Nature of the Business and Basis of Presentation	12 Months Ended
Dec. 31, 2019
Nature of the Business and Basis of Presentation
Nature of the Business and Basis of Presentation	1. Nature of the Business and Basis of Presentation Kiniksa Pharmaceuticals, Ltd. (the “Company”) is a biopharmaceutical company focused on discovering, acquiring, developing and commercializing therapeutic medicines for patients suffering from debilitating diseases with significant unmet medical need. The Company was incorporated in July 2015 as a Bermuda exempted company. The Company has a pipeline of product candidates across various stages of development. The Company is subject to risks and uncertainties common to early‑stage companies in the biotechnology industry. There can be no assurance that the Company’s research and development will be successfully completed, that adequate protection for the Company’s technology will be obtained, that any products developed will obtain necessary government regulatory approval or that any products, if approved, will be commercially viable. The Company does not currently generate revenue from sales of any products, and it may never be able to develop or commercialize a marketable product. The Company has not yet successfully completed any Phase 3 or other pivotal clinical trials, obtained any regulatory approvals, manufactured a commercial‑scale drug, or conducted sales and marketing activities. The Company operates in an environment of rapid technological innovation and substantial competition from pharmaceutical and biotechnological companies. In addition, the Company is dependent upon the services of its employees, consultants and service providers. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales. Principles of Consolidation The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and include the accounts of the Company and its wholly owned subsidiaries, Kiniksa Pharmaceuticals Corp. (“Kiniksa US”), Primatope Therapeutics, Inc. (“Primatope”) and Kiniksa Pharmaceuticals (UK), Ltd. (“Kiniksa UK”) as well as the subsidiaries of Kiniksa UK, Kiniksa Pharmaceuticals (Germany) GmbH (“Kiniksa Germany”) and Kiniksa Pharmaceuticals (France) SARL (“Kiniksa France”), after elimination of all significant intercompany accounts and transactions. In assessing the consolidation requirement for variable interest entities (“VIE”s), the Company focuses on identifying whether it has both the power to direct the activities that most significantly impact the VIE’s economic performance and the obligation to absorb losses or the right to receive benefits from the VIE. In the event that the Company is the primary beneficiary of a VIE, the assets, liabilities, and results of operations of the VIE would be included in the Company’s consolidated financial statements. At December 31, 2019 and 2018 and during the years then ended, the Company was not the primary beneficiary of a VIE. Use of Estimates The preparation of the Company’s consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of expenses during the reporting period. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, the accrual for research and development expenses and the valuation of common shares and share‑based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ from those estimates. Reporting and Functional Currency The financial results of the Company's global activities are reported in U.S. dollars (“USD”) and its foreign subsidiaries generally utilize their respective local currency to be their functional currency. Transactions in other currencies are recorded in the functional currency at the rate of exchange prevailing when the transactions occur. Monetary assets and liabilities denominated in other currencies are re-measured into the functional currency at the rate of exchange in effect at the balance sheet date. Exchange gains and losses arising from re-measurement of foreign currency-denominated monetary assets and liabilities are included in income in the period in which they occur. For our foreign subsidiaries where the local currency is the functional currency, assets and liabilities denominated in local currencies are translated into USD at end-of-period exchange rates and the resulting translation adjustments are reported as a component of accumulated other comprehensive income (loss) within shareholders' equity (deficit). Reverse Share Split On May 11, 2018, the Company effected a 1‑for‑2.73235 reverse share split of its authorized, designated, issued and outstanding common shares and preferred shares. Accordingly, all share and per share amounts for all periods presented in the accompanying consolidated financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect this reverse share split. Initial Public Offering On May 23, 2018, the Company’s registration statement on Form S‑1 relating to its initial public offering of its Class A common shares (the “IPO”) was declared effective by the Securities and Exchange Commission (“SEC”). On May 29, 2018, the Company completed the IPO of 8,477,777 Class A common shares at $18.00 per share for gross proceeds of $152,600. In addition, on June 22, 2018, the Company completed the sale of 1,006,425 Class A common shares to the underwriters of the IPO following the exercise of their over‑allotment option to purchase additional shares at $18.00 per share for gross proceeds of $18,116. The aggregate net proceeds to the Company from the IPO, inclusive of the over‑allotment option exercise, was $155,536 after deducting underwriting discounts and commissions and other offering costs. Upon the closing of the IPO, all convertible preferred shares then outstanding automatically converted into 5,546,019 Class A common shares, 1,070,502 Class B common shares, 12,995,954 Class A1 common shares and 16,057,618 Class B1 common shares. In connection with the closing of the IPO, the Company amended and restated its bye‑laws (the “Amended & Restated Bye‑Laws”). Follow-on Offering and Private Placement On February 4, 2019, the Company completed a follow-on offering of 2,654,984 Class A common shares at a public offering price of $18.26 and a concurrent private placement of 2,000,000 Class A1 common shares at an offering price of $18.26 per share for aggregate gross proceeds of $85,000. In addition, on March 1, 2019, the Company completed the sale of 161,126 Class A common shares to the underwriters of the follow-on offering following the exercise in part of their over-allotment option to purchase additional shares at a public offering price of $18.26 per share for gross proceeds of $2,942. The aggregate net proceeds to the Company from the follow-on offering and concurrent private placement, inclusive of the over-allotment option exercise, was $82,988 after deducting underwriting discounts and commissions and other offering costs Liquidity In accordance with Accounting Standards Update (“ASU”) 2014‑15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205‑40), the Company has evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date the consolidated financial statements are issued. As of December 31, 2019, the Company had an accumulated deficit of $356,092. During the year ended December 31, 2019, the Company incurred a net loss of $161,867 and used $158,369 of cash in operating activities. The Company expects to continue to generate operating losses and cash used in operations for the foreseeable future. As of December 31, 2019, the Company had cash, cash equivalents and short‑term investments of $233,380. Based on its current operating plan, the Company expects that its cash, cash equivalents and short-term investments, will be sufficient to fund its operating expenses and capital expenditure requirements for at least twelve months from the issuance date of these consolidated financial statements. The future viability of the Company beyond that point is dependent on its ability to raise additional capital to finance its operations. The Company will need to finance its operations through public or private securities offerings, debt financings or other sources, which may include licensing, collaborations or other strategic transactions or arrangements. Although the Company has been successful in raising capital in the past, there is no assurance that it will be successful in obtaining such additional financing on terms acceptable to the Company, if at all. If the Company is unable to obtain funding, the Company could be forced to delay, reduce or eliminate some or all of its research and development programs for product candidates, product portfolio expansion or commercialization efforts, which could adversely affect its business prospects, or the Company may be unable to continue operations.

