8-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): April 12, 2021 (April 10, 2021)

ITEOS THERAPEUTICS, INC.

(Exact name of Registrant as Specified in Its Charter)

Delaware	001-39401	84-3365066
(State or Other Jurisdiction of Incorporation)	(Commission File Number)	(IRS Employer Identification No.)
iTeos Therapeutics, Inc. 139 Main Street Cambridge, MA		02142
(Address of Principal Executive Offices)		(Zip Code)

Registrant’s Telephone Number, Including Area Code: (339) 217-0161

Not Applicable

(Former Name or Former Address, if Changed Since Last Report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

☐ Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

☐ Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

☐ Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

☐ Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each class	Trading Symbol(s)	Name of each exchange on which registered
Common Stock, $.0.001 par value per share	ITOS	The Nasdaq Global Market

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company  ☒

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐

Item 7.01 Regulation FD Disclosure.

On April 10, 2021, iTeos Therapeutics, Inc., a Delaware corporation (the “Company”), issued a press release titled “iTeos Therapeutics Announces New Preliminary Data Indicating Clinical Activity with its Anti-TIGIT Antibody, EOS-448, at the AACR Annual Meeting 2021.” A copy of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K and is incorporated herein by reference.

The information under this Item 7.01 (including Exhibit 99.1) is being furnished herewith and shall not be deemed “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall it be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as expressly set forth by specific reference in such a filing.

Item 8.01 Other Events

The Company from time to time presents and/or distributes to the investment community slide presentations to provide updates and summaries of its business. On April 12, 2021, the Company will host a conference call and webcast to provide and overview of its preliminary data for EOS-448. A copy of its “Immunotherapies to Improve and Extend Lives of People with Cancer - EOS-448 Update” slide presentation is being filed herewith as Exhibit 99.2 to this Current Report on Form 8-K and incorporated herein by reference. The Company undertakes no obligation to update, supplement or amend the materials attached hereto as Exhibit 99.2.

Statements contained under this Item 8.01, including Exhibit 99.2, regarding matters that are not historical facts are “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. Because such statements are subject to risks and uncertainties, actual results may differ materially from those expressed or implied by such forward-looking statements. Such statements include, but are not limited to: the initiation, timing and progress of iTeos’ current and future clinical trials and preclinical studies of its product candidatres, including inupadenant and EOS-448 and its research and development programs; iTeos’ ability to successfully establish or maintain collaborations or strategic relationships for its product candidates; and the potential impact of COVID-19 on the Company’s strategy, future operations and clinical trials.

Any forward-looking statements are based on management’s current expectations and beliefs and involve risks and uncertainties that could cause actual results to differ materially from those discussed in such forward-looking statements. Risks that contribute to the uncertain nature of the forward-looking statements include, without limitation: uncertainties inherent in clinical studies and in the availability and timing of data from ongoing clinical studies; whether interim results from a clinical trial will be predictive of the final results of the trial; that the results from the Company’s clinical trials for inupadenant and EOS-448 may not support further development and marketing apporval; the risk that the Company may be unable to gain approval for its product candidates on a timely basis, or at all; the risk that the current COVID-19 pandemic will impact iTeos’ clinical trials and operations and other risks set forth under the caption “Risk Factors” in iTeos’ most recent Annual Report on Form 10-K and its other filings with the Securities and Exchange Commission. All forward-looking statements contained in this presentation speak only as of the date on which they were made. The Company undertakes no obligation to update such statements to reflect events that occur or circumstances that exist after the date on which they were made.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits

Exhibit Number	Description
99.1	Press release dated April 10, 2021
99.2	Copy of iTeos Therapeutics slide presentation dated April 12, 2021

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	ITEOS THERAPEUTICS, INC.
Date: April 12, 2021	By:	/s/ Michel Detheux
		Michel Detheux
		President and Chief Executive Officer

