6/23/2026
Pitt-NCI preclinical study shows the combination of radiopharmaceutical and CAR T therapy converts immune-resistant solid tumors into targets for CAR T cell therapy, a potential path forward for children with relapsed neuroblastoma.
PITTSBURGH — Researchers at the University of Pittsburgh, UPMC Hillman Cancer Center and the National Cancer Institute found that pairing CAR T cell immunotherapy with a targeted radioactive drug produced greater tumor regression in preclinical models of neuroblastoma, an aggressive childhood cancer, than either treatment alone. The findings were published in Cell Reports Medicine.
Key Takeaways
- A preclinical study by researchers at the University of Pittsburgh, UPMC Hillman Cancer Center and the National Cancer Institute found that combining CAR T cell therapy with the radiopharmaceutical [67Cu]Cu-LLP2A produced greater tumor regression in neuroblastoma models than either treatment alone.
- Compared to radiopharmaceutical therapy alone, adding CAR T cell therapy increased tumor shrinkage and complete response rates by 80% in the preclinical models.
- The combination worked through two distinct mechanisms: directly damaging radiation-sensitive tumor cells to prime them for immune attack and reshaping the tumor microenvironment in radiation-resistant tumors to allow CAR T cells to penetrate.
- The findings suggest radiopharmaceutical combination therapy may offer a new path for expanding CAR T treatment to solid tumors, where CAR T has shown limited efficacy to date.
- Next steps include identifying patient biomarkers, exploring imaging-guided dosing and establishing safety and toxicity profiles before the approach can move into human studies.
CAR T cell therapy is a form of cancer immunotherapy in which a patient's own T cells are collected, genetically engineered to recognize and attack cancer cells and returned to the body. The approach has transformed outcomes in certain blood cancers but has shown limited effectiveness in solid tumors like neuroblastoma.
Neuroblastoma is one of the most common solid tumors diagnosed in children. Outcomes for those with relapsed or high-risk disease remain poor despite aggressive treatment, and effective options are extremely limited.
How a Radioactive Drug Helped CAR T Cells Reach Solid Tumors
The tumor microenvironment, the network of cells, signaling molecules and structural tissue surrounding a solid tumor, often suppresses immune activity and prevents engineered T cells from entering or functioning. This is a central barrier to CAR T therapy in solid tumors.
In the study, researchers used [67Cu]Cu-LLP2A, a radioactive drug delivered through the bloodstream that targets a receptor called VLA-4 found on both tumor and immune cells. Unlike external beam radiation, which targets a fixed location, the drug circulates and can reach tumors wherever they have spread.
"In this study, we used CAR T cell therapies that have been tested in clinical trials at the National Cancer Institute for children with recurrent neuroblastoma," said senior author Ravi Patel, M.D., Ph.D., director of radiopharmaceutical therapy in the Department of Radiation Oncology at UPMC Hillman Cancer Center. "However, current cellular therapy approaches have limited efficacy in solid tumors such as neuroblastoma. Our results may offer a way to improve the therapeutic effect of these CAR T cell therapies in solid tumor cancers."
CAR T for Solid Tumors: Two Mechanisms Depending on Tumor Type
The researchers found the combination worked differently depending on a tumor's sensitivity to radiation.
In radiation-sensitive tumors, the drug damaged cancer cells directly and triggered an inflammatory response that primed the tumor to respond to CAR T cells. In radiation-resistant tumors, a common and difficult-to-treat phenotype, the drug did not kill cancer cells directly. Instead, it remodeled the tumor microenvironment, reducing suppressive immune cells and enabling CAR T cells to infiltrate. Researchers describe this as converting a "cold" tumor into one more open to immune attack.
The combination outperformed each treatment alone, including complete tumor regression in a substantial portion of cases. Compared to radiopharmaceutical therapy alone, adding CAR T increased tumor shrinkage and complete response rates by 80%.
"That's the innovation that this paper presents," Patel said. "Radiopharmaceuticals have typically been used on their own, and combinations are still being explored. Using them with CAR T cells is a new approach."
Identifying Which Patients Benefit Most From This Combination Therapy
The research is preclinical, tested in laboratory models, not patients. Additional work is required before it can move into human studies. The team's next steps include identifying biomarkers to determine which patients are most likely to benefit, exploring how imaging could guide more precise treatment decisions and establishing safe dosing and toxicity profiles.
Because the combination works through different mechanisms depending on tumor radiation sensitivity, biomarker identification could help determine in advance which patients would benefit from each pathway, a step toward more personalized treatment.
If validated in future clinical studies, this approach could offer new options for children with hard-to-treat solid tumors where neither therapy alone has succeeded.
Frequently Asked Questions
Q: Why has CAR T cell therapy worked for blood cancers but not yet for solid tumors like neuroblastoma?
A: In blood cancers, malignant cells circulate in the bloodstream and are accessible to engineered T cells. Solid tumors form a suppressive environment around them that blocks T cells from entering and functioning, a barrier this research aimed to address using a radioactive drug to remodel that environment before CAR T cells arrive.
Q: What did researchers find when they combined radiopharmaceutical therapy with CAR T cell therapy?
A: The combination produced greater tumor regression than either treatment alone in preclinical neuroblastoma models. It worked through two mechanisms: priming radiation-sensitive tumors for immune attack and remodeling radiation-resistant tumors to allow CAR T cells to infiltrate, an approach the researchers describe as converting a "cold" tumor into one susceptible to immune attack.
Q: When could this approach move into clinical trials for children with neuroblastoma?
A: The research is preclinical and additional work is required before human studies can begin. The team's stated next steps include identifying patient biomarkers, exploring imaging-guided dosing and establishing safe dosing and toxicity profiles.
Additional Resources
- Published study: A radiopharmaceutical enhances CAR T cells against radio-sensitive and radio-resistant neuroblastoma by tumor sensitization and TME remodeling in Cell Reports Medicine
- EurekAlert! release: New approach could expand CAR T therapy from blood cancers to solid tumors, Pitt-NCI study finds
Authors and Funding
Authors: Pitt co-authors of this research are Robert S. Edinger, Ph.D., George Diehl, Ph.D., and Hannah Khan, Ph.D.; additional co-authors are from the National Cancer Institute, National Institutes of Health, Rutgers Cancer Institute of New Jersey, Rutgers Robert Wood Johnson Medical School and the University of Missouri. Additional corresponding authors of the study are Freddy E. Escorcia, M.D., Ph.D. and Rosa Nguyen, Ph.D., of the National Cancer Institute.
Funding and disclosures: This work was supported by the Center for Cancer Research (ZIA BC 012066 and ZIA BC 011800), National Institutes of Health (iCURE program and grants R01CA275766, K08CA241319, R01CA204018 and P30CA047904) and New Jersey Pediatric Hematology Oncology Research Center of Excellence.
