Disease burden in patients with acute hepatic porphyria: experience from the phase 3 ENVISION study

Long-term complications in acute porphyria

New treatment options and low attack-related mortality have changed the life expectancy of patients with acute porphyria (AP) to that of the general population. Clinicians should therefore be aware of the long-term complications of AP, which typically include chronic neuropathy and encephalopathy, high blood pressure and porphyria-associated kidney disease. Patients have an increased risk of primary liver cancer (PLC), but no increased risk of non-hepatic cancers. Chronic pain occurs in patients with recurrent attacks, combined with chronic fatigue and nausea, leading to poor quality of life. Patients with sporadic attacks may also have chronic symptoms, which should be distinguished from mild recurrent attacks and treated appropriately. Sequels of acute polyneuropathy after an attack should be distinguished from ongoing chronic polyneuropathy, as the management is different. Overestimation of chronic neuropathy or encephalopathy caused by AP should be avoided, and other causes should be treated accordingly. Prevention of recurrent attacks is the best strategy for managing chronic comorbidities and should be actively accomplished. Hormonal interventions in female patients, or in severe cases, prophylactic givosiran or haematin, may be helpful before liver transplantation to prevent recurrent attacks. Regular monitoring can be personalised according to the patient's age, comorbidities and AP activity. Blood pressure, renal function and cardiovascular risk factors should be monitored annually in patients with previous symptoms. Appropriate medication and lifestyle management, including nutrition and hydration, are necessary to prevent complications. As PLC is common, especially in patients with acute intermittent porphyria, bi-annual surveillance after the age of 50 is important.

Targeting the Liver with Nucleic Acid Therapeutics for the Treatment of Systemic Diseases of Liver Origin

Systemic diseases of liver origin (SDLO) are complex diseases in multiple organ systems, such as cardiovascular, musculoskeletal, endocrine, renal, respiratory, and sensory organ systems, caused by irregular liver metabolism and production of functional factors. Examples of such diseases discussed in this article include primary hyperoxaluria, familial hypercholesterolemia, acute hepatic porphyria, hereditary transthyretin amyloidosis, hemophilia, atherosclerotic cardiovascular diseases, α-1 antitrypsin deficiency-associated liver disease, and complement-mediated diseases. Nucleic acid therapeutics use nucleic acids and related compounds as therapeutic agents to alter gene expression for therapeutic purposes. The two most promising, fastest-growing classes of nucleic acid therapeutics are antisense oligonucleotides (ASOs) and small interfering RNAs (siRNAs). For each listed SDLO disease, this article discusses epidemiology, symptoms, genetic causes, current treatment options, and advantages and disadvantages of nucleic acid therapeutics by either ASO or siRNA drugs approved or under development. Furthermore, challenges and future perspectives on adverse drug reactions and toxicity of ASO and siRNA drugs for the treatment of SDLO diseases are also discussed. In summary, this review article will highlight the clinical advantages of nucleic acid therapeutics in targeting the liver for the treatment of SDLO diseases. SIGNIFICANCE STATEMENT: Systemic diseases of liver origin (SDLO) contain rare and common complex diseases caused by irregular functions of the liver. Nucleic acid therapeutics have shown promising clinical advantages to treat SDLO. This article aims to provide the most updated information on targeting the liver with antisense oligonucleotides and small interfering RNA drugs. The generated knowledge may stimulate further investigations in this growing field of new therapeutic entities for the treatment of SDLO, which currently have no or limited options for treatment.

Portuguese Consensus on Acute Porphyrias: Diagnosis, Treatment, Monitoring and Patient Referral

Acute porphyrias are a group of rare genetic metabolic disorders, caused by a defect in one of the enzymes involved in the heme biosynthesis, which results in an abnormally high accumulation of toxic intermediates. Acute porphyrias are characterized by potentially life-threatening attacks and, for some patients, by chronic manifestations that negatively impact daily functioning and quality of life. Clinical manifestations include a nonspecific set of gastrointestinal, neuropsychiatric, and/or cutaneous symptoms. Effective diagnostic methods are widely available, but due to their clinical heterogeneity and non-specificity, many years often elapse from symptom onset to diagnosis of acute porphyrias, delaying the treatment and increasing morbidity. Therefore, increased awareness of acute porphyrias among healthcare professionals is paramount to reducing disease burden. Treatment of acute porphyrias is centered on eliminating the potential precipitants, symptomatic treatment, and suppressing the hepatic heme pathway, through the administration of hemin or givosiran. Moreover, properly monitoring patients with acute porphyrias and their relatives is fundamental to preventing acute attacks, hospitalization, and long-term complications. Considering this, a multidisciplinary panel elaborated a consensus paper, aiming to provide guidance for an efficient and timely diagnosis of acute porphyrias, and evidence-based recommendations for treating and monitoring patients and their families in Portugal. To this end, all authors exhaustively reviewed and discussed the current scientific evidence on acute porphyrias available in the literature, between November 2022 and May 2023.

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.

CLINICALTRIALS

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.

Acute hepatic porphyrias: Recommendations for diagnosis and management with real-world examples

Acute hepatic porphyria (AHP) is a group of four rare inherited diseases, each resulting from a deficiency in a distinct enzyme in the heme biosynthetic pathway. Characterized by acute neurovisceral symptoms that may mimic other medical and psychiatric conditions, lack of recognition of the disease often leads to a delay in diagnosis and initiation of effective treatment. Biochemical testing for pathway intermediates that accumulate when the disease is active forms the basis for screening and establishing a diagnosis. Subsequent genetic analysis identifies the pathogenic variant, supporting screening of family members and genetic counseling. Management of AHP involves avoidance of known exogenous and hormonal triggers, symptomatic treatment, and prevention of recurrent attacks. Here we describe six case studies from our own real-world experience to highlight current recommendations and challenges associated with the diagnosis and long-term management of the disease.