1. Nature of the Business and Basis of Presentation

Kiniksa Pharmaceuticals, Ltd. (the “Company”) is a biopharmaceutical company focused on discovering, acquiring, developing and commercializing therapeutic medicines for patients suffering from debilitating diseases with significant unmet medical need. The Company was incorporated in July 2015 as a Bermuda exempted company. The Company has a pipeline of product candidates across various stages of development.

The Company is subject to risks and uncertainties common to early‑stage companies in the biotechnology industry. There can be no assurance that the Company’s research and development will be successfully completed, that adequate protection for the Company’s technology will be obtained, that any products developed will obtain necessary government regulatory approval or that any products, if approved, will be commercially viable. The Company does not currently generate revenue from sales of any products, and it may never be able to develop or commercialize a marketable product. The Company has not yet successfully completed any Phase 3 or other pivotal clinical trials, obtained any regulatory approvals, manufactured a commercial‑scale drug, or conducted sales and marketing activities. The Company operates in an environment of rapid technological innovation and substantial competition from pharmaceutical and biotechnological companies. In addition, the Company is dependent upon the services of its employees, consultants and service providers. Even if the Company’s product development efforts are successful, it is uncertain when, if ever, the Company will realize significant revenue from product sales.

Principles of Consolidation

The accompanying consolidated financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) and include the accounts of the Company and its wholly owned subsidiaries, Kiniksa Pharmaceuticals Corp. (“Kiniksa US”), Primatope Therapeutics, Inc. (“Primatope”) and Kiniksa Pharmaceuticals (UK), Ltd. (“Kiniksa UK”) as well as the subsidiaries of Kiniksa UK, Kiniksa Pharmaceuticals (Germany) GmbH (“Kiniksa Germany”) and Kiniksa Pharmaceuticals (France) SARL (“Kiniksa France”), after elimination of all significant intercompany accounts and transactions.

In assessing the consolidation requirement for variable interest entities (“VIE”s), the Company focuses on identifying whether it has both the power to direct the activities that most significantly impact the VIE’s economic performance and the obligation to absorb losses or the right to receive benefits from the VIE. In the event that the Company is the primary beneficiary of a VIE, the assets, liabilities, and results of operations of the VIE would be included in the Company’s consolidated financial statements. At December 31, 2019 and 2018 and during the years then ended, the Company was not the primary beneficiary of a VIE.

