Sinotau today announced that clinical data for XTR022 ([²²⁵Ac]Ac-XT381), its novel alpha-particle radioligand therapy, were presented in a poster session at the 2026 American Society of Clinical Oncology (ASCO) Annual Meeting. The study evaluated the safety, tolerability and preliminary efficacy of XTR022 in patients with previously treated, PSMA-positive metastatic castration-resistant prostate cancer (mCRPC).
Study Design and Status
The study utilized a “3+3” dose-escalation design, with XTR022 administered intravenously once every six weeks for a maximum of six cycles. As of the data cutoff on April 1, 2026, a total of 13 previously treated patients with PSMA-positive mCRPC had been enrolled.
Baseline Characteristics
Patients had a median age of 67.6 years, and nine patients had received three or more prior lines of therapy. The mean baseline prostate-specific antigen (PSA) level was 146.6 ng/mL.
Efficacy Data
Among the 13 patients evaluable for PSA response after at least one treatment, 10 achieved a PSA50 response (one pending confirmation), resulting in a PSA50 response rate of 76.9%. Five patients achieved a PSA90 response, yielding a PSA90 response rate of 38.5%.
In the nine patients with RECIST-measurable disease, the objective response rate (ORR) was 33.3% (three partial responses) and the disease control rate (DCR) was 88.9%.
Notably, one 70-year-old patient who had received four prior lines of therapy achieved a confirmed partial response (cPR) after completing six cycles at the 50 kBq/kg dose level, with a 97.7% reduction in PSA from baseline.
Safety Data
No dose-limiting toxicities (DLTs) were observed across the dose levels ranging from 25 to 100 kBq/kg.
The most common treatment-related adverse event was dry mouth, all cases of which were Grade 1 or 2.
Hematologic adverse events included leukopenia in 46.2% (6/13) of patients, all Grade 1–2; lymphopenia in 38.5% (5/13), with Grade ≥3 events in 15.4% (2/13); and thrombocytopenia in 23.1% (3/13), with Grade ≥3 events in 7.7% (1/13).
Other laboratory abnormalities included weight loss (23.1%), aspartate aminotransferase elevation (23.1%), alanine aminotransferase elevation (15.4%), and blood bilirubin elevation (7.7%).
Summary
These data demonstrate that XTR022 has a manageable safety profile and exhibits encouraging preliminary antitumor activity in heavily pretreated mCRPC patients. The findings support the potential of this PSMA-targeted novel alpha-particle radioligand therapy and warrant further clinical development.
About XTR022 ([²²⁵Ac]Ac-XT381)
XTR022 is a novel alpha-particle radioligand therapy independently developed by Sinotau. Registered as a Class 1 innovative drug, it features an entirely new molecular design with excellent PSMA-targeting capability, tumor uptake and retention properties. Compared with beta-emitting radioligand therapies such as ¹⁷⁷Lu-PSMA, XTR022 employs the alpha emitter ²²⁵Ac, which delivers higher radiation energy over a shorter range. This enables more precise tumor cell killing while minimizing damage to surrounding healthy tissue, offering a differentiated and potentially superior therapeutic profile.
Contacts
Investor Relations: ir@sinotau.com
Business Development: bd@sinotau.com
About Sinotau
Sinotau, founded in 2005, is a front-runner and leader in the Chinese radiopharmaceutical market, possessing end-to-end capabilities across the entire industry value chain, from radionuclide development and production to radiopharmaceutical R&D, manufacturing, and commercialization. Adhering to its mission of “Invent radiopharmaceuticals for lives”, Sinotau is rooted in China with a global vision. The company is headquartered in Beijing, with an R&D center in Shanghai, and modern radiopharmaceutical production bases in Jiangsu, Guangdong, and Sichuan; it also has a branch in the United States. Driven by unmet clinical needs, Sinotau focuses on three major therapeutic areas: neurodegenerative diseases, cardiovascular diseases, and oncology, having established a comprehensive, differentiated, and synergistic product portfolio with significant potential in radiopharmaceutical theranostics. Among its products, Florbetaben [18F] Injection is the first innovative PET tracer approved for marketing in China in nearly 20 years; its diverse pipeline, at various stages, broadly covers global innovative targets in radiopharmaceuticals, demonstrating the strong competitiveness of our pipeline and leading the new speed of innovative radiopharmaceutical development.
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