EX-99.1

Exhibit 99.1

iTeos Therapeutics Announces New Preliminary Data Indicating Clinical Activity with its Anti-TIGIT Antibody, EOS-448, at the AACR Annual Meeting 2021

• Initial data from the Phase 1 dose escalation part of the Phase 1/2a trial in adult patients with advanced solid tumors indicated EOS-448 was generally well tolerated with no dose-limiting toxicities observed

• EOS-448 showed preliminary signs of clinical activity as a monotherapy, including a partial response in one pembrolizumab-resistant melanoma patient, and stable disease in multiple patients

• EOS-448 reduced TIGIT⁺ suppressive T regulatory cells and CD8 T cells considered to be exhausted at all tested doses, indicating engagement of FcgR, an essential component in many immune system effector functions

• Company to advance EOS-448 into combination trials with pembrolizumab and other novel agents in both checkpoint-naïve and resistant patients

• Company to host conference call on Monday, April 12^th at 8:00 a.m. EDT to discuss results

CAMBRIDGE, Mass. and GOSSELIES, Belgium, Apr. 10, 2021 — iTeos Therapeutics, Inc. (Nasdaq: ITOS), clinical-stage biopharmaceutical company pioneering the discovery and development of a new generation of highly differentiated immuno-oncology therapeutics for patients, today announced a presentation featuring preliminary clinical data from 22 adult patients in the ongoing Phase 1/2a trial of its anti-TIGIT antibody, EOS-448, at the American Association of Cancer Research (AACR) Annual Meeting 2021, taking place virtually April 10-15. The presentation highlights initial findings from the completed dose escalation monotherapy portion of the trial, indicating a favorable tolerability profile and early signs of clinical activity in advanced cancers.

“We are pleased to share these data showing promising preliminary signs of clinical activity and a favorable tolerability profile with our anti-TIGIT antibody, EOS-448, in patients with advanced cancers,” said Joanne Jenkins Lager, M.D., chief medical officer of iTeos Therapeutics. “The results support our excitement around TIGIT as a therapeutic target capable of harnessing the immune system to treat patients with advanced, difficult to treat cancers. We believe the depletion of TIGIT⁺ suppressive and exhausted cells shown at even the lowest tested dose provides evidence of engagement of the FcgR, and therefore the potential of EOS-448 to activate multiple immune mechanisms. Based on these encouraging results, we are enrolling a total of 40 patients in this study to evaluate the effects of EOS-448 within the tumor. We are advancing EOS-448 into the next stage of clinical development as both a monotherapy and in combination for the treatment of multiple indications, with the goal of improving outcomes for people with advanced cancers.”

Summary of the Data Presented

The objective of the dose escalation portion of the ongoing EOS-448 trial, presented at AACR, is to evaluate primary objectives of safety and tolerability, and secondary objectives of pharmacokinetics (PK), pharmacodynamics (PD), and antitumor activity of EOS-448 as a monotherapy in patients with advanced solid tumor cancers. As of the data cut-off (December 31, 2020), the trial had enrolled 22 advanced cancer patients with solid tumors for whom no standard treatment was available. The patients received EOS-448 intravenously (IV) once every two weeks (Q2W) or once every four weeks (Q4W) according to their dose and schedule allocation. Doses of 20, 70, 200, 700 mg Q2W and 1400 mg Q4W were evaluated. Since the data cut-off for the AACR poster, as of March 9, 2021, an additional 11 patients have received single agent EOS-448. In addition to the five dose levels which were described at AACR, patients have also received doses of 400mg Q4w and 700mg Q4w.

EOS-448 was generally well-tolerated at all tested doses in patients with advanced cancer. Preliminary evidence of clinical activity as a monotherapy, including a confirmed partial response in one pembrolizumab-refractory melanoma patient and disease stabilization in nine patients, was also observed. The most common treatment related adverse events were itching, infusion-related reactions, fatigue, rash and fever, and one treatment related serious adverse event, a grade 2 systemic inflammatory response, was observed. As of March 9, 2020, two additional treatment-related serious events have been reported: Grade 2 Systemic Inflammatory Response and Grade 3 infusion-related reaction.