Use of Estimates

The preparation of the Company’s consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of expenses during the reporting period. Significant estimates and assumptions reflected in these consolidated financial statements include, but are not limited to, the accrual for research and development expenses and the valuation of common shares and share‑based awards. Estimates are periodically reviewed in light of changes in circumstances, facts and experience. Changes in estimates are recorded in the period in which they become known. Actual results could differ from those estimates.

Reporting and Functional Currency

The financial results of the Company's global activities are reported in U.S. dollars (“USD”) and its foreign subsidiaries generally utilize their respective local currency to be their functional currency.

Transactions in other currencies are recorded in the functional currency at the rate of exchange prevailing when the transactions occur. Monetary assets and liabilities denominated in other currencies are re-measured into the functional currency at the rate of exchange in effect at the balance sheet date. Exchange gains and losses arising from re-measurement of foreign currency-denominated monetary assets and liabilities are included in income in the period in which they occur.

For our foreign subsidiaries where the local currency is the functional currency, assets and liabilities denominated in local currencies are translated into USD at end-of-period exchange rates and the resulting translation adjustments are reported as a component of accumulated other comprehensive income (loss) within shareholders' equity (deficit).

Reverse Share Split

On May 11, 2018, the Company effected a 1‑for‑2.73235 reverse share split of its authorized, designated, issued and outstanding common shares and preferred shares. Accordingly, all share and per share amounts for all periods presented in the accompanying consolidated financial statements and notes thereto have been adjusted retroactively, where applicable, to reflect this reverse share split.

Initial Public Offering

On May 23, 2018, the Company’s registration statement on Form S‑1 relating to its initial public offering of its Class A common shares (the “IPO”) was declared effective by the Securities and Exchange Commission (“SEC”). On May 29, 2018, the Company completed the IPO of 8,477,777 Class A common shares at $18.00 per share for gross proceeds of $152,600. In addition, on June 22, 2018, the Company completed the sale of 1,006,425 Class A common shares to the underwriters of the IPO following the exercise of their over‑allotment option to purchase additional shares at $18.00 per share for gross proceeds of $18,116. The aggregate net proceeds to the Company from the IPO, inclusive of the over‑allotment option exercise, was $155,536 after deducting underwriting discounts and commissions and other offering costs.

Upon the closing of the IPO, all convertible preferred shares then outstanding automatically converted into 5,546,019 Class A common shares, 1,070,502 Class B common shares, 12,995,954 Class A1 common shares and 16,057,618 Class B1 common shares. In connection with the closing of the IPO, the Company amended and restated its bye‑laws (the “Amended & Restated Bye‑Laws”).

Follow-on Offering and Private Placement

On February 4, 2019, the Company completed a follow-on offering of 2,654,984 Class A common shares at a public offering price of $18.26 and a concurrent private placement of 2,000,000 Class A1 common shares at an offering price of $18.26 per share for aggregate gross proceeds of $85,000. In addition, on March 1, 2019, the Company completed the sale of 161,126 Class A common shares to the underwriters of the follow-on offering following the exercise in part of their over-allotment option to purchase additional shares at a public offering price of $18.26 per share for gross proceeds of $2,942. The aggregate net proceeds to the Company from the follow-on offering and concurrent private placement, inclusive of the over-allotment option exercise, was $82,988 after deducting underwriting discounts and commissions and other offering costs

Liquidity

In accordance with Accounting Standards Update (“ASU”) 2014‑15, Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern (Subtopic 205‑40), the Company has evaluated whether there are conditions and events, considered in the aggregate, that raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date the consolidated financial statements are issued. As of December 31, 2019, the Company had an accumulated deficit of $356,092. During the year ended December 31, 2019, the Company incurred a net loss of $161,867 and used $158,369 of cash in operating activities. The Company expects to continue to generate operating losses and cash used in operations for the foreseeable future. As of December 31, 2019, the Company had cash, cash equivalents and short‑term investments of $233,380.

Based on its current operating plan, the Company expects that its cash, cash equivalents and short-term investments, will be sufficient to fund its operating expenses and capital expenditure requirements for at least twelve months from the issuance date of these consolidated financial statements. The future viability of the Company beyond that point is dependent on its ability to raise additional capital to finance its operations. The Company will need to finance its operations through public or private securities offerings, debt financings or other sources, which may include licensing, collaborations or other strategic transactions or arrangements. Although the Company has been successful in raising capital in the past, there is no assurance that it will be successful in obtaining such additional financing on terms acceptable to the Company, if at all. If the Company is unable to obtain funding, the Company could be forced to delay, reduce or eliminate some or all of its research and development programs for product candidates, product portfolio expansion or commercialization efforts, which could adversely affect its business prospects, or the Company may be unable to continue operations.