Experimental Treatment Directly Kills Prostate Tumor Cells While Reawakening Antitumor Immunity | Newsroom | Weill Cornell Medicine

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Experimental Treatment Directly Kills Prostate Tumor Cells While Reawakening Antitumor Immunity

June 15, 2026

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Multiplex immunofluorescence image of a prostate tumor 10 days after treatment with prostate-targeted C' dots and immunotherapy showing extensive infiltration of immune cells throughout the tumor. Different colors represent distinct immune cell populations, including anti-tumor T cells, helper T cells, regulatory T cells, and macrophages. The image illustrates the coordinated immune response triggered within the tumor following treatment. Credit: Bradbury Lab.

Prostate-targeted, engineered nanoparticles made of amorphous silica are effective in killing prostate tumors directly while enhancing anti-tumor immunity, according to a preclinical study led by investigators at Weill Cornell Medicine and the Cornell College of Engineering. The particles, derived from silicon dioxide, a common component of healthy foods or fossilized sedimentary structures from single-celled organisms, induced several complete remissions of aggressive tumors in mouse models, supporting the further investigation of their use in clinical trials.<br>Originally developed for medical imaging applications, these particles, known as ultrasmall fluorescent core-shell silica nanoparticles, or Cornell Prime dots (C' dots), have progressed into advanced-phase clinical trials for image-guided surgery and therapeutic applications. In recent years, the researchers have found that the C’ dots on their own can exert therapeutic effects against cancerous cells, while sparing healthy cells. In the new study, published June 15 in Cancer Research, a journal of the American Association for Cancer Research, the researchers evaluated the particles’ effects on mouse models of aggressive prostate cancer. They showed that the particles make the tumor cells highly susceptible to a powerful self-destruct process, and simultaneously convert the normally inactive, “cold” prostate tumor immune microenvironment into a “hot” one featuring strong antitumor immune activity—which can dramatically enhance the effects of other immunotherapies.<br>Dr. Michelle Bradbury

“We’re very encouraged by these results; a treatment that directly induces tumor-cell death while transforming the immune microenvironment, as this does, would represent a new clinical paradigm,” said study senior author Dr. Michelle Bradbury, the Endowed Professor of Imaging Research in Radiology and director of the Molecular Imaging Innovations Institute at Weill Cornell Medicine and a neuroradiologist at NewYork-Presbyterian/Weill Cornell Medical Center.<br>The study was part of a long-term collaboration between Dr. Bradbury’s laboratory and the laboratory of co-corresponding author Dr. Ulrich Wiesner, the Spencer T. Olin Professor of Engineering in the Department of Materials Science and Engineering and a professor in the Department of Design Tech in the College of Architecture, Art, and Planning. It was funded in part by the Parker Institute for Cancer Immunotherapy at Weill Cornell Medicine.<br>As detailed in the study, the unusual effects of the C’ dots include pushing prostate tumor cells toward a self-destruct mode called “ferroptosis,” in which the overwhelming oxidation of molecules in the cells, especially the fat-related molecules that make up cell membranes, leads to the degradation of those membranes. Precisely how the particles trigger ferroptosis remains unclear, but the researchers have found evidence that the particles, originally designed as carriers for imaging agents, often pick up positively charged iron ions in the bloodstream, and transport those reactive cargoes inside tumor cells—where they ultimately can help catalyze runaway oxidation.<br>The C’ dots had numerous immunological impacts, including the conversion of T cells, macrophages and other immune cells in the tumor vicinity from inert or actively immunosuppressive modes to robust antitumor activity. These results led to C’ dots sensitizing tumors to clinically approved anticancer immunotherapies. The experiments also revealed extensive growth-inhibiting metabolic disruptions in different cell populations within the tumor microenvironment.<br>The silica particles were specifically targeted to prostate tumor cells by a molecule that homes in on a prostate cell surface protein called PSMA, but even in non-prostate tissues where the particles were briefly concentrated, such as the spleen, there was no sign of toxicity.<br>Dr. Uli Wiesner

“It seems unreal—how is it possible that rather than a single pathway we see all these effects happening simultaneously and only in tumors and not in healthy tissues?” Dr. Wiesner said. “I have to wonder whether ultrasmall silica’s very early and ubiquitous presence in...