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Evidence generation: The key to opening up access to treatments for Sickle Cell patients



Sickle Cell Disease (SCD) is the UK’s fastest growing genetic condition, with almost 300 babies born with SCD each year.

However, with the MHRA’s recent withdrawal of marketing authorisation for pioneering new treatment Crizanlizumab, there remains just one treatment – hydroxyurea – that is licensed and approved by the NHS for patients.

Fundamentally, over the past 30 years there have been numerous treatment options approved in the United States for the treatment of SCD, however despite this only a few of those options have been made available in the UK for patients.

Hydroxyurea, which works by reducing the frequency of vaso-occlusive pain crises (VOCs) for those living with SCD, remains the most prevalent.

L-glutamine and Crizanlizumab are both treatments that have been approved by the FDA in the US but remain out of reach to SCD patients in the UK. L-glutamine works by slowing the damage that can happen by blockages caused by sickle cells.

Crizanlizumab works by binding to a protein in the blood cells to prevent the restriction of blood and oxygen supply that leads to a VOC.

When it was approved by the NHS in 2020, it was the first new treatment for SCD patients in the UK for over 20 years.

A lack of evidence in the Phase III study of Crizanlizumab of the drug’s clinical benefit for SCD patients was cited in the withdrawal of its marketing authorisation.

A dearth of real-world evidence is a running theme in SCD treatments.

Voxelotor, another treatment, is a haemoglobin oxygen-affinity modulator that inhibits red blood cell sickling.

It has demonstrated reduced markers of haemolysis, anaemia improvement, and is one of a small number of novel disease-modifiers approved in the US for SCD treatment.

While it has received marketing authorisation in the UK, it is still awaiting reimbursement appraisal.

Questions remain over the impacts of Voxelotor on health-related quality of life for SCD patients, and there is a pressing need for greater amounts of real-world evidence on this subject.

A recent study led by Sanius Health aimed to investigate how side effects of Voxelotor impact on quality of life, and found significant improvements across quality of life scores and other metrics including sleep quality.

More evidence-based insights are needed into pioneering treatments such as Voxelotor to ensure they make it to SCD patients in the UK.

There is good news on the horizon, however; in December 2023 the FDA approved the first gene therapy – Casgevy – that utilises CRISPR to increase the body’s production of HbF.

This radical new treatment has already reported positive results, with initial trial findings published in 2020 indicating that 29 out of 31 treated patients experienced no VOCs in 12 months.

However, UK SCD patients would be wise to accompany any optimism with a degree of caution: over the past three decades, UK patients have been consistently denied access to a range of treatments for SCD.

The severe paucity of treatments available to them warrants greater examination, given that the condition predominantly affects those of African or Caribbean heritage.

It would not be unreasonable to attribute some of the stasis over new SCD treatments to systemic racism and discrimination.

For example Cystic Fibrosis, another genetic condition with a similarly sized patient population (10,500 patients) currently has 511 approved treatments.

There is understandable frustration within the UK Sickle Cell community that for decades, they have been limited to the same tiny selection of treatment options while breakthroughs continue to be made in the US.

Only by acknowledging the systemic barriers in place that prevent SCD patients from living well and by improving evidence generation into the positive impacts of novel treatments might SCD patients in the UK start to see the range of treatments they are surely entitled to.

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