Update on heme biosynthesis, tissue-specific regulation, heme transport, relation to iron metabolism and cellular energy.

Heme is a primordial macrocycle upon which most aerobic life on Earth depends. It is essential to the survival and health of nearly all cells, functioning as a prosthetic group for oxygen-carrying proteins and enzymes involved in oxidation/reduction and electron transport reactions. Heme is essential for the function of numerous hemoproteins and has numerous other roles in the biochemistry of life. In mammals, heme is synthesised from glycine, succinyl-CoA, and ferrous iron in a series of eight steps. The first and normally rate-controlling step is catalysed by 5-aminolevulinate synthase (ALAS), which has two forms: ALAS1 is the housekeeping form with highly variable expression, depending upon the supply of the end-product heme, which acts to repress its activity; ALAS2 is the erythroid form, which is regulated chiefly by the adequacy of iron for erythroid haemoglobin synthesis. Abnormalities in the several enzymes of the heme synthetic pathway, most of which are inherited partial enzyme deficiencies, give rise to rare diseases called porphyrias. The existence and role of heme importers and exporters in mammals have been debated. Recent evidence established the presence of heme transporters. Such transporters are important for the transfer of heme from mitochondria, where the penultimate and ultimate steps of heme synthesis occur, and for the transfer of heme from cytoplasm to other cellular organelles. Several chaperones of heme and iron are known and important for cell health. Heme and iron, although promoters of oxidative stress and potentially toxic, are essential cofactors for cellular energy production and oxygenation.

Drug-Induced Liver Injury in Pregnancy: The U.S. Drug-Induced Liver Injury Network Experience.

There are limited data on the causative agents and characteristics of drug-induced liver injury in pregnant individuals. Data from patients with drug-induced liver injury enrolled in the ongoing multicenter Drug-Induced Liver Injury Network between 2004 and 2022 and occurring during pregnancy or 6 months postpartum were reviewed and compared with cases of drug-induced liver injury in nonpregnant women of childbearing age. Among 325 individuals of childbearing age in the Drug-Induced Liver Injury Network, 16 cases of drug-induced liver injury (5%) occurred during pregnancy or postpartum. Compared with drug-induced liver injury in nonpregnant women, pregnancy-related drug-induced liver injury was more severe ( P <.05). One elective termination and three miscarriages were documented; there were no maternal deaths. We recommend that isoniazid for latent tuberculosis be deferred to the postpartum period whenever feasible and that ß-blockers or calcium channel blockers rather than methyldopa be used for hypertension management during pregnancy.

Drug-induced liver injury (DILI) ascribed to non-steroidal anti-inflammatory drugs (NSAIDs) in the USA-Update with genetic correlations.

OBJECTIVE: To describe patients with NSAID-DILI, including genetic factors associated with idiosyncratic DILI. METHODS: In DILIN, subjects with presumed DILI are enrolled and followed for at least 6 months. Causality is adjudicated by a Delphic approach. HLA sequencing of multiethnic NSAID-DILI patients and HLA allele imputation of matching population controls were performed following overall, class and drug-based association analysis. Significant results were tested in a non-Hispanic White (NHW) case-control replication cohort. RESULTS: Between September 2004 and March 2022, causality was adjudicated in 2498, and 55 (41 [75%] women) were assessed as likely due to NSAIDs. Median age at onset was 55 y (range 22-83 y). Diclofenac was the causative drug in 29, celecoxib in 7, ibuprofen in 5, etodolac and meloxicam each in 4. Except for meloxicam and oxaprozin (n = 2), the liver injury was hepatocellular with median R 15-25. HLA-DRB1*04:03 and HLA-B*35:03 were significantly more frequent in NSAID-DILI patients than in non-NSAID DILI controls. Interestingly, 85% of the HLA-DRB1*04:03 carriers developed DILI due to the use of acetic acid derivative NSAIDs, supporting the hypothesis that HLA-DRB1*04:03 could be a drug and/or class risk factor. HLA-B*35:03 but not HLA-DRB1*04:03 association was confirmed in the independent NHW replication cohort, which was largely driven by diclofenac. CONCLUSIONS: Despite prevalent use, NSAID-DILI is infrequent in the United States. Diclofenac is the most commonly implicated, and adherence to warnings of risk and close observation are recommended. The increased frequency of HLA-B*35:03 and DRB1*04:03, driven by diclofenac, suggests the importance of immune-mediated responses.

