Instil Bio Announces ImmuneOnco's Presentation of '2510 Monotherapy Data in Patients with 2L+ Squamous NSCLC at the 2025 World Conference on Lung Cancer

ORR of 35% in previously treated squamous NSCLC patients with responses across PD-L1 TPS scores

Differentiated structure of ‘2510 potentially results in best-in-class monotherapy activity in 2L+ NSCLC for PD-(L)1xVEGF bispecifics

Instil Bio, Inc. ("Instil") (Nasdaq: TIL), a clinical-stage biopharmaceutical company focused on developing a pipeline of novel therapies, today announced that ImmuneOnco Biopharmaceuticals (Shanghai) Inc. (HKEX Code: 1541.HK) ("ImmuneOnco") presented preliminary efficacy and safety data of ‘2510 (IMM2510AXN-2510) as monotherapy in a Phase 1 study of patients in China with previously treated squamous non-small cell lung cancer (sq-NSCLC) at the 2025 World Conference on Lung Cancer hosted by the International Association for the Study of Lung Cancer in Barcelona, Spain on September 9, 2025.

ImmuneOnco reported that 23 patients with sq-NSCLC had been treated with monotherapy ‘2510 as of June 13, 2025. All patients had failed previous PD-(L)1 inhibitor plus platinum-doublet chemotherapy, and 6 patients had previously received VEGF-directed therapy. Patients were treated with ‘2510 at different dose levels (3, 6, 10, or 20 mg/kg Q2W), with the majority of patients treated at the 20 mg/kg Q2W dose level. In the 17 efficacy evaluable patients, the objective response rate ("ORR") was 35.3%, with the majority of responses seen in patients with negative and low PD-L1 TPS scores. Most patients remain on treatment with the opportunity for additional tumor assessments, including multiple patients currently with stable disease. In general, ‘2510 was safe and well tolerated across the Phase 1 trial, with mostly manageable low grade infusion reactions in the first cycle as previously reported. In the squamous subset there were two Grade 3 VEGF-related adverse events of proteinuria and bleeding. Enrollment is continuing at the 20 mg/kg Q2W dose level in this study.

"'2510 was designed for potential best-in-class activity with a VEGF trap for broader neutralization of VEGF ligands and ADCC enhancement for direct tumor killing," said Jamie Freedman, M.D., Ph.D., Chief Medical Officer of Instil. "ImmuneOnco's promising preliminary monotherapy data for ‘2510 in patients with sq-NSCLC who have failed prior therapies compares favorably with other molecules in the PD-(L)1xVEGF bispecific class."

About Instil Bio

Instil Bio is a clinical-stage biopharmaceutical company focused on developing a pipeline of novel therapies. Instil's lead asset, AXN-2510, is a novel and differentiated PD-L1xVEGF bispecific antibody in development for the treatment of multiple solid tumors. For more information, visit www.instilbio.com .

Forward-Looking Statements

This press release contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as "anticipates," "believes," "expects," "future," "intends," "may," "plans," "potentially," "targets" and "will" or similar expressions are intended to identify forward-looking statements. Forward-looking statements include express or implied statements regarding our expectations with respect to the therapeutic potential ‘2510, the strategic position of ‘2510 and its safety and efficacy profile, the clinical development of ‘2510 including enrollment of clinical trials and the generation of clinical data therefrom, and other statements that are not historical fact. Forward-looking statements are based on management's current expectations and are subject to various risks and uncertainties that could cause actual results to differ materially and adversely from those expressed or implied by such forward-looking statements, including risks and uncertainties associated with the costly and time-consuming drug product development process, the uncertainty of clinical success, including the risk that preliminary or interim results of clinical trials will not be indicative of final results, and other risks and uncertainties affecting us and our plans and development programs, including those discussed in the section titled "Risk Factors" in our Quarterly Report on Form 10-Q for the quarter ended June 30, 2025 filed with the SEC, as well as our other filings with the SEC. Additional information will be made available in other filings that we make from time to time with the SEC. Accordingly, these forward-looking statements do not constitute guarantees of future performance, and you are cautioned not to place undue reliance on these forward-looking statements. These forward-looking statements speak only as the date hereof, and we disclaim any obligation to update these statements except as may be required by law.

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