Therapy for rare skeletal disorder granted orphan status


The US Food and Drug Administration (FDA) has granted Orphan Drug Designation to SiSaf’s small interfering RNA (siRNA) therapeutic for skeletal disorder Autosomal Dominant Osteopetrosis Type 2 (ADO2).

In addition, due to the serious manifestations of this rare disease in children, SIS-101-ADO has been granted Rare Pediatric Disease Designation for the treatment of Autosomal Dominant Osteopetrosis.

FDA Orphan Drug Designation provides SiSaf with incentives such as tax credits for clinical trials, exemption from user fees, and expanded marketplace exclusivity. The Rare Pediatric Disease Designation entitles the company to apply for a priority review voucher that can be used to have the drug approval process expedited by the FDA.

The FDA awarded SIS-101-ADO Rare Pediatric Disease Designation on the basis of the serious or life-threatening manifestations of ADO that primarily affect children including blindness from optic nerve compression, anomalies in dental and craniofacial development, and scoliosis.

There are currently no approved treatments for Osteopetrosis ADO2 and no other treatments currently in clinical trials. SiSaf is currently preparing for first-in-human clinical trials.

SIS-101-ADO combines an siRNA that suppresses the expression of CLCN7 with Bio-Courier delivery technology. By downregulating the expression of CLCN7, a mutant gene expressed by osteoclasts and other cell types responsible for causing ADO2, the RNA therapy restores bone mass and quality to nearly normal levels.

SiSaf’s Founder and CEO, Dr Suzanne Saffie-Siebert, said, “Being granted Orphan Drug Designation and Rare Pediatric Disease Designation is a major milestone in our drive to move our revolutionary siRNA treatment forward to alleviate the pain and suffering that Osteopetrosis ADO2 inflicts. SIS-101-ADO ushers in the potential for a new era of personalised care and treatment options for ADO2 and other rare bone and skeletal diseases.”

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