First-in-human phase I study of anti-HER2 ADC MRG002 in patients with relapsed/refractory solid tumors.

Abstract

TPS1101 Background: MRG002 is an antibody drug conjugate (ADC) composed of a humanized anti-HER2 IgG1 monoclonal antibody conjugated to a microtubule disrupting agent monomethyl auristatin E (MMAE). MRG002 is presently being investigated in an ongoing phase I study for safety, tolerability, pharmacokinetics (PK), and preliminary antitumor activity in patients (pts) with solid tumors. Methods: MRG002 is evaluated as monotherapy for the treatment of pts with confirmed HER2 positive locally advanced or metastatic cancers, including breast cancer (BC), gastric cancer (GC), salivary gland cancer (SGC) and others. The primary objective is to determine the maximum tolerated dose (MTD) and a recommended phase II dose (RP2D). Secondary objectives include evaluation of PK, tumor response, and immunogenicity. In the dose escalation phase with “3+3” design, approximately 24 pts will be enrolled to identify MTD. The starting dose of MRG002 is 0.3 mg/kg, followed by 0.6, 1.2, 1.8, 2.2, 2.6, and 3.0 mg/kg. In the dose expansion phase, about 50 pts with HER2 positive advanced cancers will be enrolled to further evaluate the safety, antitumor activity, and PK at an appropriate confirmed dose. In this phase I study, each pt receives single agent MRG002 once every 3 weeks (Q3W) for a maximum of 8 treatment cycles. Pts with BC and GC should have HER2 positive advanced solid tumors per College of American Pathologists (CAP) guidelines. For other cancers, pts must have IHC status of 2+ or 3+, regardless of FISH results. Pts should have either failed or are ineligible for standard treatments. All pts must have at least 1 measurable lesion per RECIST 1.1. ECOG should be 0-1, and bone marrow, hepatic, renal, cardiac functions should be adequate. Observations include adverse events (AEs), dose-limiting toxicity (DLT), and antitumor activity, which is assessed every two treatment cycles. Further clinical trial details can be found on chinadrugtrials.org.cn (CTR20181778). Enrollment is ongoing since November 2018. Clinical trial information: CTR20181778 .