ARX517 Antibody-Drug Conjugate Joins Growing PSMA Pipeline


The first patient was treated in a phase 1 study of the new agent ARX517 targeted at PSMA in patients with prostate cancer and other solid tumors expressing PSMA, according to Ambrx, the developer of the experimental antibody conjugate -medicine (ADC).1

ARX517 Joins Growing PSMA Pipeline That Continues To Grow As Researchers Aim To Achieve Similar Success To That 177Lu-PSMA-617 achieved in phase 3 VISION trial.

ADC first showed promise in preclinical models of prostate cancer when pharmacokinetics (PK) and toxicity profile were adequate in tumors sensitive and resistant to enzalutamide (Xtandi). Now, the multicenter, open label, dose escalation phase 1 study (APEX-01; NCT04662580) will evaluate the safety, pharmacokinetics and antitumor activity of the agent in patients with prostate and pancreatic cancers. , lung and ovarian with PSMA expression. .

“I am delighted to announce that we have administered our first patient in our Phase 1 trial, and have thus taken the first steps to assess the potential clinical benefit of ARX517 in cancer patients with tumors overexpressing PSMA”, Feng Tian, ​​PhD, chairman of the board, chairman and chief executive officer of Ambrx, said in a press release. “ARX517 is the second ADC in our internal pipeline to enter the clinic …”

APEX-01 will recruit approximately 76 patients who will be divided into 6 dose cohorts and evaluated in 2 parts. The doses of ARX517 in the study will vary from 0.32 mg / kg to 2.0 mg / kg. At all dose levels assessed, patients will receive treatment every 3 weeks by intravenous infusion. The number of patients included in Part 2 of the study will not exceed 40, according to Ambrx.

Safety / tolerability is the primary endpoint of the study in Part 1, along with determining the maximum tolerated dose of ARX517 and establishing the Phase 2 Recommended Dose (RP2D). In Part 2, the main end point of the study is to further assess the safety and tolerability of ARX517 over RP2D. The pharmacokinetics and the presence of anti-drug antibodies at baseline, during treatment and at follow-up are the secondary endpoints of the study. Researchers will also explore surrogate biomarkers during the study, including circulating tumor cells, PSA, and imaging.

The study is actively recruiting male patients 18 years of age or older with pathologically confirmed prostate adenocarcinoma and other solid tumors. All patients must have metastatic disease according to the calculated typography, an ECOG performance index of 0 or 1 at screening, adequate organ function, a life expectancy of at least 6 months at the time of screening and have stopped all radiotherapy 4 weeks before the start of treatment. study to be eligible for enrollment.

Patients with prostate cancer must meet all comprehensive inclusion requirements, but must also be on continuous hormone therapy, be pre-treated with an FDA-approved drug for the treatment of metastatic resistant prostate cancer at castration, have disease progression and have stopped all non-steroidal therapy. anti-androgens 4 weeks before joining APEX-01.

The primary recruitment site for the first human study of ARX517 in solid tumors expressing PSMA is the Urology Cancer Center of the XCancer Research Network located in Omaha, Nebraska. The site survey manager is Luke Nordquist, MD, FACP.


1. Ambrx announces the first patient to receive a dose in a phase 1 trial for ARX517, an ADC in development to treat tumors expressing PSMA. Press release. August 3, 2021. Accessed August 3, 2021.


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