Nexviadyme (Avalglucosidase Alfa)

What Is Nexviadyme and What Is It Used For?

Nexviadyme (avalglucosidase alfa) is an enzyme replacement therapy designed to treat Pompe disease, a rare genetic condition in which the body lacks the enzyme acid alpha-glucosidase (GAA). Without sufficient GAA, glycogen accumulates in cells, particularly in muscle tissue, leading to progressive muscle weakness and respiratory problems.

Pompe disease, also known as glycogen storage disease type II or acid maltase deficiency, is a rare autosomal recessive lysosomal storage disorder. It affects approximately 1 in 40,000 births worldwide, though the exact incidence varies by population and ethnicity. The disease is caused by mutations in the GAA gene, which encodes the lysosomal enzyme acid alpha-glucosidase. This enzyme is responsible for breaking down glycogen within lysosomes – the cellular compartments that act as recycling centres within cells.

When GAA activity is absent or severely reduced, glycogen progressively accumulates within lysosomes, ultimately damaging cells and tissues. The effects are most pronounced in skeletal muscle and cardiac muscle, but other tissues including smooth muscle, the liver, and the nervous system can also be affected. In the infantile-onset form of Pompe disease, babies typically present with severe cardiomyopathy, profound muscle weakness (hypotonia), and respiratory insufficiency within the first months of life. Without treatment, infantile-onset Pompe disease is usually fatal within the first year. In the late-onset form, symptoms may appear at any age from childhood to adulthood and typically involve progressive limb-girdle muscle weakness and respiratory decline.

Nexviadyme contains avalglucosidase alfa, a recombinant (laboratory-produced) form of human GAA enzyme. It was specifically engineered to have approximately 15 times more mannose-6-phosphate (M6P) residues on its surface compared to alglucosidase alfa (Myozyme/Lumizyme), the first-generation enzyme replacement therapy. The M6P residues serve as targeting signals that allow the enzyme to be recognized and taken up by cells via cation-independent mannose-6-phosphate receptors (CI-MPR) on the cell surface. Once inside the cell, the enzyme is transported to lysosomes where it can break down accumulated glycogen.

Nexviadyme is approved by both the European Medicines Agency (EMA) and the U.S. Food and Drug Administration (FDA) for the treatment of Pompe disease in patients of all ages. It was granted approval based on clinical trial data demonstrating its efficacy in both treatment-naive and treatment-experienced patients. The pivotal COMET trial, a randomised, double-blind, head-to-head study comparing Nexviadyme with alglucosidase alfa, showed that Nexviadyme was superior in improving respiratory function (forced vital capacity) and non-inferior in improving walking endurance (six-minute walk test) in late-onset Pompe disease patients who had been previously treated with alglucosidase alfa.

What Should You Know Before Taking Nexviadyme?

Before starting treatment with Nexviadyme, your healthcare provider will evaluate your overall health, allergy history, and current medications. Nexviadyme must not be used in patients who have had life-threatening allergic reactions to avalglucosidase alfa that recurred after rechallenge.

Contraindications

Nexviadyme is contraindicated in patients who have experienced life-threatening hypersensitivity (allergic) reactions to avalglucosidase alfa or any of its excipients, and where the reactions recurred upon restarting treatment after discontinuation. This is the primary absolute contraindication for Nexviadyme. If you have had a severe allergic reaction such as anaphylaxis during a previous Nexviadyme infusion, your doctor will carefully assess whether it is safe to attempt treatment again. In most cases, isolated allergic reactions can be managed with slower infusion rates and premedication, but repeated life-threatening reactions after rechallenge require permanent discontinuation.

Warnings and Precautions

Infusion-associated reactions (IARs) are the most significant safety concern with Nexviadyme. These reactions can range from mild symptoms such as flushing and headache to severe manifestations including anaphylaxis. They typically occur during the infusion or within several hours afterwards. Healthcare professionals administering Nexviadyme should be trained in the management of allergic reactions and should have appropriate medical support readily available.

If you experience symptoms of a severe allergic reaction during infusion – such as difficulty breathing, chest tightness, swelling of the lips or tongue, severe skin rash, or a sudden drop in blood pressure – the infusion must be stopped immediately and appropriate emergency treatment initiated. Your doctor will determine whether it is safe to continue Nexviadyme treatment after such an event.

Patients may also experience generalised oedema (swelling) during treatment. If you notice that your legs are swelling or you feel generally puffy, inform your doctor promptly. Your physician will assess whether the infusion should be paused and will provide appropriate medical management.

