Phase 1 SLR-108 PTK7-targeted antibody–radionuclide conjugate for immuno-PET imaging.

This Phase 1, interventional, open-label imaging study from Solve Therapeutics is testing whether SLR-108 can feasibly visualize metastatic solid tumors on PET after a single IV administration. SLR-108 is a PTK7-directed monoclonal antibody labeled with a positron-emitting radionuclide (an antibody–radionuclide conjugate) intended for “immuno-PET,” aiming to quantify biodistribution, radiation dosimetry, image quality, and the best post-dose imaging time window. The protocol explores multiple cohorts that vary total antibody protein dose (low/medium/high) and radioactivity dose, with later parts adjusting doses based on early readouts; the study also references SLX-1411, a non-radiolabeled PTK7-directed monoclonal antibody used to support the imaging regimen. Eligible participants have relapsed/refractory metastatic solid tumors (tumor-agnostic enrollment rather than one histology). Commercially, the key angle is using PTK7 imaging to potentially enable patient selection and dose optimization for future PTK7-targeted therapeutics; today’s care for metastatic solid tumors is standard CT/MRI plus blood tests to follow disease and guide sequential systemic therapy (chemo, targeted therapy, and immunotherapy depending on tumor type/biomarkers), and this trial tests whether a target-specific PET tracer can add actionable biologic information beyond anatomy alone.