• 225Ac-PSMA-Trillium (BAY 3563254) is an investigational next-generation PSMA-targeted alpha therapy with potential to treat patients with advanced metastatic prostate cancer
  • Prostate cancer is the second most commonly diagnosed cancer in men1, with less than three years median survival among metastatic patients, who have developed castration-resistance2
  • Bayer remains committed to advancing medical innovations for patients across all stages of prostate cancer

BERLIN, Germany I May 15, 2024 I Bayer announced today initiation of dosing in a Phase I first-in-human clinical study with 225Ac-PSMA-Trillium (BAY 3563254), a next-generation targeted alpha therapy. The investigational candidate, labeled with actinium-225 and comprising a novel PSMA (prostate-specific membrane antigen) -targeting small molecule with a customized albumin-binding moiety, is designed to potentially improve therapeutic efficacy and reduce side effects in normal organs such as salivary glands. The dose-escalation study (NCT06217822) will evaluate the safety, tolerability and efficacy of 225Ac-PSMA-Trillium in patients with advanced metastatic castration resistant prostate cancer (mCRPC).

“Despite recent advances in the treatment landscape for prostate cancer, there is still a high unmet need for novel precision therapy options to improve outcomes for patients with metastatic castration-resistant prostate cancer,” said Fred Saad, MD, FRCS, Professor and Chairman of Surgery at University of Montreal and Director of Genitourinary Oncology at University of Montreal Hospital Center (CHUM), Canada.“225Ac-PSMA-Trillium is a novel approach, which could provide a new treatment to address this unmet need in mCRPC.”

“Targeted radionuclide therapy is a strategic pillar of precision oncology at Bayer, holding the promise to shift the treatment paradigm for patients, including those whose disease has developed resistance to other treatments,” said Dominik Ruettinger, M.D., Ph.D., Head of Research and Early Development for Oncology at Bayer. “We are excited to announce initiation of the phase I and dosing of the first patient with 225Ac-PSMA-Trillium. With its unique design, we believe it could offer a meaningful benefit for patients with metastatic prostate cancer, and we look forward to advancing the program through clinical development.”

Prostate cancer is the second most commonly diagnosed cancer in men1 and a key area of focus at Bayer. Despite significant advances in the last decade, mCRPC remains a deadly disease with a median survival of about 31 months.2 Bayer remains committed to advancing medical innovations for patients across all stages of prostate cancer.

In April, Bayer introduced 225Ac-PSMA-Trillium during the New Drugs on the Horizon session at the AACR (American Association of Cancer Research) Annual Meeting.3 Along with preclinical in vitro and in vivo characterization, the results were presented for a Phase 0 clinical imaging and dosimetry study conducted in participants with prostate cancer.

About Targeted Alpha Therapy

Targeted alpha therapy is an emerging class of radionuclide therapy that can be used against a variety of tumors. It is designed to deliver alpha particle radiation directly to the tumor inside the body, either via its bone-seeking property (radium-223) or by combining alpha radionuclides, such as actinium-225, with specific targeting moieties. This localized delivery of the radioactive payload induces difficult to repair double-strand DNA breaks in tumor cells; damage that can cause cell cycle arrest or cell death. At the same time, because the energy does not travel very far, there is a potential for reduced damage to nearby normal tissues.4-6

About Bayer

Bayer is a global enterprise with core competencies in the life science fields of health care and nutrition. In line with its mission, “Health for all, Hunger for none,” the company’s products and services are designed to help people and the planet thrive by supporting efforts to master the major challenges presented by a growing and aging global population. Bayer is committed to driving sustainable development and generating a positive impact with its businesses. At the same time, the Group aims to increase its earning power and create value through innovation and growth. The Bayer brand stands for trust, reliability and quality throughout the world. In fiscal 2023, the Group employed around 100,000 people and had sales of 47.6 billion euros. R&D expenses before special items amounted to 5.8 billion euros. For more information, go to www.bayer.com.


  1. GLOBOCAN. World fact sheet. 2022. Available at: https://gco.iarc.who.int/media/globocan/factsheets/populations/900-world-fact-sheet.pdf. Accessed March 2024.
  2. Amit D Raval et al. Prediction model for real-world survival in men with castration-resistant prostate cancer and bone metastases in the United States: A real-world database study. JCO Oncol Pract 19, 507-507 (2023).
  3. Zitzmann-Kolbe S, et al. Presented at: American Association of Clinical Research Annual Meeting; April 5-10, 2024; San Diego, CA, USA. Abstract ND09.
  4. Parker C, et al. JAMA Oncol. 2018;4(12):1765-1772.
  5. Tafreshi NK, et al. Molecules. 2019;24(23):4314.
  6. Hagemann UB, et al. Cancer Biother Radiopharm. 2020;35(7):497-510.

Find more information at www.pharma.bayer.co