On December 10, 2020 Ambrx Inc., a clinical-stage biopharmaceutical company focused on developing Precision Biologics using an expanded genetic code, reported a clinical update on their lead program ARX788, a homogeneous and highly stable, site-specific antibody drug conjugate (ADC) targeting HER2 positive cancers (Press release, Ambrx, DEC 10, 2020, View Source [SID1234572609]).
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"As presented at the 2020 San Antonio Breast Cancer Symposium, ARX788 Phase 1 studies demonstrated promising antitumor activity in heavily pre-treated cancer patients at the recommended Phase 2 dose," said Joy Yan, MD, PhD, Ambrx Chief Medical Officer.
• ORR of 74% (14/19) and DCR of 100% in the 1.5 mg/kg cohort of the Phase 1 HER2-positive breast cancer trial in China
• ORR of 67% (2/3) and DCR of 100% in the 1.5 mg/kg cohort of Phase 1 HER2-positive pan tumor trial in U.S. and Australia
• mDOR or mPFS at the 1.5 mg/kg dose have not been reached.
• ARX788 was well-tolerated, with most adverse events being mild or moderate, and were manageable.
Patients who failed prior Kadcyla (T-DM1) or Enhertu (DS-8201a) achieved clinical responses, as assessed by RECIST v1.1 in the ACE-Pan Tumor-01 (ARX788-1711) trial, which enrolled patients with HER2 expressing cancers including breast cancer, gastric/gastroesophageal junction adenocarcinoma, non-small cell lung cancer, bladder, colorectal, biliary track, and salivary gland cancers in US and Australia.
"The randomized controlled Phase 2/3 HER2-positive breast cancer pivotal trial in China has treated 22 subjects as of December 5th, 2020 and continues to quickly enroll patients," said Dr. Xichun Hu, the leading PI of the ongoing ARX788 Phase 1 and Phase 2/3 trials in China.
"We remain on track to open multiple global ARX788 registrational studies next year, with the first study in HER2-positive breast cancer patients who failed prior T-DM1, T-DXd, or tucatinib-containing regimens starting in early 2021. These global registrational studies are designed to obtain BLA and sBLA in HER2 positive breast cancer, HER2 positive gastric cancer, HER2-low breast cancer, and other HER2-expressing or HER2-mutated solid tumors," said Dr. Yan.
About ARX788
ARX788 is a homogeneous and highly stable antibody drug conjugate (ADC) targeting the HER2 receptor. ARX788 is a Precision Biologic ADC that consists of two cytotoxic payloads site-specifically conjugated to a Herceptin (trastuzumab) based antibody. ARX788 was designed for maximum performance in the preclinical setting by optimizing the number, position and chemical bonds that conjugate the cytotoxic AS269 payload to the antibody. AS269 is a proprietary tubulin inhibitor specifically designed to form a highly stable covalent bond with our synthetic amino acids, a fundamental step in the creation of a Precision ADC. Ambrx is developing and commercializing ARX788 with its partner NovoCodex.