Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2023 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-40925 Xilio Therapeutics, Inc. (Exact name of registrant as specified in its charter) Delaware 85-1623397 ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2023 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-40925 Xilio Therapeutics, Inc. (Exact name of registrant as specified in its charter) Delaware 85-1623397 (Sta ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2023 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-40925 Xilio Therapeutics, Inc. Indicate by check mark whether the registrant (1) has filed all reports requir ...

Unleashing the Potential of Immuno-Oncology Therapies March 2, 2023 1 © 2023 Xilio Therapeutics, Inc. Forward-Looking Statements This presentation contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including, without limitation, statements regarding plans, timing and expectations related to: the initiation of patient enrollment in a Phase 2 clinical trial for XTX202 and reporting data from the Phase 1/2 clinical trial for XTX202; repor ...

Immuno-Oncology Therapies Development - The company is developing tumor-activated immuno-oncology therapies aimed at improving cancer treatment outcomes while minimizing systemic side effects [30]. - The company’s goal is to transform cancer treatment by developing highly potent, tumor-selective therapies that provide effective and durable options for patients [41]. - The company aims to explore combination therapies using XTX202 and XTX301 to increase the potential for curative regimens in oncology [40]. - The company intends to explore XTX202 in additional solid tumor indications, including non-small cell lung cancer (NSCLC) and head and neck squamous cell cancer [119]. - The company has a clinical-stage cytokine pipeline that includes tumor-activated product candidates XTX202 (IL-2) and XTX301 (IL-12) [186]. XTX202 Clinical Trials and Data - XTX202, an engineered IL-2 therapy, is currently in a Phase 1 clinical trial with a recommended Phase 2 dose expected to be established; no signs of vascular leak syndrome have been observed to date [31]. - The company plans to report preliminary anti-tumor activity, safety, pharmacokinetic, and pharmacodynamic data from the Phase 1/2 trial of XTX202 in Q3 2023, involving approximately 15-20 patients [44]. - Preliminary data from the Phase 1 trial of XTX202 shows increased numbers of tumor-infiltrating lymphocytes and CD8+ effector T cells, indicating tumor-selective activation [62]. - The ongoing Phase 1 clinical trial for XTX202 has treated 16 patients at dose levels ranging from 0.27 mg/kg to 1.4 mg/kg, with no signs of vascular leak syndrome observed [108]. - The company plans to initiate a Phase 2 trial for XTX202 in patients with unresectable or metastatic melanoma and metastatic renal cell carcinoma (RCC) in April 2023 [105]. XTX301 Clinical Trials and Data - XTX301, an engineered IL-12 therapy, has received FDA clearance for clinical evaluation, with preliminary safety data anticipated by Q4 2023 [32]. - XTX301, a tumor-activated IL-12 product candidate, has received FDA clearance for evaluation in patients with advanced solid tumors, with a starting dose of 5.0 µg/kg [122]. - Preliminary safety data from the Phase 1 clinical trial is expected to be reported in Q4 2023, focusing on monotherapy dose-escalation [140]. - XTX301 demonstrated potent anti-tumor activity in preclinical studies without inducing significant systemic toxicity, indicating effective masking design [129]. - XTX301 was tolerated in non-human primates (NHPs) at doses up to 2 mg/kg once weekly, with a circulating half-life of approximately 4 days [132]. XTX101 Clinical Trials and Data - XTX101, an anti-CTLA-4 monoclonal antibody, is in a Phase 1 trial, with a recommended Phase 2 dose of 150 mg every six weeks established; preliminary data is expected in Q2 2023 [33][35]. - XTX101 aims to achieve a three-fold increase in therapeutic index, potentially transforming treatment outcomes for patients [145]. - XTX101 demonstrated 67% overall activation in a study of 82 tumor biopsies across various solid tumors [29]. - The combination of XTX101 with an anti-PD-1/PD-L1 antibody resulted in robust tumor growth inhibition of 82%, with minimal toxicity observed [159]. - As of March 1, 2023, 24 patients have been treated with XTX101 in a Phase 1 trial, with enrollment in monotherapy dose-expansion ongoing [162]. GPS Platform and Technology - The GPS platform is designed to create tumor-activated molecules that minimize systemic toxicity, enhancing the therapeutic index of immuno-oncology therapies [39]. - The GPS platform has shown preclinical validation for developing tumor-activated cytokines and antibodies, with promising early clinical evidence [62]. - The proprietary GPS platform aims to develop additional product candidates for tumor-selective activation and improved therapeutic index [165]. - The company aims to develop novel immuno-oncology (I-O) therapies using its GPS platform, focusing on overcoming the limitations of cytokines, such as short half-life and significant toxicity [48]. - XTX202 was engineered to be activated preferentially within the tumor microenvironment, enhancing its therapeutic index [78]. Financial and Regulatory Considerations - The company has paid AskGene an upfront payment of $6.0 million and is obligated to pay up to $13.0 million upon achieving specified regulatory milestones for licensed IL-2 products [202]. - The company must secure FDA approval for new drug or biological products, which involves multiple regulatory steps and compliance with good clinical practices [218][224]. - The company is obligated to pay up to $10.3 million for the first three licensed products or services achieving specified milestones [208]. - The company must pay tiered royalties in the low single digits on aggregate annual net sales of licensed products on a country-by-country basis until the expiration of the last-to-expire patent [208]. - The company has entered into a cross-license agreement with AskGene, granting exclusive licenses for AskGene patent rights related to non-antigen binding IL-2 products in oncology [201]. Patent and Intellectual Property - The company has 16 patent application families related to its business, with statutory expiration dates ranging between 2037 and 2043 [180]. - The company owns, co-owns, or exclusively in-licenses three patent families related to masked anti-CTLA-4 antibody constructs, including XTX101, with statutory expiration dates ranging between 2037 and 2042 [187]. - The company owns two patent families relating to masked IL-2 cytokines, including XTX202, with six pending U.S. applications and one issued U.S. patent [188]. - The company has a statutory expiration date for its IL-12 patent family in 2041, without considering any possible patent term adjustments or extensions [188]. - The company intends to apply for patent term extensions on issued patents covering product candidates once they receive FDA approval [197].

Unleashing the Potential of Immuno-Oncology Therapies November 9, 2022 Placeholder area for citations and references 1 © 2022 Xilio Therapeutics, Inc. Forward-Looking Statements This presentation contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995, as amended, including, without limitation, statements regarding plans, timing and expectations related to the initiation of patient enrollment in a monotherapy expansion cohort for the Phase 1 clinical tr ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended September 30, 2022 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-40925 Xilio Therapeutics, Inc. (Exact name of registrant as specified in its charter) Delaware 85-1623397 ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended June 30, 2022 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-40925 Xilio Therapeutics, Inc. (Exact name of registrant as specified in its charter) Delaware 85-1623397 (Sta ...

Table of Contents UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 FORM 10-Q (Mark One) ☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the quarterly period ended March 31, 2022 or ☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 For the transition period from to Commission File Number: 001-40925 Xilio Therapeutics, Inc. (Exact name of registrant as specified in its charter) Delaware 85-1623397 (St ...

| --- | --- | --- | --- | --- | --- | --- | |-------|----------------------------------------------------------------------------------------|-------|-------|-------|-------|-------| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | XILIO THERAPEUTICS (NASDAQ: XLO) | | | | | | | | HARNESSING THE IMMUNE SYSTEM TO IMPROVE THE LIVES OF PEOPLE WITH CANCER MARCH 1, 2022 | | | | | | © 2022 Xilio Therapeutics, Inc. Forward-looking st ...