Natera is partnering with Angiex to incorporate Signatera minimal residual disease (MRD) testing into Angiex’s Phase I trial of AGX101, a nuclear-delivered antibody-drug conjugate targeting TM4SF1. The collaboration will include longitudinal Signatera ctDNA measurements intended to complement imaging and assess treatment response during therapy. By adding repeated molecular sampling alongside radiology, the companies aim to clarify whether ctDNA dynamics track with changes seen on scans—particularly when imaging does not clearly indicate viable tumor. The approach reflects growing efforts to operationalize MRD testing not only for recurrence risk but also for monitoring response over the course of treatment. The Phase I program is enrolling patients with unresectable locally advanced or metastatic solid tumors, and the trial design will generate data on the interpretability of ctDNA trajectories during ADC exposure.