Subsequent Events	6 Months Ended
Jun. 30, 2025
Subsequent Events [Abstract]
Subsequent Events	Note 14. Subsequent events On July 18, 2025, the Company entered into an Agreement and Plan of Merger (the "Merger Agreement") with Concentra Biosciences, LLC, a Delaware limited liability company (“Concentra”), and Concentra Merger Sub VIII, Inc., a Delaware corporation and a wholly owned subsidiary of Concentra (“Merger Sub”). The Merger Agreement provides for, among other things: (i) the acquisition of all of the Company’s outstanding shares of common stock by Concentra through a tender offer (the “Offer”), for a price per share of common stock of (A) $10.047 in cash (the “Cash Amount”), subject to applicable tax withholding and without interest, plus (B) one contingent value right (a “CVR”) (together with the Cash Amount, the “Offer Price”), which represents the contractual right to receive contingent payments equal to (y) 100% of the amount by which Closing Net Cash (as defined in the Merger Agreement and as finally determined pursuant to the Merger Agreement) exceeds $475 million, subject to adjustment downward for any claims or downward or upward, as applicable, for any changes in amounts accrued in the Closing Net Cash that, in each case, are not accounted for in such Closing Net Cash, and (z) 80% of the Net Proceeds (as defined in the agreement governing the CVR (the “CVR Agreement”)), if any, from any sale, transfer, license or other disposition by Concentra or any of its affiliates, including the Company after the Merger, of all or any part of the Company’s and its subsidiaries’ (1) product candidates known as EOS-984 and EOS-215, including, in each case, any form or formulation, and any improvement or enhancement, of any such product candidate, (2) preclinical obesity program targeting ENT1, including EOS-518 and EOS-855 and any product candidate contained in or arising from such program, (3) program developing a small molecule inhibiting PTPNI1/2, and any product candidate contained in or arising from, such program, and (4) any product or product candidate covered by the claims of a patent, patent application, provisional patent application or similar instrument owned by the Company or a subsidiary of the Company as of the closing date of the Merger ((1)-(4), collectively, the “CVR Products”, and the closing date of the Merger, the “Merger Closing Date”), in each case that occurs within the period beginning on the Merger Closing Date and ending on the six month anniversary following the Merger Closing Date (the “Disposition Period”) and (ii) the Merger, with the Company surviving the Merger. Following the completion of the Offer, upon the terms and subject to the conditions of the Merger Agreement, Merger Sub will merge with and into the Company, with the Company surviving as a wholly owned subsidiary of Concentra, pursuant to the procedure provided for under Section 251(h) of the Delaware General Corporation Law (“DGCL”), without any additional Company stockholder approvals. The Merger will be effected as soon as practicable following the time of purchase by Concentra of shares of Common Stock validly tendered and not withdrawn in the Offer. Concentra’s obligation to accept shares of common stock tendered in the Offer is subject to conditions, including: (i) that the number of shares of voting common stock validly tendered (and not properly withdrawn) prior to the expiration of the Offer (excluding shares tendered pursuant to guaranteed delivery procedures that have not yet been “received” by the “depository,” as such terms are defined by Section 251(h) of the DGCL) that, when considered together with all other shares of the voting common stock (if any) owned by Concentra and its “affiliates” (as defined in Section 251(h)(6)(a) of the DGCL), equals at least one share more than 50% of all shares of voting common stock then issued and outstanding as of the expiration of the Offer; (ii) the absence of any Legal Restraint (as defined in the Merger Agreement) in effect preventing or prohibiting the consummation of the Offer, the Merger or any of the other transactions contemplated by the Merger Agreement or the CVR Agreement; (iii) the accuracy of the representations and warranties made by the Company in the Merger Agreement, subject to specified materiality qualifications and exceptions; (iv) compliance by the Company with its covenants under the Merger Agreement in all material respects; and (v) the Closing Net Cash (as defined in the Merger Agreement) shall be no less than $475 million, unless following a final determination in accordance with the Merger Agreement that Closing Net Cash is less than $475 million, the Merger Agreement has not been terminated by Concentra within five (5) business days thereafter. The obligations of Concentra and Merger Sub to consummate the Offer and the Merger under the Merger Agreement are not subject to a financing condition. The Merger Agreement contains representations and warranties from both the Company, on the one hand, and Concentra and Merger Sub, on the other hand, customary for a transaction of this nature. The Merger Agreement also contains customary covenants and agreements, including with respect to the operations of the business of the Company between the date of the Merger Agreement and the closing of the Merger.The Merger Agreement contains customary termination rights for both Concentra and Merger Sub, on the one hand, and the Company, on the other hand, including, among others, for failure to consummate the Offer on or before October 16, 2025. If the Merger Agreement is terminated under certain circumstances specified in the Merger Agreement, including in connection with the Company’s entry into an agreement with respect to a Superior Company Proposal (as defined in the Merger Agreement), the Company will be required to pay Concentra a termination fee of $8.4 million. If Concentra terminates the Merger Agreement due to the Company having Closing Net Cash of less than $475.0 million, the Company will be required to reimburse expenses incurred by Concentra up to a maximum amount of $0.5 million. Pursuant to the terms of the Merger Agreement, as of immediately prior to the effective time of the Merger (the “Effective Time”), by virtue of the Merger and without any action on the part of the holders of Common Stock: (i) each outstanding share of Common Stock, other than any shares of Common Stock owned by Concentra, Merger Sub or any other subsidiary of Concentra, or by any stockholders of the Company who are entitled to and who properly exercise appraisal rights under Delaware law, will be converted into the right to receive the Offer Price without