Nature of Business and Basis of Presentation	9 Months Ended
Sep. 30, 2020
Disclosure Text Block [Abstract]
Nature of Business and Basis of Presentation	Note 1. Nature of business and basis of presentation Description of business and corporate reorganization iTeos Therapeutics, Inc. (iTeos Inc. or the Company), a Delaware corporation headquartered in Cambridge, Massachusetts (incorporated on October 4, 2019), is the successor to iTeos Belgium SA (iTeos Belgium) a company organized under the laws of Belgium in 2011 and headquartered in Charleroi, Belgium. The Company is a clinical stage biopharmaceutical company that focuses on developing cancer immunotherapies by targeting key mechanisms of immunosuppression in the tumor microenvironment. The most advanced clinical program is EOS-850, a small molecule antagonist of the A_2AR, which is currently in an open-label multi-arm Phase 1/2a clinical trial in adult cancer patients. The second clinical program is EOS-448, an antibody directed to TIGIT, which is an ongoing Phase 1/2a clinical trial in adult cancer patients. The Company also has a preclinical pipeline targeting additional mechanisms. On October 4, 2019, the Company completed a corporate reorganization in which iTeos Inc., iTeos Belgium, and the stockholders of iTeos Belgium entered into an Equity Contribution and Exchange Agreement (Share Exchange), pursuant to which all outstanding shares of preferred stock, common stock and profit certificates of iTeos Belgium were exchanged on a one-for-one basis for newly issued shares of iTeos Inc. iTeos Inc. was a newly-formed holding company, and as a result of the Share Exchange, iTeos Belgium became a wholly owned subsidiary of iTeos Inc. iTeos Therapeutics U.S. Inc. (iTeos U.S.) included the Company’s U.S. operations and was located in Cambridge, Massachusetts. iTeos U.S., which was a wholly owned subsidiary of iTeos Belgium prior to the Share Exchange, continued to be a wholly owned subsidiary of iTeos Belgium throughout 2019. On February 28, 2020, iTeos Inc. purchased iTeos U.S. from iTeos Belgium and then the entities effectively merged. The Share Exchange was accounted for in accordance with the Financial Accounting Standards Board (FASB) Accounting Standard Codification (ASC) 805-50, Business Combinations—Related Issues. The Company evaluated the guidance in ASC 805-50 with respect to the transaction between entities under common control and concluded that since all shareholders of iTeos Inc. and iTeos Belgium have nearly identical ownership percentages and interests before and after the transaction, the Share Exchange lacks economic substance and represents a transaction between entities with common ownership and should be accounted for in a manner consistent with common control transactions and did not result in a change in control at the ultimate parent or the controlling shareholder level. Reverse Stock Split and Initial Public Offering On July 20, 2020, the Company effected a 1-for-3.3115 reverse stock split of the Company’s common stock and adjusted the ratio at which the Company’s preferred stock is convertible into common stock, as well as the number of shares under the 2019 Stock Option and Grant Plan and the Amended and Restated Certificate of Incorporation of iTeos Therapeutics, Inc., as well as the share amounts of stock grants under the plan and the number of options and exercise prices of options under the plan. All shares of common stock, stock options exercisable for shares of common stock, and per share information presented in the accompanying consolidated financial statements and notes thereto have been adjusted, where applicable, to reflect the reverse stock split on a retroactive basis for all periods presented. There was no change in the par value of the Company’s common stock. On July 28, 2020, the Company completed its initial public offering (IPO), in which the Company issued and sold 10,586,316 shares of its common stock, for aggregate gross proceeds of $201.1 million and its shares started trading on The Nasdaq Global Select Market under the ticker symbol “ITOS.” The Company received approximately $184.1 million in net proceeds after deducting underwriting discounts and commissions and other estimated offering expenses payable by the Company. Upon closing of the IPO, all of the Company's outstanding shares of convertible preferred stock automatically converted into 22,460,076 shares of common stock. On August 5, 2020, the underwriters purchased an additional 1,505,359 shares of common stock pursuant to their option to purchase additional shares for net proceeds of $26.6 million after deducting underwriting discounts and commissions. Liquidity and capital resources Since inception, the Company’s activities have consisted primarily of performing research and development to advance its product candidates. The Company is still in the development phase and has not been marketing any developed products to-date. Since inception, the Company has incurred recurring losses, including a net loss of $23.1 million for the nine months ended September 30, 2020. As of September 30, 2020, the Company had an accumulated deficit of $59.0 million. The Company expects to continue to generate operating losses in the foreseeable future. As of November 12, 2020, the issuance date of the condensed consolidated financial statements for the nine months ended September 30, 2020, the Company expected that its cash and cash equivalents would be sufficient to fund its operating expenses, capital expenditure requirements and debt service payments through at least 12 months from the issuance date of the condensed consolidated financial statements. The Company may seek additional funding in order to reach its development and commercialization objectives. The Company may not be able to obtain funding on acceptable terms, or at all, and the Company may not be able to enter into collaborations or other arrangements. The terms of any funding may adversely affect the holdings or the rights of the Company’s stockholders. 