Antitumor Activity Seen With Targeted Alpha Therapy [212Pb]VMT-α-NET in SSTR2+ NETs

Updated interim data from a phase 1/2a trial (NCT05636618) show that [²¹²Pb]VMT-α-NET, an investigational targeted alpha-particle therapy, exhibited preliminary antitumor activity in patients with advanced somatostatin receptor type 2-positive (SSTR2+) neuroendocrine tumors (NETs), including evidence of durable disease control and deepening tumor responses.¹ These updated data were presented recently at the 2026 American Society of Clinical Oncology (ASCO) Gastrointestinal Cancers Symposium.

As of the latest data cutoff on December 10, 2025, 76% of patients treated at the 2.5 mCi (n = 2; cohort 1) and 5.0 mCi (n = 23; cohort 2) dose levels remained alive without progression. The objective response rate among cohort 2, regardless of SSTR2 expression, was 39% per RECIST v1.1. In addition, deepening of best response was observed in 7 patients.

“With longer follow-up and a growing body of clinical experience, we continue to see evidence of sustained and deepening antitumor activity for VMT-α-NET at the dose level evaluated in [c]ohort 2, while the favorable tolerability profile is maintained, possibly even at a higher dose,” said Vikas Prasad, MD, Washington University School of Medicine, in a news release.¹ “These data further support continued dose optimization, and I look forward to discussing the evolving results with the gastrointestinal oncology community as this study progresses.”

[²¹²Pb]VMT-α-NET is a targeted alpha particle therapy in development for SSTR2-expressing NETs. It is designed to improve cancer treatment precision and effectiveness by selectively delivering potent alpha radiation to cancerous cells, with the aim of minimizing off-target effects.²

Safety Findings

The safety analysis, which included 56 patients across cohorts 1 and 2 plus a third cohort treated at the 6.0 mCi dose level, indicated that the agent was well-tolerated, with no dose-limiting toxicities or treatment-related discontinuations reported. Of these patients, 21 (37.5%) experienced grade 3 or higher treatment-emergent adverse events (AEs). Five patients experienced serious AEs, none of which were deemed related to the treatment.

About the Phase 1/2a Trial and Next Steps

This first-in-human, multicenter, open-label, dose-escalation and -expansion study was designed to evaluate the safety and preliminary efficacy of [²¹²Pb]VMT-α-NET in up to 260 patients with unresectable or metastatic SSTR2+ NETs who have not received a prior radiopharmaceutical therapy and whose tumors have shown radiological evidence of disease progression in the 12 months prior to enrollment.² The study is ongoing and recruiting patients across sites in the US.

With these new findings, the study remains on track for further evaluation of the remaining patients in cohorts 2 and 3. Additionally, Perspective Therapeutics, sponsor of the trial, has announced plans for engagement with regulatory bodies throughout the year regarding [²¹²Pb]VMT-α-NET’s continued development.

“With the robust clinical dataset being accrued from strong patient enrollment into our study, we believe we will be able to have meaningful engagement with regulatory agencies during 2026 on proceeding with VMT-α-NET into a registrational trial,” said Markus Puhlmann, chief medical officer of Perspective Therapeutics, in the news release.¹

REFERENCES

1. Perspective Therapeutics presents updated interim data of [212Pb]VMT-α-NET in its ongoing phase 1/2a clinical trial at the 2026 ASCO Gastrointestinal Cancers Symposium. News release. Perspective Therapeutics. January 9, 2026. Accessed January 15, 2026. https://tinyurl.com/t7797sy7

2. Targeted alpha-particle therapy for advanced somatostatin receptor type 2 (SSTR2)-positive neuroendocrine tumors. ClinicalTrials.gov. Updated November 24, 2025. Accessed January 15, 2026. https://clinicaltrials.gov/study/NCT05636618