Chiesi signs $1.9bn deal to buy KalVista and its HAE drug

Italian pharma group Chiesi has bolstered its rare disease business with an agreement to buy US biopharma KalVista Pharma and Ekterly, the first oral drug for treating exacerbations of the rare disease hereditary angioedema (HAE).

Chiesi is offering $27-per-share for Framingham, Massachusetts-based KalVista, valuing the company at around $1.9 billion, and said it hopes to complete the acquisition in the third quarter of this year.

Oral kallikrein inhibitor Ekterly (sebetralstat) was approved by the FDA last July for on-demand treatment of HAE attacks, the unpredictable bouts of debilitating and painful swelling in various parts of the body that characterise the disease, in patients aged 12 and over.

In March, KalVista said the product had made just over $49 million in sales from its launch on 7th July to the end of 2025, with around 1,700 patients starting on the drug over that time and most of the revenue booked in the fourth quarter coming from refills.

Overseas, Ekterly has started to roll out in Germany, as well as in Japan, where it is licensed to Kaken Pharma, and has been approved in the EU, UK, Switzerland, Australia, and Singapore.

Analysts at Jefferies have previously said that Ekterly could make sales of around $500 million a year in the US and Europe as the first oral alternative to injectable on-demand therapies for attacks such as Takeda's bradykinin B2 receptor antagonist Firazyr (icatibant) and plasma kallikrein inhibitor Kalbitor (ecallantide), and Pharming's Ruconest and CSL Behring's Berinert, which are both recombinant C1 esterase inhibitors.

Chiesi said that if the acquisition goes through, it expects the product to "meaningfully contribute" to its 2030 target of building annual revenues to €6 billion ($7 billion) or more from a 2025 level of €3.6 billion.

KalVista is also working on expanding Ekterly's label, with studies exploring its use for treating HAE attacks in children aged two to 11.

"This acquisition supports our strategy to accelerate impact in rare diseases by bringing together science, innovation and expertise to address areas of highest unmet need," said Chiesi's interim group chief executive, Jean-Marc Bellemin, who stepped in to lead the company after Giuseppe Accogli said he was leaving to pursue another opportunity.

"KalVista's proven drug discovery and development capabilities, combined with our global footprint and operational excellence, will enable us to deliver innovation to patients at greater scale," he added.

If the deal completes, it will be the largest acquisition in Chiesi's nearly 100-year history, coming in ahead of its takeover of $25 billion purchase of Amryt Pharma, another rare disease specialist, in 2023.