Ariceum Therapeutics has announced the dosing of first patient in the SANTANA-225 Phase I/II clinical trial for 225Ac-SSO110, a treatment intended for people with Merkel cell carcinoma (MCC) and extensive-stage small cell lung cancer (ES-SCLC).
225Ac-SSO110 is an Actinium-225-labelled somatostatin type 2 receptor (SSTR2) antagonist, a radioligand therapy (RLT) developed for the neuroendocrine tumour types.
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SANTANA-225 is an open-label, global clinical study that aims to assess preliminary efficacy, safety, and tolerability, and establish the recommended dose for Phase II in participants with ES-SCLC, who have previously been treated with checkpoint inhibitor in first-line maintenance therapy or MCC subjects with first-line CPI treatment.
The dose escalation phase will include 20 participants, with expansion cohorts planned as the study progresses.
In February, 225Ac-SSO110 receive orphan drug designation (ODD) from the US Food and Drug Administration (FDA) for ES-SCLC treatment.
Ariceum Therapeutics chief medical officer Germo Gericke said: “RLTs are redefining precision oncology by enabling targeted delivery of radiation directly to tumour cells while minimising exposure to healthy tissue.
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By GlobalData“225Ac-SSO110 is the first SSTR2 antagonist RLT in clinical development, designed to deliver higher doses of alpha radiation directly to patients’ tumours while maintaining a favourable safety profile for individuals with neuroendocrine cancers, including ES-SCLC and MCC.
“Dosing the first patient in the SANTANA-225 trial is a significant step for our lead programme and an important milestone towards addressing urgent patient needs in these aggressive cancers.
The company plans to release initial safety results from the SANTANA-225 trial in 2026. These findings could support expanding into additional neuroendocrine tumour indications and further validate the distinct mechanism of action of 225Ac-SSO110.
ES-SCLC is an aggressive cancer with a high unmet medical need. Most subjects are diagnosed at an advanced stage, with a 5%-10% five-year survival rate.
Similarly, MCC is a rare and aggressive skin cancer with low survival in those unresponsive to first-line checkpoint inhibitors. Both ES-SCLC and MCC commonly express SSTR2, making them strong initial indications for SSTR2-targeted therapy.
