 (CD40 ligand) 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-CD154 interaction

is an attractive approach to address multiple autoimmune disease pathologies.

Mavrilimumab is an investigational

fully human monoclonal antibody that blocks activity of GM-CSF by specifically binding to the alpha subunit of the GM-CSF receptor (GM-CSFR ).

Phase 2 clinical trials of mavrilimumab in rheumatoid arthritis and giant cell arteritis achieved their primary and secondary endpoints

with statistical significance. Kiniksa is evaluating the development of mavrilimumab in rare cardiovascular diseases where the GM-CSF

mechanism has been implicated.

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 expectation (i) that

the proof-of-concept portion of the Phase 2 clinical trial of KPL-404 in rheumatoid arthritis will begin after completion of the multiple

ascending dose portion of such trial, and (ii) that we will report data from such trial in the first half of 2024; our pursuit of

collaborative study agreements to evaluate the potential of mavrilimumab in rare cardiovascular diseases where the GM-CSF mechanism has

been implicated; our expectation that ARCALYST full-year 2023 net product revenue will be between $190 million and $205 million; our expectation

about our cash reserves funding our current operating plan into at least 2025; our beliefs about the mechanisms of action of our product

candidates and potential impact of their approach, including (i) that KPL-404 has significant potential for differentiation in targeting

chronic autoimmune diseases and (ii) that using KPL-404 to disrupt the CD40-CD154 interaction is an attractive approach to address

multiple autoimmune disease pathologies; and our belief that all of our product candidates offer the potential for differentiation.

These 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; delays or difficulty in completing our

clinical trials as originally designed; potential for changes between final data and any preliminary, interim, top-line or other data

from clinical trials; our inability to replicate results from our earlier clinical trials or studies; impact of additional data from us

or other companies, including the potential for our data to produce negative, inconclusive or commercially uncompetitive results; potential

undesirable side effects caused by our products and product candidates; our inability to demonstrate safety and efficacy to the satisfaction

of applicable regulatory authorities; potential for applicable regulatory authorities to not accept our filings, delay or deny approval

of any of our product candidates or require additional data or trials to support approval; inability to successfully execute on our commercial

strategy for ARCALYST; our reliance on third parties as the sole source of supply of the drug substance and drug product used in our products

and product candidates; our reliance on Regeneron as the sole manufacturer of ARCALYST; raw material, important ancillary product and

drug substance and/or drug product shortages; our reliance on third parties to conduct research, clinical trials, and/or certain regulatory

activities for our product candidates; complications in coordinating requirements, regulations and guidelines of regulatory authorities

across jurisdictions for our clinical trials; the impact of the COVID-19 pandemic and any subsequent pandemic and measures taken in response

to such pandemics on our business and operations as well as the business and operations of our manufacturers, CROs upon whom we rely to

conduct our clinical trials, and other third parties with whom we conduct business or otherwise engage, including the FDA and other regulatory

authorities; changes in our operating plan and funding requirements; and existing or new competition.

These and other important factors discussed in our filings with the

U.S. Securities and Exchange Commission, including under the caption "Risk Factors" contained therein, could cause actual

results to differ materially from those indicated by the forward-looking statements made in this press release. Any such forward-looking

statements represent management's estimates as of the date of this press release. Except as required by law, we disclaim any intention

or obligation to update or revise any forward-looking statements. These forward-looking statements should not be relied upon as representing

our views as of any date subsequent to the date of this press release.

ARCALYST is a registered trademark of Regeneron Pharmaceuticals, Inc.

All other trademarks are the property of their respective owners.

Every Second Counts!

Kiniksa Investor and Media Contact

KINIKSA PHARMACEUTICALS, LTD.

CONSOLIDATED STATEMENTS OF OPERATIONS

(In thousands, except share and per share amounts)

KINIKSA PHARMACEUTICALS, LTD.

SELECTED CONSOLIDATED BALANCE SHEET DATA