Obstacles to Early Diagnosis of Acute Hepatic Porphyria: Current Perspectives on Improving Early Diagnosis and Clinical Management.

Porphyrias are, for the most part, inherited disorders of the heme biosynthetic pathway which lead to accumulation of specific intermediates responsible for most of the symptoms and signs of biochemically active disease. Acute hepatic porphyrias usually come to clinical attention primarily in women in their reproductive years who present with episodic, severe, generalized abdominal pain. Such acute attacks may also be associated with tachycardia, systemic arterial hypertension, hyponatremia, recent history of dark reddish to brownish urine, and anxiety, delirium, and sensory or motor neuropathies. Diagnosing AHPs is often challenging, requiring a high index of suspicion and the appropriate testing showing elevated ALA and/or PBG in a random urine specimen. Obstacles to diagnosis include inappropriate testing for porphyrins only, inadequate sample handling, and ordering genetic testing as the initial diagnostic test. While some of these pitfalls in diagnosis are surmountable with current knowledge, others are in need of more research.

Efficacy and safety of givosiran for acute hepatic porphyria: Final results of the randomized phase III ENVISION trial.

BACKGROUND & AIMS: Acute hepatic porphyria (AHP) is caused by defects in hepatic heme biosynthesis, leading to disabling acute neurovisceral attacks and chronic symptoms. In ENVISION (NCT03338816), givosiran treatment for 6 months reduced attacks and other disease manifestations compared with placebo. Herein, we report data from the 36-month final analysis of ENVISION. METHODS: Ninety-four patients with AHP (age ≥12 years) and recurrent attacks were randomized 1:1 to monthly double-blind subcutaneous givosiran 2.5 mg/kg (n = 48) or placebo (n = 46) for 6 months. In the open-label extension (OLE) period, 93 patients received givosiran 2.5 or 1.25 mg/kg for 6 months or more before transitioning to 2.5 mg/kg. Endpoints were exploratory unless otherwise noted. RESULTS: During givosiran treatment, the median annualized attack rate (AAR) was 0.4. Through Month 36, annualized days of hemin use remained low in the continuous givosiran group (median, 0.0 to 0.4) and decreased in the placebo crossover group (16.2 to 0.4). At end of OLE, in the continuous givosiran and placebo crossover groups, 86% and 92%, respectively, had 0 attacks. AAR was lower than historical AAR in 98% and 100%, respectively (post hoc analysis), and there were 0 days of hemin use in 88% and 90%, respectively. The 12-item short-form health survey physical and mental component summary scores increased by 8.6 and 8.1, respectively (continuous givosiran) and 9.4 and 3.2, respectively (placebo crossover). EQ-5D health-related questionnaire scores increased by 18.9 (continuous givosiran) and 9.9 (placebo crossover). Lower urinary delta-aminolevulinic acid and porphobilinogen levels were sustained. Safety findings demonstrated a continued positive risk/benefit profile for givosiran. CONCLUSIONS: Long-term monthly givosiran treatment provides sustained and continued improvement in clinical manifestations of AHP. GOV IDENTIFIER: NCT03338816. EUDRACT NUMBER: 2017-002432-17. IMPACT AND IMPLICATIONS: Acute hepatic porphyria (AHP) is a group of rare, chronic, multisystem disorders associated with overproduction and accumulation of neurotoxic heme intermediates (delta-aminolevulinic acid and porphobilinogen), sometimes resulting in recurrent acute attacks and long-term complications. Givosiran, a small-interfering RNA that prevents accumulation of delta-aminolevulinic acid and porphobilinogen, is approved for the treatment of AHP. These final 36-month results of ENVISION, a phase III study of givosiran in patients with AHP and recurrent attacks, show that long-term monthly treatment with givosiran leads to continuous and sustained reductions in annualized attack rate and use of hemin over time, as well as improved quality of life, with an acceptable safety profile. These results are important for physicians, patients, families, and caregivers who are grappling with this debilitating and potentially life-threatening disease with few effective and tolerable treatment options.

