Dapsone ‘Should Be Considered’ as Pediatric ITP Treatment, Research Shows

Dapsone demonstrates efficacy and acceptable safety with low costs as treatment for pediatric immune thrombocytopenic purpura (ITP), according to a prospective cohort study presented at the 66th American Society of Hematology Annual Meeting & Exposition.

Fifty-eight patients—including 14 with newly diagnosed ITP, 23 with persistent ITP, and 21 with chronic ITP—received dapsone after one to four prior treatments. As for transfusions prior to therapy, 31% of patients required red blood cells and 8.6% required platelets. Dapsone was administered at a mean dose of 1.23 mg/kg per day and at 1.48 mg/kg per day for those who did not respond to treatment.

The median follow-up period was 142 days. The overall response rate was 58.6%, the median time to response was 40 days, and the median duration of response was 151 days. Most (94.1%) patients achieved a response within six months of treatment, and 44.8% maintained a response at the last follow-up. Some (37.5%) patients who did not respond had a treatment duration of 16 to 62 days.

The researchers noted that there were similar response and remission across ITP types, age, and sex, according to Kaplan-Meier curves. Cox regression showed an association between response and dapsone dose but no association with sex, age, previous treatment numbers, response to prior treatment, ITP type, baseline platelet count, or concurrent treatments. An increase in the dapsone dose of 1 mg/kg per day was associated with the hazard of 2.39 of achieving response or remission (P=.001, 95% CI, 1.4-4.1). However, “the association was not seen when change in hemoglobin (Hb) from the baseline was added in the model, suggesting that dapsone acts on platelets by reducing Hb (p=0.5),” the researchers noted.

Eighteen patients experienced adverse events such as skin rashes (n=8), altered liver function (n=11), conjunctivitis (n=1), and methemoglobinemia (n=1). Two patients discontinued dapsone due to skin rashes (n=1) and conjunctivitis (n=1), and one patient with symptomatic methemoglobinemia experienced improvement after a dose reduction.

“Dapsone responses were dose dependent and were mediated via drop in Hb,” the researchers concluded. “Dapsone should be considered in relapsed/refractory ITP not requiring rapid rise in platelets due to (1) its effectiveness irrespective of age, sex, number and response to prior treatments, ITP types, concomitant treatments, and baseline platelets, (2) low cost, (3) acceptable safety profile, and (4) comparable response rates to other treatment options except thrombopoietin receptor agonists and splenectomy.”

Reference

Shah SD, Rathod DA, Rathod ND, et al. Dapsone in relapsed/refractory adult and pediatric ITP- a longitudinal panel data analysis demonstrates efficacy, safety, and dose dependent response rate mediated through drop in hemoglobin. Abstract #2557. Presented at the 66th American Society of Hematology Annual Meeting & Exposition; December 7-10, 2024; San Diego, California.