Allergan ($AGN) has continued on its post-Pfizer ($PFE) deal-that-never-was M&A spree with a $639 million deal to acquire small cap dermatology biotech Vitae Pharmaceuticals ($VTAE).

The deal, worth $21 a share, is a major premium on the $8 a share it was trading on last night before the acquisition was announced, when it had a market cap of $238 million.

Allergan buys into the Fort Washington, PA-based biotech’s dermatology pipeline that includes VTP-43742, a midstage, first-in-class, orally active ROR?t (retinoic acid receptor-related orphan receptor gamma) inhibitor for the potential treatment of psoriasis, as well as other autoimmune disorders.