Drug Interactions

No formal drug interaction studies have been conducted with Nexviadyme. However, you should always inform your doctor and pharmacist about all medicines you are currently taking, have recently taken, or might take. This includes prescription medicines, over-the-counter medications, herbal supplements, and vitamins. As an enzyme replacement therapy that acts specifically within lysosomes, Nexviadyme has a low potential for pharmacokinetic interactions with other drugs. However, any medication that may affect lysosomal function or trafficking could theoretically interfere with its efficacy.

Pregnancy and Breastfeeding

There is limited clinical data on the use of Nexviadyme during pregnancy. Animal reproductive studies have not revealed direct harmful effects, but the potential risk to humans is not fully established. As a precaution, Nexviadyme should not be used during pregnancy unless the treating physician determines that the expected benefit to the mother justifies any potential risk to the foetus. Women of childbearing potential should discuss family planning with their physician before starting treatment.

It is not known whether avalglucosidase alfa is excreted in human breast milk. A decision on whether to continue or discontinue breastfeeding, or to continue or discontinue Nexviadyme therapy, should be made after considering the benefit of breastfeeding for the infant and the benefit of Nexviadyme treatment for the mother.

Driving and Operating Machinery

Nexviadyme may have a minor effect on the ability to drive and operate machinery. Dizziness, low blood pressure, and drowsiness have been reported as infusion-related reactions and may temporarily impair alertness and coordination. Patients are advised not to drive or operate heavy machinery on the day of infusion if they experience any of these symptoms.

How Does Nexviadyme Interact with Other Drugs?

No formal drug interaction studies have been performed with Nexviadyme. As an enzyme replacement therapy with a specific intracellular mechanism, its potential for pharmacokinetic drug interactions is considered low. However, certain medications that affect lysosomal pathways or immune responses may theoretically influence its efficacy or safety profile.

Because Nexviadyme is a recombinant protein that functions within lysosomes, it does not undergo hepatic metabolism via cytochrome P450 enzymes and is not expected to interact with most conventional medications. Nevertheless, healthcare professionals should be aware of the following theoretical and practical considerations when administering Nexviadyme alongside other treatments.

It is important to note that immune tolerance induction protocols using immunosuppressive agents such as rituximab, methotrexate, and intravenous immunoglobulin (IVIg) have been used in some patients who develop high titres of anti-drug antibodies (ADAs) against enzyme replacement therapies for Pompe disease. The development of ADAs can reduce the effectiveness of treatment. If your doctor suspects that antibody formation is affecting your response to Nexviadyme, they may consider adding immunomodulatory therapy.

What Is the Correct Dosage of Nexviadyme?

The recommended dose of Nexviadyme is 20 mg per kilogram of body weight, administered as an intravenous infusion every two weeks. The dose is the same for adults, children, and elderly patients. In infantile-onset Pompe disease, a dose of 40 mg/kg may be used.

Nexviadyme is supplied as a lyophilised (freeze-dried) powder that must be reconstituted and diluted before infusion. The preparation and administration should be performed by or under the supervision of a healthcare professional experienced in treating patients with Pompe disease. Strict aseptic technique must be used throughout the reconstitution and dilution process.

Standard Dosing

Premedication

To reduce the risk and severity of infusion-associated reactions, patients typically receive premedication approximately 30 to 60 minutes before each infusion. A standard premedication regimen may include an antihistamine (such as diphenhydramine or cetirizine), a corticosteroid (such as methylprednisolone or dexamethasone), and an antipyretic (such as paracetamol/acetaminophen). The specific premedication protocol may vary based on institutional guidelines and the patient's history of infusion reactions.

Missed Dose

If you miss a scheduled infusion, contact your healthcare provider as soon as possible to arrange a replacement appointment. Maintaining the regular two-week infusion schedule is important for sustained enzyme activity and optimal treatment outcomes. Your doctor will advise on the best timing for the next infusion to restore the regular schedule.

Overdose

No cases of overdose with Nexviadyme have been reported in clinical trials. Excessive infusion rates may result in flushing and other infusion-related reactions. If an overdose or excessively rapid infusion rate occurs, the infusion should be slowed or temporarily stopped, and supportive care provided as clinically indicated. There is no specific antidote for avalglucosidase alfa.

Home Infusion

Home infusion of Nexviadyme may be considered for patients who meet specific eligibility criteria. The treating physician must confirm that the patient has been receiving infusions under medical supervision for several months, is medically stable, and has a documented pattern of well-tolerated infusions without moderate or severe infusion-associated reactions. The home infusion setting must have trained healthcare personnel present throughout the entire infusion and for an appropriate period afterwards. If any adverse reaction occurs during home infusion, the infusion must be stopped immediately and appropriate medical treatment initiated. Subsequent infusions may need to be given in a hospital or clinical setting until the patient can again be safely treated at home.