Reducing diagnostic delays in Acute Hepatic Porphyria using electronic health records data and machine learning: a multicenter development and validation study

Importance

Acute Hepatic Porphyria (AHP) is a group of rare but treatable conditions associated with diagnostic delays of fifteen years on average. The advent of electronic health records (EHR) data and machine learning (ML) may improve the timely recognition of rare diseases like AHP. However, prediction models can be difficult to train given the limited case numbers, unstructured EHR data, and selection biases intrinsic to healthcare delivery.

Objective

To train and characterize models for identifying patients with AHP.

Design Setting and Participants

This diagnostic study used structured and notes-based EHR data from two centers at the University of California, UCSF (2012-2022) and UCLA (2019-2022). The data were split into two cohorts (referral, diagnosis) and used to develop models that predict: 1) who will be referred for testing of acute porphyria, amongst those who presented with abdominal pain (a cardinal symptom of AHP), and 2) who will test positive, amongst those referred. The referral cohort consisted of 747 patients referred for testing and 99,849 contemporaneous patients who were not. The diagnosis cohort consisted of 72 confirmed AHP cases and 347 patients who tested negative. Cases were female predominant and 6-75 years old at the time of diagnosis. Candidate models used a range of architectures. Feature selection was semi-automated and incorporated publicly available data from knowledge graphs.

Main Outcomes and Measures

F-score on an outcome-stratified test set.

Results

The best center-specific referral models achieved an F-score of 86-91%. The best diagnosis model achieved an F-score of 92%. To further test our model, we contacted 372 current patients who lack an AHP diagnosis but were predicted by our models as potentially having it (≥ 10% probability of referral, ≥ 50% of testing positive). However, we were only able to recruit 10 of these patients for biochemical testing, all of whom were negative. Nonetheless, post hoc evaluations suggested that these models could identify 71% of cases earlier than their diagnosis date, saving 1.2 years.

Conclusions and Relevance

ML can reduce diagnostic delays in AHP and other rare diseases. Robust recruitment strategies and multicenter coordination will be needed to validate these models before they can be deployed.

Novel Therapeutic Approaches in Inherited Neuropathies: A Systematic Review

The management of inherited neuropathies relies mostly on the treatment of symptoms. In recent years, a better understanding of the pathogenic mechanisms that underlie neuropathies has allowed for the development of disease-modifying therapies. Here, we systematically review the therapies that have emerged in this field over the last five years. An updated list of diseases with peripheral neuropathy as a clinical feature was created based on panels of genes used clinically to diagnose inherited neuropathy. This list was extended by an analysis of published data by the authors and verified by two experts. A comprehensive search for studies of human patients suffering from one of the diseases in our list yielded 28 studies that assessed neuropathy as a primary or secondary outcome. Although the use of various scales and scoring systems made comparisons difficult, this analysis identified diseases associated with neuropathy for which approved therapies exist. An important finding is that the symptoms and/or biomarkers of neuropathies were assessed only in a minority of cases. Therefore, further investigation of treatment efficacy on neuropathies in future trials must employ objective, consistent methods such as wearable technologies, motor unit indexes, MRI or sonography imaging, or the use of blood biomarkers associated with consistent nerve conduction studies.

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.

Pain in acute hepatic porphyrias: Updates on pathophysiology and management

Acute hepatic porphyrias (AHPs) typically present with recurrent acute attacks of severe abdominal pain and acute autonomic dysfunction. While chronic symptoms were historically overlooked in the literature, recent studies have reported increased prevalence of chronic, mainly neuropathic, pain between the attacks. Here we characterize acute and chronic pain as prominent manifestations of the AHPs and discuss their pathophysiology and updated management. In addition to the severe abdominal pain, patients could experience low back pain, limb pain, and headache during acute attacks. Chronic pain between the attacks is typically neuropathic and reported mainly by patients who undergo recurrent attacks. While the acute abdominal pain during attacks is likely mediated by autonomic neuropathy, chronic pain likely represents delayed recovery of the acute neuropathy with ongoing small fiber neuropathy in addition to peripheral and/or central sensitization. δ-aminolaevulinic acid (ALA) plays a major role in acute and chronic pain via its neurotoxic effect, especially where the blood-nerve barrier is less restrictive or absent i.e., the autonomic ganglia, nerve roots, and free nerve endings. For earlier diagnosis, we recommend testing a spot urine porphobilinogen (PBG) analysis in any patient with recurrent severe acute abdominal pain with no obvious explanation, especially if associated with neuropathic pain, hyponatremia, autonomic dysfunction, or encephalopathy. Of note, it is mandatory to exclude AHPs in any acute painful neuropathy. Between the attacks, diagnostic testing for AHPs should be considered for patients with a past medical history of acute/subacute neuropathy, frequent emergency room visits with abdominal pain, and behavioral changes. Pain during the attacks should be treated with opiates combined with hemin infusions. Symptomatic treatment of chronic pain should start with gabapentinoids and certain antidepressants before opiates. Givosiran reduces levels of ALA and PBG and likely has long-term benefits for chronic pain, especially if started early during the course of the disease.