Boston Scientific pads case for radioactive microspheres with liver cancer survival win

Fed into a cancer patient's bloodstream, millions of microscopic, radioactive glass beads migrate to a tumor and deliver a high-but-tailored dose of radiation. That's the idea behind Boston Scientific's TheraSphere treatment, approved by the FDA earlier this month, and a new study showed the therapy can do just that.

Researchers delivered new data showing TheraSphere—which delivers an isotope of yttrium with a half-life of under three days—could be safely optimized at higher doses to better kill off tumor cells. The delivery system limits the damage to healthy tissue while shrinking inoperable liver lesions, helping patients live longer, the company said Monday.

The company's TheraSphere treatment, approved by the FDA earlier this month, includes an isotope of yttrium with a half-life of under three days. Now, researchers delivered new data showing that doses could potentially be safely optimized at higher levels to help better kill off tumor cells.

Boston Scientific added the microbeads to its portfolio in 2019 through its $4.2 billion acquisition of BTG, in a major deal that aimed to transform its oncology franchise from one centered around delivery and diagnostic tools to direct treatments. Delivered via a catheter in an outpatient procedure that typically takes up to an hour, TheraSpheres are also being studied in lung and breast cancer, as well as bone metastases.

The latest data in hepatocellular carcinoma, or HCC, were presented as a late-breaking clinical trial at the annual meeting of the Society of Interventional Radiology. Imaging software was used to calculate the dose delivered to each patient's liver, and the single-arm, retrospective study, named Target, showed a predictable correlation between the levels of radiation absorbed and increases in overall survival, reaching a median of 20.3 months. 

Meanwhile, only 4.8% of treated patients showed serious side effects, the company said, including jaundice related to abnormal or hampered liver function. This could allow future treatments to be optimized at higher doses.

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The implant’s full FDA approval this month codifies a humanitarian device exemption first granted by the agency in 1999. 

The green light was based on a separate phase 3 trial of 162 patients, which showed 100% complete or partial patient responses after up to two treatments—including at least a 30% decrease in size or the disappearance of lesions within the liver.

After three years, 93% of patients were still alive after receiving subsequent transplants or surgeries to remove the remainder of the tumors.

"We expect to continue to focus our efforts on bringing this treatment to more patients, both by planning a randomized trial to study the combination of TheraSphere and immunotherapy in patients with HCC not eligible for curative treatments, as well as further investigating the therapy for different cancer segments, including prostate and brain," said Boston Scientific’s president of interventional oncology and peripheral interventions, Peter Pattison.