In the United States, Orphan Drug designation is granted to drugs or biologics intended to treat, prevent, or diagnose rare diseases or conditions. Rare conditions are defined as those affecting under 200,000 U.S. citizens. As a benefit for drug developers, this designation also comes with incentives such as fee waivers, tax credits, increased regulatory assistance, and 7 years of market exclusivity upon approval. In early March 2022, Targeted Oncology reported that the FDA granted Orphan Drug designation to HT-KIT, designed for those with mastocytosis.
Developed by Hoth Therapeutics (“Hoth”), HT-KIT is a new molecular entity (NME) which is being designed to treat anaphylaxis and mast-cell derived cancers. According to Hoth, the treatment targets the tyrosine kinase KIT receptor. This receptor plays a role in hematopoietic stem cell proliferation and differentiation in mast cells. However, mutations within the KIT pathway have been linked with different cancers. KIT also plays a role in anaphylaxis.
The Orphan Drug designation hinges on data from preclinical studies which found that HT-KIT prevented tumor growth and the spread of mastocytosis symptoms; caused the death of neoplastic mast cells; and slowed cancer progression in malignant mast cells.
About Mastocytosis
Genetic mutations, which cause overactive mast cell receptors, cause nearly all adult-onset mastocytosis diagnoses and around 80% of pediatric diagnoses. These mutations are typically spontaneous rather than inherited. Mastocytosis is a chronic condition in which an abnormal amount of mast cells, a type of immune cell, builds up in the skin, bone marrow, liver, spleen, lymph nodes, or gastrointestinal tract. Normally, mast cells play a role in healing and protecting against foreign invaders. However, when abnormal amounts build up, it can cause a variety of different health issues.
Various subtypes of mastocytosis exist and these subtypes range in both severity and symptoms. For example, cutaneous mastocytosis impacts the skin and causes the appearance of flat, brown spots which become more obvious the more the skin is scratched. These lesions may blister, especially in young children. If this subtype progresses to become diffuse cutaneous mastocytosis, it may also manifest in thickened skin, gastrointestinal bleeding, diarrhea, intense itchiness, and anaphylactic shock.
Another form of mastocytosis is systematic mastocytosis, which is more common in adult patients. Those with this form often do not have skin manifestations. However, they may experience impaired liver or bone marrow function, an enlarged liver or spleen, abdominal discomfort, or softened bones.
Learn more about mastocytosis.