interest, less any applicable withholding taxes; (ii) (A) each option to purchase shares of Common Stock from the Company (“Company Stock Options,” and each such option, a “Company Stock Option”) that is then outstanding but not then vested or exercisable and that is held by a Company service provider who is subject to an individual employment or other agreement and/or a Company severance and change in control plan or agreement that provides for accelerated vesting of time-based equity awards upon the occurrence of a sale of the Company or a qualifying termination of employment or service in connection with, or within a specified time following a sale of the Company (each such option an “Accelerated Vesting Stock Option”) will become immediately vested and exercisable in full, (B) each Company Stock Option that has an exercise price per share that is less than the Cash Amount (each, an “In-the-Money Option”) that is then outstanding will be cancelled and, in exchange therefor, the holder of such cancelled In-the-Money Option will be entitled to receive in consideration of the cancellation of such In-the-Money Option (x) an amount in cash without interest, subject to any applicable tax withholding, equal to the product obtained by multiplying (1) the excess of the Cash Amount over the exercise price per share of Common Stock underlying such In-the-Money Option by (2) the number of shares of Common Stock underlying such In-the-Money Option as of immediately prior to the Effective Time and (y) one CVR for each share of Common Stock underlying such In-the-Money Option, and (C) each Company Stock Option that has an exercise price per share that is equal to or greater than the Cash Amount, and each unvested Company Stock Option that is not an Accelerated Vesting Stock Option, that is then outstanding will be cancelled for no consideration; and (iii) (A) each restricted stock unit of the Company (“Company Restricted Stock Units,” and each such restricted stock unit, a “Company Restricted Stock Unit”) that is held by a Company service provider who is subject to an individual employment or other agreement and/or a Company severance and change in control plan or agreement that provides for accelerated vesting of time-based equity awards upon the occurrence of a sale of the Company or a qualifying termination of employment or service in connection with, or within a specified time following a sale of the Company (each such Company Restricted Stock Unit an “Accelerated Vesting Restricted Stock Unit”) that is then outstanding but not then vested will become immediately vested in full, (B) each Accelerated Vesting Restricted Stock Unit that is then outstanding will be cancelled and, in exchange therefor, the holder of such cancelled Company Restricted Stock Unit will be entitled to receive in consideration of the cancellation of such Company Restricted Stock Unit (x) an amount in cash without interest, subject to any applicable tax withholding, equal to the Cash Amount and (y) one CVR and (C) each unvested Company Restricted Stock Unit that is not an Accelerated Vesting Restricted Stock Unit that is then outstanding will be cancelled for no consideration. GSK Termination Agreement On July 18, 2025, iTeos Belgium and GSK entered into the GSK Termination Agreement, pursuant to which iTeos Belgium will pay a settlement payment of $32.0 million no later than 20 business days after receipt of an invoice from GSK to close out the remaining clinical activity costs for which it is responsible under the contract. Unless there is a material safety or efficacy issue requiring pause or cessation, both iTeos Belgium and GSK are required to complete within certain specified time periods certain ongoing activities related to the wind-down and completion of clinical trials. Pursuant to the GSK Termination Agreement, GSK will revert to iTeos Belgium control of prosecution of certain patents and GSK and iTeos Belgium will complete data migration activities and publish certain scientific and medical publications related to activities performed under the GSK Agreement. Termination of the Company’s 2020 ESPP On July 18, 2025, in connection with the execution of the Merger Agreement, the Company terminated the 2020 ESPP, and as a result, the Company will refund all amounts in the accounts of 2020 ESPP participants in accordance with the terms of the 2020 ESPP. Termination of employees On July 3, 2025, the Company entered into a collective bargaining agreement for a planned termination with the employees of iTeos Belgium in connection with the Company's announced intention to wind-down operations. The first round of employee terminations for iTeos Belgium is planned for mid-August 2025. In addition, on July 7, 2025, the Company terminated a portion of its U.S. based employees of iTeos Inc. The Company accrued for termination benefits determined to be part of an ongoing benefit arrangement under ASC 712, Compensation - Nonretirement Postemployment Benefits, because the terminations were considered probable as of June 30, 2025. The total amount recognized in the period ended June 30, 2025 was $16.3 million. The remaining termination benefit costs of $8.2 million were deemed to be additional benefits that were not part of an ongoing plan and therefore under the scope of ASC 420, Exit and disposal costs. These costs were not recognized in the period ended June 30, 2025 due to the communication and mutual understanding of these additional benefits not occurring until July 2025, and will be subsequently recorded in July 2025. Termination of leases On July 2 and 3, 2025, the Company agreed to terminate its leases in Belgium. The notice period for the April 2016 lease is 12 months and the notice period for the May 2023 lease is 6 months, obligating the Company to make lease payments for the duration of these terms for each respective lease. In connection with the termination of Belgian employees, the Company will make lease payments for leased employee cars for a duration of three months after the terminated employees' termination date. The total expected cost the Company expects to pay for these terminated leases is $2.4 million. Government grants On July 25, 2025, the Company received notice from the Walloon Region government authorities in Belgium that the substantial majority of the repayable liability owed to the Walloon Region will be relieved. The Company will be required to pay 50% of the current portion of the repayable liability, amounting to $0.2 million. The Company will also be required to reimburse advance payments received from the Walloon Region of $1.5 million, which is recorded in deferred income on the balance sheet as of June 30, 2025.

