Appealing a CRISPR Gene Therapy Denial
Appealing a CRISPR Gene Therapy Denial
Your Insurer Called Casgevy "Experimental." Here Is Why That Denial Is Worth Fighting.
6 minute read
Casgevy became the first CRISPR-based gene therapy approved by the FDA when it received authorization in December 2023 for sickle cell disease and transfusion-dependent beta-thalassemia.¹ It is not a clinical trial. It is not an experimental treatment. It is an FDA-approved therapy for two specific, serious conditions. And yet patients and their families are receiving denial letters from insurers that describe Casgevy as "experimental," "investigational," or "not medically necessary." If you have received one of those letters, it is worth understanding why that language is being used, why it may be legally wrong, and what you can do about it.
Why "Experimental" Is the Go-To Denial for Gene Therapy
Insurance denial language is not arbitrary. When an insurer categorizes a treatment as experimental or investigational, it is applying a definition from its coverage contract, not a medical judgment. Most insurance contracts define experimental or investigational treatments as those that: have not received regulatory approval for the condition being treated, lack sufficient published evidence of effectiveness, are being evaluated under an active clinical trial, or are not generally accepted as standard care by the relevant medical community.
For Casgevy, FDA approval exists for sickle cell disease and transfusion-dependent beta-thalassemia. The published clinical evidence supporting the approval is substantial, and it is the same evidence the FDA reviewed in granting approval.¹ The American Society of Hematology has published guidance on gene therapy for sickle cell disease that reflects the evolving but real clinical consensus around these treatments.
The problem is that many insurers have not yet updated their internal coverage policies to reflect FDA approval. Their medical policy departments may be working from templates or criteria that lag behind the regulatory record. In some cases, insurer policies require additional evidence beyond FDA approval, such as long-term outcomes data or a threshold number of peer-reviewed publications, before a treatment is removed from the experimental category.
This means your denial may be based on a coverage policy that has not caught up to the current regulatory and clinical reality. That gap is appealable.
The Documentation You Need for a Successful Appeal
Appealing a denial on experimental grounds requires building a case that directly contradicts the insurer's characterization of the treatment. Here is what that case needs to include.
The FDA approval record. FDA approval letters and product labeling are public documents available on the FDA website. The approval letter for Casgevy and the prescribing information both specifically name the conditions for which the treatment is approved.¹ Your appeal should cite the FDA approval directly and explicitly connect your diagnosis to the approved indication.
Your physician's letter of medical necessity. This is arguably the most important single document in your appeal. Your physician needs to write a letter that: confirms your diagnosis (using the same diagnostic language as the FDA indication), summarizes your disease history and severity, explains why gene therapy is medically appropriate for your specific situation, and directly addresses the insurer's "experimental" characterization by citing the FDA approval and relevant clinical evidence.
Published clinical evidence. The clinical trials that led to Casgevy's approval have been published in peer-reviewed journals. Your physician or a patient advocate can identify the key publications and include citations in the appeal. Published evidence demonstrating safety and efficacy directly contradicts an "experimental" denial.
Specialty society support. If the relevant specialty society (American Society of Hematology for sickle cell disease) has issued a position statement, guideline, or clinical practice recommendation that includes gene therapy as a treatment option, cite it. Specialty society positions are specifically referenced in most insurance contract definitions of "generally accepted medical practice."
The insurer's own coverage policy. Request your insurer's written coverage policy for gene therapy or for Casgevy specifically. Compare the stated criteria to your documentation. If the policy's definition of "experimental" does not apply to an FDA-approved treatment, make that argument explicitly.
The Legal Framework for Your Appeal
Your appeal rights depend on what type of insurance you have.
For commercial insurance governed by ERISA (most employer-sponsored plans), you have the right to a full and fair review of any adverse benefit determination. The plan is required to provide you with the specific reasons for the denial, the specific plan provisions on which the denial was based, and information about the internal appeals process.² After exhausting internal appeals, you typically have the right to external independent review.
For state-regulated insurance (individual market and fully insured employer plans), most states have laws requiring that insurers cover treatments that have received FDA approval for the patient's diagnosed condition, and that denials on "experimental" grounds be subject to independent external review when the treatment has regulatory approval.
For Medicare, the appeals process includes a redetermination request, a reconsideration by a Qualified Independent Contractor, a hearing before an Administrative Law Judge, a review by the Medicare Appeals Council, and federal district court review.³
At any level of appeal, an independent external reviewer who is not employed by or financially connected to your insurer will review your case. External reviewers overturn insurer denials at significant rates in many states, particularly in cases involving treatments with regulatory approval that have been denied as experimental.
What This Means for You
If you received a denial for Casgevy or another FDA-approved gene therapy on "experimental" grounds, do not accept it as final.
Read the denial letter carefully and note the specific reason cited. "Experimental" or "investigational" denial language triggers specific appeal rights.
Contact your treating physician immediately. Ask them to begin preparing a letter of medical necessity that addresses the FDA approval record and directly counters the experimental characterization.
Request your insurer's written coverage policy for gene therapy. Compare it to the FDA approval record. If there is a gap, document it in your appeal.
File your appeal within the deadline specified in your denial letter. Missing the deadline can forfeit your appeal rights. If you need more time, contact your insurer in writing to request an extension.
Ellen can help you understand your denial and build your appeal. Start here
Frequently Asked Questions
Can an insurer deny an FDA-approved treatment as experimental?
Yes, insurers can deny FDA-approved treatments as experimental if their coverage policy requires criteria beyond FDA approval alone. However, this type of denial is often successfully appealed, particularly when the treating physician provides documentation connecting the patient's diagnosis to the approved indication and citing published clinical evidence. At the external review level, these denials are overturned at meaningful rates.
What is the appeals deadline and can I miss it?
The deadline for filing an internal appeal is typically 180 days from the date of the denial, but your denial letter will specify the applicable deadline. For urgent or life-threatening situations, you can request an expedited appeal, and some external review processes have shorter timelines. Missing the internal appeal deadline may forfeit your right to external review, so treat it as a hard deadline.
What if my insurer's medical policy was written before FDA approval?
This is a common scenario with recently approved gene therapies. Medical policies are updated periodically, and policies written before a new FDA approval may not reflect current regulatory status. You can point this out explicitly in your appeal, citing the specific FDA approval date and contrasting it with any date or version reference in the insurer's policy. This is strong grounds for overturning an experimental denial.
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