When Is Suspected Drug-Induced Liver Injury (DILI) Not DILI? An Analysis of Unlikely Cases From the Drug-Induced Liver Injury Network.

INTRODUCTION: Diagnosis of drug-induced liver injury (DILI) is difficult. We reviewed cases in the DILI Network prospective study that were adjudicated to have liver injury due to other causes to discover pearls for improved diagnostic accuracy. METHODS: Cases were adjudicated by expert opinion and scored from 1 (definite DILI) to 5 (unlikely DILI). Confirmed cases (1-3) were compared with unlikely cases (5). RESULTS: One hundred thirty-four of the 1,916 cases (7%) were unlikely DILI. Alternative diagnoses were autoimmune hepatitis (20%), hepatitis C (20%), bile duct pathology (13%), and hepatitis E (8%). DISCUSSION: Thorough evaluation, including follow-up, is essential to minimize incorrect diagnosis of idiosyncratic DILI.

Dersimelagon in Erythropoietic Protoporphyrias.

BACKGROUND: Erythropoietic protoporphyria and X-linked protoporphyria are inborn errors of heme biosynthesis that cause elevated circulating levels of metal-free protoporphyrin and phototoxicity. Both disorders are characterized by excruciating phototoxic attacks after exposure to visible light. Dersimelagon is a new, orally administered, selective melanocortin 1 receptor agonist that increases levels of skin eumelanin. METHODS: We conducted a randomized, placebo-controlled, phase 2 trial to investigate the efficacy and safety of dersimelagon with respect to the time to onset and the severity of symptoms associated with sunlight exposure in patients with erythropoietic protoporphyria or X-linked protoporphyria. Patients 18 to 75 years of age were randomly assigned in a 1:1:1 ratio to receive placebo or dersimelagon at a dose of 100 or 300 mg once daily for 16 weeks. The primary end point was the change from baseline to week 16 in the time to the first prodromal symptom associated with sunlight exposure. Patients recorded daily sunlight exposure and symptom data in an electronic diary. Quality of life and safety were also assessed. RESULTS: Of the 102 patients (93 with erythropoietic protoporphyria and 9 with X-linked protoporphyria) who underwent randomization, 90% completed the treatment period. The mean daily time to the first prodromal symptom associated with sunlight exposure increased significantly with dersimelagon: the least-squares mean difference from placebo in the change from baseline to week 16 was 53.8 minutes in the 100-mg dersimelagon group (P = 0.008) and 62.5 minutes in the 300-mg dersimelagon group (P = 0.003). The results also suggest that quality of life improved in patients receiving dersimelagon as compared with placebo. The most common adverse events that occurred or worsened during treatment were nausea, freckles, headache, and skin hyperpigmentation. CONCLUSIONS: At both doses evaluated, dersimelagon significantly increased the duration of symptom-free sunlight exposure in patients with erythropoietic protoporphyria or X-linked protoporphyria. (Funded by Mitsubishi Tanabe Pharma; Endeavor ClinicalTrials.gov number, NCT03520036.).

Recurrent symptoms of acute intermittent porphyria after biochemical normalization with givosiran-An ongoing clinical conundrum.

A 47-year-old woman with acute intermittent porphyria (AIP) has had recurring symptoms after achieving biochemical normalization of her urinary 5-aminolevulinic acid (ALA), porphobilinogen (PBG), and total porphyrins with givosiran. She has had normal liver tests, mildly decreased renal function, and sustained normal urinary ALA, PBG, and porphyrins with no rebound in her laboratory test results throughout treatment. She continues to tolerate monthly givosiran injections with no adverse effects, but she still experiences what she believes are acute porphyric attacks every 1-2 months.