PK assessments indicated a linear and dose-proportional response and PD assessments showed complete target engagement. Biomarker analyses showed evidence of FcgR engagement, as demonstrated by a reduction in suppressive immune cells and immune cells considered to be exhausted in the blood, including TIGIT⁺ regulatory T cells (Tregs) and TIGIT⁺ CD8 T cells, with only a slight reduction in the total CD8⁺ T cell count. A shift towards a more functional immune response was observed, with a two-fold increase in the ratio of CD8⁺ T cells to Treg and a four-fold increase in the ratio of CD8⁺ TIGIT^- T cells to CD8⁺ TIGIT⁺ T cells.

“I am highly encouraged by these initial results from the EOS-448 trial, particularly the clinically meaningful response to treatment in the pembrolizumab-refractory melanoma patient,” said Mario Sznol, M.D., professor of medicine and leader, Melanoma/RCC Disease-Associated Research Team, at Yale University. “The treatment of patients who develop resistance to checkpoint inhibitors is challenging in a number of tumor types, and these data give us hope that EOS-448 could provide benefit in adult solid tumor patients who don’t respond to or who progress on current checkpoint inhibitors.”

The e-poster and abstract can be accessed on the AACR conference website. The abstract and presentation details are as follows:

Title: Preliminary data from Phase I first-in-human study of EOS884448, a novel potent anti-TIGIT antibody, monotherapy shows favorable tolerability profile and early signs of clinical activity in immune-resistant advanced cancer

Session: Phase I Clinical Trials

Poster #: CT118

Authors: Tom Van den Mooter, et al.

The Company will host a conference call and webcast to provide an overview of the data on Monday, April 12 at 8:00 a.m. EDT. Details are as follows:

Participant Dial-In: (833) 607-1661

International Dial-In: (914) 987-7874

Conference ID: 2888301

Webcast: https://edge.media-server.com/mmc/p/ke2wtf4w

The abstract was posted online at 12:01 a.m. EDT on Friday, April 9 and the e-poster launched at 8:30 a.m. EDT on Saturday, April 10 on the AACR conference website.

EOS-448 Further Clinical Development Plans

Based on these preliminary results, the Company plans to advance EOS-448 using combination trials in both checkpoint-naïve and resistant patients. These Phase 1b trials will assess the safety of EOS-448 in combination with pembrolizumab and in combination with iTeos novel agent inupadenant in patients with solid tumors, and as a monotherapy and in combination with an Immunomodulatory Drug (IMiD) in patients with multiple myeloma. Subsequent disease-specific Phase 2a trials are planned in patients with non-small cell lung cancer, head and neck cancer, melanoma, and myeloma. The Company is also planning for later-stage trials of EOS-448, including in combination with pembrolizumab.

About iTeos Therapeutics, Inc.

iTeos Therapeutics is a clinical-stage biopharmaceutical company pioneering the discovery and development of a new generation of highly differentiated immuno-oncology therapeutics for patients. iTeos Therapeutics leverages its deep understanding of cancer immunology and immunosuppressive pathways to design novel product candidates with the potential to fully restore the immune response against cancer. The Company’s innovative pipeline includes two clinical-stage programs targeting novel, validated immuno-oncology pathways designed with optimized pharmacologic properties for improved clinical outcomes. The initial antibody product candidate, EOS-448, is a high affinity, potent, anti-TIGIT antibody with a functional Fc domain, designed to enhance the anti-tumor response through a multifaceted immune modulatory mechanism. An open-label Phase 1/2a clinical trial of EOS-448 is ongoing in adult cancer patients with advanced solid tumors with preliminary data indicating clinical activity as a monotherapy and a favorable tolerability profile. The Company is also advancing inupadenant, a next-generation adenosine A2A receptor antagonist tailored to overcome cancer immunosuppression. iTeos is conducting an open-label multi-arm Phase 1/2a clinical trial of inupadenant in adult cancer patients with advanced solid tumors. Preliminary results indicate encouraging single-agent activity in the dose escalation portion of the trial. iTeos Therapeutics is headquartered in Cambridge, MA with a research center in Gosselies, Belgium.

