RCUS reports 59% ORR and tolerable safety in Phase 2 gastric study

Rhea-AI Filing Summary

Arcus Biosciences (RCUS) reported first overall survival results from Arm A1 of its Phase 2 EDGE-Gastric study in advanced gastric, GEJ, or esophageal adenocarcinoma. At data cutoff on March 3, 2025, all 41 treated patients were evaluated with a median follow-up of 26.4 months.

The regimen of domvanalimab plus zimberelimab and chemotherapy showed median overall survival of 26.7 months (90% CI: 18.4, NE) in the overall population and 26.7 months (90% CI: 19.5, NE) in PD‑L1 positive patients. In PD‑L1 high patients, median overall survival was not estimable (90% CI: 17.4, NE). The 24‑month overall survival rate was 50.2% (90% CI: 36.3, 62.6). Median progression‑free survival was 12.9 months (90% CI: 9.8, 14.6), and confirmed objective response rate was 59% (24/41; 90% CI: 45%, 72%).

No unexpected safety signals were observed. The safety profile was generally well tolerated and consistent with anti‑PD‑1 plus chemotherapy. Immune‑mediated TEAEs occurred in 9 patients (22%), and infusion‑related reactions in 3 patients (7%).

Insights

Oncology clinical development analyst

Phase 2 gastric arm shows 26.7‑month OS with manageable safety.

The update details Arm A1 of a Phase 2 study combining domvanalimab, zimberelimab, and chemotherapy in advanced gastric/GEJ/esophageal adenocarcinoma (n=41). With a median follow‑up of 26.4 months, the regimen reported median overall survival of 26.7 months in the overall and PD‑L1 positive groups, and not estimable in PD‑L1 high, alongside a 59% confirmed ORR.

Durability signals include a 24‑month overall survival rate of 50.2% and median PFS of 12.9 months. Safety was described as generally well tolerated with immune‑mediated TEAEs in 22% (9/41) and infusion reactions in 7% (3/41), and no unexpected safety signals at the cutoff.

These results come from a single arm (n=41) within a Phase 2 setting; actual impact depends on comparative data and subsequent studies. Further disclosures in company materials may add context on next steps.

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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): October 12, 2025

________________________________________________________

Arcus Biosciences, Inc.

(Exact name of Registrant as Specified in Its Charter)

________________________________________________________

Delaware

001-38419

47-3898435

(State or Other Jurisdiction of Incorporation)

(Commission File Number)

(IRS Employer Identification No.)

3928 Point Eden Way

Hayward, California

94545

(Address of Principal Executive Offices)

(Zip Code)

Registrant’s Telephone Number, Including Area Code: (510) 694-6200

(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:

o			Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
o			Soliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)
o			Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
o			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, Par Value $0.0001 Per Share

RCUS

The New York Stock Exchange

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 o

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. o

Item 8.01    Other Events.

On October 12, 2025, Arcus Biosciences, Inc. (the “Company”) announced the first overall survival results from Arm A1 of the Phase 2 EDGE-Gastric study in patients with locally advanced unresectable or metastatic gastric, gastroesophageal junction or esophageal adenocarcinoma. At data cutoff (March 3, 2025), safety and efficacy were evaluated in all patients enrolled and treated (n=41) and median study follow-up was 26.4 months. Efficacy was observed across all PD-L1 subgroups. With a median time on treatment of 49 weeks (range: <1-117 weeks), the domvanalimab plus zimberelimab and chemotherapy regimen demonstrated sustained efficacy with longer follow-up. A summary of the efficacy results is as follows:

			Overall* (N = 41)			PD-L1 Positive (TAP ≥1%) (n = 29)			PD-L1 High (TAP ≥5%) (n = 16)
Median OS, months (90% CI)			26.7 (18.4, NE)			26.7 (19.5, NE)			NE (17.4, NE)
24 months OS rate, % (90% CI)			50.2 (36.3, 62.6)			53.8 (37.3, 67.7)			56.3 (33.9, 73.6)
Median PFS, months (90% CI)			12.9 (9.8, 14.6)			13.2 (11.3, 15.2)			14.5 (11.3, NE)
24 months PFS rate, % (90% CI)			25.9 (14.8, 38.5)			24.9 (12.1, 39.9)			31.3 (14.0, 50.2)
Confirmed ORR, % (n) per RECIST v1.1 (90% CI)			59% (24) (45%, 72%)			62% (18) (45%, 77%)			69% (11) (45%, 87%)
One patient did not have tissue available for central laboratory TAP scoring (SP263 assay). Local lab results showed the patient was PD-L1 low according to 22C3 assay. *All patients who enrolled and received study treatment. CI: confidence interval NE: not estimable TAP: tumor area positivity

No unexpected safety signals were observed at the time of data cut off. The safety profile of domvanalimab plus zimberelimab and chemotherapy was generally well tolerated and is consistent with that of anti-PD-1 plus chemotherapy. Immune-mediated TEAEs related to domvanalimab and/or zimberelimab occurred in 9 patients (22%), and infusion-related reactions occurred in 3 patients (7%).

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.

			ARCUS BIOSCIENCES, INC.
Date: October 14, 2025			By:			/s/ Terry Rosen, Ph. D.
						Terry Rosen, Ph.D.
						Chief Executive Officer (Principal Executive Officer)

FAQ

What did Arcus Biosciences (RCUS) report in its Phase 2 EDGE-Gastric Arm A1?

Arcus reported first overall survival results showing median OS of 26.7 months in the overall population, with efficacy across PD‑L1 subgroups.

How many patients were evaluated and what was the follow-up in the RCUS study?

All 41 treated patients were evaluated with a 26.4‑month median follow-up at the March 3, 2025 data cutoff.

What were the key efficacy metrics for RCUS’s regimen?

Median OS 26.7 months (overall), 24‑month OS rate 50.2%, median PFS 12.9 months, and confirmed ORR 59% (24/41).

Were there safety concerns reported for the RCUS combination therapy?

No unexpected safety signals were observed; immune‑mediated TEAEs occurred in 22% (9/41) and infusion reactions in 7% (3/41).

How did PD‑L1 subgroups perform in the RCUS study?

Median OS was 26.7 months in PD‑L1 positive and not estimable in PD‑L1 high; efficacy was observed across PD‑L1 subgroups.

What treatments were used in the RCUS Phase 2 regimen?

The regimen combined domvanalimab plus zimberelimab with chemotherapy.