FDA Clears 225Ac-SSO110 for Phase 1/2 SCLC and Merkel Cell Carcinoma Trial

• The FDA has cleared its investigational new drug (IND) application, allowing for the start of a phase 1/2 trial of ²²⁵Ac-SSO110 (satoreotide) for the treatment of patients with small cell lung cancer (SCLC) or Merkel cell carcinoma (MCC).
• Investigators will assess the safety, tolerability, and preliminary efficacy of ²²⁵Ac-SSO110 in patients with extensive-stage SCLC (ES-SCLC) and MCC in the SANTANA-225 trial.
• SANTANA-225 is expected to begin enrolling patients in the first quarter of 2025.

The FDA has granted clearance to the IND application of ²²⁵Ac-SSO110, allowing for the commencement of a phase 1/2 trial titled SANTANA-225 in patients with SCLC or MCC.¹

SANTANA-225 is a global, open-label, phase 1/2 trial evaluating the safety, tolerability, preliminary efficacy, and recommended phase 2 dose of ²²⁵Ac-SSO110 when used as a treatment for patients with ES-SCLC or MCC. Patients must be on first-line maintenance therapy with checkpoint inhibitors.

The trial plans to begin enrolling patients in the US and other countries in the first quarter of 2025.

“This is an important milestone, not only for Ariceum but for the whole field of targeted radionuclide cancer treatments. ²²⁵Ac-SSO110 is the first SSTR2 antagonist labelled with Actinium-225 to undergo human trials, providing the optimum combination of a long half-life α particle emitter with a long tumor retention tracer. Based on encouraging clinical data with ¹⁷⁷Lu-SSO110 and very promising preclinical data of ²²⁵Ac-SSO110, we are very optimistic about the potential for patients with difficult to treat cancers," said Germo Gericke, chief medical officer at Ariceum Therapeutics, in a press release.

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²²⁵Ac-SSO110 is a somatostatin receptor 2 (SST2) antagonist currently under clinical development for the potential treatment of patients with SCLC and MCC. The agent is being developed together with ⁶⁸Ga-SSO120 as part of a theranostic approach for targeted radionuclide therapy.

In addition, Ariceum, the developer of ²²⁵Ac-SSO110, has recently broadened its global supply agreements for key medical radionuclides, Actinium-225 and Lutetium-177, which will be utilized for radiolabeling SSO110 in these therapeutic applications.

At the 2024 European Association of Nuclear Medicine Annual Conference preclinical data showed the superior antitumor efficacy of satoreotide-based radiolabeled antagonists compared with DOTA-TATE-based agonists in SCLC and pancreatic cancer.²

In addition to outperforming DOTA-TATE in antitumor efficacy at lower doses, ²²⁵Ac-SSO110 was well tolerated across all dose levels. These findings supported the further clinical development of the agent for SSTR2-expressing tumors.

REFERENCES:

1. FDA clears Ariceum Therapeutics' 225Ac-satoreotide phase I/II clinical study in patients with small cell lung cancer or merkel cell carcinoma. News release. Ariceum Therapeutics. January 14, 2025. Accessed January 15, 2025. https://tinyurl.com/yeymj6u2

2. Ariceum Therapeutics presents outstanding data on its first-in-class radiopharmaceutical drug 225Ac-satoreotide at the european association of nuclear medicine 2024. News release. Ariceum Therapeutics. October 22, 2024. Accessed January 15, 2025. https://tinyurl.com/mzvy7795