Pharmaceutical Technology

Chiesi widens rare disease portfolio with $1.9bn KalVista buyout

Chiesi will assume ownership of Ekterly, an on-demand pill approved for hereditary angioedema.

Chiesi has conducted the largest acquisition in its 90-year history, agreeing to buy KalVista Pharmaceuticals in a deal worth around $1.9bn.

The Italian pharma company will buy KalVista for $27 per share, representing a 36% premium to the US biotech’s stock at market close on 28 April. The deal is anticipated to close in Q3 2026.

The centre piece of the transaction is Ekterly (sebetralstat), KalVista’s drug for hereditary angioedema (HAE). The pill, which was approved by the US Food and Drug Administration (FDA) in June last year, represents a major advancement in treatment options for the genetic swelling disorder. Unlike BioCryst’s Orladeyo (berotralstat hydrochloride), which is taken daily for prophylaxis, Ekterly is administered following the onset of symptoms, offering patients an on-demand treatment.

Patients with HAE either lack C1 esterase inhibitor (C1INH) or have low activity of the protein. This causes painful and debilitating attacks of tissue swelling at various points in the body, which can, in some cases, be fatal.

HAE has traditionally been treated with injections that either counter an attack or are administered in a preventative manner. However, 2025 saw two new injections approved by the FDA – CSL Behring’s Andembry (garadacimab-gxii) and Ionis Pharmaceuticals’ Dawnzera (donidalorsen). These FDA nods came after four years of regulatory dormancy for HAE in the US.

Also approved in the UK, Europe, and Japan, Ekterly generated $49m in 2025 sales. Chiesi said the KalVista deal will bolster Chiesi Global Rare Diseases, its business unit marketing therapies in the sector. The pharma company also said that bringing the HAE pill on board will help reach its 2030 revenue target of €6bn ($7bn).

Giacomo Chiesi, executive vice president of Chiesi Global Rare Diseases, said: “This acquisition is a strong strategic fit for our rare disease portfolio and reflects our commitment to people living with rare conditions. In HAE, patients continue to face significant unmet needs, and KalVista’s innovation meaningfully expands our presence in rare immunology by adding a differentiated, on-demand treatment option that can bring meaningful advancement in how the disease can be managed.”

Chiesi’s acquisition comes in a week headlined by high-value dealmaking. This was led by Sun Pharma’s $11.75bn takeover of Organon, while Eli Lilly outlaid $2.3bn to acquire Ajax Therapeutics.