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2027 Event Site
The first generation of cell and gene therapies proved that genetic disease can be treated at its source. The next generation focuses on making those therapies easier to deliver, safer, less expensive, and available to many more patients.
Roger Hajjar MD brought together Hanny Al-Samkari MD, Florian Eichler MD, Samarth Kulkarni PhD and Patty Musolino MD, PhD to examine what the field has learned. Kulkarni pointed to the curative potential of CRISPR-based therapy in sickle cell disease and beta thalassemia, while acknowledging the cost, hospitalization and conditioning required by current autologous approaches. Al-Samkari emphasized that the risk-benefit calculation changes dramatically by disease. Patients with severe sickle cell disease may accept risks that make far less sense in hemophilia, where highly effective alternatives already exist.
Mousolino focused on delivery, from lipid nanoparticles and engineered viral capsids to more localized approaches that could reduce dose and toxicity. Eichler added another essential variable: timing. In neurological disease, correcting a mutation may come too late once irreversible tissue injury has occurred, making newborn screening, biomarkers and earlier diagnosis increasingly important.
The discussion also looked beyond rare disease. Gene editing is beginning to move into cardiovascular disease, hypertension and autoimmune conditions, while manufacturing improvements and allogeneic approaches could make treatment much more scalable. But the panel cautioned that better technology alone will not determine success. Clinical trial infrastructure, regulatory pathways, patient selection, meaningful biomarkers and true unmet need will shape which therapies ultimately reach patients.
Session Focus
Hajjar framed the panel around continuity rather than replacement. The first generation of cell and gene therapies established that intervention at the genetic level can fundamentally change the course of specific diseases. The session examined what that first wave taught the field and what the next generation requires to reach many more patients.
What the First Approval Demonstrated
Samarth Kulkarni PhD described CRISPR Therapeutics as founded roughly a dozen years ago to turn CRISPR into medicines for serious disease, culminating in the first approved CRISPR-based therapy.
The mechanism is autologous and patient by patient: cells are taken from the patient, edited to upregulate fetal hemoglobin, and returned through a transplant procedure, for sickle cell disease and beta thalassemia.
He was willing to use a word the field uses cautiously. It is curative. Clinical trials involved roughly 100 patients, and close to 500 have now been treated or are in process.
He was equally direct about the limitations that define the next generation.
Cost of goods are very high, which drives a price point that will not serve all patients globally. He named the constraint plainly: it will be hard for patients in Africa to afford this therapy, while it can be affordable across most of the developed world.
The process requires hospitalization, conditioning and transplant. Work underway on gentler conditioning agents could reduce a three-week hospital stay to perhaps two or three days, with direct in vivo delivery to bone marrow as a further horizon.
What a Hematologist Weighs at the Bedside
Hanny Al-Samkari MD described the calculus for an individual patient, noting that biology is somewhat ahead of delivery in some cases.
For a sickle cell patient considering gene therapy, the immediate questions are whether disease is advanced enough to disqualify them from the required myeloablative conditioning, and whether they understand that conditioning’s risks including sterility and longer-term malignancy risk.
He explained why that conversation resolves differently by disease. In sickle cell disease the average patient dies in their forties of the disease itself, which changes the risk calculation. In thalassemia there are fewer treatment options, so interest progresses further.
Hemophilia is the instructive contrast. Several non-factor targeted therapeutics have changed the game there. Multiple hemophilia gene therapies exist, some withdrawn from the market by manufacturers for lack of interest, despite not requiring myeloablation or a transplant-like process.
His explanation for the divergence: hemoglobinopathy gene therapies have seen greater uptake because they appear genuinely curative and lack good alternatives, while hemophilia has excellent alternatives and its gene therapies appear not to be curative.
Getting Cargo to the Right Tissue
Patty Musolino MD, PhD laid out where delivery currently stands.
Lipid nanoparticles are versatile, and the liver is the organ with substantial human data, where dozens of patients have been cured of severe hypercholesterolemia. Moving to a different target narrows the pool of human data considerably.
Efforts are expanding the targeting capacity of these particles, and other nanoparticle types are in development with very different profiles depending on destination. Compartment matters too, since the ear and eye are far more accessible.
Her key architectural point concerns modularity. Unlike viral delivery, which produces prolonged expression, associated side effects and a piece of gene placed in the nucleus, lipid nanoparticles can be modularized. The same delivery vehicle carries an editing enzyme customized to the specific site of change, which is what allows scalability.
The approach borrows from existing pharmacology. Drugs on the shelf are molecules targeting ligands in different cell types, and those same ligands, backed by human data, can be placed on the surface of these carriers.
On the viral side she described a parallel revolution. AAV carries forty years of data and more than 7,000 patients dosed, which is how the field understands the tissue tropism and the safety and toxicity price. Most gene therapies use wild-type capsids. Engineered capsids can cut dosing by up to a hundredfold, and blood-brain barrier-penetrating capsids have already reached the clinic across multiple trials.
Her conclusion connected back to the bedside. Not all patients will accept the same risk, which makes a portfolio of options essential so patients at different disease stages and severities have genuine alternatives.
When Intervention Comes Too Late
Hajjar posed the question neurological disease makes unavoidable: correcting a mutation successfully may produce limited therapeutic effect because irreversible tissue injury has already occurred by the time of diagnosis and treatment.
Florian Eichler MD endorsed the panel’s framing of first wave informing second wave as continuous learning.
His point echoed Al-Samkari’s. The stage of the patient and the stage of the disease are critical in determining what approach will be tolerated, including what immunosuppression or myeloablation is acceptable in the context of ex vivo cell delivery.
He began his program with Bluebird Bio fifteen years ago, and the field now has two approved therapies for leukodystrophies. The opportunities those created remain bounded by precisely the timing problem Hajjar described.
Key Takeaways
1. The first approved CRISPR therapy is curative, with close to 500 patients treated or in process.
2. Cost of goods, not efficacy, determines who can access it, excluding much of the world outside developed markets.
3. Next-generation work targets the process rather than the edit: gentler conditioning, shorter stays, direct in vivo delivery.
4. Uptake tracks the quality of alternatives. Hemophilia gene therapies were withdrawn because good non-curative options exist.
5. Lipid nanoparticles are modular, separating delivery vehicle from editing enzyme, which is what enables scalability.
6. Engineered AAV capsids can cut dosing a hundredfold, and blood-brain barrier-penetrating versions are already in trials.
7. Disease stage governs everything. Irreversible injury before diagnosis limits what any successful correction can achieve.
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