Lack of knowledge about conditions, situations, or body ailments that are unexplainable often scares people and leads to people jumping to conclusions or say myths that are not at all backed by science and logic. Myths are a seemingly convenient way to explain what the mind perceives as unexplainable.
This, however, is not the case with only one rare condition. Rare Disease, the term itself can be quite misleading in the literal sense. The term implies that the cases and people affected with rare diseases are thin on the ground. Thus, it is easy for one to believe that rare is rare. Going by the definition, a rare disease affects fewer than 2,00,00 people in the US. However, over 300 million people are living with one or the other rare disease, with many others living still in dark about their condition owing to lack of knowledge.
For an instance, let us talk about a condition that causes severe pain upon sun exposure. Skin gets itchy, tingling, and turns red due to burning. Its signs and symptoms might have pointed out the existence of vampires. However, it is one of a group of disorders known as porphyrias, a rare condition, Erythropoietic protoporphyria (EPP). Now that this condition has an existence somewhere in the world, it seems quite settling and explanatory.
Erythropoietic protoporphyria is a rare inherited metabolic disorder that is a result of a deficiency or inappropriate functioning of the enzyme ferrochelatase (FECH) owing to mutations in the FECH gene. Ultimately, excessive amounts of protoporphyrin accumulate in the bone marrow, blood plasma, and red blood cells. Some patients with EPP often report another mutation in the ALAS2 gene, and this condition is referred to as X‐linked protoporphyria (XLPP).
At present, there is no cure for the treatment. The primary aim of most treatment options is to provide extra layers of protection from the sunlight. A multitude of treatment options ranging from medications to reduce protoporphyrin overproduction in the bone marrow to augment its excretion into bile. To leverage cytoprotective properties, other agents are also used in combination with measures to reduce the circulating pool of protoporphyrin and, on occasion, liver transplantation to correct end‐organ damage. Cutaneous protection is given with the help of opaque sunscreens. The only topical sunscreens effective at blocking wavelengths greater than 400 nm, with a high sun protection factor (>30), are light‐opaque, contain zinc oxide or titanium dioxide, and may be cosmetically unacceptable to some patients. Betacarotene is used to improve light tolerance significantly. However, some studies demonstrated a link between carotenoids and lung cancer mainly in smokers. A high potency form of oral beta‐carotene (Lumitene, Tishcon) is also used to improve an affected individual’s tolerance to sunlight. However, their efficacy remains debatable. Clinuvel Pharmaceuticals’ Scenesse (afamelanotide), an injectable implant, is approved in Europe and the US for the prevention of phototoxicity (anaphylactoid reactions and burns) in adult patients with Erythropoietic protoporphyria. The drug works by increasing skin pigmentation, which provides protection and improves sun tolerance.
Other treatment approaches include administration of Vitamin C and E, and cysteine (500 mg/twice daily), orally. Antihistamines are also available to help limit the phototoxic reaction.
To provide relief from acute skin symptoms, cold baths or wet towels, analgesics, and topical and/or oral corticosteroids are available. In cases, where the above-mentioned measures fail to work, hematin and/or red blood cell hypertransfusion (i.e., to above‐normal hemoglobin levels) may reduce protoporphyrin overproduction. Further, administration of bile acids can also facilitate biliary excretion of protoporphyrin. Oral cholestyramine or charcoal has been used to interrupt the enterohepatic circulation of protoporphyrin and increase fecal excretion.
EPP patients with end‐stage liver disease require liver transplantation. Hematopoietic stem cell transplantation is a curative option in the EPP treatment market, however, is not routinely done owing to safety concerns.
Overall, for effective treatment of EPP, a regimen constituting the judicious use of all available treatment options can help to prevent disease progression. However, Erythropoietic protoporphyria treatment aims to minimize direct sun damage, track the health and status of the liver, and stabilize cholestatic liver disease. Bone marrow transplantation has helped improve patient outcomes, however, the Erythropoietic protoporphyria market lacks a curative option.
Nevertheless, approval of scenesse gave the EPP market size growth a significant push. Besides, other pharmaceutical companies such as Mitsubishi Tanabe Pharma Corporation (MTPC) and others are proactively working to launch their novel therapeutic candidates in the EPP market in the near future. Dersimelagon (MT‐7117), a novel synthetic, orally‐administered, non‐peptide small molecule, has completed phase II trials successfully meeting primary endpoints. Dersimelagon is an investigational medication and not approved by the FDA, however, had been granted fast track designation. If the drug gets approval, it will be the first oral treatment option for EPP and the company believes that it could be a clinically meaningful alternative for patients.
Erythropoietic protoporphyria poses a huge burden to healthcare. It causes huge distress to the younger population. Further, lack of proper diagnosis adds to the conundrums as it often leads to liver damage. The rarity of the disease makes it difficult for researchers to study, and run clinical trials for its therapies. Although, much of the symptoms and sequelae can be relieved using topical creams, however, an effective standard cure is still in the far sight. Conclusively, knowledge of the disorder, its signs, and symptoms, advanced diagnostics technologies, and EPP emerging therapies are expected to make a visible shift in the Erythropoietic protoporphyria market.