SOUTH SAN FRANCISCO, Calif., May 7, 2026
ALX Oncology announced promising new clinical findings showing that its investigational CD47 inhibitor evorpacept, when combined with Jazz Pharmaceuticals’ zanidatamab, generated durable responses in patients with heavily pretreated HER2-positive metastatic breast cancer and high CD47 expression. The new data were presented during the ESMO Breast Cancer 2026 Congress, further strengthening the company’s biomarker-driven oncology development strategy and highlighting the growing importance of precision medicine in advanced breast cancer treatment.
Biomarker-Driven Therapy Shows Strong Clinical Responses
The Phase 1b/2 clinical trial evaluated evorpacept in combination with zanidatamab in patients with advanced HER2-positive metastatic breast cancer who had already received multiple HER2-targeted therapies, including prior treatment with ENHERTU. Researchers reported that patients with centrally confirmed HER2-positive disease and high CD47 expression demonstrated a 100% confirmed objective response rate (5/5 patients), compared with a 25% response rate among patients with lower CD47 expression levels.
The study also showed major differences in progression-free survival between the two groups. Patients with high CD47 expression achieved a median progression-free survival of 22.1 months, while patients with lower CD47 expression showed progression-free survival of only 3.4 months. Additionally, the median duration of response among high-CD47 patients reached 20.2 months, underscoring the potential durability of the treatment combination.
Investigators believe the findings reinforce the value of biomarker-guided treatment strategies in difficult-to-treat metastatic breast cancer populations. According to researchers presenting the data, CD47 expression could emerge as an important predictive biomarker for identifying patients most likely to benefit from evorpacept-based therapies.
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Advanced HER2-Positive Breast Cancer Remains a Critical Need
Experts note that there remains a substantial unmet need for patients with advanced HER2-positive breast cancer whose disease progresses after currently available therapies. The trial included heavily pretreated patients with a median of five prior HER2-targeted treatments, making the results particularly significant for late-stage oncology care.
The combination therapy also demonstrated a manageable safety profile in earlier analyses presented at the 2024 San Antonio Breast Cancer Symposium. In the current exploratory analysis involving 24 patients, researchers observed encouraging anti-tumor activity across multiple patient groups. Among all patients enrolled in the study, the confirmed objective response rate reached 33%, while centrally confirmed HER2-positive patients achieved a higher response rate of 60%.
ALX Oncology stated that the findings are consistent with previous observations from the randomized ASPEN-06 gastric cancer trial, where CD47 expression also appeared to predict improved therapeutic activity. The company believes this strengthens confidence in its precision oncology development strategy and supports broader exploration of biomarker-driven immuno-oncology combinations.
ALX Oncology Expands Precision Immuno-Oncology Strategy
ALX Oncology executives said the latest results further validate evorpacept’s potential role as a foundational immuno-oncology therapy across multiple cancer indications. The company is continuing development through the ongoing ASPEN-09-Breast Phase 2 trial, which is evaluating evorpacept combined with trastuzumab and chemotherapy in HER2-positive breast cancer patients.
Industry analysts say the strong response rates and durable outcomes observed in biomarker-selected patients may support future precision medicine approaches in breast cancer treatment. The oncology sector continues to invest heavily in targeted immunotherapies capable of improving survival outcomes while helping physicians personalize treatment decisions using tumor biomarker analysis.
As competition intensifies in the HER2-positive breast cancer market, new therapeutic combinations that improve outcomes for post-ENHERTU patients could represent a major advancement in metastatic cancer care. Researchers and clinicians will continue monitoring larger studies to determine whether CD47-guided treatment selection can consistently improve clinical benefit across broader patient populations.
Source: ALX Oncology press release
