New Cancer Therapy Reprograms Immune System Using Smart Nanoparticles

Researchers at the University of Adelaide have developed intelligent lipid nanoparticles designed to reprogram tumor-associated macrophages and stimulate T-cell activity against cancer cells, according to a study published in Science Advances.

One of the most persistent difficulties in cancer treatment involves the tumor microenvironment. While the human immune system possesses the capacity to attack tumors, the local environment often creates conditions that paradoxically favor cancer growth and shield malignant cells from the body’s natural defenses.

Targeting Tumor-Associated Macrophages

The new study focuses specifically on macrophages associated with tumors, which frequently adopt an immunosuppressive behavior. These altered immune cells help construct an environment that prevents T-lymphocytes—the primary weapons of the immune system against abnormal cells—from reaching and penetrating the tumor mass.

One of the major challenges in cancer immunotherapy is that, while the immune system can attack a tumor, the tumor microenvironment can prevent these immune cells from performing their function, Chunxia Zhao, a professor at the Faculty of Chemical Engineering and lead researcher on the project, said in a statement released by the University of Adelaide.

Our approach is designed to modify that microenvironment from inside the tumor, Zhao added. By specifically targeting the macrophages associated with the tumor, we can manage the treatment where it is needed and stimulate the T cells of the immune system, in charge of fighting cancer, to penetrate the tumor and activate.

Mechanisms of the Nanoparticle Therapy

The treatment strategy relies on lipid nanoparticles, which are microscopic structures capable of transporting specific molecules directly into cells. Each nanoparticle carries a dual payload consisting of a molecule called resiquimod, which stimulates immune system pathways, and messenger RNA that provides instructions for producing CXCL9.

CXCL9 functions as a chemical recruitment signal designed to attract cytotoxic or CD8+ T-lymphocytes into the tumor environment. To ensure precision, researchers coated the exterior of the nanoparticles with antibodies targeting TREM2, a protein found predominantly on immunosuppressive macrophages associated with tumors rather than on the cancer cells themselves.

Laboratory experiments demonstrated that this antibody coating improved the delivery of messenger RNA to the targeted macrophages while reducing unintended accumulation in tumor cells. Once inside the macrophages, the resiquimod component actively reprogrammed the cells to suppress their immunosuppressive behavior.

Laboratory and Animal Model Results

In vitro tests showed that nanoparticles directed at TREM2 generated the highest levels of CXCL9 production. Furthermore, the targeted treatment reduced the expression of ARG1—a marker associated with immunosuppressive activity—by 2.5 times, while increasing the expression of NOS2, which relates to an inflammatory profile, by 89.5 times.

Following the laboratory phase, the research team administered the treatment to mice carrying 4T1 breast cancer tumors. After three doses, the subjects showed a measurable reduction in tumor growth alongside a substantial increase in CXCL9 concentrations within the tumor tissue.

According to the findings, treated mice exhibited a CXCL9 concentration approximately four times higher than that of the control group. The intervention simultaneously decreased the proportion of immunosuppressive macrophages within the tumors by 63.2 percent while successfully elevating the presence and activity of cytotoxic T-lymphocytes.