gene therapy for hemophilia may soon become a reality — but when?
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hemophilia is a bleeding disorder where the blood cannot properly clot. getty
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cutting edge treatments are on the horizon for patients with hemophilia and other blood disorders — but advocates worry that history will repeat itself with supported access to the medications taking precious years.
hemophilia is part of a family of about 25 different bleeding disorders where the ingredients in the blood that help it clot don’t work properly or are missing all together, according to the canadian hemophilia society (cha). the lack of a clotting mechanism means that injuries, like cuts and abrasions, may bleed for longer than would be expected. the main danger to hemophilia, however, is internal bleeding that may occur. in this instance, the blood can pool in joints and organs, triggering an immune response that damages the affected area.
new gene therapies for the condition are on the horizon, with treatments for hemophilia a and hemophilia b showing promise in stage three clinical trials.
however, advocates are treating exciting news with caution, as previously cutting-edge treatments have taken some time to reach their patient base.
“we were fully two years behind the rest of the developed world.” says david page, the national director of health policy for the canadian hemophilia society, about the rollout process for mono-colonial antibody called hemlibra (emicizumab). “ … sometimes there’s economic issues involved and those have to be worked out, we get that, but it’s very frustrating to have an approved product which really provides benefits to patients and it takes so long.”
hemlibra was approved for use by health canada to treat hemophilia a in august of 2018, with the canadian agency for drugs and technologies in health (cadth) noting this medication would create a cost savings for the medical system as well as providing better treatment. however, the medication was only made available to a specific subset of patients by june 2019, being expanded to adults with severe hemophilia a (outside of quebec) by october 2021, according to the cha. (in quebec, access was expanded by march 2022.)
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by contrast, in the european union, the drug was approved for use for a subset of hemophilia patients in 2018 and expanded to those with severe hemophilia a in 2019.
in canada, medications must go through several stages before they are funded by the provincial health bodies — and many medications are approved but are not funded at all, as is the case with many cancer drugs in ontario. page explains that while regulations are understandable and necessary to protect the health of patient populations, it can be a heartbreaking experience to see a medication successfully being prescribed elsewhere while canadians can’t get access.
the canadian blood services, which played a critical part in the roll out of hemlibra, wrote to healthing in a statement that the review process to approve and make the medication for a wider population took 11 months, from december 2020 to october 2021.
“the process for a medication to be considered for inclusion on canadian blood services’ national formulary is initiated by the pharmaceutical company,” reads the statement. “in june 2020, the manufacturer of hemlibra® formally requested approval for a wider range of patients with hemophilia, which prompted the necessary comprehensive review of the medication’s efficacy, potential risks and long-term value for patients and health-care systems. prior to this, preliminary approval was granted for patients with hemophilia who had developed inhibitors to other medications.”
finding a better treatment for hemophilia and rare bleeding disorders
determining the treatment of a complex disorder is a tall order, but understanding the treatment needs in a rare blood disorder like hemophilia makes it that much more difficult. (hemophilia a affects approximately 1 in 10,000 canadians, with hemophilia b affecting 1 in 50,000.)
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whenever there is an injury, proteins and other factors respond in a complex sequence to cause the blood to clot around the injury. because this sequence has many steps and patterns that must be completed to be effective, there are many areas where there could be a breakdown — resulting in a one of the many blood disorders. modern medications look to target the specific break down in each disorder, bridging the gap to ensure the sequence continues as needed, explains ludovic helfgott executive vice president and head of rare disease for novo nordisk. clotting factors can be introduced to replace what is missing, while new agents bypass the gap altogether to ensure the entire clotting pathway as a whole can exist.
“ever since the 1950s, the treatment has been to replace those missing factors firstly with fresh frozen plasma, which was not terribly effective, but was at least this treatment,” says page. “then it became cryoprecipitate, which has a slightly more concentrated form of plasma. and then they separated the factors out of plasma and made clotting factor concentrates.”
medications for blood disorders must strike a fine line — too effective and the clotting factors could actually cause thrombosis or restrict flow through the blood vessels, too weak and the blood won’t coagulate properly whenever there is an injury.
a rare disorder makes it even more difficult to find a treatment, as smaller patient populations can mean fewer resources for clinical trials. helfgott explains that to approach hemophilia treatments, you must look at the many different blood disorders and these clotting pathways as a whole.
“if you take a step back, and if you look not just at the two core diseases, but you look at the adjacent diseases around the core disease, you actually multiply your potential patient population by 10,” says helfgott. ” … and if you then start to look at the biology, you can even increase that number because some common biological patterns and pathways are actually [similar] to other diseases.”
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update 2020-06-23: a statement from the canadian blood services regarding the roll out of hemlibra was added.
emma jones is a multimedia editor with healthing. you can reach her at emjones@postmedia.com or on instagram and twitter @jonesyjourn.
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