SiSaf Announces Michael J. Econs MD, World-leading Expert in Metabolic Bone Disease, as Clinical Advisor

Guildford, England

27 January 2022

SiSaf Ltd, a company developing RNA therapeutics for rare genetic skeletal disorders, today announced that it has appointed Professor Michael J. Econs, MD as Clinical Advisor.

Distinguished Professor of Medicine and Medical and Molecular Genetics at Indiana University School of Medicine, Professor Econs is director of the division of Endocrinology and Metabolism, and a world leading expert in the area of metabolic bone disease.

In addition to his role as Clinical Advisor to the company, Professor Econs has agreed to be Principal Investigator in the planned Phase I clinical study of SiSaf’s lead programme, SiS-101-ADO2, being developed for the treatment of autosomal dominant osteopetrosis type 2 (ADO2), a therapeutically neglected rare autosomal dominant disorder. He is supporting the trial design for the IND package with the aim of submitting an application to the U.S. FDA during H2 2022.

Mutant gene expressed by osteoclasts and other cell types is responsible for ADO2 in adults. SiS-101-ADO2 is an ADO2-specific siRNA combined with SiSaf’s Bio-Courier platform that downregulates the expression of the mutant CLCN7 gene and rescues bone mass and quality to nearly normal levels.

Dr Econ’s lab is currently performing translational studies in ADO2 using its mouse model of the disease and has initiated a natural history study in ADO2 patients, which will support endpoint design and study evaluation.

Given the urgent medical need in ADO2 patients and the lack of any existing therapies, SiSaf intends to file for Orphan Drug Designation for its therapy.

Dr Econ’s past research led to the discovery of FGF23, which provided the foundation for the first new therapy in over 30 years for X-linked hypophosphatemic rickets (XLH) and tumour induced osteomalacia. His work to describe novel clinical features of autosomal dominant hypophosphatemia rickets (ADHR) led to an understanding of the relationship between iron deficiency and increases in FGF23.

SiSaf’s CEO Dr Suzanne Saffie-Siebert said, “I am delighted that Michael has agreed to help us realise our goal to develop safe, effective and accessible RNA therapies for bone diseases with very high unmet needs using our silicon stabilized hybrid lipid nanoparticles.

Michael brings a wealth of knowledge and highly relevant expertise in translational studies. He previously led the clinical studies of Interferon Gamma-1b for the treatment of ADO2. Although this did not show clinical benefit, the experience gained will be invaluable in guiding SiSaf in its clinical studies.”

Professor Michael J. Econs, MD said, “SiSaf is founded on transformational science, and I am looking forward to supporting the Company’s ADO2 programme and to delivering on the promise of RNA therapeutics to transform the treatment of genetic diseases in bone and more widely.”



SiSaf is delivering on the promise of RNA therapeutics to transform the treatment of genetic diseases. It has developed the Bio-Courier® platform of silicon-based delivery technologies, which include silicon stabilized hybrid lipid nanoparticles (sshLNPTM). SiSaf is using these next-generation lipid nanoparticles to advance an in-house pipeline of RNA therapeutics for rare genetic skeletal disorders.

Being a bioabsorbable silicon-lipid hybrid, sshLNP optimize the delivery of gene therapeutics, offering superior stability and protection of its payload and lipids while reducing the potential of adverse immune events.

Founded by entrepreneur and leading biomaterials specialist Dr Suzanne Saffie-Siebert, SiSaf is headquartered in Guildford, UK, with fully integrated state-of-the-art research labs, pilot manufacturing and bioanalytical facilities. SiSaf partners with speciality pharmaceutical companies to maximize the potential applications of its Bio-Courier platform.

SiSaf is a private company supported by venture capital investors including Vickers Venture Partners & UK Future Fund.

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