The FDA has slapped a clinical hold on a Phase Ib trial of Vyne Therapeutics’ investigational BET blocker VYN202 for plaque psoriasis, the biotech revealed Friday.
The regulatory freeze stems from testicular toxicity observed in dogs during a toxicology study of the asset. Following this safety signal, Vyne has also suspended screening, enrollment and dosing of all patients in the early-stage trial—though it maintains that no serious adverse events have been documented in this study to date.
Vyne was down 28% in pre-market trading Friday after the news broke. The biotech is trading at $1.35 per share, down from $1.88 at the previous market close.
“We are disappointed by this unexpected development,” Vyne CEO David Domzalski said in a statement, adding that the biotech’s top priority is the safety of its trial participants. Domzalski committed to working closely with the FDA to resolve the safety issue and determine the next steps forward for VYN202.
Importantly, Vyne clarified that the clinical hold on VYN202 will not affect its ongoing Phase IIb study of repibresib gel in vitiligo. Repibresib, which similarly targets the BET protein but acts via a different pathway, “is a distinct and unique compound from VYN202,” according to the company. Vyne expects to release topline Phase IIb data for the gel by mid-year.
Designed to be taken orally, VYN202 works by binding to specific part of the BET protein, which is an important player in the regulation of genes involved in inflammation and oncogenesis, as per Vyne’s website. Broadly, BET proteins consist of two bromo-domain subunits—dubbed BD1 and BD2—and an extra-terminal domain.
Whereas the locally administered repibresib shows broad activity and binds to both BD domains, VYN202 selectively seeks out BD2. According to Vyne, this specific binding activity of VYN202 “may be the key to optimizing the benefit/risk profile of BET inhibitors for autoimmune diseases.” The biotech is testing VYN202 for moderate-to-severe plaque psoriasis and rheumatoid arthritis.
Vyne’s clinical pause is the latest development in what has turned out to be a busy week for the immunology & inflammation space. On Thursday, Swiss startup Granite Bio debuted with $100 million to advance two antibody therapies for autoimmune diseases. Granite has a star-studded support line-up that includes Sanofi Ventures, Novartis Venture Fund, Versant Ventures and Forbion.
On Wednesday, the field saw a deal between Genentech and Flagship Pioneering’s Repertoire Immune Medicines worth a potential $765 million. The partners will work together to discover and develop therapies that target T cells, though their priority autoimmune indication has yet to be disclosed.
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