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The complexities associated with the disease and lack of validated risk predictors makes such a model challenging to implement.
Although the therapeutic options for sickle cell anemia have expanded over the past years, the clinical complications of the condition as well as the limitations of these pharmacotherapies have called for an urgent need to implement a personalized treatment strategy for patients that is based on risk stratification.
In a recent article, Emily Meier, MD, of the Indiana Hemophilia and Thrombosis Center, elucidated on the key considerations in the prescribing of such therapies as well as the current barriers that preclude healthcare providers from achieving an optimal treatment strategy for these patients.
“With increasing therapeutic options, the ideal scenario for children with SCA would be one similar to childhood acute lymphoblastic leukemia (ALL) risk stratification: treatment intensity varies with risk level,” Meier wrote.
Thus, children who are at low risk for sickle cell anemia complications would receive less intense therapies, which includes a continuation of hydroxyurea. On the other hand, those with the highest risk would be recommended to immediately receive one or more curative therapies, such as hematopoietic stem cell transplant, gene therapy, transfusion therapy, voxelotor, and/or crizanlizumab.
Of course, as Meier noted, there are certain limitations that must be considered before implementing such a strategy.
For one, crizanlizumab and voxelotor are approved for ages ≥16 and 12 years, respectively. According to the risk based therapy model, high-risk patients should only use both therapies once age appropriate.
Similarly, patients with medium risk of complications should only use L-glutamine once they reach the appropriate age of ≥5 years.
Additionally, there is no validated predictor for the overall severity of the disease prior to the onset of associated complications. Currently available predictors of a severe outcome is an abnormal velocity on transcranial Doppler ultrasonography. These predictors identity children at highest risk for stroke.
Meier noted that there are no predictors for vaso-occlusive episodes or acute chest syndrome.
Furthermore, there is no unanimous agreement of what constitutes severe sickle cell anemia. However, the inclusion criteria for hematopoietic stem cell transplant is considered a promising start.
Overall, Meier suggested that hydroxyurea should be the standard of care in pediatric and adult patients, regardless of disease severity.
In adults with sickle cell anemia, a risk-based strategy should still be utilized, but the end organ injury makes such an approach more challenging to implement.
She suggested that the additional FDA-approved treatments should be based on clinical and laboratory complications that are still present even after hydroxyurea dosing has been maximized.
According to the seminal trials in support of these agents, L-glutamine and crizanlizumab should be considered as additional therapy in patients who continue to experience vaso-occlusive episodes. Meier also encouraged the addition of voxelotor to hydroxyurea for those adults who continue to have significant anemia.
“Hopefully, as the number of SCA modifying and curative therapies increase, more innovative treatment strategies will be tested and lead to improved quality of life and increased life expectancy for individuals with SCA,” she concluded.
The opinion piece, “What are the key considerations when prescribing pharmacotherapy for sickle cell anemia?” was published online at Taylor & Francis Online.