AstraZeneca said on Friday its Alexion unit had agreed to buy US drugmaker Pfizer’s early-stage rare disease gene therapy portfolio for up to $1 billion, plus royalties on sales, as the British drugmaker bets on new genetic therapies.

The British company also said Sharon Barr, head of research and development at Alexion, would succeed Mene Pangalos, the long-time biopharmaceuticals head of research at AstraZeneca.

Pangalos was the public face of the company’s COVID vaccine.

AstraZeneca bought Alexion for $39 billion in 2021. It focuses on rare diseases and plans to close the deal with Pfizer in the third quarter.

The deal will bring a number of novel adeno-associated virus (AAV) capsids to Alexion and help build on Alexion and AstraZeneca’s capabilities in genomic medicine.

AAV capsids have been shown to be an effective mechanism for delivering therapeutic gene cargos for gene therapy and gene editing, the company said.

AstraZeneca last October also bought US-based gene therapy developer LogicBio Therapeutics for $68 million, a huge 660% premium. Drugmakers including AstraZeneca, Merck & Co and AbbVie said in April they were open to acquisitions.

A drop in valuation of smaller US biotech companies from pandemic highs has made deals more attractive.

AstraZeneca in January also struck a deal to buy US-based drug developer CinCor Pharma for up to $1.8 billion to increase its stock of heart and kidney drugs.

Separately on Friday, AstraZeneca delivered better-than-expected profits and sales in the second quarter as a strong performance of its blockbuster cancer drugs helped offset the loss of COVID vaccine sales.