ALX Oncology has taken a significant step forward in the fight against advanced breast cancer, presenting new data at the ESMO Breast Cancer Congress 2026 that highlights the potential of a biomarker-driven approach using CD47. The biotechnology company announced that exploratory analyses from a Phase 1b/2 clinical trial—evaluating the combination of its investigational CD47 inhibitor, evorpacept, with zanidatamab (ZIIHERA®) from Jazz Pharmaceuticals—show promising results in patients with HER2-positive metastatic breast cancer (mBC). These findings, detailed in a poster presentation on May 7, 2026, suggest that CD47 expression levels may serve as a predictive biomarker for patient response, offering a more tailored treatment strategy for those with this aggressive form of cancer.
The data, which were first reported in January 2026, build on earlier observations from the ASPEN-06 trial in HER2-positive gastric cancer, where CD47 expression was also linked to treatment efficacy. The Phase 1b/2 trial included patients with heavily pretreated HER2-positive mBC, many of whom had received multiple prior therapies, including the HER2-targeted drug Enhertu. The exploratory analysis revealed that responses to the evorpacept and zanidatamab combination were largely confined to patients with higher CD47 expression, reinforcing the idea that this biomarker could help identify which patients are most likely to benefit from the treatment.
For patients with metastatic breast cancer, especially those whose disease has progressed despite multiple lines of therapy, new treatment options are desperately needed. The HER2-positive subtype, while responsive to targeted therapies, often develops resistance over time, leaving many patients with limited options. The new data from ALX Oncology suggest that evorpacept, when combined with zanidatamab, could offer a novel pathway forward, particularly for those whose tumors express high levels of CD47. This approach aligns with a growing trend in oncology toward precision medicine, where treatments are matched to the unique biological characteristics of a patient’s cancer.
Key Findings and What They Mean for Patients
The Phase 1b/2 trial, conducted across multiple centers, enrolled patients with inoperable, locally advanced, or metastatic HER2-expressing breast cancer. The primary results, presented at the 2024 San Antonio Breast Cancer Symposium, showed that the combination of evorpacept and zanidatamab generated promising antitumor activity, with a confirmed objective response rate of 56% (5 out of 9 patients) and a median progression-free survival of 7.4 months among those with centrally confirmed HER2-positive disease. These outcomes are particularly notable given that the patients in the trial had received a median of six prior therapies, indicating a high level of treatment resistance.
The exploratory biomarker analysis further clarified that the efficacy of the combination was closely tied to CD47 expression. Patients with higher levels of CD47 on their cancer cells were more likely to respond to the treatment, a finding that aligns with ALX Oncology’s broader research into the role of CD47 in cancer biology. CD47 is a protein that helps cancer cells evade the immune system, and inhibiting it with evorpacept may restore the body’s ability to target and destroy tumor cells, especially when combined with HER2-targeted agents like zanidatamab.
Why CD47 Matters
CD47 is increasingly recognized as a critical player in cancer progression and immune evasion. By blocking CD47, evorpacept may help macrophages—immune cells that normally clear away damaged or infected cells—recognize and attack cancer cells more effectively. This mechanism has shown promise in preclinical and early clinical studies across several cancer types, including breast, gastric, and lung cancers. The new data from ALX Oncology’s trial suggest that CD47 expression could serve as a biomarker to guide patient selection for evorpacept-based therapies, potentially sparing those without high CD47 expression from unnecessary treatment and its associated side effects.
Next Steps and Ongoing Trials
ALX Oncology is not stopping at these exploratory findings. The company is advancing the ASPEN-09-Breast Phase 2 trial, which is specifically designed to further evaluate the evorpacept and zanidatamab combination in patients with HER2-positive metastatic breast cancer. This trial will provide more definitive data on the safety, efficacy, and biomarker-driven potential of the combination, building on the promising signals observed in the Phase 1b/2 study.
In addition to the breast cancer program, ALX Oncology is exploring evorpacept in other cancer types, including gastric, lung, and ovarian cancers, where CD47 inhibition may also play a role in improving patient outcomes. The company’s pipeline reflects a broader shift in oncology toward combination therapies that target multiple pathways in cancer biology, rather than relying on single-agent approaches.
What’s Next for Patients and Researchers
The ESMO Breast Cancer Congress presentation marked a key milestone for ALX Oncology, offering a glimpse into how biomarker-driven strategies could reshape the treatment landscape for metastatic breast cancer. For patients, these data represent hope for more effective and personalized therapies, especially for those with HER2-positive disease that has become resistant to current treatments. For researchers, the findings underscore the importance of continued investigation into CD47 and other biomarkers that could unlock new avenues for cancer treatment.
ALX Oncology will continue to share updates on the ASPEN-09-Breast trial and other ongoing studies through its investor relations channels and at upcoming scientific conferences. Patients and caregivers interested in learning more about clinical trials involving evorpacept or zanidatamab can consult the [National Cancer Institute’s clinical trials database](https://www.cancer.gov/about-cancer/treatment/clinical-trials) or contact their oncology care team for guidance on participation.
Looking Ahead
The next major checkpoint for ALX Oncology will be the presentation of full data from the ASPEN-09-Breast Phase 2 trial, which is expected to provide deeper insights into the combination’s efficacy and safety profile. Until then, the company will continue to engage with regulatory agencies and the broader medical community to advance the development of evorpacept and other pipeline candidates. For patients and advocates, staying informed about emerging therapies and clinical trials remains crucial, as new options for metastatic breast cancer are likely to evolve rapidly in the coming years.
As the field of immuno-oncology continues to advance, the story of evorpacept and zanidatamab serves as a reminder of the power of precision medicine. By leveraging biomarkers like CD47, researchers are not only refining treatment strategies but also offering new hope to patients who have exhausted standard options. For now, the focus remains on translating these promising early results into tangible benefits for those battling advanced breast cancer.
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