The Impact of Patient Age and Corticosteroids in Patients With Sulfonamide Hepatotoxicity.

INTRODUCTION: Sulfonamides are widely used to treat and prevent various bacterial and opportunistic infections. The aim of this study was to describe the clinical presentation and outcomes of a large cohort of patients with sulfonamide hepatotoxicity. METHODS: Between 2004 and 2020, 105 patients with hepatotoxicity attributed to trimethoprim/sulfamethoxazole (TMP-SMZ) (n = 93) or other sulfonamides (n = 12) were enrolled. Available liver biopsies were reviewed by a single hepatopathologist. RESULTS: Among the 93 TMP-SMZ cases, 52% were female, 7.5% younger than 20 years, and the median time to drug-induced liver injury (DILI) onset was 22 days (range: 3-157). Younger patients were significantly more likely to have rash, fever, eosinophilia, and a hepatocellular injury pattern at onset that persisted at the peak of liver injury compared with older patients ( P < 0.05). The 18 (19%) TMP-SMZ patients treated with corticosteroids had more severe liver injury and a higher mortality but a trend toward more rapid normalization of their laboratory abnormalities compared with untreated patients. During follow-up, 6.2% of the TMP-SMZ patients died or underwent liver transplantation. Chronic DILI developed in 20% and was associated with cholestatic injury at onset and higher peak total bilirubin levels. DISCUSSION: Sulfonamide hepatotoxicity is characterized by a short drug latency with frequent hypersensitivity features at onset. Subject age is an important determinant of the laboratory profile at presentation, and patients with cholestasis and higher total bilirubin levels were at increased risk of developing chronic DILI. Corticosteroids may benefit a subgroup of patients with severe injury, but further studies are needed.

Ledipasvir/Sofosbuvir Is Effective as Sole Treatment of Porphyria Cutanea Tarda with Chronic Hepatitis C.

BACKGROUND AND AIMS: Chronic hepatitis C [CHC] is a risk factor for porphyria cutanea tarda [PCT]. To assess whether ledipasvir/sofosbuvir is effective for treating both PCT and CHC, we treated patients with CHC + PCT solely with ledipasvir/sofosbuvir and followed them for at least 1 year to assess cure of CHC and remission of PCT. METHODS: Between September 2017 and May 2020, 15 of 23 screened PCT + CHC patients were eligible and enrolled. All were treated with ledipasvir/sofosbuvir at recommended doses and durations, according to their stage of liver disease. We measured plasma and urinary porphyrins at baseline and monthly for the first 12 months and at 16, 20, and 24 mos. We measured serum HCV RNA at baseline, 8-12, and 20-24 mos. Cure of HCV was defined as no detectable serum HCV RNA ≥ 12 weeks after the end of treatment (EOT). Remission of PCT was defined clinically as no new blisters or bullae and biochemically as urinary uro- plus hepta-carboxyl porphyrins ≤ 100 mcg/g creatinine. RESULTS: All 15 patients, 13 of whom were men, were infected with HCV genotype 1. 2/15 withdrew or were lost to follow-up. Of the remaining 13, 12 achieved cure of CHC; 1 had complete virological response, followed by relapse of HCV after ledipasvir/sofosbuvir but was subsequently cured by treatment with sofosbuvir/velpatasvir. Of the 12 cured of CHC, all achieved sustained clinical remission of PCT. CONCLUSIONS: Ledipasvir/sofosbuvir [and likely other direct-acting antivirals] is an effective treatment for HCV in the presence of PCT and leads to clinical remission of PCT without additional phlebotomy or low-dose hydroxychloroquine treatment. TRIAL REGISTRATION: ClinicalTrials.gov NCT03118674.

AGA Clinical Practice Update on Diagnosis and Management of Acute Hepatic Porphyrias: Expert Review.