Forward-Looking Statement

This press release may contain forward-looking statements and information within the meaning of The Private Securities Litigation Reform Act of 1995 and other federal securities laws, including express or implied statements regarding the Company’s future expectations, plans and prospects, including, without limitation, statements regarding expectations and plans for presenting clinical data, projections regarding our long-term growth, the anticipated timing of our clinical trials and regulatory filings, the development of our product candidates and advancement of our clinical programs, as well as other statements containing words such as “may,” “will,” “could”, “should,” “expects,” “intends,” “plans,” “anticipates,” “believes,” “estimates,” “predicts,” “projects,” “seeks,” “endeavor,” “potential,” “continue” or the negative of such words or other similar expressions that can be used to identify forward-looking statements. The express or implied forward-looking statements included in this press release are only predictions and are subject to a number of risks, uncertainties and assumptions, including, without limitation: uncertainties inherent in clinical studies and in the availability and timing of data from ongoing clinical studies; whether interim results from a clinical trial will be predictive of the final results of the trial; whether results from pre-clinical studies or earlier clinical studies will be predictive of the results of future trials; the expected timing of submissions for regulatory approval or review by governmental authorities; whether the Company will receive regulatory approvals to conduct trials or to market products; whether the Company’s cash resources will be sufficient to fund its foreseeable and unforeseeable operating expenses and capital expenditure requirements; risks, assumptions and uncertainties regarding the impact of the continuing COVID-19 pandemic on the Company’s business, operations, strategy, goals and anticipated timelines, the Company’s ongoing and planned pre-clinical activities, the Company’s ability to initiate, enroll, conduct or complete ongoing and planned clinical trials, the Company’s timelines for regulatory submissions and the Company’s financial position; and other risks concerning the Company’s programs and operations set forth under the caption “Risk Factors” in the Company’s Annual Report on Form 10-K filed on March 24, 2021, as updated by its other filings with the Securities and Exchange Commission. In light of these risks, uncertainties and assumptions, the forward-looking events and circumstances discussed in this press release may not occur and actual results could differ materially and adversely from those anticipated or implied in the forward-looking statements. You should not rely upon forward-looking statements as predictions of future events. Although the Company believes that the expectations reflected in the forward-looking statements are reasonable, it cannot guarantee that the future results, levels of activity, performance or events and circumstances reflected in the forward-looking statements will be achieved or occur. Moreover, except as required by law, neither the Company nor any other person assumes responsibility for the accuracy and completeness of the forward-looking statements included in this press release. Any forward-looking statement included in this press release speaks only as of the date on which it was made. We undertake no obligation to publicly update or revise any forward-looking statement, whether as a result of new information, future events or otherwise, except as required by law.

For further information, please contact:

Investor Contacts:

Ryan Baker

iTeos Therapeutics, Inc.

Ryan.Baker@iteostherapeutics.com

Media Contacts:

media@iteostherapeutics.com

EX-99.2

Immunotherapies to Improve and Extend the Lives of People with Cancer EOS-448 update - April 12th, 2021 Exhibit 99.2

