NEW YORK — Scientists from Weill Cornell Medicine and the Cornell Duffield College of Engineering published a preclinical study on June 15, 2026, in the journal Cancer Research. The study demonstrated that ultrasmall silica nanoparticles induced tumor cell death and activated immune responses in mouse models of aggressive prostate cancer.

The nanoparticles, known as Cornell Prime dots (C' dots), are composed of amorphous silica. They were equipped with a targeting molecule that recognizes PSMA, a protein found on the surface of prostate tumor cells. The nanoparticles induced ferroptosis, a form of cell death driven by oxidation, in tumor cells. Evidence suggests the nanoparticles collect positively charged iron ions from the bloodstream and transport them into tumor cells.

The study observed T cells and macrophages near the tumors shifted from inactive states to active cancer-fighting states. The researchers found no signs of toxicity in organs outside the tumors, although some particles accumulated in the spleen. Michelle Bradbury, Endowed Professor of Imaging Research in Radiology and director of the Molecular Imaging Innovations Institute at Weill Cornell Medicine, stated, "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." She added, "We think there's nothing else out there that has such a strong and durable tumor growth suppressing effect." Bradbury also said, "This study reflects years of collaborative effort across multiple laboratories and would not have been possible without the dedication, creativity and perseverance of this tremendous research team that helped drive the science forward."

Combining these nanoparticles with an immune checkpoint blockade therapy resulted in complete or nearly complete remissions in four out of ten mice. Adding CSF-1R blockade to this combination therapy further increased the number of complete remissions to five out of ten mice. Ulrich Wiesner, Spencer T. Olin Professor in the Department of Materials Science and Engineering at Cornell University, said, "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?" Jedd Wolchok, Meyer Director of the Sandra and Edward Meyer Cancer Center and professor of medicine at Weill Cornell Medicine, said, "One of the most intriguing aspects of this work is the convergence of direct tumor cell killing with broad immune remodeling." Wolchok added, "By creating conditions that support a more effective antitumor immune response, these particles may help unlock the full potential of immunotherapy in prostate cancer, where durable responses have historically been difficult to achieve."

The nanoparticles were originally developed to improve medical imaging and have advanced into late-stage clinical trials for image-guided surgery and other therapeutic uses. The Parker Institute for Cancer Immunotherapy at Weill Cornell Medicine provided partial support for this research.