An 18-year survivor of neuroblastoma, a solid tumour that primarily affects individuals in their childhood, marks a significant step forward as potentially the longest reported remission in a patient treated with CAR-T Cancer Therapy. This outcome, reported by Nature Medicine, observed in a phase 1 clinical trial follow-up, highlights the therapy’s potential, though challenges remain in extending its success to a broader range of solid tumours.
CAR-T Cancer Therapy: A Promising Immunotherapy
Nearly two decades ago, a 4-year-old girl suffering from a rare nerve cell cancer received a groundbreaking treatment: genetically modified immune cells. Remarkably, she remains cancer-free to this day, making her a potential record holder for long-term survival after receiving this treatment. This CAR-T Cancer Therapy involves extracting a patient’s T-cells, modifying them to target cancer cells, and then reintroducing them into the body.
Since 2017, the FDA has approved seven CAR-T Cancer Therapy treatments for blood cancers. Solid tumours, however, have been increasingly difficult to treat with this therapy. Approximately 90% of all cancers are solid tumours. Helen Heslop, a physician-scientist at Baylor College of Medicine, notes that solid tumors are difficult to penetrate and possess molecules that hinder the engineered cells.
Despite these challenges, Carl June, a cancer immunotherapist, finds the potential curative effects of CAR-T Cancer Therapy in neuroblastoma exciting. Heslop’s team’s clinical trial involved 19 children with neuroblastoma. Doctors infused them with CAR-T cells between 2004 and 2009. While 12 patients relapsed and died within seven years, five at high risk of relapse remained disease-free for 10 to 15 years. One patient with active cancer at the time of treatment has survived for over 18 years.
June suggests further research to understand why some patients didn’t benefit, possibly due to insufficient persistence of engineered cells or the tumour losing the targeted protein. Researchers are exploring ways to enhance CAR-T cells, like adding molecules to improve their longevity and tumour-tracking. A 2023 study showed promising results using next-generation CAR-T cells in neuroblastoma patients. Heslop hopes for sustained benefits in these patients, viewing this as a promising sign for treating neuroblastoma and other solid tumours with CAR-T Cancer Therapy. However, she acknowledges that much more research is needed.
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How CAR-T Cell Therapy Functions
In CAR-T Cancer Therapy, T-cells are isolated in a patient, genetically engineered to express CARs (chimeric antigen receptors), and then reintroduced to that patient from which the cells were derived. These CAR-T cells recognize and eliminate cancer cells by binding to specific surface proteins in the cancer.
The FDA-approved CAR-T Cancer Therapy treatments target CD19 or BMCA, markers primarily found on B-cells, thus limiting toxicity to other tissues. While successful in blood cancers, CAR-T Cancer Therapy’s efficacy against solid tumours faces limitations. These limitations include antigen selection, tolerability, and safety concerns. Therefore, improvements in design are essential to make the therapy safer and more effective.
CAR-T Cell Therapy for Neuroblastoma
Neuroblastoma, a rare solid tumour with a high rate of relapse, primarily affects young children. In the clinical trial, researchers genetically modified activated T-cells to target GD2, Aa protein frequently overproduced in neuroblastoma cells. This approach utilized both activated T-cells (ATCs) and Epstein-Barr virus (EBV)-specific T-cells (VSTs). The CAR transgene remained detectable in patients’ blood for an extended period.
The trial enrolled children with both active relapsed neuroblastoma and those at high risk of relapse. Results indicated that some patients with active disease experienced complete or partial remission, with these positive responses lasting in a few cases. Among patients who were disease-free at the time of infusion, some remained disease-free for as long as 15 years.
The 18-year remission patient didn’t require further cancer treatment and had successful pregnancies. However, she experienced hearing loss potentially related to previous chemotherapy. Low levels of the GD2 CAR transgene were detected, suggesting CAR-T cells persisted long-term in the patient’s immune system.
Long-Term Implications and Future Directions
The study offers evidence of long-term survival in children with neuroblastoma treated with GD2 CAR-T Cancer Therapy. The 18-year remission is potentially the longest reported for a solid tumour treated with this therapy. However, as the research is still ongoing, more results and findings will come forth in the future.
The trial used first-generation CAR-T cells, which did not include the co-stimulatory molecules found in newer designs. However, the long-term persistence of the transgene in survivors highlights the role of CAR-T cells in controlling the disease. The results indicate that GD2 CAR-T therapy is a safe option that may lead to long-term remission in children with relapsed neuroblastoma, without additional complications. GD2-CART01 was found to be safe and effective for high-risk neuroblastoma, though some treatment-related side effects did occur.
Ongoing efforts focus on improving CAR-T Cancer Therapy for solid tumours. Challenges remain, including limited cell trafficking (the difficulty of immune cells reaching the tumour site), tumour heterogeneity (the diversity of cancer cells within a tumour), and an immunosuppressive microenvironment (the tumour’s ability to block immune responses). Researchers are investigating factors that contribute to CAR-T cell expansion and function in solid tumour patients.Recent studies stress the importance of improving CAR design, creating bispecific CARs, using targeted delivery methods, and combining treatments to improve results. “Off-the-shelf” CAR T-cell therapies using T-cells from healthy donors show potential. These advancements offer new hope for CAR-T Cancer Therapy as a remission path for more cancers in the future.
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