Sickle cell disease does its worst damage early. Vaso-occlusive crises, the severe and unpredictable pain episodes that define the disease, can begin in infancy, and the organ damage they cause accumulates with every year a child goes untreated. Until this month, the one-time gene therapy built to address the disease at its root was only available starting at age 12. That gap, the years between diagnosis and eligibility, has just gotten smaller.

Sickle cell disease is caused by a single mutation that distorts red blood cells into a rigid, curved shape. Those misshapen cells block blood vessels, causing vaso-occlusive crises, episodes of severe pain that can require emergency hospitalization and that, over years, damage the kidneys, lungs, heart, and brain. Transfusion-dependent beta thalassemia, a related inherited blood disorder, forces patients into a lifetime of regular blood transfusions just to survive. Both conditions are present from birth. Both do cumulative damage the longer they go unaddressed.

On July 1, the FDA expanded approval of Casgevy (exagamglogene autotemcel) to include children as young as 2 with either condition. It was previously approved only for patients 12 and older. Casgevy is now the first gene therapy authorized for children this young with sickle cell disease.

Casgevy works differently from most of the cell therapies covered in this newsletter. It does not use donor cells or lab-grown replacements. It uses the patient's own hematopoietic stem cells, the cells in bone marrow responsible for producing all blood cells, extracted from the patient's own body, edited outside the body using CRISPR/Cas9, and then returned by infusion after a round of conditioning chemotherapy that clears space in the bone marrow for the edited cells to take hold. The edit increases production of fetal hemoglobin, a form of hemoglobin the body normally stops making after infancy. Fetal hemoglobin does not sickle the way adult hemoglobin does, so raising its levels reduces or eliminates the crises that define the disease. Because the cells are the patient's own, there is no ongoing immunosuppression required, unlike donor-based cell therapies.

The evidence supporting the age expansion is a Phase 3 open-label trial: 11 patients aged 5 to 11 with sickle cell disease, 8 evaluable for efficacy. In the beta thalassemia arm of the same age range, 15 patients were treated and 9 were evaluable, with 8 of those 9 achieving transfusion independence for at least 12 consecutive months. These are small numbers, appropriate to how rare severe pediatric cases are, and they build on a substantially larger base of evidence already established in patients 12 and older, for whom Casgevy has been approved since 2023.

The FDA's own language on the decision, from Dr. Megha Kaushal of the agency's Center for Biologics Evaluation and Research, ties directly to the evidence: earlier treatment reduces the risk of lasting organ damage, which is why extending eligibility to younger children matters clinically, not just as an access milestone.

What the expansion does not change: Casgevy still requires a demanding treatment process, including chemotherapy conditioning, and it remains a one-time procedure that families and clinicians will need to weigh carefully against a child's disease severity. Approval means the option now exists. It does not mean every family will choose it.

Published in Cell Stem Cell (June 16, 2026) | Mouse study | UCLA, Dr. Arjun Deb's laboratory

What they did: Researchers examined kidney biopsies from people with chronic kidney disease and found elevated levels of a protein called ENPP1 compared to healthy tissue. They then tested whether blocking ENPP1 with AD-NP1, a monoclonal antibody Deb's lab had previously developed for heart repair, would improve kidney healing in mice with induced kidney injury.

What they found: Mice treated with the antibody had less scar tissue formation and better kidney function than untreated mice after injury. The mechanism appears to be metabolic: injured tissue overproduces ENPP1, which disrupts the energy supply that surrounding cells need to proliferate and repair the damage. Blocking the protein removes that obstruction.

Evidence level: Mouse study. AD-NP1 is currently in a Phase 1 human trial, but that trial is for heart repair, not kidney disease. No human kidney data exists yet.

Key caveat: A drug working in mice, even one already cleared for human trials in a different organ, is a meaningfully earlier stage than a therapy with human kidney data. The path from this finding to a kidney treatment would require its own clinical development.

Why it matters anyway: Current treatments for chronic kidney disease slow its progression; none reverse the damage already done. A drug-based approach to actual tissue repair, if it holds up in further study, would address a gap nothing currently fills.

Casgevy uses autologous cells: the patient's own stem cells, removed, edited, and returned to the same person. Because the immune system recognizes its own cells, there's no rejection risk and no need for ongoing immunosuppression.

Many of the therapies covered in past issues, including donor islet transplants and iPSC-derived cell therapies, are allogeneic: cells that come from someone else, or are manufactured in a lab from a different cell line. Those therapies face the immune rejection problem discussed in a previous issue's lead story, and typically require immunosuppression to keep the transplanted cells from being attacked.

The tradeoff runs in the opposite direction, too. Autologous therapies like Casgevy require harvesting and editing each patient's own cells individually, which is slower and more expensive to manufacture at scale. Allogeneic therapies can, in principle, be manufactured in advance and used off the shelf. Neither approach is simply better. Each solves a different problem.

A two-year-old cannot consent to chemotherapy, cannot understand what a gene edit is, and will not remember the procedure that may spare them a lifetime of crises. Someone else has to carry that decision for them. This approval does not make that decision easier. It just means it is now a decision families get to make earlier.