DESCRIPTION: The acute hepatic porphyrias (AHP) are rare, inborn errors of heme-metabolism and include acute intermittent porphyria, hereditary coproporphyria, variegate porphyria, and porphyria due to severe deficiency of 5-aminolevulinic acid dehydratase. Acute intermittent porphyria is the most common type of AHP, with an estimated prevalence of patients with symptoms of approximately 1 in 100,000. The major clinical presentation involves attacks of severe pain, usually abdominal and generalized, without peritoneal signs or abnormalities on cross-sectional imaging. Acute attacks occur mainly in women in their childbearing years. AHP should be considered in the evaluation of all patients, and especially women aged 15-50 years with recurrent severe abdominal pain not ascribable to common causes. The screening tests of choice include random urine porphobilinogen and δ-aminolevulinic acid corrected to creatinine. All patients with elevations in urinary porphobilinogen and/or δ-aminolevulinic acid should initially be presumed to have AHP. The cornerstones of management include discontinuation of porphyrinogenic drugs and chemicals, administration of oral or intravenous dextrose and intravenous hemin, and use of analgesics and antiemetics. Diagnosis of AHP type can be confirmed after initial treatment by genetic testing for pathogenic variants in HMBS, CPOX, PPOX, and ALAD genes. AHP is also associated with chronic symptoms and long-term risk of systemic arterial hypertension, chronic renal and liver disease, and hepatocellular carcinoma. Patients who have recurrent acute attacks (4 or more per year) should be considered for prophylactic therapy with intravenous hemin or subcutaneous givosiran. Liver transplantation is curative and reserved for patients with intractable symptoms who have failed other treatment options. METHODS: This expert review was commissioned and approved by the American Gastroenterological Association (AGA) Institute Clinical Practice Updates Committee (CPUC) and the AGA Governing Board to provide timely guidance on a topic of high clinical importance to the AGA membership, and underwent internal peer review by the CPUC and external peer review through standard procedures of Gastroenterology. These Best Practice Advice (BPA) statements were drawn from a review of the published literature and from expert opinion. Because systematic reviews were not performed, these BPA statements do not carry formal ratings of the quality of evidence or strength of the presented considerations. Best Practice Advice Statements BEST PRACTICE ADVICE 1: Women aged 15-50 years with unexplained, recurrent severe abdominal pain without a clear etiology after an initial workup should be considered for screening for an AHP. BEST PRACTICE ADVICE 2: Initial diagnosis of AHP should be made by biochemical testing measuring δ-aminolevulinic acid, porphobilinogen, and creatinine on a random urine sample. BEST PRACTICE ADVICE 3: Genetic testing should be used to confirm the diagnosis of AHP in patients with positive biochemical testing. BEST PRACTICE ADVICE 4: Acute attacks of AHP that are severe enough to require hospital admission should be treated with intravenous hemin, given daily, preferably into a high-flow central vein. BEST PRACTICE ADVICE 5: In addition to intravenous hemin, management of acute attacks of AHP should include pain control, antiemetics, management of systemic arterial hypertension, tachycardia, and hyponatremia, and hypomagnesemia, if present. BEST PRACTICE ADVICE 6: Patients should be counseled to avoid identifiable triggers that may precipitate acute attacks, such as alcohol and porphyrinogenic medications. BEST PRACTICE ADVICE 7: Prophylactic heme therapy or givosiran, administered in an outpatient setting, should be considered in patients with recurrent attacks (4 or more per year). BEST PRACTICE ADVICE 8: Liver transplantation for AHP should be limited to patients with intractable symptoms and significantly decreased quality of life who are refractory to pharmacotherapy. BEST PRACTICE ADVICE 9: Patients with AHP should be monitored annually for liver disease. BEST PRACTICE ADVICE 10: Patients with AHP, regardless of the severity of symptoms, should undergo surveillance for hepatocellular carcinoma, beginning at age 50 years, with liver ultrasound every 6 months. BEST PRACTICE ADVICE 11: Patients with AHP on treatment should undergo surveillance for chronic kidney disease annually with serum creatinine and estimated glomerular filtration rate. BEST PRACTICE ADVICE 12: Patients should be counseled on the chronic and long-term complications of AHP, including neuropathy, chronic kidney disease, hypertension, and hepatocellular carcinoma, and need for long-term monitoring.

