As reported on ScienceDaily, a research team at the Icahn School of Medicine at Mount Sinai has unveiled a novel immunotherapy that tackles metastatic cancer by attacking the tumor’s protective immune cells rather than the cancer cells themselves. The findings, originally published January 22 in Cancer Cell, point to a promising new route for treating aggressive solid tumors that have been unresponsive to existing immunotherapies.
A Trojan Horse Approach to Tumor Defense
Most solid tumors rely on a dense, immunosuppressive microenvironment to evade treatment. Central to this defense are tumor‑associated macrophages—immune cells that, instead of fighting disease, become co‑opted to shield cancer and encourage its growth and spread.
Mount Sinai scientists created an engineered therapy designed to remove these hostile macrophages, effectively dismantling the protective barrier and enabling the immune system to engage the tumor more efficiently.
Lead author Jaime Mateus‑Tique, PhD, explains that cancer should be considered not just a mass of malignant cells but a protected structure reinforced by supportive immune cells. By targeting the “guards” rather than the tumor itself, the new therapy aims to convert a hostile microenvironment into one that favors immune activation.
Reimagining CAR T Cell Therapy
The treatment builds on CAR T cell technology, which typically programs a patient’s T cells to seek and destroy cancer cells directly. While CAR T therapy has excelled in certain blood cancers, solid tumors have remained difficult to target due to the lack of uniform cancer‑specific markers.
To overcome this challenge, the research team redirected the engineered T cells toward tumor macrophages. In addition, the modified cells were designed to release interleukin‑12 (IL‑12), a potent immune‑stimulating molecule known to boost anti‑tumor activity but difficult to deliver safely through systemic administration.
In mouse models of metastatic lung and ovarian cancer, this dual‑action strategy produced striking outcomes: substantial survival benefits and complete tumor elimination in many treated animals.
Transforming the Tumor Microenvironment
Advanced spatial genomic analyses revealed that the therapy dramatically reshaped the tumor landscape. With macrophages depleted, the tumors lost their immune‑suppressive properties and became infiltrated by activated immune cells capable of destroying cancer.
Because the therapy does not rely on identifying specific cancer antigens, the researchers believe it may be broadly applicable across a wide range of solid tumors, including those that have resisted current immunotherapies.
Senior author Brian Brown, PhD, notes that macrophages are abundant across nearly all tumor types, making them an appealing universal target. By reprogramming these cells from tumor allies into immune supporters, the therapy opens a new category of immunotherapeutic strategy.
Next Steps Toward Translation
While the results are promising, the researchers emphasize that the work remains at a preclinical stage. The team is now refining the approach in animal models, with a particular focus on regulating IL‑12 delivery to maximize therapeutic benefit and minimize potential toxicity.
If future studies continue to show strong results, the strategy could pave the way for a new class of CAR T therapies designed to remodel tumors through their surrounding support cells—not just the malignant cells themselves.