Disclaimer This Presentation has been prepared by iTeos Therapeutics, Inc. (“we,” “us,” our “our”) and contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995 and other federal securities laws. Forward-looking statements are neither historical facts nor assurances of future performance. Instead, they are based on our current beliefs, expectations and assumptions regarding the future of our business, future plans and strategies, our development plans, our clinical results and future conditions. All statements, other than statements of historical facts, contained in this Presentation, including statements regarding our strategy, future financial condition, future operations, projected costs, prospects, plans, objectives of management and expected market growth, are forward-looking statements. In some cases, you can identify forward-looking statements by terminology such as ‘‘aim,’’ ‘‘anticipate,’’ ‘‘assume,’’ ‘‘believe,’’ ‘‘contemplate,’’ ‘‘continue,’’ ‘‘could,’’ ‘‘design,’’ ‘‘due,’’ ‘‘estimate,’’ ‘‘expect,’’ ‘‘goal,’’ ‘‘intend,’’ ‘‘may,’’ ‘‘objective,’’ ‘‘plan,’’ ‘‘predict,’’ ‘‘positioned,’’ ‘‘potential,’’ ‘‘seek,’’ ‘‘should,’’ ‘‘target,’’ ‘‘will,’’ ‘‘would’’ and other similar expressions that are predictions of or indicate future events and future trends, or the negative of these terms or other comparable terminology. These forward-looking statements include statements about the initiation, timing, progress and results of our current and future clinical trials and current and future preclinical studies of our product candidates, including our clinical trials of Inupadenant (EOS-850), our clinical trials of EOS-448 and of our research and development programs; our ability to successfully establish or maintain collaborations or strategic relationships for our product candidates; our ability to manufacture our product candidates, including Inupadenant and EOS-448, or any other product candidate in conformity with the Food and Drug Administration’s requirements and to scale up manufacturing of our product candidates to commercial scale, if approved; our financial performance; the effect of the COVID-19 pandemic, including mitigation efforts and economic effects, on any of the foregoing or other aspects of our business operations, including but not limited to our preclinical studies and future clinical trials; and our plans to develop and commercialize our current product candidates and any future product candidates and the implementation of our business model and strategic plans for our business, current product candidates and any future product candidates. We may not actually achieve the plans, intentions or expectations disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements. These statements are based on management’s current expectations and beliefs and are forward-looking statements which involve risks and uncertainties that could cause actual results to differ materially from those discussed in such forward-looking statements. Such risks and uncertainties include, among others: uncertainties inherent in clinical studies and the availability and timing of data from ongoing clinical studies; whether interim results from a clinical trial will be predictive of the final results of a trial; that the results from our clinical trials for Inupadenant and EOS-448 may not support further development and marketing approval; the risk that we may be unable to gain approval for our product candidates on a timely basis, if at all; the risk that the current COVID-19 pandemic will impact our clinical trials and operations; and other risks set forth under the caption ‘Risk Factors’ in our most recent Quarterly Report on Form 10-K for the quarter ended December 31, 2020, as filed with the SEC on March 24, 2021, and in our future filings with the SEC available at the SEC’s website at www.sec.gov. New risks and uncertainties may emerge from time to time, and it is not possible to predict all risks and uncertainties. You should not place undue reliance on any forward-looking statements, which speak only as of the date they are made. Certain information contained in this Presentation and statements made orally during this Presentation relate to or is based on studies, publications, surveys and other data obtained from third-party sources and the Company’s own internal estimates and research. While the Company believes these third-party studies, publications, surveys and other data to be reliable as of the date of the Presentation, it has not independently verified, and makes no representation as to the adequacy, fairness, accuracy or completeness of, any information obtained from third-party sources. In addition, no independent sources has evaluated the reasonableness or accuracy of the Company’s internal estimates or research and no reliance should be made on any information or statements made in this Presentation relating to or based on such internal estimates and research. While we may elect to update these forward-looking statements at some point in the future, we assume no obligation to update or revise any forward-looking statements except to the extent required by applicable law. Although we believe the expectations reflected in such forward-looking statements are reasonable, we can give no assurance that such expectations will prove to be correct. Accordingly, readers are cautioned not to place undue reliance on these forward-looking statements. No representations or warranties (expressed or implied) are made about the accuracy of any such forward-looking statements.