Idiosyncratic drug-induced liver injury caused by givosiran in a patient with acute intermittent porphyria.

A 39-year-old woman with biochemically and clinically active acute intermittent porphyria (AIP) developed moderately severe liver injury after receiving her second dose of givosiran. Serologic evaluation ruled out hepatitis caused by viral, autoimmune, or other metabolic etiologies. The updated Roussel Uclaf Causality Assessment Method (RUCAM) score was 8 and the Revised Electronic Causality Assessment Method (RECAM) score for givosiran was 9. Results of liver tests returned to normal after givosiran was discontinued, and she has not received any more givosiran.

Clinical features, outcomes, and HLA risk factors associated with nitrofurantoin-induced liver injury.

BACKGROUND & AIMS: Nitrofurantoin (NTF) is widely used for the treatment (short-term) and prevention (long-term) of urinary tract infections. We aimed to describe the clinical characteristics, outcomes, and HLA risk factors for NTF-induced liver injury (NTF-DILI) among individuals enrolled in the Drug Induced Liver Injury Network (DILIN). METHODS: Seventy-eight individuals with definite, highly likely, or probable NTF-DILI were enrolled into DILIN studies between 2004-2020. HLA alleles were compared between NTF-DILI and three control groups: population (n = 14,001), idiopathic autoimmune hepatitis (n = 231), and non-NTF DILI (n = 661). RESULTS: Liver injury was hepatocellular in 69% and icteric in 55%. AST > ALT was more common in the 44 long-exposure (≥1 year) NTF-DILI cases than in the 18 short (≤7 days) and 16 intermediate (>7 to <365 days) exposure cases (73% vs. 33% vs. 50%, respectively, p = 0.018), as was ANA or SMA positivity (91% vs. 44% vs. 50%, respectively, p <0.001), and corticosteroid use (61% vs. 27% vs. 44%, respectively, p = 0.06). In long-term NTF-DILI, bridging fibrosis, nodularity or cirrhosis, or clinical and imaging evidence for cirrhosis were present in 38%, with massive or sub-massive necrosis in 20%. No one in the short-term exposure group died or underwent transplantation, whereas 7 (12%) patients from the other groups died or underwent transplantation. After covariate adjustments, HLA-DRB1∗11:04 was significantly more frequent in NTF-DILI compared to population controls (odds ratio [OR] 4.29, p = 1.15 × 10-4), idiopathic autoimmune hepatitis (OR 11.77, p = 7.76 × 10-5), and non-NTF DILI (OR 3.34, p = 0.003). CONCLUSION: NTF-DILI can result in parenchymal necrosis, bridging fibrosis, cirrhosis, and death or liver transplantation, especially with long-term exposure, and is associated with HLA-DRB1∗11:04. To mitigate against serious liver injury associated with NTF, regulators should revise the prescribing information and consider other mitigation strategies. IMPACT AND IMPLICATIONS: Nitrofurantoin is a recognized cause of drug-induced liver injury (DILI). In this study consisting of a large cohort of well-phenotyped individuals with nitrofurantoin-induced liver injury, two distinct patterns of liver injury were identified: liver injury associated with short-term exposure, which is generally self-limiting, and liver injury associated with long-term exposure, which can lead to advanced fibrosis, cirrhosis and liver failure. HLA DRB1∗11:04 is a risk factor for liver injury due to long-term nitrofurantoin exposure. Our findings are important for regulators as well as physicians prescribing and pharmacists dispensing nitrofurantoin.

Liver Injury Associated with Turmeric-A Growing Problem: Ten Cases from the Drug-Induced Liver Injury Network [DILIN].