Subsequent Events

6 Months Ended

Jun. 30, 2025

Note 14. Subsequent events

On July 18, 2025, the Company entered into an Agreement and Plan of Merger (the "Merger Agreement") with Concentra Biosciences, LLC, a Delaware limited liability company (“Concentra”), and Concentra Merger Sub VIII, Inc., a Delaware corporation and a wholly owned subsidiary of Concentra (“Merger Sub”). The Merger Agreement provides for, among other things: (i) the acquisition of all of the Company’s outstanding shares of common stock by Concentra through a tender offer (the “Offer”), for a price per share of common stock of (A) $10.047 in cash (the “Cash Amount”), subject to applicable tax withholding and without interest, plus (B) one contingent value right (a “CVR”) (together with the Cash

Amount, the “Offer Price”), which represents the contractual right to receive contingent payments equal to (y) 100% of the amount by which Closing Net Cash (as defined in the Merger Agreement and as finally determined pursuant to the Merger Agreement) exceeds $475 million, subject to adjustment downward for any claims or downward or upward, as applicable, for any changes in amounts accrued in the Closing Net Cash that, in each case, are not accounted for in such Closing Net Cash, and (z) 80% of the Net Proceeds (as defined in the agreement governing the CVR (the “CVR Agreement”)), if any, from any sale, transfer, license or other disposition by Concentra or any of its affiliates, including the Company after the Merger, of all or any part of the Company’s and its subsidiaries’ (1) product candidates known as EOS-984 and EOS-215, including, in each case, any form or formulation, and any improvement or enhancement, of any such product candidate, (2) preclinical obesity program targeting ENT1, including EOS-518 and EOS-855 and any product candidate contained in or arising from such program, (3) program developing a small molecule inhibiting PTPNI1/2, and any product candidate contained in or arising from, such program, and (4) any product or product candidate covered by the claims of a patent, patent application, provisional patent application or similar instrument owned by the Company or a subsidiary of the Company as of the closing date of the Merger ((1)-(4), collectively, the “CVR Products”, and the closing date of the Merger, the “Merger Closing Date”), in each case that occurs within the period beginning on the Merger Closing Date and ending on the six month anniversary following the Merger Closing Date (the “Disposition Period”) and (ii) the Merger, with the Company surviving the Merger.