iTeos Made Great Progress in 2020 Building the Foundation to Support the Evolution of our Pipeline Integrated pioneering work in tumor immunology from Ludwig Cancer Research to build our immuno-oncology drug discovery and development capabilities Continued to develop EOS-448, a FcgR-engaging anti-TIGIT antibody and Inupadenant (EOS-850), an A2A receptor antagonist, with exciting partial responses in difficult-to-treat patients Leveraged a global talent pool through our sites in both Cambridge, MA and Belgium, to bring the next generation of immunotherapies to patients with cancer Remain well capitalized with approximately $336MM of cash on the balance sheet as of December 31, 2020

Fc��R-engaging Anti-TIGIT Antibody Program Update EOS-448 EOS-448

EOS-448: Fc��R-Engaging Anti-TIGIT Antibody EOS-448 EOS-448 is an anti-TIGIT antibody targeted therapy designed to achieve maximal immune stimulatory effects High TIGIT binding affinity and selected to maximize potency IgG1 isotype antibody, containing an Fc domain with the ability to engage Fc��R-expressing effector cells High affinity TIGIT-binding domain Functional Fc domain

EOS-448 Is Designed to Enhance the Anti-tumor Response Through a Multifaceted Immune Modulation Mechanism Tumor cell CD155 CD226 CD112 TIGIThigh Treg and exhausted T cells FCgR FCgR NK Macro phages DC TIGIT NK or T cell TIGIT EOS-448 EOS-448 Pro-inflammatory cytokines T cell and NK cell killing of tumor cells Pro-inflammatory cytokine release and activation of APCs Depletion of Tregs and exhausted T cells 1 1 3 3 2 2 High affinity TIGIT-binding domain Functional Fc domain

AACR 2021 Phase 1 first-in-human study in patients with advanced cancers EOS-448 EOS-448

First-in-human Phase 1 Trial of EOS-448 in Patients with Advanced Solid Tumors First-in-human, open-label dose-escalation, phase 1 trial (NCT04335253) in adults with advanced solid tumors for whom no standard treatment was available. Baseline characteristics Advanced or metastatic cancer for whom no standard treatment was available ECOG PS 0-1 No anti-cancer therapy within 4 weeks No CNS metastasis 20 mg Q2W 70 mg Q2W Primary endpoints: Safety and tolerability Secondary and exploratory endpoints included: ORR (investigator assessed) PK and PD Cohort 1 200 mg Q2W 700 mg Q2W 1400 mg Q4W Cohort 2 Cohort 3 Cohort 4 Cohort 5 Inclusion Criteria

Early Clinical Activity as Monotherapy in Patients with Advanced Cancers Who Have Exhausted Treatment Options  Response Evaluable Patients [n] (N=20) Best Overall Response [n (%)] Complete Response (CR) 0 (0%) Partial Response (PR) 1 (5%) Stable Disease (SD) 9 (45%) Progressive Disease (PD) 10 (50%) Response Summary Based on Investigator Assessment per RECIST v1.1 1 partial response was observed in a patient with checkpoint inhibitor-resistant, BRAF-mutated melanoma Stable disease was observed in 9 participants, 4 of whom remain on therapy Van den Mooter, TFA et al. AACR 2021.

Early Clinical Activity as Monotherapy in Patients with Advanced Cancers Who Have Exhausted Treatment Options    Best Change from Baseline and Response Duration in Target Lesions on Investigator Assessment per Recist v1.1 Swimmer plot of Study Treatment Period, Best Response and Progression Sacral Van den Mooter, TFA et al. AACR 2021.