BACKGROUND: Turmeric is a commonly used herbal product that has been implicated in causing liver injury. The aim of this case series is to describe the clinical, histologic, and human leukocyte antigen (HLA) associations of turmeric-associated liver injury cases enrolled the in US Drug-Induced Liver Injury Network (DILIN). METHODS: All adjudicated cases enrolled in DILIN between 2004 and 2022 in which turmeric was an implicated product were reviewed. Causality was assessed using a 5-point expert opinion score. Available products were analyzed for the presence of turmeric using ultra-high-performance liquid chromatography. Genetic analyses included HLA sequencing. RESULTS: Ten cases of turmeric-associated liver injury were found, all enrolled since 2011, and 6 since 2017. Of the 10 cases, 8 were women, 9 were White, and median age was 56 years (range 35-71). Liver injury was hepatocellular in 9 patients and mixed in 1. Liver biopsies in 4 patients showed acute hepatitis or mixed cholestatic-hepatic injury with eosinophils. Five patients were hospitalized, and 1 patient died of acute liver failure. Chemical analysis confirmed the presence of turmeric in all 7 products tested; 3 also contained piperine (black pepper). HLA typing demonstrated that 7 patients carried HLA-B*35:01, 2 of whom were homozygous, yielding an allele frequency of 0.450 compared with population controls of 0.056-0.069. CONCLUSION: Liver injury due to turmeric appears to be increasing in the United States, perhaps reflecting usage patterns or increased combination with black pepper. Turmeric causes potentially severe liver injury that is typically hepatocellular, with a latency of 1 to 4 months and strong linkage to HLA-B*35:01.

Illuminating Dersimelagon: A Novel Agent in the Treatment of Erythropoietic Protoporphyria and X-Linked Protoporphyria.

Erythropoietic protoporphyria (EPP) is a genetic disorder stemming from reduced ferrochelatase expression, the final enzyme in the pathway of heme biosynthesis. A closely related condition, X-linked protoporphyria (XLP), bears similar clinical features although it arises from the heightened activity of δ-aminolevulinic acid synthase 2 (ALAS2), the first and normally rate-controlling enzyme in heme biosynthesis in developing red blood cells. Both of these abnormalities result in the buildup of protoporphyrin IX, leading to excruciating light sensitivity and, in a minority of cases, potentially fatal liver complications. Traditionally, managing EPP and XLP involved sun avoidance. However, the emergence of innovative therapies, such as dersimelagon, is reshaping the therapeutic landscape for these conditions. In this review, we summarize salient features of the properties of dersimelagon, shedding light on its potential role in advancing our understanding of treatment options for EPP and XLP.

A pilot study of oral iron therapy in erythropoietic protoporphyria and X-linked protoporphyria.

The use of iron supplementation for anemia in erythropoietic protoporphyria (EPP) is controversial with both benefit and deterioration reported in single case reports. There is no systematic study to evaluate the benefits or risks of iron supplementation in these patients. We assessed the potential efficacy of oral iron therapy in decreasing erythrocyte protoporphyrin (ePPIX) levels in patients with EPP or X-linked protoporphyria (XLP) and low ferritin in an open-label, single-arm, interventional study. Sixteen patients (≥18 years) with EPP or XLP confirmed by biochemical and/or genetic testing, and serum ferritin ≤30 ng/mL were enrolled. Baseline testing included iron studies, normal hepatic function, and elevated plasma porphyrins and ePPIX levels. Oral ferrous sulfate 325 mg twice daily was administered for 12 months. The primary efficacy outcome was the relative difference in total ePPIX level between baseline and 12 months after starting treatment with iron. Secondary measures included improvement in serum ferritin, plasma porphyrins, and clinical symptoms. Thirteen patients had EPP (8 females, 5 males) and 3 had XLP (all females) and the mean age of participants was 38.8 years (SD 14.5). Ten patients completed all study visits limiting interpretation of results. In EPP patients, a transient increase in ePPIX levels was observed at 3 months in 9 of 12 (75%) patients. Iron was discontinued in 2 of these patients after meeting the protocol stopping rule of a 35% increase in ePPIX. Seven patients withdrew before study end. Ferritin levels increased on iron replacement indicating an improvement in iron status. A decrease in ePPIX was seen in both XLP patients who completed the study (relative difference of 0.67 and 0.5 respectively). No substantial changes in ePPIX were seen in EPP patients at the end of the study (n = 8; median relative difference: -0.21 (IQR: -0.44, 0.05). The most common side effects of iron treatment were gastrointestinal symptoms. Hepatic function remained normal throughout the study. Our study showed that oral iron therapy repletes iron stores and transiently increases ePPIX in some EPP patients, perhaps due to a transient increase in erythropoiesis, and may decrease ePPIX in XLP patients. Further studies are needed to better define the role of iron repletion in EPP. Trial registration: NCT02979249.

