CRISPR's First Cure Has a Problem Nobody Saw Coming

A Therapy That Works, If You Can Get It

The cruel irony is that Casgevy's clinical results are remarkable. In the pivotal trial, 29 out of 31 evaluable patients (93.5%) went at least 12 months without a severe pain crisis. Longer follow-up data look even better: across 45 patients tracked for up to five or six years, 43 out of 45 (95.6%) achieved at least 12 months free of pain crises, and all 45 were free from inpatient hospitalization for severe pain crises for at least 12 months.

The therapy recently got an expanded FDA approval for children as young as 2, adding an estimated 5,500 more eligible patients in the U.S. alone. Quality-of-life improvements have been substantial across the board: less pain, better physical function, stronger emotional well-being.

So the drug isn't the issue. Getting patients to the drug is.

Wall Street Is Patient, But Only Barely

Vertex pulled in $116 million in Casgevy revenue for 2025, with $54 million of that coming in Q4 alone. That's a big jump from the roughly $10 million the therapy generated in its first year on the market. Analysts expect 2026 sales to land somewhere between $227 million and $344 million, representing a 2x to 3x increase.

But the quarterly pattern has been bumpy. Q3 2025 sales came in at just $17 million, a 44% drop from the prior quarter, which spooked investors. Evercore ISI's Cory Kasimov called the Casgevy launch "relatively disappointing." Raymond James analyst Christopher Raymond warned that investors might not "look past the clear revenue misses." Cantor Fitzgerald described it as a "show-me story," which is Wall Street code for: prove it.

Vertex shares dipped about 10% intraday after an earnings miss before recovering. The company's massive cystic fibrosis franchise (Trikafta brings in over $2.5 billion per quarter) acts as a financial safety net, keeping the stock from cratering even when Casgevy disappoints.

The Bigger Picture for Gene Editing

Casgevy's struggles aren't just a Vertex problem. They're a warning sign for the entire gene therapy sector.

Both approved gene therapies for sickle cell disease (Casgevy and bluebird bio's Lyfgenia) require the same brutal treatment journey: stem cell collection, months of manufacturing, high-dose chemotherapy to wipe out existing bone marrow, weeks of hospitalization, and long recovery. The total cost runs around $2 to $3 million per patient.

The treatment centers capable of delivering these therapies remain scarce. Referral pathways are fragmented. Insurance approvals are slow. And the patients who need these cures the most, predominantly Black Americans living with sickle cell disease, often face systemic healthcare barriers that make accessing specialized transplant centers even harder.

Meanwhile, the chronic disease-modifying drug market is heating up. Pyruvate kinase activators like mitapivat and etavopivat offer oral options that don't require hospitalization or chemotherapy. They won't cure anyone, but they could help a lot more people a lot sooner.

What Comes Next

Vertex insists the trajectory is upward. More than 75 treatment centers are now activated globally. Patient initiations nearly tripled from 109 in 2024 to 301 in 2025. By 2027, the company expects revenue patterns to smooth out as the patient pipeline matures.

The FDA's pediatric expansion is genuinely significant, both for the kids it could help and for the signal it sends about regulatory confidence in CRISPR technology. No editing-specific safety concerns have emerged; the major risks remain tied to the chemotherapy conditioning, not the gene edit itself (though one child did die from busulfan-related liver failure, a known transplant risk).

The field's long-term hopes rest on next-generation approaches: targeted conditioning that avoids full bone marrow destruction, in vivo gene editing that skips the cell collection problem entirely, and manufacturing improvements that speed up turnaround. Those solutions are still years away.

For now, Casgevy remains a genuine scientific triumph trapped inside an operational nightmare. The cure exists. The challenge is building a system that can actually deliver it.

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