Roller-coaster ride for Solid Bio ahead of downsized IPO

Solid Biosciences’ plans for an IPO looked in disarray after it revealed that the FDA had placed a clinical hold on its Duchenne muscular dystrophy gene therapy candidate yesterday. But it pressed on—with a cut-price offering for an upsized stake.

The biotech priced the offering at $16 per share—below its plan of $18-$19—and increased the number of shares issued to 7.8 million from 5.9 million, to bring in gross proceeds of around $125 million. Underwriters have a 30-day option on another 1.1 million shares at the IPO price.

Solid’s scramble to rejig the IPO came after at added a disclosure to the IPO prospects via an SEC filing, which revealed that the FDA has implemented a partial clinical hold on a phase 1/2 trial of DMD therapy SGT-001—its lead therapy—preventing the company from proceeding to tests of a higher-dose cohort.

The announcement attracted some heavy flack for the company on Twitter, perturbed that the filing indicates that the FDA informed the company of the hold by letter back in November. The setback wasn’t disclosed in Solid’s IPO prospectus in December, or indeed in subsequent filings, but still went ahead—reflecting the bullish climate for biotech stocks at the moment.

Solid can continue to dose patients in the lower-dose SGT-001 cohort but says that to progress to the higher dose—which accounts for half the 32-patient study—it will have to “decrease the number of vials and utilize no more than a single production lot per patient and demonstrate that we have the appropriate manufacturing processes in place to support the higher-dose group.”

The company said it intends to submit a response to the FDA soon and does not expect the timing for completing the trial to be affected. It acknowledged, however, that if the agency doesn’t lift the hold “we may be unable to continue or complete our clinical trial” which would put the future of SGT-001 in jeopardy.

Late disclosure aside, there are other concerns about Solid’s lead program. Earlier this month, one of the company’s key scientific advisors, eminent gene therapy specialist James Wilson of the University of Pennsylvania, resigned his position citing “emerging concerns about the possible risks of high systemic dosing” of adeno-associated virus (AAV) vectors—the vector technology used in SGT-001.

In a filing to disclose Wilson’s departure from the advisory board, Solid said that it had seen integration of AAV into host cell genomes, which is not usually expected to occur with this viral vector.

Solid’s Nasdaq-listed shares are due to make their debut this morning, and all eyes will be on the early performance of the stock in light of the tumultuous events leading up to the IPO.

Editor's note: This story has been updated to correct the name of Solid Bio's Duchenne muscular dystrophy treatment. It is SGT-001, not SGT-100.