Armored CAR T-Cell Therapy Produces Durable Complete Response in Pediatric Solid Tumors

An investigational chimeric antigen receptor (CAR) T-cell therapy produced complete regression of chemotherapy-resistant metastatic hepatoblastoma in a 3-year-old patient, according to a case report published in The New England Journal of Medicine. The response remained ongoing 1 year after treatment and was achieved without cytokine release syndrome (CRS) or dose-limiting toxicities.^1,2

Although the finding involves a single patient in an early-phase trial, it offers encouraging evidence that appropriately engineered CAR T cells can produce durable activity against a solid tumor. CAR T-cell therapies have transformed the treatment of several hematologic malignancies, but their effectiveness in solid tumors has been limited by poor cellular persistence, an immunosuppressive tumor microenvironment, and difficulty reaching tumor cells.³

An Unmet Need in Refractory Hepatoblastoma

Hepatoblastoma is the most common pediatric liver malignancy. Treatment typically combines cisplatin-based chemotherapy with complete surgical resection or liver transplantation. Outcomes can be favorable for children with localized, resectable disease, but metastatic, recurrent, or chemotherapy-resistant hepatoblastoma remains difficult to treat.⁴

The patient described in the report initially presented with a large primary liver tumor and pulmonary metastases. Before entering the CARE trial (NCT04715191), the child received 3 lines of chemotherapy, underwent complete resection of the primary tumor, and had 2 lung metastases surgically removed. The cancer stopped responding to chemotherapy, and another pulmonary metastasis developed following surgery.^1,2

The researchers then treated the patient with autologous glypican-3–specific CAR T cells engineered to coexpress IL-15 and IL-21. Glypican-3, or GPC3, is expressed on hepatoblastoma cells and other solid tumors, making it a potential target for cellular therapy.²

Engineering CAR T Cells for Solid Tumors

The investigational product, referred to as CARE T cells, was manufactured from the patient’s own T cells. Researchers used one vector to encode a second-generation GPC3-directed CAR and another to encode IL-15, IL-21, and an inducible caspase-9 safety switch.²

The added cytokines are intended to support T-cell expansion, survival, and antitumor activity after infusion. The inducible caspase-9 component provides a mechanism for eliminating the engineered cells if severe toxicity develops. The ongoing phase 1 CARE trial is evaluating the treatment’s safety, maximum tolerated dose, manufacturing feasibility, cellular persistence, and preliminary antitumor activity in patients aged 1 to 21 years with relapsed or refractory GPC3-positive solid tumors.³

Participants receive lymphodepleting chemotherapy with cyclophosphamide and fludarabine before CAR T-cell infusion. The trial’s planned follow-up extends for 15 years, reflecting the need to evaluate delayed toxicities associated with genetically modified cellular products.³

Complete Response After 2 Outpatient Infusions

The child received 2 CARE T-cell infusions 8 weeks apart in the outpatient setting. Imaging showed a partial response following the first infusion and complete resolution of metastatic disease after the second. The complete response was maintained for at least 1 year.^1,2

No dose-limiting toxicities or CRS occurred. This safety finding is notable because CRS and immune effector cell–associated neurotoxicity syndrome are established risks of CAR T-cell therapy. However, the experience of 1 patient cannot establish the treatment’s overall safety profile or predict outcomes at other dose levels.⁵

Implications for Oncology Pharmacy Practice

If GPC3-directed CAR T-cell therapy advances through clinical development, oncology pharmacists will play an important role throughout treatment. Responsibilities could include reviewing lymphodepletion regimens, coordinating supportive care, screening for drug interactions, and monitoring for infection, cytopenias, CRS, and neurologic toxicities. Pharmacists may also contribute to patient and caregiver education about the investigational nature of treatment and the importance of long-term surveillance.

The outpatient administration reported in this case is particularly relevant to future care delivery. Moving cellular therapy beyond prolonged hospitalization could reduce treatment burden, but outpatient use requires reliable caregiver support, rapid access to emergency evaluation, and standardized toxicity-management procedures.

These findings should be interpreted cautiously. The report documents an exceptional response in one child rather than efficacy across a study population. Results from additional participants are needed to establish response rates, durability, and the frequency of serious adverse events. Even so, the case provides an important proof of concept for cytokine-armored CAR T cells in GPC3-positive pediatric solid tumors.

REFERENCES

1. Steffin D, Courtney AN, Choe M, et al. Complete regression of hepatoblastoma after interleukin-15- and interleukin-21-coexpressing CAR T-cell therapy. N Engl J Med. 2026;395(10):1029-1032. doi:10.1056/NEJMc2605958

2. CARE study reports complete regression of liver cancer in a child treated with novel immunotherapy. News release. Texas Children’s. Published September 10, 2026. Accessed September 22, 2026. https://www.texaschildrens.org/content/news-release/care-study-reports-complete-regression-liver-cancer-child-treated-with-novel

3. Interleukin-15 and -21 armored glypican-3-specific chimeric antigen receptor expressing autologous T cells for the treatment of children with solid tumors. National Cancer Institute. Accessed September 22, 2026. https://www.cancer.gov/research/participate/clinical-trials-search/v?id=NCI-2024-05480

4. PDQ Pediatric Treatment Editorial Board. Childhood Liver Cancer Treatment (PDQ®): Health Professional Version. In: PDQ Cancer Information Summaries. Bethesda (MD): National Cancer Institute (US); January 6, 2025. Accessed September 22, 2026. https://www.ncbi.nlm.nih.gov/books/NBK65790/

5. National Cancer Institute. CAR T cells: engineering immune cells to treat cancer. Updated February 26, 2025. Accessed September 22, 2026. https://www.cancer.gov/about-cancer/treatment/research/car-t-cells