Rare Daily Staff

Solid Biosciences said it closed its initial public offering of more than 8.9 million shares of common stock at $16 per share despite a last-minute disclosure of a previously unannounced FDA partial clinical hold on its trial dating back to November and news that a prominent member of its scientific advisory board resigned over concerns about the safety of its gene therapy for Duchenne muscular dystrophy.

Despite the negative news prior consummating its IPO, the underwriters used the entire overallotment from the offering and the shares have performed well. Though the company’s $16 share price came below its $18 to $19 expected range, the stock has traded as high as $29.

James Wilson, a member of the company’s scientific advisory board resigned over concerns of possible risks associated with high systemic dosing of AAV, according to the company’s registration statement. Wilson is director of the Orphan Drug Center at the University of Pennsylvania’s Perelman School of Medicine and a pioneer in the field of gene therapy and an investigator in the 1999 trial that resulted in the death of patient that brought the field to a halt.

A peer-reviewed paper published online at the end of January in the journal Human Gene Therapy that looked at high-dose intravenous administration of a gene therapy for the neuromuscular disease using an AAV9 vector, which has been used to carry gene therapy in human infants with spinal muscular atrophy.

The study by Wilson and colleagues looked at high-dose AAV9 vector gene therapy in rhesus macaques and piglets. It found the animals developed severe liver and neuron damage. Gene therapy stocks broadly sold off on news of the study.

“The present results and those of another recent study utilizing a different AAV9 variant and transgene indicate that systemic and sensory neuron toxicity may be general properties of intravenous delivery of AAV vectors at high doses irrespective of the capsid serotype or transgene,” the study said. “Preclinical and clinical studies involving high systemic doses of AAV vectors should include careful monitoring for similar toxicities.”

As for the partial clinical hold on the Solid gene therapy trial, the company said the FDA has permitted it to proceed with administering its proposed low dose to patients. Prior to dosing patients in the higher-dose group, the company will be required to resolve the partial clinical hold on its SGT-001 gene therapy.

To do so, the company said it will need to decrease the number of vials and use no more than a single production lot per patient and demonstrate that it has the appropriate manufacturing processes in place to support the higher-dose group.

“We expect that we will be able to address the specific deficiencies identified by the FDA by submitting additional information demonstrating manufacturing capacity and product attributes that will support the high-dose group,” the company said.

February 1, 2018

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