Confirmed Partial Response in a Patient with Pembrolizumab-resistant Melanoma  Partial response in a 65-year-old female with BRAF mutant Cutaneous Melanoma 2 prior lines of therapy: BRAF-MEK inhibitor combo followed by pembrolizumab with documented PD Confirmed PR per RECIST with a 58% reduction in size of target lesions Received EOS-448 700 mg Q2W Therapy continued for 24 weeks  Baseline 1st Assessment 8 Weeks 2nd Assessment 16 Weeks Gallbladder Peritoneal Van den Mooter, TFA et al. AACR 2021.

Manageable Tolerability Profile, Consistent with Other Checkpoint Inhibitors Adverse Event Summary in Patients Treated with EOS-448 TEAE Related to EOS-448 Occurring in at Least 2 Patients by Preferred Term,  Number (%) of Patients (N=22) Patients with At Least One [n (%)] TEAE Related to EOS-448  18 (82%) Pruritus 7 (32%) Infusion related reaction 4 (18%) Fatigue 4 (18%) Pyrexia 3 (14%) Rash maculo-papular 2 (9%) Eczema 2 (9%) Hypothyroidism 2 (9%) Blood creatinine increased 2 (9%) Most common treatment related adverse events were rash, itching, infusion-related reactions and fatigue One treatment related serious adverse event, a grade 2 systemic inflammatory response, was observed Van den Mooter, TFA et al. AACR 2021.

Strong depletion of TIGIT+ suppressive Tregs observed at all doses Evidence for Fc��R-Engagement and Depletion of TIGIT+ Suppressive Tregs  Van den Mooter, TFA et al. AACR 2021.

Depletion TIGIT+ suppressive Tregs observed throughout dosing interval Evidence for Fc��R-Engagement and Depletion of TIGIT+ Suppressive Tregs and Exhausted T cells Van den Mooter, TFA et al. AACR 2021. CD8+ T cells (200mg Q2W) Tregs (200mg Q2W) Depletion TIGIT+ CD8+ exhausted T cells and restoration of TIGIT- CD8+ T cells

Fc��R-engaging Anti-TIGIT Antibody Advancement in next stage of clinical development EOS-448 EOS-448

Currently Anticipated EOS-448 Phase 1/2a Clinical Plan: Novel Combinations in Settings with Significant Clinical Need Trials in three checkpoint-naïve and resistant settings Phase 1b Safety and PK/PD Phase 2a Disease-specific trials Anticipate start in mid-2021 EOS-448 + IMID Multiple Myeloma EOS-448 + pembrolizumab  Solid Tumors EOS-448 + Inupadenant Solid Tumors Multiple Myeloma: Relapsed/refractory Melanoma: PD-1 pre-treated NSCLC: PD-L1 high and low HNSCC: PD-L1 high and low Combination with PD-1 inhibition Novel combination post-PD-1 inhibition Novel combination where PD-1/PD-L1 inhibition has been unsuccessful Planning for future trials of EOS-448

EOS-448: Encouraging Results and Rapid Advancement into Next Stage of Clinical Development EOS-448 showed a favorable tolerability profile and early signs of clinical activity in advanced cancer patients who have exhausted treatment options Promising early clinical activity as monotherapy, including a PR in a pembrolizumab-resistant melanoma patient and disease stabilization in multiple patients Manageable tolerability profile, consistent with MOA of TIGIT class Reduction of TIGIT+ suppressive and exhausted T cells populations, supporting Fc��R-engaging MOA Development plan for EOS-448 combinations will target 3 different checkpoint-naïve and resistant settings Additional analyses of patients in the Phase 1/2a trial to be presented in near future

iTeos has Built the Foundation to Support Transformative Acceleration in 2021 Exciting partial responses in difficult-to-treat patients Progress EOS-448 and Inupadenant in multiple tumor types with different combinations Anticipate additional updates on programs in the near future Company well capitalized to fund ambitious growth of our preclinical and clinical pipeline Driven by a culture of scientific innovation, collaboration and excellence, together we passionately discover, develop and deliver breakthrough immunotherapies to improve and extend the lives of people with cancer

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