Perspective Therapeutics (CATX) Study Update summary

Study background and objectives

• [212Pb] VMT-α-NET targets SSTR2 to treat neuroendocrine tumors (NETs), addressing a critical unmet need with limited efficacy from current therapies like Lutathera.

• The Phase 1/2 study enrolled 55 patients with advanced, unresectable, or metastatic NETs, focusing on SSTR2+ tumors and including both pancreatic and non-pancreatic types.

• The trial used a Bayesian Optimal Interval design to determine safety, tolerability, and recommended Phase 2 dose (RP2D), with expansion into additional SSTR2+ tumor types under evaluation.

• Patients were selected based on SSTR2 expression, with analyses comparing all-comers to those where all tumors expressed SSTR2, aligning with NETTER-1 criteria.

• The radiopharmaceutical platform uses alpha-emitting isotope 212Pb for targeted therapy and complementary imaging diagnostics.

Patient population and treatment exposure

• 55 patients were treated across three dose cohorts (2.5, 5.0, and 6.0 mCi), with a median age of 63 and 95% having gastroenteropancreatic NETs.

• Most patients had prior systemic therapy, and 87% had received somatostatin analogues.

• Median follow-up was 41 weeks for key cohorts, with 25 patients having at least 9 months of follow-up.

• The trial used modern PET imaging for SSTR2 assessment, which is more sensitive than SPECT imaging used in prior studies.

• Dose escalation cohorts included 2.5, 5, and 6 mCi regimens, with the 5 mCi cohort being the primary focus for efficacy and safety.

Efficacy and clinical activity

• Objective response rate was 44% (7/16) in Cohort 2 with SSTR2 expression in all tumors, and 35% in Cohort 2 overall with ≥9 months follow-up.

• 87.5% (14/16) of patients with uniform SSTR2 expression in Cohort 2 remained progression-free at a median follow-up of 41 weeks.

• Waterfall, swimmer, and spider plots demonstrated significant and sustained tumor shrinkage, with some responses occurring up to a year after treatment initiation.

• Excluding patients with heterogeneous SSTR2 uptake, no progressors were identified, suggesting uniform SSTR2 expression may predict better outcomes.

• Two patients in Cohort 1 maintained stable disease for over 1.5 years.