Radiopharm reports confirmed partial response in Phase 1 trial of RAD204

Radiopharm Theranostics disclosed updated results from the first two patients in the third dosing cohort of its Phase 1 trial of RAD204, a PD-L1-targeted lutetium-177 nanobody radiotherapeutic being tested in patients with advanced solid tumors following immunotherapy.¹ The company had previously received clearance from its Data and Safety Monitoring Committee to advance dosing to the current highest dose level #3 at 90 mCi after completing cohorts 1 and 2.¹

For Patient 1, tumor reduction in target lesions went from 19% after the first dose to 43% after the second dose, meeting RECIST criteria for partial response, and this was maintained at 43% after the third dose before settling at 35% after the fourth dose while still meeting partial response criteria.¹ This patient has remained progression-free for more than seven months with continued follow-up.¹

Patient 2 showed an early 7% reduction in target lesions after the first treatment cycle and remains on treatment and progression-free with further monitoring planned.¹

On safety, the company reported a favorable safety and tolerability profile across all patients dosed through dose levels 1 to 3, with no dose-limiting toxicities observed in any cohort.¹ Kidney uptake was measured at a cumulative 8.1 Gy across four cycles in Patient 1 and was not considered an obstacle to escalating to dose level 4.¹

The Phase 1 study's stated goals are to evaluate safety, tolerability, dosimetry, pharmacokinetics and preliminary anti-tumor activity, with primary objectives to establish a recommended Phase 2 dose and secondary endpoints covering tumor response and duration.¹ A third patient in cohort 3 is currently under screening evaluation.¹