ALX Oncology Announces Nature Medicine Publication of ASPEN-06 Phase 2 Clinical Data Demonstrating Strong Responses and Durable Clinical Benefit with Evorpacept in HER2-Positive Gastric Cancer

Trial participants had progressed after prior HER2-directed therapy and fluoropyrimidine- or platinum-containing chemotherapy.

Rhea-AI Summary

ALX Oncology (ALXO) published randomized Phase 2 ASPEN-06 data on investigational evorpacept in previously treated HER2-positive advanced gastric or gastroesophageal junction cancer. The Nature Medicine results cover 127 patients enrolled in the Phase 2 portion. Evorpacept added to trastuzumab, ramucirumab and paclitaxel produced a 40.3% objective response rate, versus 26.6% with the three-drug regimen alone.

In a post-hoc analysis of patients with retained HER2-positive disease and elevated CD47 expression, response rates were 63.6% and 23.1%, respectively. Median progression-free survival was 19.5 versus 7.0 months, and median response duration was 25.5 versus 8.4 months, respectively. ALX Oncology will not pursue a U.S. Phase 3 registrational trial in gastric cancer and may explore development partnerships. Topline data from 80 patients in its ongoing Phase 2 ASPEN-09-Breast trial are expected in mid-2027.

Key Figures

Objective response rate: 40.3% vs. 26.6% Objective response rate: 48.9% vs. 25.0% Objective response rate: 63.6% vs. 23.1% +4 more

Objective response rate

40.3% vs. 26.6%

Intent-to-treat population; evorpacept plus TRP vs. TRP alone

Objective response rate

48.9% vs. 25.0%

Retained HER2-positive disease; evorpacept plus TRP vs. control

Objective response rate

63.6% vs. 23.1%

Retained HER2-positive disease with elevated CD47 expression; evorpacept plus TRP vs. control

Median progression-free survival

19.5 months vs. 7.0 months

Retained HER2-positive disease with elevated CD47 expression; evorpacept plus TRP vs. control

Median duration of response

25.5 months vs. 8.4 months

Retained HER2-positive disease with elevated CD47 expression; evorpacept plus TRP vs. control

CD47 expression threshold

≥5% CD47 IHC3+ staining

Criterion for the elevated-CD47 subgroup analysis

Phase 2 enrollment

127 adult patients

ASPEN-06 Phase 2 portion

Key Terms

objective response rate, ctdna, intent-to-treat, progression-free survival, +1 more

5 terms

objective response rate medical

"achieved an objective response rate (ORR) of 40.3%"

The objective response rate (ORR) is the percentage of patients in a clinical trial whose tumors measurably shrink or disappear according to preset rules. Investors use it as a quick, objective signal of a drug’s ability to produce a clear treatment effect—like counting how many plants visibly respond after applying a new fertilizer—and higher ORR can improve odds of regulatory approval, commercial success, and company valuation.

ctdna medical

"ERBB2 gene amplification detected in circulating tumor DNA (ctDNA)"

Circulating tumor DNA (ctDNA) is tiny fragments of genetic material shed by cancer cells into the bloodstream, like breadcrumbs that can reveal a tumor’s presence and genetic makeup without needing a biopsy. For investors, ctDNA matters because tests and technologies that detect and analyze these fragments can speed diagnosis, track treatment response, and signal relapse, creating commercial opportunities in diagnostics, personalized therapies, and monitoring services.

intent-to-treat medical

"in the intent-to-treat (ITT) population"

A method for analyzing clinical trial results that counts every participant in the group they were originally assigned to, regardless of whether they completed the treatment or followed instructions. Like grading a class by the seats students were assigned rather than who finished the exam, it preserves the trial’s original comparisons and gives a realistic, often more conservative, estimate of how a drug or device performs in real-world use — information investors use to judge reliability and regulatory risk.

progression-free survival medical

"improvements in median progression-free survival (PFS) to 19.5 months"

Progression-free survival is the length of time during and after a treatment that a patient's disease does not get worse, measured from the start of treatment until the disease shows measurable signs of progression or the patient dies. Investors care because longer progression-free survival in clinical trials often signals that a drug is effective, improving chances of regulatory approval, market adoption, and revenue potential—think of it as a stopwatch showing how long a therapy can keep the illness at bay.

duration of response medical

"median duration of response (DOR) of 25.5 versus 8.4 months"

Duration of response is the length of time a patient’s condition stays improved after a treatment until it starts to worsen again; think of it as how long a freshly charged battery continues to power a device. For investors, longer duration of response implies a treatment provides sustained benefit, which can boost a drug’s commercial value, support stronger regulatory labeling and payer coverage, and reduce the need for additional therapies.

