AstraZeneca has struck a $1bn (£773m) deal to buy a Belgian biotech company that specialises in cancer immunotherapies, the latest in a string of acquisitions that also yielded positive results for a late-stage rare disease drug on Monday.

EsoBiotec, a small privately held firm , develops in-vivo CAR-T cell therapies that empower the immune system to attack cancers, and could offer many more patients access to cell therapy treatments, provided in minutes rather than weeks.

The deal marks the latest acquisition by AstraZeneca, which is Britain’s biggest listed company valued at £184bn, as the pharmaceutical group continues to expand its global operations. Its share price fell by 1% on Monday morning.

EsoBiotec’s approach uses highly targeted lentiviruses to deliver genetic instructions to specific immune cells, such as T-cells, which program them to recognise and destroy tumour cells for cancer treatment, or tackle autoreactive cells (that target the body’s own tissues or cells) for potential use in autoimmune diseases. This means cell therapies can be given through a simple injection.

The EsoBiotec chief executive, Jean-Pierre Latere, described them as “cost-effective, off-the-shelf therapies” that use the patient’s own body in vivo to produce the treatment. “It’s super effective. Effectively it turns the patient into a factory,” he said.

He founded the business four years ago after serving as chief operating officer of the Belgian biotech company Celyad Oncology and working for the US chemical producer Dow Corning, having begun his career as a senior scientist at the US drugmaker Johnson & Johnson.

EsoBiotec, which is based in Mont-Saint-Guibert in Walloon Brabant, is backed by the Benelux venture capital groupd UCB Ventures, SRIW Life Sciences, Thuja Capital and Sambrinvest.

The company’s approach is much quicker and less complicated than traditional cell therapies, where cells are taken from a patient, genetically modified outside the body, and then put back into the patient as a medicine after immune cell depletion. This can take three to five weeks and costs $450,000 to $500,00 for each treatment.

Susan Galbraith, the executive vice-president of oncology research and development at AstraZeneca, said the company had been “looking for things out of the ordinary” and negotiated the deal quickly after seeing EsoBiotec present data from its first patient at JP Morgan’s healthcare conference in San Francisco in mid-January. In December, the Belgian group launched a clinical trial for its lead product for multiple myeloma, a type of bone marrow cancer, to demonstrate proof of concept for the technology.

Galbraith added: “We believe it has the potential to transform cell therapy and will enable us to scale these innovative treatments so that many more patients around the world can access them.”

She said only 10% to 20% of people who could benefit from cell therapy can obtain it at the moment because clinics in many countries are not set up for the weeks-long process, whereas EsoBiotec’s technology means treatments can be given as a simple infusion “at a fraction” of the cost of traditional cures. If trials show the approach works, it could ease the pressure on health systems including the NHS. AstraZeneca has seven cell therapy programmes in its pipeline.

AstraZeneca, which fended off a hostile £69bn takeover approach from the US drugmaker Pfizer in 2014, will pay $425m initially for the Belgian company, and up to $575m based on development and regulatory milestones. It has been beefing up its drug portfolio with targeted acquisitions, such as China’s Gracell Biotechnologies, which also develops CAR-T cancer therapies.

AstraZeneca’s biggest deal was the $39bn acquisition of the US rare disease drug developer Alexion in 2020, but it was criticised for paying a high price. Marc Dunoyer, who runs the division and is AstraZeneca’s chief strategy officer, defended the deal as a “fantastic acquisition” last month when the company took a $753m hit for scrapping one of the Alexion drugs, while two other products from the acquisition have also been abandoned.

Separately, Britain’s biggest pharmaceutical company said on Monday that its Imfinzi treatment had been approved in the EU as the first and only immunotherapy for patients with limited-stage small cell lung cancer, whose disease has not progressed after platinum-based chemoradiation therapy.

AstraZeneca also announced that a drug for a rare endocrine disease, hypoparathyroidism, which can lead to bone density loss and osteoporosis, had met its goal of normalising calcium levels in the blood after 24 weeks. It was well tolerated by patients, and the trial continues as planned to 52 weeks. The company acquired the medicine along with the French rare disease specialist Amolyt Pharma in a deal worth more than $1bn a year ago.