ACP3

Bringing forward a potential best-in-class
pipeline of radiopharmaceuticals

RYZ701 and 711 Targeting ACP3 for Metastatic Prostate Cancer

Prostate cancer is the second most common cancer in men and the fifth most common cause of death in men worldwide. It is estimated that 1.4 M men worldwide were diagnosed with prostate cancer in 2020, including nearly 300,000 in the U.S. Prostate cancer diagnoses are projected to increase to 2.9 M by 2040[1,2].

Radiopharmaceuticals (RPTs) have shown compelling clinical benefit across lines of therapy in prostate cancer. They are continuing to be developed at a rapid pace to leverage the radiation responsiveness in this population1.

ACP3, or acid phosphatase 3 was one of the earliest biomarkers for prostate cancer3and is a marker differentiated from prostate-specific membrane antigen (PSMA). It is highly expressed in >95% of prostate cancers including tumors which do not expressPSMA and compared to PSMA, it is minimally expressed in healthy tissues such as salivary glands and kidneys[4,5,6].

OncoACP3 is potentially first-in-class radiopharmaceutical being developed for the treatment and diagnosis of metastatic prostate cancer. OncoACP3 offers a unique and potentially differentiated product particularly for patients who are either non-responsive or have progressed on PSMA targeted RPT agents. About 15% of RPT-naïve patients are PSMA negative and are not candidates for currently available RPTs, with chemotherapy often being the only option7. This asset may provide an opportunity for RPT treatment in such patients.

Imaging studies in prostate cancer patients with 68Ga-labeled OncoACP3 demonstrated high tumor uptake in lesions with high and low PSMA expression, with minimal to no normal tissue uptake—especially in salivary glands – highlighting potential for safely targeting ACP3 in Prostate cancer patients including PSMA-negative/low patients8.

Previously known as the OncoACP3 therapeutic and diagnostic, RYZ701 and RYZ711 are currently being developed as a therapeutic and diagnostic agent, respectively, for potential use in patients with metastatic prostate cancer.

  1. Sartor, O., & de Bono, J.S. Metastatic Prostate Cancer: Radioligand Therapy and Future Approaches. Nat Rev Clin Oncol. 2024; 21(4): 221-235. 
  2. Epenetos, A.A. et al. Human acid phosphatase: biochemistry and clinical perspectives. Biochemical Journal. 1977; 167(2):347-354. 
  3. Gutman, E.B., Gutman, A.B., and Blumenthal, H.T. An acid phosphatase occurring in the serum of patients with metastasizing carcinoma of the prostate gland. J Pharmacol Exp Ther. 1936; 58: 135-141. 
  4. Macdonald, J. et al. ACP3 Expression in Prostate Tissue and Carcinoma. J Urol. 2022; 208(1):15-23. 
  5. Am J Clin Exp Urol 2024;12(5):255-265, www.ajceu.us /ISSN:2330-1910/AJCEU0160028; https://doi.org/10.62347/DZIU5992. Original Article: Transmembrane prostatic acid phosphatase: a therapeutic target in advanced prostate cancer.
  6. Hofman, M.S. et al. ^177Lu-PSMA-617 Radioligand Therapy in Patients with Advanced Prostate Cancer. Lancet. 2021; 397(10276): 797-804. 
  7. Backhaus, P. A new theranostic target in prostate cancer: First results from prostatic acid phosphatase (ACP3) imaging with [68Ga]Ga-OncoACP3-DOTA PET in prostate cancer patients and comparison to [18F]F-PSMA-1007, Presented at SNMMI, 2025 
  8. RayzeBio, Preclinical ACP3 Data, 2024.