ALX Oncology evorpacept combination data presented at ESMO congress

ALX Oncology (ALXO) announced that data from exploratory analyses in the Phase 1b/2 clinical trial evaluating the company’s investigational CD47-inhibitor evorpacept in combination with Jazz Pharmaceuticals’ (JAZZ) zanidatamab in patients with heavily pre-treated HER2-positive metastatic breast cancer were presented for the first time in a poster session at the ESMO Breast Cancer 2026 congress. The findings show that patients with centrally confirmed HER2-positive mBC and high CD47 expression experienced a promising, durable response. Specifically, patients in the trial with ccHER2-positive disease and high CD47 expression had a confirmed objective response rate of 100%, while the cORR was 25% among those with lower CD47 expression. Those patients whose tumors expressed higher levels of CD47 also had longer median progression-free survival: 22.1 months as compared to 3.4 months in the low-CD47 expression group. The median duration of response among patients whose tumors expressed high levels of CD47 was also notable at 20.2 months. The Phase 1b/2 open-label, multi-center clinical trial evaluating evorpacept plus zanidatamab included patients with heavily pre-treated HER2-positive mBC, all of whom had received prior Enhertu therapy. The primary trial results, presented at the 2024 San Antonio Breast Cancer Symposium, demonstrated that the investigational combination generated promising anti-tumor activity and a manageable safety profile. The exploratory analyses comprised 24 patients, including 10 with ccHER2-positive disease. Seventeen of 24 samples were evaluable for CD47 expression, including samples from nine of the 10 ccHER2-positive patients. Patients received zanidatamab plus evorpacept at dosages of 20 mg/kg or 30 mg/kg. As of the August 1, 2024 data cut-off, key findings from the analyses include: the cORR among all 24 patients was 33% and the mPFS was 3.6 months. Patients with ccHER2-positive disease had higher response rates, with a cORR of 60% and mPFS of 8.3 months. All of the patients with ccHER2-positive disease and high CD47 expression responded, with an mDOR of 20.2 months and mPFS of 22.1 months. In comparison, among the patients with ccHER2-positive disease and low CD47 expression and mPFS was 3.4 months.