Following the completion of the Offer, upon the terms and subject to the conditions of the Merger Agreement, Merger Sub will merge with and into the Company, with the Company surviving as a wholly owned subsidiary of Concentra, pursuant to the procedure provided for under Section 251(h) of the Delaware General Corporation Law (“DGCL”), without any additional Company stockholder approvals. The Merger will be effected as soon as practicable following the time of purchase by Concentra of shares of Common Stock validly tendered and not withdrawn in the Offer.

Concentra’s obligation to accept shares of common stock tendered in the Offer is subject to conditions, including: (i) that the number of shares of voting common stock validly tendered (and not properly withdrawn) prior to the expiration of the Offer (excluding shares tendered pursuant to guaranteed delivery procedures that have not yet been “received” by the “depository,” as such terms are defined by Section 251(h) of the DGCL) that, when considered together with all other shares of the voting common stock (if any) owned by Concentra and its “affiliates” (as defined in Section 251(h)(6)(a) of the DGCL), equals at least one share more than 50% of all shares of voting common stock then issued and outstanding as of the expiration of the Offer; (ii) the absence of any Legal Restraint (as defined in the Merger Agreement) in effect preventing or prohibiting the consummation of the Offer, the Merger or any of the other transactions contemplated by the Merger Agreement or the CVR Agreement; (iii) the accuracy of the representations and warranties made by the Company in the Merger Agreement, subject to specified materiality qualifications and exceptions; (iv) compliance by the Company with its covenants under the Merger Agreement in all material respects; and (v) the Closing Net Cash (as defined in the Merger Agreement) shall be no less than $475 million, unless following a final determination in accordance with the Merger Agreement that Closing Net Cash is less than $475 million, the Merger Agreement has not been terminated by Concentra within five (5) business days thereafter. The obligations of Concentra and Merger Sub to consummate the Offer and the Merger under the Merger Agreement are not subject to a financing condition.

The Merger Agreement contains representations and warranties from both the Company, on the one hand, and Concentra and Merger Sub, on the other hand, customary for a transaction of this nature. The Merger Agreement also contains customary covenants and agreements, including with respect to the operations of the business of the Company between the date of the Merger Agreement and the closing of the Merger.The Merger Agreement contains customary termination rights for both Concentra and Merger Sub, on the one hand, and the Company, on the other hand, including, among others, for failure to consummate the Offer on or before October 16, 2025. If the Merger Agreement is terminated under certain circumstances specified in the Merger Agreement, including in connection with the Company’s entry into an agreement with respect to a Superior Company Proposal (as defined in the Merger Agreement), the Company will be required to pay Concentra a termination fee of $8.4 million. If Concentra terminates the Merger Agreement due to the Company having Closing Net Cash of less than $475.0 million, the Company will be required to reimburse expenses incurred by Concentra up to a maximum amount of $0.5 million.

Pursuant to the terms of the Merger Agreement, as of immediately prior to the effective time of the Merger (the “Effective Time”), by virtue of the Merger and without any action on the part of the holders of Common Stock: (i) each outstanding share of Common Stock, other than any shares of Common Stock owned by Concentra, Merger Sub or any other subsidiary of Concentra, or by any stockholders of the Company who are entitled to and who properly exercise appraisal rights under Delaware law, will be converted into the right to receive the Offer Price without interest, less any applicable withholding taxes; (ii) (A) each option to purchase shares of Common Stock from the Company (“Company Stock Options,” and each such option, a “Company Stock Option”) that is then outstanding but not then vested or exercisable and that is held by a Company service provider who is subject to an individual employment or other agreement and/or a Company severance and change in control plan or agreement that provides for accelerated vesting of time-based equity awards upon the occurrence of a sale of the Company or a qualifying termination of employment or service in connection with, or within a specified time following a sale of the Company (each such option an “Accelerated