What Are the Side Effects of Nexviadyme?

The most common side effects of Nexviadyme are related to the intravenous infusion itself. Infusion-associated reactions occur in a significant proportion of patients and can include headache, nausea, rash, itching, and hypersensitivity. Most reactions are mild to moderate and manageable with premedication and infusion rate adjustments.

Like all medicines, Nexviadyme can cause side effects, although not everybody gets them. The side effects observed with Nexviadyme primarily occur during or shortly after the intravenous infusion. You should inform your healthcare provider immediately if you experience any symptoms during or after your infusion. Your doctor may slow down or temporarily stop the infusion and provide appropriate treatment.

The side effects observed in children and adolescents are similar to those seen in adults. Most infusion-related reactions are mild to moderate in severity and tend to decrease over time with continued treatment. If you experience recurrent or troublesome side effects, speak with your doctor about adjusting premedication protocols or infusion rates.

How Should You Store Nexviadyme?

Unopened vials of Nexviadyme must be stored in a refrigerator at 2°C to 8°C (36°F to 46°F). The medicine should not be frozen. After reconstitution and dilution, specific time and temperature limits apply to ensure product stability and sterility.

Proper storage of Nexviadyme is essential to maintain the integrity and efficacy of the enzyme. As a biological product, avalglucosidase alfa is sensitive to temperature and must be handled according to strict guidelines throughout the supply chain and at the point of administration.

Unopened Vials

Store in a refrigerator at 2°C to 8°C (36°F to 46°F). Do not freeze. Keep the vials in the outer carton to protect from light. Before reconstitution, remove the required number of vials from the refrigerator and allow them to reach room temperature for approximately 30 minutes.

After Reconstitution

Each vial is reconstituted with 10.0 mL of water for injections to yield a 10 mg/mL solution. Immediate use for dilution is recommended. If not used immediately, the reconstituted solution may be stored for up to 24 hours at 2°C to 8°C.

After Dilution

The diluted solution (in 5% glucose) should be used as soon as possible. If not administered immediately, it may be stored for up to 24 hours at 2°C to 8°C, followed by up to 9 hours at room temperature (up to 25°C / 77°F). The total time from reconstitution to the end of infusion should not exceed the combined storage periods.

Do not use Nexviadyme after the expiry date stated on the vial label and outer carton. The expiry date refers to the last day of that month. Do not dispose of medicines via household waste or wastewater. Ask your pharmacist about proper disposal methods for medications you no longer need. These measures help protect the environment.

What Does Nexviadyme Contain?

Each vial of Nexviadyme contains 100 mg of avalglucosidase alfa as the active substance. After reconstitution with 10 mL of water for injections, the resulting solution contains 10 mg/mL. The final concentration after dilution in 5% glucose ranges from 0.5 mg/mL to 4 mg/mL.

Active Ingredient

The active substance is avalglucosidase alfa, a recombinant human acid alpha-glucosidase produced by recombinant DNA technology in Chinese hamster ovary (CHO) cells. It has been specifically designed with a high proportion of mannose-6-phosphate (bis-M6P) glycans to enhance cellular uptake and lysosomal targeting.

Inactive Ingredients (Excipients)

• Histidine – acts as a buffer to maintain stable pH
• Histidine hydrochloride monohydrate – buffer component
• Glycine – stabilising agent
• Mannitol – bulking agent for lyophilisation
• Polysorbate 80 – surfactant to prevent protein aggregation

Appearance

Nexviadyme is supplied as a white to pale yellow lyophilised powder in a glass vial. After reconstitution, it forms a clear, colourless to pale yellow solution. The reconstituted solution must be further diluted in 5% glucose before infusion. Each pack may contain 1, 5, 10, or 25 vials, though not all pack sizes may be marketed in every country.

During reconstitution, the water for injections should be added slowly down the inside wall of the vial to avoid foaming. The vial should be gently tilted and rolled – never inverted, swirled, or shaken. The reconstituted solution should be visually inspected for particles and discolouration before dilution. Do not use if the solution is cloudy, contains visible particles, or is discoloured. A 0.2 µm in-line low-protein-binding filter is recommended during administration to remove any particles that may form during preparation. After the infusion is complete, flush the infusion line with 5% glucose solution. Nexviadyme must not be mixed with or infused through the same line as other medicinal products.