Cell and gene therapy: How innovation is changing rare disease treatment

Cell and gene therapies (CGTs) are reshaping what it means to treat disease. Instead of managing symptoms over a lifetime, these approaches aim to address disease at its source, by correcting, replacing, silencing, or supplementing faulty biological instructions, or by using living cells as therapeutic tools. For rare diseases, many of which are driven by genetic mutations and have few effective treatment options, this shift is especially significant. In this article, we explain how cell and gene therapies work, where they are already changing patient outcomes, and why their development matters for patients, sponsors, and healthcare systems.

Key Takeaways

• Gene vs. Cell Therapy: Gene therapy modifies DNA to fix mutations, while cell therapy transfers whole cells to treat or prevent conditions.
• Rare Disease Impact: Since 80% of rare diseases are genetic, these therapies offer potential cures where traditional medicine fails.
• Long-term Solutions: Many of these treatments are one-off administrations, potentially eliminating the need for lifelong medical intervention.
• Economic Value: Despite high initial costs, these therapies can reduce lifetime care expenses by millions of dollars per patient.
• Societal Benefits: Successful treatment improves quality of life, increases workforce productivity, and reduces strain on healthcare systems.

What is gene therapy?

Gene therapy can involve any of the following: 

• Gene replacement: Where an unhealthy copy of a gene is removed and replaced with a healthy one
• Gene addition: In cases where a condition is caused by a missing gene, a healthy, functioning copy is introduced
• Gene inactivation: Where a gene is not functioning correctly and causing a condition, a therapy can be introduced to “turn off” the disease-causing gene.
• Gene editing: Where targeted tools are used to disrupt harmful genes or repair mutated genes directly within the genome, offering a precise alternative to traditional gene therapy approaches

These modifications are delivered into the body using different approaches. In in vivo gene therapy, the genetic material is introduced directly into the patient, often using viral vectors, which are viruses engineered to carry therapeutic genes without causing disease. In ex vivo gene therapy, cells are removed from the patient, genetically modified outside the body, and then returned. Other delivery vehicles include plasmid DNA and bacterial vectors, each suited to different therapeutic goals.

What is cell therapy?

Cell and gene therapy are similar but, rather than altering genetic material, cell therapy focuses on transferring whole cells into a person’s body to treat or prevent a condition. There are two types of cells used in this type of therapy: 

• Autologous cells: Harvested, processed, and reintroduced into the same patient, which lowers the risk of immune rejection, as seen in treatments such as stem cell transplants for blood disorders. 
• Allogeneic cells: Sourced from a donor and are often available more quickly, though they carry a higher risk of immune rejection and complications like graft-versus-host disease (GVHD).

The transferred cells may serve different purposes: they can replace damaged or dysfunctional cells, boost the immune system, or promote tissue regeneration. 

Some treatments involve both cell and gene therapies, too. For example, CAR-T cell therapy involves genetically modified cells being transferred into the patient.

Why CGTs matters for rare disease

CGTs hold significant promise in the rare disease space, as approximately 80% of these conditions have a genetic component, many of which are monogenic, meaning they are caused by a single genetic change. This means that these types of therapy are highly applicable to rare diseases and have the potential to provide a viable treatment or cure where other more traditional approaches have failed. Approved gene therapies already exist for inherited blood disorders, neuromuscular conditions, and genetic eye diseases, with more in development across a growing number of indications.

CGTs can offer a long-term solution for conditions, and some can be administered as a one-off treatment. For patients, this can mean an end to lifelong treatment regimens. It also has the potential to significantly increase longevity, slow disease progression, and improve quality of life.

Cost versus benefit of CGTs

From an innovation perspective, while CGTs have high upfront costs, they also have the potential to reduce lifetime care expenses and alleviate the burden on strained healthcare systems. For example, the Institute for Clinical and Economic Review (ICER) estimates that lifetime treatment costs for spinal muscular atrophy (SMA) patients range from $15 million to $100 million, which is three times the cost for those treated with onasemnogene abeparvovec (Zolgensma), a gene therapy that delivers a functional copy of the SMN1 gene.

Beyond reducing the lifetime cost of individual care, gene and cell therapies can lower the overall disease burden. By effectively treating or curing debilitating conditions, these therapies enable individuals to participate more fully in work and community life. They reduce strain on healthcare systems through fewer hospitalizations and lower long-term care needs. For families managing rare or chronic conditions, the impact extends beyond clinical outcomes to include reduced emotional and financial burden. Collectively, these effects have the potential to drive meaningful economic and social progress.

To ensure the successful development and adoption of these treatments, it is critical to increase patient understanding of how these therapies work, their risks and benefits, and the costs behind their development. Gene therapy products are classified as biological products and are subject to rigorous regulatory oversight, including investigational new drug applications and biologics license approvals before reaching patients. Greater transparency around both the science and the regulatory process will foster informed acceptance and support for these therapies.

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