Alx Oncology Signals Promise, But Validation Looms

Alx Oncology Holdings, Inc. ((ALXO)) has held its Q1 earnings call. Read on for the main highlights of the call.

Alx Oncology’s latest earnings call carried a cautiously upbeat tone, as management highlighted strong, reproducible efficacy signals for evorpacept combinations in select HER2-positive cancers and a growing safety database. Executives also acknowledged the early, exploratory nature of the data, uncertainties around biomarker cutoffs, and the need for a registrational trial, framing the story as promising but still high risk.

Robust Responses in Heavily Pretreated HER2-Positive Breast Cancer

Phase Ib/II data for evorpacept plus zanidatamab in metastatic HER2-positive breast cancer showed a confirmed objective response rate of 33% in 24 heavily pretreated patients, all of whom had previously received T-DXd. Among the 10 patients whose tumors were centrally confirmed as HER2-positive, the response rate jumped to 60%, underscoring the importance of rigorous HER2 testing.

CD47-High Subset Emerges as a Potent Driver of Benefit

Using a retrospective CD47 cutoff of at least 20%, all five centrally confirmed HER2-positive, CD47-high patients responded, translating to a 100% objective response rate in this subset. These patients experienced a median progression-free survival of about 22 months versus roughly 3.4 months in CD47-low counterparts, suggesting that CD47 overexpression may be critical to unlocking the regimen’s full potential.

Parallel Signals in Gastric Cancer Reinforce Biomarker Story

Independent data from the randomized Phase II ASPEN-06 study in HER2-positive gastric cancer showed similar patterns, with an intent-to-treat response rate near 41% and higher efficacy in HER2-retained patients at around 49% or more. In CD47-overexpressing gastric patients, response rates reached 65%, with median progression-free survival around 18.4 months and a hazard ratio of approximately 0.39, reinforcing the consistency of the CD47 biomarker signal across tumor types.

Durable Responses Hint at Immuno-Oncology Mechanism

Across breast and gastric studies, responders showed long-lasting benefit, with median durations of response hovering around 20 months in breast cancer and 25.5 months in gastric cancer. Management framed this durability as consistent with an immuno-oncology mode of action, positioning evorpacept combinations as potentially differentiated from shorter-acting cytotoxic regimens.

Large Safety Database and Differentiated CD47 Design

Evorpacept’s safety profile is supported by a clinical database of more than 800 treated patients, giving investors a relatively deep look at tolerability. The molecule is engineered without an active Fc domain to avoid activating macrophages on healthy cells, aiming to sidestep the on-target hematologic toxicities that have plagued earlier CD47 inhibitors and to support chronic administration.

ALX2004 ADC Program Advances Through Dose Escalation

Alx Oncology’s second program, ALX2004, an EGFR-targeted antibody-drug conjugate, is progressing through dose-escalation cohorts up to 4 mg/kg. Enrollment is ongoing, and the company is targeting an initial safety readout in the second half of 2026, though management emphasized that the program remains early and subject to typical development risks.

Execution, Hiring, and Financing Bolster Corporate Position

Management highlighted recent operational milestones, including key leadership additions such as a Chief Development Officer and Chief Operating Officer. A February financing, anchored by institutional investors, has strengthened the balance sheet and is expected to fund major milestones over the next one to two years, including progress on the ASPEN-09 Phase II breast study.

Small Cohorts Underscore Preliminary Nature of Data

Despite the impressive numbers, the company underscored that the zanidatamab-evorpacept breast cohort remains small, with only 24 patients overall, 10 centrally confirmed HER2-positive cases, and just five CD47-high patients. Such limited sample sizes make the results vulnerable to variability and highlight the need for larger, prospectively defined studies before drawing definitive conclusions.

CD47 Assay and Cutoff Still a Moving Target

The CD47 biomarker strategy remains in flux, with the current analysis using a 20% total membrane staining cutoff while prior work referenced different thresholds such as 10% or IHC 3+. ASPEN-09 is designed to refine and optimize the companion diagnostic and may ultimately establish a validated CD47 cutoff, but until then, assay standardization and regulatory alignment remain key open questions.

Limited Benefit in All-Comers and CD47-Low Patients

In the broader population, the regimen’s benefit appeared modest, with median progression-free survival of about 3.6 months overall and roughly 3.4 months in CD47-low patients. Objective response rates were also lower in non-centrally-confirmed HER2 patients, suggesting that evorpacept combinations may be best positioned as a targeted therapy for biomarker-positive subsets rather than a universal solution.

Regulatory Pathway Hinges on Registrational Trials

Management tempered expectations for accelerated approval, noting that single-arm data would need to be extraordinary to support such a path given the retrospective biomarker work. The base case now assumes a registrational Phase III trial in a prospectively selected CD47-high population, introducing execution, timeline, and regulatory risk while also offering a clearer, more standard path to potential approval.

HER2 Testing Discordance Complicates Patient Selection

Of the 24 breast cancer patients treated, only 10 were centrally confirmed as HER2-positive, highlighting discordance between local archival and central fresh testing. Factors such as assay variability, tissue age, and tumor heterogeneity may be contributing, and the company will need to address these challenges to ensure that future trials enroll the right patients and that any approved therapy is used appropriately.

ALX2004 Still Early with Safety and Efficacy Unknowns

While ALX2004’s advancement through multiple dose levels is encouraging, management cautioned that the program remains at an early stage with an initial safety readout not expected until the second half of 2026. Larger datasets will be needed to clarify the drug’s safety, efficacy, and commercial potential, leaving investors with significant uncertainty around this second pillar of the pipeline.

Guidance Points to 2027 as Pivotal Year

Looking ahead, the company reaffirmed that ASPEN-09 will enroll up to 120 patients, with top-line data from roughly 80 CD47-overexpressing patients anticipated around mid-2027 and objective response rate as the primary endpoint. Alx Oncology aims to be ready for registrational studies by the end of 2027, while ALX2004’s dose escalation continues toward an initial safety update in the second half of 2026, all supported by a bolstered balance sheet and an estimated multibillion-dollar addressable market.

Alx Oncology’s earnings call painted a picture of a company with emerging, biomarker-driven momentum but still substantial clinical and regulatory hurdles. Investors will be watching closely as larger trials validate the CD47-high strategy, HER2 testing is standardized, and the early ALX2004 program matures, determining whether today’s promising signals can translate into durable commercial success.