Vesting Stock Option”) will become immediately vested and exercisable in full, (B) each Company Stock Option that has an exercise price per share that is less than the Cash Amount (each, an “In-the-Money Option”) that is then outstanding will be cancelled and, in exchange therefor, the holder of such cancelled In-the-Money Option will be entitled to receive in consideration of the cancellation of such In-the-Money Option (x) an amount in cash without interest, subject to any applicable tax withholding, equal to the product obtained by multiplying (1) the excess of the Cash Amount over the exercise price per share of Common Stock underlying such In-the-Money Option by (2) the number of shares of Common Stock underlying such In-the-Money Option as of immediately prior to the Effective Time and (y) one CVR for each share of Common Stock underlying such In-the-Money Option, and (C) each Company Stock Option that has an exercise price per share that is equal to or greater than the Cash Amount, and each unvested Company Stock Option that is not an Accelerated Vesting Stock Option, that is then outstanding will be cancelled for no consideration; and (iii) (A) each restricted stock unit of the Company (“Company Restricted Stock Units,” and each such restricted stock unit, a “Company Restricted Stock Unit”) that is held by a Company service provider who is subject to an individual employment or other agreement and/or a Company severance and change in control plan or agreement that provides for accelerated vesting of time-based equity awards upon the occurrence of a sale of the Company or a qualifying termination of employment or service in connection with, or within a specified time following a sale of the Company (each such Company Restricted Stock Unit an “Accelerated Vesting Restricted Stock Unit”) that is then outstanding but not then vested will become immediately vested in full, (B) each Accelerated Vesting Restricted Stock Unit that is then outstanding will be cancelled and, in exchange therefor, the holder of such cancelled Company Restricted Stock Unit will be entitled to receive in consideration of the cancellation of such Company Restricted Stock Unit (x) an amount in cash without interest, subject to any applicable tax withholding, equal to the Cash Amount and (y) one CVR and (C) each unvested Company Restricted Stock Unit that is not an Accelerated Vesting Restricted Stock Unit that is then outstanding will be cancelled for no consideration.

GSK Termination Agreement

On July 18, 2025, iTeos Belgium and GSK entered into the GSK Termination Agreement, pursuant to which iTeos Belgium will pay a settlement payment of $32.0 million no later than 20 business days after receipt of an invoice from GSK to close out the remaining clinical activity costs for which it is responsible under the contract. Unless there is a material safety or efficacy issue requiring pause or cessation, both iTeos Belgium and GSK are required to complete within certain specified time periods certain ongoing activities related to the wind-down and completion of clinical trials. Pursuant to the GSK Termination Agreement, GSK will revert to iTeos Belgium control of prosecution of certain patents and GSK and iTeos Belgium will complete data migration activities and publish certain scientific and medical publications related to activities performed under the GSK Agreement.

Termination of the Company’s 2020 ESPP

On July 18, 2025, in connection with the execution of the Merger Agreement, the Company terminated the 2020 ESPP, and as a result, the Company will refund all amounts in the accounts of 2020 ESPP participants in accordance with the terms of the 2020 ESPP.

Termination of employees

On July 3, 2025, the Company entered into a collective bargaining agreement for a planned termination with the employees of iTeos Belgium in connection with the Company's announced intention to wind-down operations. The first round of employee terminations for iTeos Belgium is planned for mid-August 2025. In addition, on July 7, 2025, the Company terminated a portion of its U.S. based employees of iTeos Inc. The Company accrued for termination benefits determined to be part of an ongoing benefit arrangement under ASC 712, Compensation - Nonretirement Postemployment Benefits, because the terminations were considered probable as of June 30, 2025. The total amount recognized in the period ended June 30, 2025 was $16.3 million. The remaining termination benefit costs of $8.2 million were deemed to be additional benefits that were not part of an ongoing plan and therefore under the scope of ASC 420, Exit and disposal costs. These costs were not recognized in the period ended June 30, 2025 due to the communication and mutual understanding of these additional benefits not occurring until July 2025, and will be subsequently recorded in July 2025.

Termination of leases

On July 2 and 3, 2025, the Company agreed to terminate its leases in Belgium. The notice period for the April 2016 lease is 12 months and the notice period for the May 2023 lease is 6 months, obligating the Company to make lease payments for the duration of these terms for each respective lease. In connection with the termination of Belgian employees, the Company will make lease payments for leased employee cars for a duration of three months after the terminated employees' termination date. The total expected cost the Company expects to pay for these terminated leases is $2.4 million.

Government grants

On July 25, 2025, the Company received notice from the Walloon Region government authorities in Belgium that the substantial majority of the repayable liability owed to the Walloon Region will be relieved. The Company will be required to pay 50% of the current portion of the repayable liability, amounting to $0.2 million. The Company will also be required to reimburse advance payments received from the Walloon Region of $1.5 million, which is recorded in deferred income on the balance sheet as of June 30, 2025.