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, product portfolio expansion or commercialization efforts, which could adversely affect its business prospects. The Company’s future results of operations involve a number of risks and uncertainties. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, uncertainty regarding results of clinical trials and reaching milestones, uncertainty of regulatory approval of the Company’s current or future product candidates, uncertainty of market acceptance of the Company’s product candidates, if approved, competition from substitute products and larger companies, securing and protecting proprietary technology, strategic relationships and dependence on key individuals and sole source suppliers. Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities and may not ultimately lead to a marketing approval and commercialization of a product. The Company’s product candidates require approvals from the U.S. Food and Drug Administration (FDA) and comparable foreign regulatory agencies prior to commercial sales in their respective jurisdictions. There can be no assurance that any product candidates will receive the necessary approvals. If the Company was denied approval, approval was delayed or the Company was unable to maintain approval for any product candidate, it could have a materially adverse impact on the Company. 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. The Company will need to generate significant revenue to achieve profitability, and it may never do so. COVID-19 In December 2019, a novel strain of coronavirus (COVID-19) emerged in Wuhan, Hubei Province, China. As of September 30, 2020, COVID-19 has spread to Europe, the United States and many other countries, and has been declared a pandemic by the World Health Organization. Efforts to contain the spread of COVID-19 have intensified. The United States, including the Commonwealth of Massachusetts where our headquarters are located, as well as countries throughout Europe and Asia have implemented severe travel restrictions, social distancing requirements and stay-at-home orders, among other restrictions, which, in some cases, have had the effect of delaying the commencement of non-COVID-19-related clinical trials. As a result, the COVID-19 pandemic has caused significant disruptions to the U.S., regional and global economies and has contributed to significant volatility and negative pressure in financial markets. The Company has been carefully monitoring the COVID-19 pandemic and its potential impact on the Company’s business and has taken important steps to help ensure the safety of employees and their families and to reduce the spread of COVID-19 in the Cambridge and Belgian communities. The Company has established a work-from-home policy for all employees, other than those performing or supporting business-critical operations, such as certain members of our laboratory and facilities staff. For those employees, the Company has implemented stringent safety measures designed to comply with applicable federal, state and local guidelines instituted in response to the COVID-19 pandemic. The Company has also maintained efficient communication with the Company’s partners and clinical sites as the COVID-19 situation has progressed. The Company has taken these precautionary steps while maintaining business continuity so that it can continue to progress with its programs. While the COVID-19 pandemic did not significantly impact the Company’s business or results of operations during the nine months ended September 30, 2020, the length and extent of the pandemic, its consequences, and containment efforts will determine the future impact on the Company’s operations and financial condition. Basis of presentation The accompanying condensed consolidated financial statements and accompanying notes have been prepared in accordance with generally accepted accounting principles in the United States of America (U.S. GAAP). The unaudited interim condensed consolidated financial statements of the Company included herein have been prepared, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these condensed consolidated financial statements should be read in conjunction with the consolidated financial statements as of and for the years ended December 31, 2019 and 2018, and the notes thereto, which are included in the Company’s final prospectus related to the Company’s IPO filed on July 27, 2020 (File No. 333-239415) with the SEC pursuant to Rule 424(b)(4) under the Securities Act of 1933, as amended. The results for any interim period are not necessarily indicative of results for any future period. In the opinion of management, the information furnished reflects all adjustments, all of which are of a normal and recurring nature, necessary for a fair presentation of the results for the reported interim periods. The Company considers events or transactions that occur after the balance sheet date but before the financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. The results of operations for interim periods are not necessarily indicative of results to be expected for the full year or any other interim period.

