As Ectory approaches one year since its FDA approval, Italy’s Chiesi Group is moving to acquire rare disease drugs and their developer, Calvista Pharmaceuticals.
According to an April 29 press release, Chiesi has finalized its offer to acquire KalVista for $27 per share in cash, for a total purchase price of $1.9 billion. The proposed amount is the largest transaction in Chiesi Pharmaceuticals’ nearly 100-year history and represents a 36% premium to Calvista’s stock price as of April 28, the companies announced on Wednesday.
Chiesi is positioning the transaction, which is expected to close in the third quarter, as a way to strengthen its position in rare diseases, where Chiesi’s Chiesi Global Rare Diseases division already has significant business.
The centerpiece of the deal is Calvista’s oral treatment for hereditary angioedema (HAE), Ectary, which overcame regulatory delays to win FDA approval last July, becoming the Massachusetts biotech’s first product.
Upon completion of the agreement, Mr. Chiesi will assume responsibility for the development of the plasma kallikrein inhibitor, also known as sevetralstat.
HAE is a rare genetic disease that causes a deficiency or malfunction of the C1 esterase inhibitor (C1INH) protein, which can cause tissue swelling and painful and debilitating attacks in various parts of the body. These attacks can be fatal depending on the part of the body affected.
Unlike several medications that have been approved for the prevention of HAE attacks, Ecutary is the first oral medication specifically approved for the on-demand treatment of HAE attacks.
Chiesi aims to accelerate patient access and strengthen scientific engagement regarding Ekterly. The Italian drugmaker expects Extery to make a “significant contribution” to its goal of reaching 6 billion euros in sales in 2030, adding that the addition of the product will significantly expand its presence in the U.S. market.
Indeed, from “day one,” Chiesi will focus on “working closely with the HAE and scientific communities to improve disease management and ensure more patients benefit from timely and effective treatments,” Chiesi global rare disease vice president Giacomo Chiesi said in a statement.
Besides the US, Ekterly has also received the green light in the UK, Japan, and the European Union. Chiesi and KalVista said Ekterly generated sales of $49 million through 2025, about half of its calendar year on the market after medical approval in July.
Chiesi has made a number of other big-ticket deals and expenditures since early 2025, most notably last March when it submitted 430 million euros (equivalent to about $464 million at the time) to build a new facility in Milan for inhalers and other health products, as well as to revitalize an old production site in Milan.
Separately, the family-owned company joined Arbor Biotechnologies’ rare disease gene therapy efforts in October, paying $115 million upfront for the rights to develop and commercialize ABO-101, a liver-targeted gene therapy for the ultra-rare genetic disease primary hyperoxaluria type 1 (PH1), along with hundreds of millions of dollars in bioback potential. The deal also allows Chiesi to use Arbor’s editing technology for other potential disease treatments.
Elsewhere in Chiesi’s commercial rare disease portfolio, the company already boasts multiple products, including epidermolysis bullosa treatment Filsuvez, lipodystrophy treatment Myalept, and Fabry disease treatment Elfabrio.
