Kiniksa Pharmaceuticals Reports Fourth Quarter and Full-Year 2023 Financial Results and Recent Portfolio Execution - ARCALYST (rilonacept) Q4 2023 and full-year 2023 net product revenue of $71.2 million and $233.2 millio

Kiniksa Pharmaceuticals

Reports Fourth Quarter and Full-Year 2023 Financial Results and Recent Portfolio Execution

(rilonacept) Q4 2023 and full-year 2023 net product revenue of $71.2 million and $233.2 million, respectively -

2024 net product revenue expected to be $360 - $380 million, representing ~59% year-over-year growth at the midpoint -

Phase 2 rheumatoid arthritis data from Cohort 4 and a new development indication expected in April 2024 -

reserves of $206.4 million expected to fund operations into at least 2027 -

call and webcast scheduled for 8:30 am ET today -

BERMUDA - February 28, 2024 - Kiniksa

Pharmaceuticals, Ltd. (Nasdaq: KNSA) (Kiniksa), a commercial-stage 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 2023 financial

results and recent portfolio execution.

"Kiniksa meaningfully advanced

its business in 2023, primarily through robust ARCALYST net product revenue and collaboration profit growth. Significant growth remains

with ARCALYST in recurrent pericarditis, and we expect to help an increasing number of patients in the years ahead. Importantly, we anticipate

our robust commercial performance to contribute to our strong financial position and ability to drive growth across our business,"

said Sanj K. Patel, Chairman and Chief Executive Officer of Kiniksa. "Additionally, abiprubart recently showed clinical effect

in the first three cohorts of the Phase 2 trial in rheumatoid arthritis. We now expect to advance the asset into a Phase 2b trial in

a new indication, funding for which is included in our current cash runway guidance. Data from the fourth cohort of the abiprubart Phase

2 trial are intended to inform trial design and are expected in April."

Portfolio and Collaboration Execution

ARCALYST (IL-1 and IL-1

Abiprubart (anti-CD40 monoclonal

antibody inhibitor of CD40-CD154 interaction)

Mavrilimumab (monoclonal antibody

inhibitor targeting GM-CSFR )

Vixarelimab (monoclonal antibody

inhibitor of signaling through OSMR )

Kiniksa is a commercial-stage biopharmaceutical

company focused on discovering, acquiring, developing, and commercializing therapeutic medicines for patients suffering from debilitating

diseases with significant unmet medical need. Kiniksa's immune-modulating assets, ARCALYST, abiprubart, 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 Pharmaceuticals, Inc. (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 exclusivity

to ARCALYST in 2021 for the treatment of recurrent

pericarditis and reduction in risk of recurrence in adults and pediatric patients 12 years

and older. The European Commission granted Orphan Drug Designation to ARCALYST for the treatment

of idiopathic pericarditis in 2021.

SAFETY INFORMATION ABOUT ARCALYST

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

is an investigational humanized monoclonal antibody that binds to CD40 and is designed to inhibit the 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 co-stimulatory interaction is an attractive approach to addressing multiple autoimmune disease pathologies.

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 potential partnership opportunities for mavrilimumab.

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 that ARCALYST 2024 net product revenue will be between $360 million and $380 million; our plan

to report data from Cohort 4 of our Phase 2 clinical trial of abiprubart in rheumatoid arthritis and a new development indication for

abiprubart in April 2024; our expectation about our cash reserves funding our current operating plan into at least 2027; our expectation

that we will help an increasing number of patients in the future; our plan to develop abiprubart in an additional indication; our plan

to present a poster at the upcoming American College of Cardiology Scientific Session in April 2024; our beliefs about the mechanisms

of our product candidates and potential impact of their approach, including that using abiprubart to disrupt the CD40-CD154 co-stimulatory

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 current sole manufacturer

of ARCALYST; risks arising from our ongoing technology transfer of ARCALYST drug substance manufacturing; 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; changes in our operating plan, business development strategy or 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. 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