Targeted light-based therapy promising in prostate-cancer treatment

By Megan Brooks

NEW YORK (Reuters Health) - 26/8/2019

Photothermal ablation of localized prostate tumors using gold-silica nanoshells is a promising targeted therapy with what appears to be a low risk of serious side effects, a pilot study suggests.

"What's unique about our study is we are using gold nanoparticles to directly target abnormalities within the prostate," lead investigator Dr. Art Rastinehad, director of Focal Therapy and Interventional Urologic Oncology at Icahn School of Medicine at Mount Sinai, in New York City, explains in a Mount Sinai video posted on YouTube (https://youtu.be/O0y7_I76GGs?).

"We use laser light to excite these nanoparticles to cause a focused ablation (of the cancer) while sparing the rest of the prostate. This could cause a large paradigm shift in how we approach prostate cancer," he said.

Dr. Rastinehad is a consultant for Nanospectra Biosciences, which sponsored the research.

In the study, 15 men with low- or intermediate-risk localized prostate cancer received an intravenous infusion of gold-silica nanoshells, which accumulate preferentially in tumor tissue via leaky tumor vasculature and absorb near-infrared light. One day later, guided by magnetic resonance-ultrasound (MR/US) fusion imaging, a laser catheter with an optical fiber delivered near-infrared light through thin tubes inserted into the prostate, heating the nanoshells.

None of the patients developed serious adverse events (grade 3 or higher) during the procedure or the ensuing three months. And none had any significant change after treatment in the International Prostate Symptom Score, Sexual Health Inventory for Men or quality of life.

All patients had evidence of coagulative necrosis on repeat biopsy. The ablation zones were negative for tumor in 62.5% of lesions at three months and 87.5% of lesions at 12 months.

The results of this pilot study in 15 men demonstrate that gold-silica nanoshell-localized photothermal ablation is safe and technically feasible for the destruction of localized prostate tumors and the efficacy results are promising, the investigators conclude in a report released August 26 that's scheduled for publication in Proceedings of the National Academy of Sciences (PNAS).

They note, however, that the trial was not powered for all end points, such as efficacy, so any interpretation of efficacy remains premature. The complete results of the multicenter clinical trial involving 45 patients with 12 months of follow-up are needed to establish its efficacy, the investigators say.

"The final results with one year data for the first 45 patients in the trial should be available within one year," Dr. Rastinehad told Reuters Health by email. "We are already moving on to the next 55 patient. The company has completed the regulatory paperwork to extend the current trial with a goal of 100 patients with one year outcomes. We expect that data to mature within the next two to three years."

Two investigators on the trial founded Nanospectra Biosciences and maintain a small equity stake in it.

SOURCE: http://bit.ly/2NziOqe

Proc Natl Acad Sci USA 2019.

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