With a $128 million series A financing, Diagonal Therapeutics Inc. launched to develop its lead program using agonist antibodies for treating, among other indications, the rare disease hereditary hemorrhagic telangiectasia. The antibodies are designed to activate a receptor complex in the TGF-β superfamily genetically impaired in patients with the bleeding disorder. Diagonal also is developing a treatment for the orphan disease pulmonary arterial hypertension.