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Achieved 40.3% ORR with evorpacept plus trastuzumab, ramucirumab and paclitaxel versus 26.6% for control, with response rates increasing to 63.6% versus 23.1% among patients with high CD47 expression and retained HER2-positive disease

Subgroup analyses support CD47 expression as a predictive biomarker

ASPEN-06 clinical findings further validate Company’s biomarker-driven development strategy and reinforce its continued advancement in the ongoing Phase 2 ASPEN-09-Breast clinical trial

On track for mid-2027 topline data readout from 80 patients in Phase 2 ASPEN-09-Breast clinical trial evaluating evorpacept in combination with trastuzumab and chemotherapy in HER2-positive metastatic breast cancer

SOUTH SAN FRANCISCO, Calif., Sept. 28, 2026 (GLOBE NEWSWIRE) -- ALX Oncology Holdings Inc. ("ALX Oncology"; Nasdaq: ALXO), a clinical-stage biotechnology company advancing a pipeline of novel therapies designed to treat cancer and extend patients’ lives, today announced the publication of clinical data from its ASPEN-06 randomized Phase 2 clinical trial in Nature Medicine.

The Nature Medicine publication, titled "Evorpacept plus trastuzumab, ramucirumab and paclitaxel in HER2-positive gastric cancer: a randomized phase 2 trial" can be accessed here. The data demonstrated that the Company’s investigational CD47-blocker, evorpacept, generated encouraging efficacy with manageable safety among patients with previously treated HER2-positive advanced gastric cancer (GC) or gastroesophageal junction (GEJ) cancer.

“Publication of our ASPEN-06 data in Nature Medicine, a prestigious peer-reviewed scientific journal, further validates the clinical potential of evorpacept and reinforces our biomarker-driven development strategy,” said Barbara Klencke, M.D., Chief Medical Officer of ALX Oncology. “Data from ASPEN-06 demonstrated that patients whose tumors retained HER2 expression and had high CD47 expression experienced the greatest benefit from evorpacept-based therapy, supporting our hypothesis that evorpacept can enhance the activity of HER2-directed treatment regimens and highlights CD47 expression as a potential predictive biomarker. These findings further strengthen our conviction in the ongoing Phase 2 ASPEN-09-Breast clinical trial in HER2-positive metastatic breast cancer, which remains on track for a topline data readout from 80 patients in mid-2027.”

The ASPEN-06 clinical trial (NCT05002127) was a randomized Phase 2 (open-label)/3 (blinded), international, multi-center study, that evaluated evorpacept in combination with HERCEPTIN^® (trastuzumab), CYRAMZA^® (ramucirumab) and paclitaxel (TRP) compared with TRP alone (control), for patients with metastatic second- or third-line HER2 overexpressing GC/GEJ adenocarcinoma who have progressed on or after prior HER2-directed therapy and fluoropyrimidine- or platinum-containing chemotherapy, and who were suitable for chemotherapy. One hundred twenty-seven adult patients were enrolled in the Phase 2 portion of the study.

Results demonstrated that evorpacept plus TRP achieved an objective response rate (ORR) of 40.3% compared with 26.6% for TRP alone in the intent-to-treat (ITT) population. Among patients with retained HER2-positive disease, based either on a fresh tumor biopsy or ERBB2 gene amplification detected in circulating tumor DNA (ctDNA), ORR increased to 48.9% versus 25.0% for the control arm.

Post-hoc biomarker analyses demonstrated CD47 expression as a potential predictive biomarker for evorpacept. Among patients with retained HER2-positive disease and elevated CD47 expression (≥5% CD47 IHC3+ staining), evorpacept plus TRP achieved an ORR of 63.6% compared with 23.1% for TRP alone, with improvements in median progression-free survival (PFS) to 19.5 months versus 7.0 months and median duration of response (DOR) of 25.5 versus 8.4 months, supporting further evaluation of CD47-guided patient selection in future studies.

