New drug can control attacks, but it’s costly
Treatment should begin right away if porphyria is suspected, without waiting for confirmation, Dr. Nance said. “There are porphyria experts in the U.S. and in many other countries who can help practitioners interpret symptoms and testing results if there is uncertainty or if treatment options are unclear.”
Patients are counseled to avoid attack triggers and eat healthy diets, she said. “Persons with porphyria are encouraged to have a plan for home management of an attack and when to come to the hospital for symptoms that don’t respond to home therapy,” she said.
Dr. Fertrin said “the typical treatment for an acute porphyric attack is the use of intravenous glucose, as well as intravenous hemin infusions, along with pain medications and fluids as needed. Some patients may need medication for high blood pressure. For patients with recurrent attacks, prophylactic doses of hemin can be used.”
Another option is givosiran (Givlaari), the biggest recent advance in porphyria treatment. It was approved by the Food and Drug Administration for acute hepatic porphyria in 2019. “It’s an inhibitory mRNA that shuts down heme synthesis by downregulating aminolevulinic acid synthase,” said hematologist Thomas DeLoughery, MD, of Oregon Health & Science University, Portland.
A 2020 study coauthored by Dr. Bonkovsky found that the drug reduced the mean annualized attack rate in acute intermittent porphyria by 74%, compared with placebo (P < .001). “Givosiran led to lower levels of urinary ALA and porphobilinogen, fewer days of hemin use, and better daily scores for pain than placebo,” the study authors write. “Key adverse events that were observed more frequently in the givosiran group were elevations in serum aminotransferase levels, changes in serum creatinine levels and the estimated glomerular filtration rate, and injection-site reactions.”
Dr. Bonkovsky said the drug is appropriate in patients whose disease is not controlled by lifestyle interventions regarding alcohol, smoking, and substance use. However, while givosiran is helpful, “it’s not a cure,” he said. “Probably about 40% of patients have found the side effects such as nausea, fatigue, headaches, and liver injury to be too adverse and have not decided to take it in the long term.”
In addition, the drug costs about $500,000 a year, and insurers may balk at the expense. Still, specialists say it can be a good option. “Before givosiran, the standard therapy was hematin, which decreased the activity of the ALA synthase,” Dr. DeLoughery said. “This is a nasty drug that can inflame the blood vessels and is not all that effective.”
The royal family may be able to breathe easy
There are other forms of porphyria besides the acute type. Cutaneous porphryias can cause blistering from sunlight exposure, and treatment is avoidance of such triggers, Dr. Fertin said. “For a rare form called erythropoietic protoporphyria, there is a subcutaneous implant with a medication called afamelanotide that increases tolerance to sunlight.”
There’s another type: variegate porphyria, which UpToDate says is “characterized by cutaneous blistering and/or acute neurovisceral attacks.” In 1966, a mother-and-son psychiatrist team theorized that Britain’s King George III suffered from this type of porphyria.
However, researchers have sharply criticized the porphyria theory with regard to that king, and a recent theory now suggests that he actually had bipolar disorder. Dr. Fertin is among the skeptics, noting the high prevalence of porphyria in affected families.
“Since King George III would now have a living number of relatives of about 900 people, we would expect around 180 cases of variegate porphyria to be connected to him, and those are nowhere to be found,” he said. “The idea that it could cause progressive psychosis and dementia is also a misconception. We do not find that porphyria is the underlying cause of psychiatric conditions on their own. Many atypical symptoms of the king were attributed to variegate porphyria, and the few more typical symptoms he reportedly had, of abdominal pain and urine discoloration, can be more easily explained by common diseases, such as kidney stones or gallstones. Finally, attempts at obtaining genetic or biochemical evidence of porphyria from relatives of King George III have been negative or inconclusive.”
That’s good news for the royals, who have many other concerns these days.
Dr. Nance discloses research study funding from Alnylam (maker of Givlaari) and payments to participate in educational activities for patients and practitioners. Dr. Bonkovsky discloses relationships with drugmakers who have developed products to treat porphyria including Alnylam, Mitsubishi Tanabe, Recordati, and Disc. Dr. Fertin is subinvestigator in a clinical trial for a novel treatment for erythropoietic protoporphyria sponsored by Mitsubishi Tanabe. Dr. DeLoughery reports no disclosures.