Treatment with Antimalarial Therapies Linked to Higher Porphyria Relapse Rates, Study Says
Relapses are more frequent among porphyria cutanea tarda patients who had previously achieved remission with antimalarial medications, a study shows.
The study, “Relapse of porphyria cutanea tarda after treatment with phlebotomy or 4‐aminoquinoline antimalarial: A Meta‐analysis,” was published in the British Journal of Dermatology.
Porphyria cutanea tarda, or PTC, is the most common subtype of porphyria. It’s caused by low levels of the enzyme uroporphyrinogen decarboxylase (UROD), a deficiency that can be inherited — known as familial PCT — or acquired.
PTC is characterized by the accumulation of porphyrin compounds in the liver that are then released into the plasma and ultimately excreted through the urine. However, high levels of these compounds circulating in the plasma can cause chronic blistering of the skin and light sensitivity.
This condition is commonly treated by repeated phlebotomy, which consists of drawing blood through small incisions in the vein, or with antimalarial medications, such as chloroquine or hydroxychloroquine. The first approach reduces the amount of circulating iron, which helps to inhibit UROD activity. Antimalarial treatments mobilize porphyrin compounds accumulated in the liver, helping with their elimination.
Both treatment strategies have been found effective for PTC, with comparable high rates of remission. But some patients experience PTC relapses upon each treatment, and there is little comparative information.
A research team at the University of Texas Medical Branch reviewed data collected from 12 previously published studies covering a total of 525 PTC patients. They had been treated with phlebotomy, a low-dose drug regimen (125 mg of chloroquine or 100 mg of hydroxychloroquine twice weekly), a high-dose drug regimen, or both phlebotomy and antimalarial therapies.
Relapse rates during the year after treatment were found to be similar for the high- and low-dose drug regimen groups (35.4% and 36.3%, respectively), and were slightly lower in the phlebotomy group (20.5%).
Pooled data analysis showed that relapse rates were 8.6 per 100 person-years for the high-dose group, 17.5 for the low-dose group, and 6.5 for the phlebotomy group.
Use of high-dose therapies without preceding phlebotomy was associated with a relapse rate of 12.2 per 100 person-years, while with high-dose treatment plus phlebotomy, the rate was 10.2.
These results revealed that “relapses were somewhat more frequent after remission with antimalarial regimens as compared to remission after phlebotomy,” the researchers wrote.
Still, they emphasized that additional studies are needed “to better define how often relapses occur with these treatments after documenting both clinical and biochemical remission of PCT.”