In conclusion, findings from the randomized Phase 2 portion of the ASPEN-06 study suggest that evorpacept in combination with TRP may provide meaningful clinical benefit as a second- or third-line treatment for patients with GC or GEJ cancer with retained HER2 expression. Post-hoc analyses further suggest that this benefit may be enhanced in patients with high CD47 expression, supporting the proposed mechanism that both retained HER2 expression and elevated CD47 levels may be important drivers of efficacy through enhanced antibody-dependent cellular phagocytosis. Given the Company’s disciplined focus and resource allocation priorities, ALX Oncology elected to not pursue a U.S. registrational path with a Phase 3 trial in GC and will consider exploring development partnerships to advance this program in gastric cancer. Importantly, findings from the ASPEN-06 study further validate the Company's biomarker-driven development approach and support the ongoing Phase 2 ASPEN-09-Breast trial (NCT07007559) evaluating evorpacept in combination with trastuzumab and chemotherapy in patients with HER2-positive metastatic breast cancer, with topline data from 80 patients expected in mid-2027.

HERCEPTIN^® and CYRAMZA^® are the registered trademarks of their respective owners.

About ALX Oncology
ALX Oncology (Nasdaq: ALXO) is a clinical-stage biotechnology company advancing a pipeline of novel therapies designed to treat cancer and extend patients’ lives. ALX Oncology’s lead therapeutic candidate, evorpacept, has demonstrated potential to serve as a cornerstone therapy upon which the future of immuno-oncology can be built. Evorpacept is currently being evaluated across multiple ongoing clinical trials in a wide range of cancer indications. ALX Oncology’s second pipeline candidate, ALX2004, is a novel EGFR-targeted antibody-drug conjugate with a differentiated mechanism of action. A Phase 1, dose-escalation trial of ALX2004 is ongoing in patients with EGFR-expressing solid tumors. More information is available at www.alxoncology.com and on LinkedIn and X.

Cautionary Note Regarding Forward-Looking Statements

This press release contains forward-looking statements that involve substantial risks and uncertainties. Forward-looking statements include statements regarding future results of operations and financial position, business strategy, product candidates, planned preclinical studies and clinical trials, results of clinical trials, such as the ongoing Phase 2 ASPEN-09-Breast clinical trial in HER2-positive metastatic breast cancer, research and development costs, regulatory approvals, timing and likelihood of success, plans and objects of management for future operations, as well as statements regarding industry trends. Such forward-looking statements are based on ALX Oncology’s beliefs and assumptions and on information currently available to it on the date of this press release. Forward-looking statements may involve known and unknown risks, uncertainties and other factors that may cause ALX Oncology’s actual results, performance or achievements to be materially different from those expressed or implied by the forward-looking statements. These and other risks are described more fully in ALX Oncology’s filings with the Securities and Exchange Commission ("SEC"), including ALX Oncology’s Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q and other documents ALX Oncology files with the SEC from time to time. Except to the extent required by law, ALX Oncology undertakes no obligation to update such statements to reflect events that occur or circumstances that exist after the date on which they were made.

Investor Relations Contact:
Kevin Lui
Director, Investor Relations
kevin.lui@precisionaq.com

Media Contact:
Genevieve Britton
Senior Director, Public Relations
genevieve.britton@precisionaq.com

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What response rates did ALX Oncology report in the ASPEN-06 trial?

Among all patients in the Phase 2 analysis, evorpacept plus trastuzumab, ramucirumab and paclitaxel had a 40.3% objective response rate, versus 26.6% for the three-drug regimen alone.

When does ALX Oncology expect results from ASPEN-09-Breast?

Topline data from 80 patients in the ongoing Phase 2 ASPEN-09-Breast trial are expected in mid-2027. The trial evaluates evorpacept with trastuzumab and chemotherapy in HER2-positive metastatic breast cancer.

How was retained HER2-positive disease identified in ALX Oncology's ASPEN-06 trial?

Retained HER2-positive disease was identified through either a fresh tumor biopsy or ERBB2 gene amplification detected in circulating tumor DNA. In that group, the objective response rate was 48.9% with evorpacept added to the three-drug regimen, versus 25.0% with the regimen alone.

Why is ALX Oncology not pursuing a U.S. Phase 3 registration trial in gastric cancer?

ALX Oncology gives its focus and resource allocation priorities as the reason it elected not to pursue that trial. It may explore development partnerships for the gastric cancer program.