[8-K] Instil Bio, Inc. Reports Material Event

Rhea-AI Filing Summary

Instil Bio (TIL) filed an 8-K (Item 8.01) reporting partner ImmuneOnco’s interim data from a Phase 2 open-label study of bispecific antibody IMM2510/AXN-2510 plus chemotherapy in first-line advanced non-small-cell lung cancer (NSCLC) patients in China.

By 1 Jul 2025, 33 patients had received 10 mg/kg; 21 were efficacy-evaluable. The overall partial response rate (PRR) was 62 %, with a pronounced signal in squamous NSCLC (80 %, 8/10) versus non-squamous (46 %, 5/11). Most patients had undergone only a single tumor assessment at the data cut-off, limiting durability insight.

Safety appeared acceptable: no dose-limiting toxicities, no treatment-related deaths or dose reductions, and just one discontinuation. Grade ≥3 treatment-related adverse events were mainly hematologic and infrequent; VEGF-linked and immune events were uncommon and generally low-grade.

The dataset will be presented at a future medical meeting. Though preliminary and based on a small cohort, the efficacy signal and tolerability profile are encouraging for ‘2510’s continued development and could strengthen Instil’s oncology pipeline prospects.

Positive

• 62 % overall partial response rate in interim analysis, outperforming historical chemo benchmarks.
• 80 % PRR in squamous NSCLC, a subtype with high unmet need.
• No dose-limiting toxicities or treatment-related deaths; safety profile appears manageable.

Negative

• Small efficacy-evaluable cohort (n = 21) limits statistical confidence.
• Most patients had only one tumor assessment, providing little durability data.
• Results are from a single-arm study in China; lack of control arm or global data may hinder comparability.

Insights

Oncology Analyst

TL;DR — Early Phase 2 data show strong PRR and clean safety; still small but directionally positive.

The 62 % PRR, especially the 80 % in squamous disease, materially exceeds typical first-line chemo benchmarks (~25-35 %). Absence of DLTs and minimal high-grade VEGF/immune toxicities suggest an attractive risk-benefit profile. However, only one scan for most subjects and lack of complete or durability data temper enthusiasm. If confirmed in larger cohorts or randomized settings, ‘2510 could challenge PD-1/VEGF combos and expand Instil’s value beyond its TIL cell-therapy focus.

Equity Research Analyst

TL;DR — Encouraging signal but limited sample; modest positive equity impact today.

For a development-stage company, any positive mid-phase oncology read-out can catalyze sentiment. The filing highlights differentiated efficacy in a high-incidence indication and a benign safety profile, reducing clinical risk. Yet, the data are uncontrolled, geographically limited, and lack progression-free or overall survival metrics, so valuation uplift may be constrained until more mature results or a strategic update (e.g., licensing economics) emerges.

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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): July 31, 2025

Instil Bio, Inc.

(Exact name of registrant as specified in its Charter)

 

Delaware			001-40215			83-2072195
(State or Other Jurisdiction of Incorporation)			(Commission File Number)			(IRS Employer Identification No.)

 

3963 Maple Avenue, Suite 350 Dallas, Texas						75219
(Address of Principal Executive Offices)						(Zip Code)

(972) 499-3350

(Registrant’s Telephone Number, Including Area Code)

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 (see General Instructions A.2. below):

☐ 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, $0.000001 par value

TIL

The Nasdaq Stock Market LLC

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 8.01 Other Events.

On July 31, 2025, Instil Bio, Inc. reported that ImmuneOnco Biopharmaceuticals (Shanghai) Inc. (“ImmuneOnco”) announced preliminary safety and efficacy data from the ongoing Phase 2 open-label, multicenter study of IMM2510/AXN-2510 (“‘2510”) in combination with chemotherapy for first-line patients with advanced non-small cell lung cancer (“NSCLC”) conducted by ImmuneOnco in China (the “Phase 2 Chemo Combo Trial”).

Preliminary Safety and Efficacy Data from the Phase 2 Chemo Combo Trial

As of July 1, 2025, 33 patients were dosed at 10 mg/kg of ‘2510, with 21 patients having at least one tumor assessment (efficacy evaluable). Partial responses were observed in 62% of efficacy evaluable patients, comprising partial responses in 80% (8/10) of patients with squamous NSCLC and 46% (5/11) of patients with non-squamous NSCLC. The majority of efficacy evaluable patients had only one tumor assessment at data cut-off.

No dose-limiting toxicities were observed in the 33 safety evaluable patients. In these patients, there were no treatment-related adverse events (“TRAE”) leading to dose reduction or death, and only one TRAE leading to drug discontinuation. The most common Grade 3+ TRAEs were hematologic, with uncommon clinical sequelae. Adverse events typically associated with VEGF inhibition (e.g., hypertension, proteinuria, hemoptysis) and immune-related adverse events were uncommon and generally low-grade and infusion-related reactions were nearly all low-grade.

ImmuneOnco expects to present safety and efficacy data in the Phase 2 Chemo Combo Trial at a future medical conference.

SIGNATURES

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

Instil Bio, Inc.

Date:

July 31, 2025

By:

/s/ Sandeep Laumas, M.D.

Sandeep Laumas, M.D.

Chief Financial Officer and Chief Business Officer (Principal Financial Officer and Principal Accounting Officer)

FAQ

What did Instil Bio (TIL) disclose in its 8-K dated July 31 2025?

The company relayed ImmuneOnco’s interim Phase 2 data showing a 62 % partial response rate and no dose-limiting toxicities in advanced NSCLC.

How many patients were included in the Phase 2 IMM2510 chemo-combo trial?

33 patients received 10 mg/kg; 21 were evaluable for efficacy.

What was the response rate for squamous versus non-squamous NSCLC?

Squamous NSCLC showed an 80 % PRR (8/10); non-squamous had 46 % PRR (5/11).

Were any dose-limiting toxicities or treatment-related deaths reported?

No dose-limiting toxicities or treatment-related deaths occurred; only one discontinuation was linked to treatment.

When will more detailed data be available?

ImmuneOnco plans to present updated safety and efficacy results at a future medical conference.