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The Challenges and Prospects of Gene Therapies for Sickle Cell Disease

LOS ANGELES (Reuters) – Zoe Davis, a 20-year-old student, recently found herself back in the hospital due to debilitating pain caused by sickle cell disease, just as she began her junior year at North Carolina Agricultural and Technical State University. As the frequency of her pain attacks increases, she is left contemplating the potential relief that emerging gene therapies might offer to her and the approximately 100,000 Americans affected by this inherited disorder.

Davis acknowledges the promise of these novel treatments but is hesitant to commit to them just yet. “It is so new… I wanted to see more success stories before I committed to it,” she explained. Her situation reflects a broader hesitance prevalent among patients regarding these expensive therapies, which can cost between $2 million to $3 million in the United States. Interviews with health professionals and patients reveal that the uptake of these therapies has been slower than anticipated.

According to Dr. Leo Wang, a hematologist-oncologist from City of Hope Children’s Cancer Center in Los Angeles, many younger patients face academic pressures and are reluctant to introduce additional medical responsibilities into their lives. “Some kids are just not interested,” he notes, underscoring that while patients aged 20 to 40 exhibit interest, many have diseases so advanced that they do not qualify for treatment.

Approved in December, these one-time gene therapies have so far only been administered to about 100 individuals globally, including participants in clinical trials. The treatment process includes chemotherapy that raises concerns about cancer risk and infertility.

Globally, around 8 million people have sickle cell disease, a genetic condition especially prevalent among Black Americans due to its historical association with malaria resistance. The disease causes red blood cells to deform into a sickle shape, leading to painful blockages in blood vessels, which can result in severe complications such as organ damage and strokes.

As of September, 30 individuals worldwide had begun gene therapy outside of clinical trials, with two primary companies managing these therapies. Both involve an intricate procedure to extract a patient’s bone marrow stem cells, modify them genetically, and reinfuse them after chemotherapy treatment. While some patients are eager, many are stalled by uncertainties related to timing, insurance, and complications surrounding their current health conditions.

Further complicating matters, hematologists caution that while some younger patients maintain control over their symptoms with existing medications, older individuals may face severe complications, rendering them unsuitable for gene therapy. “You have to be sick, but not too sick,” Dr. Andrew Campbell remarked, emphasizing the careful considerations that must accompany patient eligibility evaluations.

The Market Response

Data suggests that over 80% of patients in the U.S. may not be eligible for these therapies, which are currently only approved for individuals over 12 experiencing severe pain crises. Bluebird Bio has lowered its forecast for its gene therapy products to a maximum of 85 patients this year, down from a previous estimate of 105. Conversely, Vertex Pharmaceuticals noted that 20 individuals had begun the treatment process for their gene therapy.

The commercial reception for these therapies has been tepid, with Bluebird’s stock price falling around 64% this year, while Vertex’s shares remain stable amid broader market trends. Analysts foresee potential high sales for Vertex’s Casgevy, but the market is still cautious, given that these gene therapies might not translate into immediate blockbuster sales.

Current Treatment Options

Existing treatments for sickle cell disease include blood transfusions, antibiotics, and analgesics such as opiates. Patients typically also take hydroxyurea, a medication that helps restore normal red blood cell shape. Pfizer’s recent withdrawal of its sickle cell treatment, Oxbryta, due to complications has further highlighted the precarious nature of therapies currently available.

Historically, bone marrow transplants have been the only potential cure but present challenges related to donor matching and the associated risks of chemotherapy.

Zoe Davis noted that her transition to college increased her disease stress, and despite her daily medication regimen, she frequently requires hospitalization for pain management. Similarly, Kayla Smith Owens, a 25-year-old advocate for sickle cell awareness, shared her struggles with accessing a bone marrow transplant, only to see her donor fall through. She is hopeful about gene therapy but is concerned about her insurance coverage as she approaches an age where she will no longer be covered under her mother’s health plan.

Overcoming Barriers

Navigating insurance criteria remains a significant hurdle for many patients. Jennifer Cameron, executive director for patient access at Children’s National Hospital, explained that insurers strictly enforce their eligibility conditions, often resulting in denied coverage for recommended treatments.

Both Vertex and Bluebird have established financial assistance programs aimed at alleviating costs associated with the gene therapies, particularly concerning fertility preservation—a significant concern given the risks of infertility from chemotherapy. However, these programs may not extend to patients on Medicaid, a coverage option for many sickle cell patients.

As Dominique Goodson, a 38-year-old patient expecting her first child, highlighted, the long-term view is crucial. She aims to receive gene therapy post-pregnancy but needs to secure options for preserving her fertility for future children. Working with organizations focused on the sickle cell community, Goodson strives for greater awareness and understanding of the complexities faced by individuals living with this condition.

Conclusion

The ongoing challenges in accessing and committing to gene therapies for sickle cell disease reflect a complex landscape filled with medical, financial, and emotional considerations. While the potential for revolutionary treatments exists, many patients remain on the sidelines, navigating the multifaceted implications of such life-altering decisions.

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