FDA grants Fast Track Designation to Perspective Therapeutics’ PSV359, an investigational FAP-targeted alpha-particle therapy for FAP-positive solitary fibrous tumors.
Written By: Rishabh Sonawnae, BPharm
Reviewed By: Pharmacally Editorial Team
The U.S. Food and Drug Administration (FDA) has granted Fast Track Designation to [²¹²Pb]PSV359 for adult patients with locally advanced, unresectable, and/or metastatic fibroblast activation protein (FAP)-positive solitary fibrous tumours (SFTs).
Fast Track Designation is intended to facilitate the development and expedite the regulatory review of investigational therapies for serious conditions with unmet medical needs. The designation provides opportunities for more frequent interactions between the sponsor and FDA during development and, when applicable criteria are met, may allow access to mechanisms such as rolling review, Accelerated Approval, or Priority Review. The designation does not constitute marketing approval and does not establish clinical efficacy.
FAP-Targeted Alpha-Particle Therapy Under Evaluation
[²¹²Pb]PSV359 is an investigational FAP-targeted alpha-particle therapy being evaluated in an ongoing Phase 1/2a clinical study (NCT06710756). The study encompasses a broader population than the newly designated SFT indication, evaluating PSV359 in patients with advanced FAP-positive solid tumours.
The therapeutic strategy targets fibroblast activation protein-alpha (FAP-α), a cell-surface protein associated with cancer-associated fibroblasts in the tumour microenvironment. By coupling a targeting moiety to the alpha-emitting isotope lead-212 (²¹²Pb), PSV359 is designed to deliver targeted radiation to FAP-expressing tumour tissue.
Published imaging research has demonstrated FAP-targeted tracer uptake in SFTs, providing a biological rationale for evaluating FAP-directed radiopharmaceutical therapy in this population.
Perspective Therapeutics has highlighted the broader applicability of FAP targeting across solid tumours and states that no therapies specifically targeting FAP-α are currently approved.
Phase 1/2a Study Evaluates Safety and Dose Selection
Perspective Therapeutics is conducting NCT06710756 as a multicenter, open-label, dose-finding and dose-expansion study evaluating [²⁰³Pb]PSV359 and [²¹²Pb]PSV359.
A key feature of the study is imaging-based patient selection. [²⁰³Pb]PSV359 is administered for imaging to identify FAP-positive disease before therapeutic treatment with [²¹²Pb]PSV359.
The dose-finding portion evaluates the safety and tolerability of different dose levels and is intended to establish a recommended Phase 2 dose. The dose-expansion portion is designed to further characterize safety and evaluate antitumour activity, including objective response.
Theranostic Strategy Connects Imaging with Treatment
The PSV359 program uses a theranostic approach in which related radiolabeled constructs support tumour imaging and targeted treatment. Lead-203 (²⁰³Pb) serves as the imaging component, while lead-212 (²¹²Pb) provides the therapeutic alpha-particle source.
Perspective Therapeutics is advancing the program using its proprietary ²²⁴Ra/²¹²Pb generator technology, which is intended to support the manufacture and supply of lead-212-based clinical products.
Alpha particles have high linear energy transfer (LET) and can produce substantial DNA damage over a short path length. The therapeutic strategy is intended to concentrate radiation within or near FAP-expressing tumour tissue while limiting radiation exposure beyond the target.
Regulatory Milestone, Not Evidence of Efficacy
FDA Fast Track Designation represents an important regulatory milestone for PSV359 in FAP-positive SFTs, a disease setting with limited treatment options.
However, the designation does not establish clinical efficacy, and the safety and therapeutic benefit of PSV359 remain under clinical evaluation. The ongoing Phase 1/2a study will help determine the appropriate dose, characterize safety and tolerability, and assess whether image-guided targeting can translate into meaningful antitumour activity.
Reference
Perspective Therapeutics Granted Fast Track Designation for [212Pb]PSV359 for the Treatment of Adult Patients with Locally Advanced Unresectable and/or Metastatic FAP-Positive Solitary Fibrous Tumors, Perspective Therapeutics, 08 October 2026
Lead-212 PSV359 Therapy for Patients with Solid Tumors, ClinicalTrials.gov ID NCT06710756
About the Writer
Rishabha Sonawane, B.Pharm (LinkedIn) is healthcare writer with a strong interest in medical writing, regulatory affairs, clinical research, and AI-driven drug discovery. He has completed specialized training from the NIH and ICMR in clinical pharmacology, clinical research, and scientific writing. Passionate about evidence-based healthcare communication, he focuses on translating complex scientific research into clear, accurate, and engaging medical content.