Nature of Business and Basis of Presentation

9 Months Ended

Sep. 30, 2020

Nature of Business and Basis of Presentation

Note 1. Nature of business and basis of presentation

Description of business and corporate reorganization

iTeos Therapeutics, Inc. (iTeos Inc. or the Company), a Delaware corporation headquartered in Cambridge, Massachusetts (incorporated on October 4, 2019), is the successor to iTeos Belgium SA (iTeos Belgium) a company organized under the laws of Belgium in 2011 and headquartered in Charleroi, Belgium. The Company is a clinical stage biopharmaceutical company that focuses on developing cancer immunotherapies by targeting key mechanisms of immunosuppression in the tumor microenvironment. The most advanced clinical program is EOS-850, a small molecule antagonist of the A_2AR, which is currently in an open-label multi-arm Phase 1/2a clinical trial in adult cancer patients. The second clinical program is EOS-448, an antibody directed to TIGIT, which is an ongoing Phase 1/2a clinical trial in adult cancer patients. The Company also has a preclinical pipeline targeting additional mechanisms.

On October 4, 2019, the Company completed a corporate reorganization in which iTeos Inc., iTeos Belgium, and the stockholders of iTeos Belgium entered into an Equity Contribution and Exchange Agreement (Share Exchange), pursuant to which all outstanding shares of preferred stock, common stock and profit certificates of iTeos Belgium were exchanged on a one-for-one basis for newly issued shares of iTeos Inc. iTeos Inc. was a newly-formed holding company, and as a result of the Share Exchange, iTeos Belgium became a wholly owned subsidiary of iTeos Inc. iTeos Therapeutics U.S. Inc. (iTeos U.S.) included the Company’s U.S. operations and was located in Cambridge, Massachusetts. iTeos U.S., which was a wholly owned subsidiary of iTeos Belgium prior to the Share Exchange, continued to be a wholly owned subsidiary of iTeos Belgium throughout 2019. On February 28, 2020, iTeos Inc. purchased iTeos U.S. from iTeos Belgium and then the entities effectively merged.

The Share Exchange was accounted for in accordance with the Financial Accounting Standards Board (FASB) Accounting Standard Codification (ASC) 805-50, Business Combinations—Related Issues. The Company evaluated the guidance in ASC 805-50 with respect to the transaction between entities under common control and concluded that since all shareholders of iTeos Inc. and iTeos Belgium have nearly identical ownership percentages and interests before and after the transaction, the Share Exchange lacks economic substance and represents a transaction between entities with common ownership and should be accounted for in a manner consistent with common control transactions and did not result in a change in control at the ultimate parent or the controlling shareholder level.

Reverse Stock Split and Initial Public Offering

On July 20, 2020, the Company effected a 1-for-3.3115 reverse stock split of the Company’s common stock and adjusted the ratio at which the Company’s preferred stock is convertible into common stock, as well as the number of shares under the 2019 Stock Option and Grant Plan and the Amended and Restated Certificate of Incorporation of iTeos Therapeutics, Inc., as well as the share amounts of stock grants under the plan and the number of options and exercise prices of options under the plan. All shares of common stock, stock options exercisable for shares of common stock, and per share information presented in the accompanying consolidated financial statements and notes thereto have been adjusted, where applicable, to reflect the reverse stock split on a retroactive basis for all periods presented. There was no change in the par value of the Company’s common stock.

On July 28, 2020, the Company completed its initial public offering (IPO), in which the Company issued and sold 10,586,316 shares of its common stock, for aggregate gross proceeds of $201.1 million and its shares started trading on The Nasdaq Global Select Market under the ticker symbol “ITOS.” The Company received approximately $184.1 million in net proceeds after deducting underwriting discounts and commissions and other estimated offering expenses payable by the Company. Upon closing of the IPO, all of the Company's outstanding shares of convertible preferred stock automatically converted into 22,460,076 shares of common stock.

On August 5, 2020, the underwriters purchased an additional 1,505,359 shares of common stock pursuant to their option to purchase additional shares for net proceeds of $26.6 million after deducting underwriting discounts and commissions.

Liquidity and capital resources

Since inception, the Company’s activities have consisted primarily of performing research and development to advance its product candidates. The Company is still in the development phase and has not been marketing any developed products to-date. Since inception, the Company has incurred recurring losses, including a net loss of $23.1 million for the nine months ended September 30, 2020. As of September 30, 2020, the Company had an accumulated deficit of $59.0 million. The Company expects to continue to generate operating losses in the foreseeable future. As of November 12, 2020, the issuance date of the condensed consolidated financial statements for the nine months ended September 30, 2020, the Company expected that its cash and cash equivalents would be sufficient to fund its operating expenses, capital expenditure requirements and debt service payments through at least 12 months from the issuance date of the condensed consolidated financial statements.

