Oral dapsone may help some ITP patients needing new options
Response linked to dose and changes in red blood cells
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Oral dapsone, an antibiotic sometimes used in treatment-resistant cases, was linked to increased platelet counts in 58.6% of treated children, adolescents, and adults with immune thrombocytopenia (ITP), including many who had not responded to previous standard therapies, a study reports.
Higher doses of dapsone were linked to better responses, but this effect appeared to be driven by greater reductions in hemoglobin levels — a marker of red blood cell breakdown — suggesting this may play a role in how the drug works.
Dapsone shows potential as option for previously treated ITP
“Dapsone may be a therapeutic option for children, adolescents, and adults with previously treated ITP, with response potentially predicted by a reduction in haemoglobin levels,” the researchers concluded, adding that these findings should be confirmed in larger prospective studies.
The study, “Dapsone response in immune thrombocytopenic purpura is associated with dapsone dose and mediated through reduction in haemoglobin: A longitudinal data analysis of 58 adult and paediatric ITP patients demonstrates efficacy and safety,” was published in the British Journal of Haematology.
In ITP, the immune system mistakenly attacks the body’s healthy platelets, blood cell fragments that help the blood clot, leading to ITP symptoms such as easy bruising and bleeding. The condition is classified as primary when it occurs on its own and secondary when it develops due to another underlying condition.
In some cases, ITP may persist and require treatment to keep platelet levels high enough to prevent bleeding. First-line treatments, including corticosteroids, aim to halt the immune system’s destruction of platelets. However, about 75% of adults either do not respond or experience relapses, meaning platelet levels drop again and additional treatment is needed.
Oral dapsone, an antibiotic used for certain infectious conditions, has been used as a treatment option for people with treatment-resistant or relapsed ITP. Although it has shown effectiveness in these patients, it is not included in guideline decision frameworks due to limited supporting data.
To address this gap, researchers in India analyzed data from 433 healthcare visits involving 58 people with newly diagnosed, persistent, or chronic primary ITP — meaning the disease had been present for less than 3 months, 3–12 months, or more than 12 months, respectively — who were treated with dapsone between 2006 and 2021 at two hematology centers.
Study included adults and children with different stages of ITP
Among participants, 39 were adults and 19 were children or adolescents, with an equal number of males and females. The median age was 40.9 years in adults and 6.4 years in children. Patients had been living with ITP for a median of seven months before starting dapsone and were followed for a median of 142 days (or about five months).
Before starting dapsone, all but one participant had received prior treatments, most commonly corticosteroids, and most (69.5%) had not responded to at least one earlier therapy. About one-third (31%) had received red blood cell transfusions, while five (8.6%) had received platelet transfusions.
At the start of treatment, no patients had signs of red blood cell destruction, and all recent transfusions had occurred more than three months earlier.
Participants received a mean oral dapsone dose of 1.19 mg per kilogram of body weight per day, and treatment lasted a median of 145 days. A total of 23 patients (39.7%) received one additional therapy, while 15.4% required two or more. No more than two therapies were used alongside dapsone, and concurrent treatment lasted a median of 32.5 days.
Overall, 58.6% of patients responded to treatment, meaning their platelet counts increased to safer levels. Responders included 67.6% of adults and 32.4% of children or adolescents. Response rates were similar across disease duration groups — 57.1% in newly diagnosed, 56.5% in persistent, and 61.9% in chronic ITP — with most responses (94.1%) occurring within six months. The median time to response was 40 days.
Some patients maintained response after treatment
At the last follow-up, 44.8% of patients maintained their response. Of these, 15.4% were off treatment, 65.4% remained on dapsone alone, and 19.2% were receiving dapsone with other medications.
Among the 19 patients followed for more than a year, 10 (52.6%) achieved remission, defined as sustained normal platelet levels. Six (31.6%) remained in remission at the last follow-up. During follow-up, patients remained clinically stable, with no need for blood product support among those followed long term. Two cases of mild bleeding were reported.
Further analyses showed that a drop in hemoglobin — the protein in red blood cells that carries oxygen — was strongly associated with treatment success. Patients who experienced a reduction in hemoglobin levels were more than five times more likely to respond to dapsone.
Higher doses were also linked to better responses, but this effect appeared to be mediated by hemoglobin reduction: higher doses increased the likelihood of hemoglobin drops, which in turn were strongly associated with a higher likelihood of response, the researchers noted.
Hemoglobin drop linked to higher likelihood of response
The team also found that hemoglobin reductions were accompanied by signs of increased red blood cell turnover, along with fewer bleeding episodes. This suggests the drop in hemoglobin was likely due to hemolysis (destruction of red blood cells) rather than blood loss or prior transfusions.
According to the researchers, these findings support the idea that dapsone may work by prompting hemolysis, which may redirect the immune system’s activity away from destroying platelets.
Dapsone was generally well tolerated. Most side effects, including changes in liver function and skin rashes, were mild. Two participants discontinued treatment due to adverse events, and none because of hemolysis.
