Kiniksa Reports Second Quarter 2021 Financial Results and Recent Corporate and Portfolio Activity - Q2 2021 ARCALYST (rilonacept) net revenue of $7.7 million with greater than 100 prescribing physicians - - Phase 3 data

Kiniksa Reports Second Quarter 2021 Financial

Results and Recent Corporate and Portfolio Activity

- Q2 2021 ARCALYST (rilonacept)

net revenue of $7.7 million with greater than 100 prescribing physicians -

- Phase 3 data from mavrilimumab clinical trial

in COVID-19-related ARDS on-track for Q1 2022; new Phase 2 data demonstrate persistent clinical effect through Day 90 -

- Initiation of KPL-404 Phase 2 proof-of-concept

clinical trial expected in Q4 2021 -

- Conference call and webcast scheduled for 8:30

- August 3, 2021 - Kiniksa Pharmaceuticals, Ltd. (Nasdaq: KNSA) ("Kiniksa"), a biopharmaceutical

company with a portfolio of assets designed to modulate immunological pathways across a spectrum of diseases, today reported second quarter

2021 financial results and recent corporate and portfolio activity.

"Our commercial team is doing a superb job with the launch of

ARCALYST in recurrent pericarditis," said Sanj K. Patel, Chief Executive Officer and Chairman of the Board of Kiniksa. "Feedback

received from physicians and patients highlights the transformational potential of ARCALYST for patients suffering from recurrent pericarditis.

We have seen strong uptake and look forward to using this momentum to accelerate broader adoption across this underserved population."

"We are executing on the development of our clinical-stage pipeline,"

said John F. Paolini, MD, PhD, Chief Medical Officer of Kiniksa. "The potential broad utility of mavrilimumab across multiple

indications is increasingly promising, and we expect data from our Phase 3 clinical trial in COVID-19-related ARDS in the first quarter

of 2022. We are enrolling a Phase 2b clinical trial of vixarelimab in prurigo nodularis and believe vixarelimab has the potential to

make a meaningful impact on these patients' lives by addressing both the pruritus and the skin nodules associated with this devastating

disease. KPL-404, our anti-CD40 program, has potential across a range of autoimmune diseases, and we plan to initiate a Phase 2 proof-of-concept

clinical trial in rheumatoid arthritis in the fourth quarter of this year."

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

Mavrilimumab (monoclonal antibody inhibitor targeting GM-CSFR )

Vixarelimab (monoclonal antibody inhibitor

of signaling through OSMR )

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

Upcoming Scientific Conference Presentations

Conference Call Information

Kiniksa will host a conference call and webcast at 8:30 a.m. Eastern Time on Tuesday, August 3, 2021 to

discuss second quarter 2021 financial results and recent corporate and portfolio activity. 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 1485623.

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 has completed.

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 assets, ARCALYST, mavrilimumab, vixarelimab and KPL-404, are based on strong biologic rationale or

validated mechanisms, target underserved conditions and offer the potential for differentiation. These assets are designed to modulate

immunological pathways across a spectrum of diseases. For more information, please visit www.kiniksa.com.

ARCALYST is a weekly, subcutaneously-injected recombinant dimeric

fusion protein that blocks interleukin-1 alpha and interleukin-1 beta signaling. ARCALYST was discovered by Regeneron and is approved

by the FDA for recurrent pericarditis, CAPS, including Familial Cold Autoinflammatory Syndrome and Muckle-Wells Syndrome, and 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 2020.

Important Information About ARCALYST Injection

For more information about ARCALYST, talk to your doctor and see

the Product Information.

Mavrilimumab is an investigational fully-human monoclonal antibody

that blocks activity of granulocyte macrophage colony stimulating factor (GM-CSF) by specifically binding to the alpha subunit of the

GM-CSF receptor. Mavrilimumab was dosed in over 550 patients with rheumatoid arthritis through Phase 2b clinical studies in Europe and

achieved prospectively-defined primary endpoints of efficacy and safety. Kiniksa is evaluating mavrilimumab in GCA, and the Phase 2 clinical

trial achieved both the primary and secondary efficacy endpoints with statistical significance. Kiniksa continues to evaluate mavrilimumab

in COVID-19-related ARDS. The FDA granted Orphan Drug designation to mavrilimumab for the treatment of GCA in 2020.

Vixarelimab 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.

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 for multiple

autoimmune disease pathologies. 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 expectations regarding payers establishing coverage policies for ARCALYST; our beliefs about the future commercial

demand for ARCALYST; our beliefs about the timing and results of the final data from the Phase 3 portion of our clinical trial for mavrilimumab

in non-mechanically-ventilated patients in the first quarter of 2022; expected timing and design of clinical trials, including (i) the

enrollment of patients in and the timing of results from our phase 3 clinical trial of mavrilimumab in COVID-19-related ARDS, (ii) the

initiation our Phase 2 proof-of-concept trial of KPL-404 in rheumatoid arthritis by the fourth quarter of 2021, (iii) the enrollment

of patients the Phase 2b portion of our clinical trial of vixarelimab in prurigo nodularis and (iv) the potential to evaluate KPL-404

across a range of other autoimmune diseases; 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 that vixarelimab

is the only monoclonal antibody in development that targets both interleukin-31 (IL-31) and oncostatin M (OSM) pathways simultaneously;

our belief that all of our product candidates offer the potential for differentiation; our ability to execute on our clinical stage pipeline;

our expectations regarding ARCALYST net revenue for the third quarter of 2021; our plans to present at any future medical conferences;

and our expectations about our cash reserves funding our current operating plan into 2023.

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; 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 ongoing 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 parties; our inability to replicate in later clinical trials the positive final data 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 or to delay or deny approval of, or emergency use authorization for, any of our product candidates

or to require additional data or trials to support any such approval or authorization; delays, difficulty or 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 products used in our products and product candidates; our reliance on Regeneron as the sole manufacturer of ARCALYST; our reliance