The Company may seek additional funding in order to reach its development and commercialization objectives. The Company may not be able to obtain funding on acceptable terms, or at all, and the Company may not be able to enter into collaborations or other arrangements. The terms of any funding may adversely affect the holdings or the rights of the Company’s stockholders. 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, product portfolio expansion or commercialization efforts, which could adversely affect its business prospects.

The Company’s future results of operations involve a number of risks and uncertainties. Factors that could affect the Company’s future operating results and cause actual results to vary materially from expectations include, but are not limited to, uncertainty regarding results of clinical trials and reaching milestones, uncertainty of regulatory approval of the Company’s current or future product candidates, uncertainty of market acceptance of the Company’s product candidates, if approved, competition from substitute products and larger companies, securing and protecting proprietary technology, strategic relationships and dependence on key individuals and sole source suppliers. Product candidates currently under development will require significant additional research and development efforts, including extensive preclinical and clinical testing and regulatory approval prior to commercialization. These efforts require significant amounts of additional capital, adequate personnel and infrastructure and extensive compliance-reporting capabilities and may not ultimately lead to a marketing approval and commercialization of a product.

The Company’s product candidates require approvals from the U.S. Food and Drug Administration (FDA) and comparable foreign regulatory agencies prior to commercial sales in their respective jurisdictions. There can be no assurance that any product candidates will receive the necessary approvals. If the Company was denied approval, approval was delayed or the Company was unable to maintain approval for any product candidate, it could have a materially adverse impact on the Company. 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. The Company will need to generate significant revenue to achieve profitability, and it may never do so.

COVID-19

In December 2019, a novel strain of coronavirus (COVID-19) emerged in Wuhan, Hubei Province, China. As of September 30, 2020, COVID-19 has spread to Europe, the United States and many other countries, and has been declared a pandemic by the World Health Organization. Efforts to contain the spread of COVID-19 have intensified. The United States, including the Commonwealth of Massachusetts where our headquarters are located, as well as countries throughout Europe and Asia have implemented severe travel restrictions, social distancing requirements and stay-at-home orders, among other restrictions, which, in some cases, have had the effect of delaying the commencement of non-COVID-19-related clinical trials. As a result, the COVID-19 pandemic has caused significant disruptions to the U.S., regional and global economies and has contributed to significant volatility and negative pressure in financial markets.

The Company has been carefully monitoring the COVID-19 pandemic and its potential impact on the Company’s business and has taken important steps to help ensure the safety of employees and their families and to reduce the spread of COVID-19 in the Cambridge and Belgian communities. The Company has established a work-from-home policy for all employees, other than those performing or supporting business-critical operations, such as certain members of our laboratory and facilities staff. For those employees, the Company has implemented stringent safety measures designed to comply with applicable federal, state and local guidelines instituted in response to the COVID-19 pandemic. The Company has also maintained efficient communication with the Company’s partners and clinical sites as the COVID-19 situation has progressed. The Company has taken these precautionary steps while maintaining business continuity so that it can continue to progress with its programs.

While the COVID-19 pandemic did not significantly impact the Company’s business or results of operations during the nine months ended September 30, 2020, the length and extent of the pandemic, its consequences, and containment efforts will determine the future impact on the Company’s operations and financial condition.

Basis of presentation

The accompanying condensed consolidated financial statements and accompanying notes have been prepared in accordance with generally accepted accounting principles in the United States of America (U.S. GAAP).

The unaudited interim condensed consolidated financial statements of the Company included herein have been prepared, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (SEC). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted from this report, as is permitted by such rules and regulations. Accordingly, these condensed consolidated financial statements should be read in conjunction with the consolidated financial statements as of and for the years ended December 31, 2019 and 2018, and the notes thereto, which are included in the Company’s final prospectus related to the Company’s IPO filed on July 27, 2020 (File No. 333-239415) with the SEC pursuant to Rule 424(b)(4) under the Securities Act of 1933, as amended. The results for any interim period are not necessarily indicative of results for any future period.

In the opinion of management, the information furnished reflects all adjustments, all of which are of a normal and recurring nature, necessary for a fair presentation of the results for the reported interim periods. The Company considers events or transactions that occur after the balance sheet date but before the financial statements are issued to provide additional evidence relative to certain estimates or to identify matters that require additional disclosure. The results of operations for interim periods are not necessarily indicative of results to be expected for the full year or any other interim period.