The FDA Office of Orphan Products Development (OOPD) has granted Orphan Drug designation to Protalex’s PRTX-100 for the treatment of immune thrombocytopenia (ITP). PRTX-100, Protalex’s lead product, is a highly purified form of Staphylococcal Protein A. The FDA previously accepted the company’s IND application for a phase I/II open-label, dose-escalating study of PRTX-100 in adults with persistent/chronic ITP. Protalex expects to enroll its first patient in an ITP study in the third quarter of 2015.

The OOPD is tasked with evaluating the scientific and clinical data submissions from sponsors to identify and designate products as promising for rare diseases and to further advance scientific development of such promising medical products. Orphan Drug designation provides certain exclusivity benefits, tax credits for certain research and a waiver of the NDA user fee. ITP is recognized by the FDA as an orphan disease, usually defined as a condition that affects fewer than 200,000 people nationwide.

ITP is an autoimmune-mediated condition characterized by bruising and increased bleeding as a result of immune-mediated accelerated destruction of platelets and impaired production of platelets. The diagnosis of ITP is based upon a low platelet count, usually less than 100,000 per microliter of blood, in the absence of other possible causes of reduced platelet numbers such as an underlying illness or medication.

“The FDA’s timely approval of our request for Orphan Drug designation for PRTX-100 to treat ITP is a key milestone that supports our broader strategy of bringing this potentially life-saving therapy to patients with ITP,” said William E. Gannon, M.D., chief medical officer of Protalex. “ITP is a chronic, debilitating disease. There are patients who do not respond to current treatment options or cannot maintain an increased platelet count requiring ongoing or additional treatment. Patients also may experience adverse events or are unable to tolerate current therapies, limiting their ability to continue treatment. So there is a need for new agents that treat the underlying mechanisms of ITP and provide effective, safe and well tolerated treatments that also are convenient for patients with ITP. We look forward to enrolling patients in our phase I/II clinical trials of PRTX-100 to treat patients with ITP and expect to have top-line data in 2016.”

The two most recently approved drugs used to treat ITP, Nplate (romiplostin) and Promacta (eltrombopag), both increase the production of platelets but do not appear to affect the underlying platelet destruction process. In contrast, preclinical data indicate that PRTX-100 may have the potential to treat ITP by reducing the immune-mediated destruction of the platelets. Furthermore, PRTX-100 has established an acceptable safety profile based on data from patients treated in five clinical studies including patients with rheumatoid arthritis, another autoimmune disease.