Italy-based Chiesi Group has completed its acquisition of Framingham, Massachusetts-based KalVista Pharmaceuticals (Nasdaq: KALV) for USD 27.00 per share in cash, representing total equity consideration of approximately USD 1.9 billion, in the largest acquisition in Chiesi's history by transaction value. The deal - first announced in April - delivers Ekterly (sebetralstat), the first approved oral on-demand plasma kallikrein inhibitor for hereditary angioedema (HAE), directly into Chiesi's Global Rare Diseases business unit and materially expands the Italy-based group's commercial infrastructure in the United States.
Chiesi conducted a tender offer through a wholly owned subsidiary, acquiring approximately 77.8% of KalVista's outstanding shares by the offer's expiration. The remaining shares were cancelled and converted into the right to receive the same USD 27.00 per share in cash through a subsequent merger, at which point KalVista became a wholly owned subsidiary of Chiesi and its common stock ceased trading on Nasdaq. The transaction carried no financing condition and was structured as an all-cash deal with no contingent value rights or milestone components. Lazard served as exclusive financial advisor to Chiesi; Centerview Partners acted as financial advisor to KalVista.
Sebetralstat is an oral, small-molecule inhibitor of plasma kallikrein, the serine protease responsible for bradykinin generation in the kallikrein-kinin system. In HAE, deficiency or dysfunction of C1 esterase inhibitor leads to uncontrolled kallikrein activation, producing recurrent episodes of subcutaneous and submucosal swelling. Ekterly is approved in the US, EU, UK, Switzerland, Australia, Singapore, and Japan for on-demand treatment of acute HAE attacks in patients aged 12 years and older, and is the first oral agent in this class to reach approval for acute attack management. Following its US commercial launch in July 2025, sebetralstat generated USD 49 million in sales for the year. A regulatory submission to expand the indication to children aged 2 to 11 is supported by the KONFIDENT-KID trial. Chiesi assumes responsibility for pre-existing regional licensing arrangements, including exclusive rights held by Kaken Pharmaceutical in Japan, Pendopharm in Canada, and Multicare Pharmaceuticals across Latin America.
The HAE space has attracted significant M&A activity as acquirers seek approved or late-stage assets in a market where the injectable standard of care remains the dominant treatment modality. BioCryst Pharmaceuticals' acquisition of Astria Therapeutics for approximately USD 700 million centered on navenibart, a long-acting injectable monoclonal antibody targeting plasma kallikrein for HAE prophylaxis that was in Phase III at the time. The approximately 2.7-fold premium in the Chiesi transaction relative to that deal reflects the distinction between sebetralstat's status as an already-commercialized, revenue-generating oral asset and a pre-approval prophylactic program. The competitive pipeline continues to evolve: Argo Biopharma's siRNA therapy BW-20805 recently received US FDA Fast Track designation for HAE, illustrating that next-generation modalities are advancing toward clinical proof-of-concept and reinforcing the strategic value of securing an approved oral asset with an established commercial trajectory.