Yttrium-90 Radioembolization to the Prostate Gland: Proof of Concept in a Canine Model and Clinical Translation

Prostatic Artery Embolization in Patients with Advanced Prostate Cancer: A Prospective Single Center Pilot Study

PURPOSE

To assess efficacy and safety of prostatic artery embolization (PAE) in patients with advanced prostate cancer (PCa).

MATERIALS AND METHODS

In this prospective single-center, single-arm, pilot study, 9 men with advanced PCa underwent PAE. PAE was performed with the use of 250-400 µm Embozene microspheres (Boston Scientific, Natick, Massachusetts, USA). International Prostate Symptoms Score (IPSS), urinary peak flow (Qmax) and post-void residual urine volume (PVR) was assessed at 12 weeks and up to 12 months. Changes in total prostate volume (TPV) and tumor responses by PSA, changes in tumor volume and evaluation of tumor regression by multiparametric magnetic resonance imaging were assessed at 12 weeks after PAE.

RESULTS

IPSS reduction in median 6 points (0-19) and a significant decrease in PVR from median 70 (20-600) mL to 10 (0-280) mL could be achieved within 12 weeks after PAE. Median TPV and tumor volumes (TV) increased slightly from 19.7 (6.4-110.8) mL to 23.4 (2.4-66.3) mL and 6.4 (4.6-18.3) mL to 8.1 (2.4-25.6) mL at a median of 12 weeks after the procedure. Significant tumor necrosis (≥ 50%) was found in one patient. Eight patients showed > 50% of viable tumor on post-PAE MRI according to MRI. Only one Clavien-Dindo Grade 1 adverse event related to PAE occurred.

CONCLUSIONS

PAE with the use of 250-400 µm microspheres is feasible, safe and effective in some patients with advanced PCa regarding functional outcomes. A cytoreductive effect might be achieved in individual patients but must be further assessed.

TRIALS REGISTRATION

NCT03457805.

Canine Prostate Cancer: Current Treatments and the Role of Interventional Oncology

Prostate carcinoma is one of the most common cancers worldwide in men, with over 3 million men currently living with prostate carcinoma. In men, routine screening and successful treatment schemes, including radiation, prostatectomy, or hormone therapy, have allowed for high survivability. Dogs are recognized as one of the only mammals to spontaneously develop prostate neoplasia and are an important translational model. Within veterinary medicine, treatment options have historically been limited in efficacy or paired with high morbidity. Recently, less invasive treatment modalities have been investigated in dogs and people and demonstrated promise. Below, current treatment options available in dogs and people are reviewed, as well as a discussion of current and future trends within interventional treatment for canine PC.

Effective therapy with Bismuth-212 labeled macroaggregated albumin in orthotopic mouse breast tumor models

Intravascularly administered radiation therapy using beta (β-)-emitting radioisotopes has relied on either intravenously injected radiolabeled peptides that target cancer or radiolabeled microspheres that are trapped in the tumor following intra-arterial delivery. More recently, targeted intravenous radiopeptide therapies have explored the use of alpha (α)-particle emitting radioisotopes, but microspheres radiolabeled with α-particle emitters have not yet been studied. Here, FDA-approved macroaggregated albumin (MAA) particles were radiolabeled with Bismuth-212 (Bi-212-MAA) and evaluated using clonogenic and survival assays in vitro and using immune-competent mouse models of breast cancer. The in vivo biodistribution of Bi-212-MAA was investigated in Balb/c and C57BL/6 mice with 4T1 and EO771 orthotopic breast tumors, respectively. The same orthotopic breast cancer models were used to evaluate the treatment efficacy of Bi-212-MAA. Our results showed that macroaggregated albumin can be stably radiolabeled with Bi-212 and that Bi-212-MAA can deliver significant radiation therapy to reduce the growth and clonogenic potential of 4T1 and EO771 cells in vitro. Additionally, Bi-212-MAA treatment upregulated γH2AX and cleaved Caspase-3 expression in 4T1 cells. Biodistribution analyses showed 87-93% of the Bi-212-MAA remained in 4T1 and EO771 tumors 2 and 4 h after injection. Following single-tumor treatments with Bi-212-MAA there was a significant reduction in the growth of both 4T1 and EO771 breast tumors over the 18-day monitoring period. Overall, these findings showed that Bi-212-MAA was stably radiolabeled and inhibited breast cancer growth. Bi-212-MAA is an exciting platform to study α-particle therapy and will be easily translatable to larger animal models and human clinical trials.

Intra-Arterial Delivery of Radiopharmaceuticals in Oncology: Current Trends and the Future of Alpha-Particle Therapeutics

A paradigm shift is underway in cancer diagnosis and therapy using radioactivity-based agents called radiopharmaceuticals. In the new strategy, diagnostic imaging measures the tumor uptake of radioactive agent “X” in a patient’s specific cancer, and if uptake metrics are realized, the patient can be selected for therapy with radioactive agent “Y”. The X and Y represent different radioisotopes that are optimized for each application. X–Y pairs are known as radiotheranostics, with the currently approved route of therapy being intravenous administration. The field is now evaluating the potential of intra-arterial dosing of radiotheranostics. In this manner, a higher initial concentration can be achieved at the cancer site, which could potentially enhance tumor-to-background targeting and lead to improved imaging and therapy. Numerous clinical trials are underway to evaluate these new therapeutic approaches that can be performed via interventional radiology. Of further interest is changing the therapeutic radioisotope that provides radiation therapy by β- emission to radioisotopes that also decay by α-particle emissions. Alpha (α)-particle emissions provide high energy transfer to the tumors and have distinct advantages. This review discusses the current landscape of intra-arterially delivered radiopharmaceuticals and the future of α-particle therapy with short-lived radioisotopes.

Oncopharmacology in Interventional Radiology

The broad scope of malignancies treated in interventional oncology is mirrored by the breadth of oncotherapeutics, drugs used to treat cancer. Many of these treatments are administered endovascularly, though a group of therapies can be delivered percutaneously. Perhaps the best taxonomy of oncotherapeutics is based on their biological inactivity or activity and the mechanism by which they interact with treated and targeted tissues. As the fields of interventional oncology and oncotherapeutics continue to grow and expand, this framework may provide a more organized approach in helping distinguish and select the best therapy for patients.

SIRT in 2025

Selective internal radiation therapy represents an endovascular treatment option for patients with primary liver malignancies, in different clinical stages. Potential applications of this treatment are in early-stage hepatocellular carcinoma, as a curative option, or in combination with systemic treatments in intermediate and advanced-stages. This review, based on existing literature and ongoing trials, will focus on the future of this treatment in patients with hepatocellular carcinoma, in combination with systemic treatments, or with the use of new devices and technological developments; it will also describe new potential future indications and structural and organizational perspectives.

Extrahepatic Applications of Yttrium-90 Radioembolization

While initially described and now accepted as treatment for primary and secondary malignancies in the liver, radioembolization therapy has expanded to include treatment for other disease pathologies and other organ systems. Advantages and limitations for these treatments exist and must be compared against more traditional treatments for these processes. This article provides an overview of the current applications for radioembolization outside of the liver, for both malignant and nonmalignant disease.