Allergan has been forced to write off the second of two drug candidates acquired when it took over Vitae Pharma less than two years ago.

The company’s chief R&D officer, David Nicholson, said on the first-quarter conference call that its lead retinoic acid receptor-related orphan receptor gamma, or RORγt, candidate VTP-3742 has been terminated "due to safety signals observed in the phase 2 studies."

Allergan took a $535 million charge in the quarter that it said was "primarily" due to the RORγT project in psoriasis.

While Nicholson went on to say that Allergan "continues to see RORγt as a valid target in drug discovery and are exploring alternative formulations and indications," the decision means that both drugs held up as the drivers for Allergan’s $639 million purchase of Vitae have now been dropped.

The other candidate—topical LXRβ (liver X receptor beta) selective agonist VTP-38543 for atopic dermatitis—was shelved in November 2016 after a failed phase 2 trial.

VTP-3742 had been held up as an orally active alternative to injectable antibody treatments like Novartis' fast-growing IL-17 inhibitor Cosentyx (secukinumab) for psoriasis and other autoimmune diseases. It was acquired by Allergan despite mixed efficacy results in a proof-of-concept trial and safety concerns including enzyme elevations that can point to liver damage.

Allergan would not provide much additional information on the safety issues that scuppered the program, but Nicholson told analysts that it observed "safety concerns at different doses of the compound … so we did the right thing. We killed early and we kill fast and we didn’t try to flee forward with that compound."

"RORγT remains a very exciting target for drug discovery," he continued. "It sits at the confluence of the IL-17, IL-23 pathways, which is so important in autoimmune disorders. So, I remain confident in RORγT as a target for drug discovery and development."

Allergan CEO Brent Saunders defended the decision to spend a high premium for Vitae, which was made during a particularly acquisitive spree by the company. He said the company’s success record when it comes to R&D "is better than those that rely solely on internal."

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