Ambrx Biopharma’s ARX788 (anvatabart opadotin), an antibody-drug conjugate (ADC) targeting HER2-positive metastatic breast cancer (mBC), presented promising results at the American Society of Clinical Oncology (ASCO) 2024. However, challenges remain for broader market access.
Study Findings:
The phase III ACE-Breast-02 trial compared ARX788 to lapatinib + capecitabine (LC), a common treatment option in China (where the trial was conducted) but not the standard of care elsewhere.
ARX788 significantly extended progression-free survival (PFS) compared to LC (11.33 months vs. 8.25 months).
Safety profiles were similar between the two arms.
Market Landscape:
Enhertu is the current gold standard for HER2-positive mBC in the US and Europe. While recently approved in China, it may not be widely accessible due to cost factors.
Other HER2-targeted therapies like Kadcyla and Tykerb are more commonly used in China.
Challenges for ARX788:
The choice of LC as a control arm limits the drug’s potential for approval in the US and Europe, where trials typically compare new drugs to established standards like Enhertu.
Head-to-head trials against Kadcyla are ongoing for other ADCs like Aidixi, potentially offering stronger clinical data for doctors.
Future Outlook:
While ARX788 demonstrates efficacy comparable to Kadcyla, its path to widespread adoption may be difficult. Focusing on markets where Enhertu access is limited and conducting further trials against more established control arms could improve its global prospects.
