Five-month-old infants don’t usually set off global science alerts—unless, like the little girl treated here last year, their cancer disappears and researchers finally figure out why.
Doctors at Sant Joan de Déu Hospital had already thrown the kitchen sink at her malignant rhabdoid kidney tumor: surgery, chemo, radiotherapy. Nothing stuck.
Then came an experimental immunotherapy regimen, and within months scans showed nothing left to cut. Today, two years on, she remains in complete remission.
On Thursday, the team published the granular, cell-by-cell autopsy of that miracle in Annals of Oncology.
Their conclusion: a very specific set of pediatric T cells—some barely days old—learned to recognize, swarm and choke the tumor.
The discovery could fast-track tailor-made cell therapies for children who currently have almost none.
From Operating Table to Sequencer: 37,000 T Cells Tell a Story
While the child slept off her final chemo cycle, scientists at the National Centre for Genomic Analysis (CNAG) and IRB Barcelona went hunting for clues.
They collected blood and tiny tumor fragments at four separate time points over twelve months.
Using single-cell RNA sequencing, they read the genetic barcodes of 37,000 individual T cells, then cross-checked them with T-cell-receptor (TCR) mapping to see which troops had the sharpest tumor-spotting eyesight.
“It was like reading a live-action comic,” said Dr. Inés Sentís, first author and now post-doc at IRB Barcelona.
“Frame one: exhausted T cells. Frame four: elite assassins.”
A handful of TCR signatures kept popping up. When the same receptors were engineered into lab-grown T cells, they zeroed in on rhabdoid cells and only rhabdoid cells—no collateral damage to healthy kidney tissue.
Checkpoint Inhibition: The Drug That Unmasked the Villain
The child received immune-checkpoint inhibitors (ICIs) under compassionate-use rules—drugs normally reserved for adult melanoma or lung cancers.
ICIs work by ripping away tumors’ invisibility cloak, the PD-L1 protein, letting T cells see the enemy for the first time.
“Adult tumors look like Times Square—neon mutations everywhere,” explained Dr. Alexandra Avgustinova, IRB group leader.
“Pediatric tumors are darker alleys. We just installed floodlights.”
Because rhabdoid tumors carry fewer mutations, the immune system needs a bigger push.
The floodlight strategy appears to have worked: pre-ICI blood samples showed scarce tumor-specific T cells; post-ICI samples revealed a 40-fold expansion of the same clones.
Designing the Next Therapy: TCR-T Cells Built to Order
Armed with the exact receptor sequences, the team is now designing an off-the-shelf TCR-T therapy—a process where a patient’s own T cells are re-programmed with the newly identified receptors and reinfused.
Dr. Holger Heyn, CNAG’s Single-Cell Genomics head, says the leap from bench to bedside could be shorter than usual:
“With mRNA technologies we can already create these receptors in vitro. The dream is to skip the lab step and edit the child’s T cells in vivo, making the treatment scalable for more pediatric cases.”
A Rare Cancer, A Global Lesson
Only a dozen rhabdoid cases surface in Spain each year, yet the findings may resonate far beyond the rare-disease clinic. The same immune-tracking pipeline is now being applied to pediatric sarcomas and brain tumors, where options are similarly grim.
“One child’s success story is not a cure,” cautioned Dr. Sentís.
“But it is a blueprint. And blueprints can be copied.”
For the five-month-old whose tumor vanished, the blueprint is already a life. For thousands still waiting, it’s a promise written in T cells.
Journal Reference
Sentís, I. et al. Spatiotemporal T-cell tracking for personalized T-cell receptor T-cell therapy designs in childhood cancer. Annals of Oncology (2025). DOI: 10.1016/j.annonc.2025.05.530
Article source: https://www.news-medical.net/news/20250716/Research-unravels-the-immune-secrets-of-a-cured-pediatric-rhabdoid-tumor.aspx
Dr. Mary G. Trice is a renowned pedodontist based in Queens, NY. With an unwavering dedication to children’s dental health. In addition to her clinical practice, Dr. Trice is the writer and manager behind the informative platform pediatricdentistinqueensny.com. Through this site, she offers valuable insights, tips, and resources for parents and guardians, aiming to bridge the gap between professional dental care and everyday oral hygiene practices at home.