Elagolix is porphyrogenic and may induce porphyric attacks in patients with the acute hepatic porphyrias.

Elagolix is an FDA-approved treatment for moderate-to-severe pain associated with endometriosis but has been associated with increased acute porphyric attacks in women with the acute hepatic porphyrias (AHPs). A fluorescence-based screening assay for drug porphyrogenicity in LMH cells indicates that elagolix is porphyrogenic; thus, elagolix should be avoided or used with caution in patients with the AHPs.

EXPLORE B: A prospective, long-term natural history study of patients with acute hepatic porphyria with chronic symptoms.

One-year data from EXPLORE Part A showed high disease burden and impaired quality of life (QOL) in patients with acute hepatic porphyria (AHP) with recurrent attacks. We report baseline data of patients who enrolled in EXPLORE Part B for up to an additional 3 years of follow-up. EXPLORE B is a long-term, prospective study evaluating disease activity, pain intensity, and QOL in patients with AHP with ≥1 attack in the 12 months before enrollment or receiving hemin or gonadotropin-releasing hormone prophylaxis. Data were evaluated in patients with more (≥3 attacks or on prophylaxis treatment) or fewer (<3 attacks and no prophylaxis treatment) attacks. Patients in the total population (N = 136), and more (n = 110) and fewer (n = 26) attack subgroups, reported a median (range) of 3 (0-52), 4 (0-52), and 1 (0-2) acute attacks, respectively, in the 12 months prior to the baseline visit. Pain, mood/sleep, digestive/bladder, and nervous system symptoms were each experienced by ≥80% of patients; most received hemin during attacks. Almost three-quarters of patients reported chronic symptoms between attacks, including 85% of patients with fewer attacks. Pain intensity was comparable among both attack subgroups; most patients required pain medication. All groups had diminished QOL on the EuroQol visual analog scale and the European Organisation for Research and Treatment of Cancer Quality-of-life Questionnaire Core 30 versus population norms. Patients with AHP with recurrent attacks, even those having fewer attacks, experience a high disease burden, as evidenced by chronic symptoms between attacks and impaired QOL.

Eslicarbazepine acetate is porphyrogenic and should be used with caution in patients with the acute hepatic porphyrias.

Eslicarbazepine acetate, a third-generation antiepileptic drug (AED), has shown improved clinical response and safety in comparison to older generation AEDs for patients with partial-onset seizures. It is currently not known whether eslicarbazepine acetate is safe to use in patients with the acute hepatic porphyrias (AHPs) since a few first-generation AEDs, such as phenobarbital and carbamazepine, are known porphyrogenic agents. In this study, we used a recently published in vitro fluorescence-based screening assay to screen for porphyrogenicity in various agents. The assay confirmed that among the tested compounds used, allyl isopropyl acetamide, carbamazepine, eslicarbazepine acetate, and phenobarbital were porphyrogenic. Thus, eslicarbazepine acetate should be avoided if possible in patients with the AHPs, but if initiated, patients should be closely monitored and the drug should be discontinued if a porphyric exacerbation occurs.