EJW: Science & Research News Edwin Williams
Hemophilia s a genetically inherited disease that prevents the clotting of blood because the gene responsible for clotting of blood does not produce certain factors necessary for clotting in required quantity. This gene is situated in an ‘X’ chromosome which the male children get from their mothers. So, it is also termed as a sex-linked chromosome disease. ‘Y’ chromosome in the male child comes from the father.
The US Food & Drug Administration has approved Hemgenix, the first gene therapy drug for hemophilia-B. Its price: a whopping $3.5million ($3,500,000)! It is beyond anyone’s imagination. Still, if used in the US, it will save the healthcare system millions of dollars for each person treated by eliminating the need for regular injections of Factor IX (FIX), a protein essential for blood coagulations. Present drug cost is about $700,000- $800,000 yearly, where patients receive FIX injections once or twice a week. If left untreated, they experience uncontrolled bleeding leading to death. Bleeding into joints result in permanent damage, while bleeding in the brain results in long term headaches, seizures or a decreased level of consciousness.
Developed by CSL Behring in Pennsylvania, US, this drug uses a modified virus to deliver a gene to recipient’s liver cells. This gene codes for a protein, factor IX (FIX) which is not produced in required quantity. A single dose of hemgenix will provide patients with moderate to severe hemophilia adequate protection from uncontrolled bleeding for 8 years, and potentially for even a longer time
Scientists are worried that its price would not be affordable in low and middle income countries, where most people with hemophilia-B live. Study on 54 patients using hemgenix showed a 50% reduction in the number of bleeding episodes per year, and more than 94% discontinued any prophylactic therapy within 2 years of receiving a single dose. The participants start making FIX very quickly: 7-8 months after a single dose. In the lowest of all responses, a 10% increase of FIX is shown to prevent spontaneous bleeding. But they may require top up prophylaxis in case of an injury or surgery where the FIX level is less than 50%. According to hematologist Dr. Edward Tuddenham of University College of London, if a patient has 10% to 40% increase in FIX, the problem is still manageable in hemophila-b. The team finds hope in an 8 year follow up study, that gene therapy is a stable and durable treatment: Nathwani, AC et al; Blood 132 (S1), 491 (2018). Dr. Leonard Valentino, Hematologist and CEO of National Hemophilia Foundation in New York City says, “Gene therapy should not be considered lightly. It is a potentially life-changing decision, and with any life altering decision there can be positive and negat¬¬ive effects.” Its approval is a milestone in the road to cure, and some recipients will be cured for many years. Dr. Tuddenham who helped design the viral vector in hemgenix, comments: “15% of the people with hemophilia can pretty much forget about hemophilia in day to day life”. There are different types of hemophilia: hemophilia A caused by low amount of factor VIII, B low amount of factor IX, C low amount of factor XI, being the major forms. Only 15% of hemophilic patients have hemophila-B, which occurs in 1 out of 40,000 males at birth. Hemgenix gene therapy is for this category of hemophilia. Acquired hemophilia are associated with cancer, auto immune disorders and pregnancy which are very rare. Thank you for watching. Please subscribe and share. I am,
Edwin Williams, EJW: Science & Research News.
