Investing in another company's drug to advance your own

On September 28, AstraZeneca announced a $2 billion investment in Summit Therapeutics alongside a collaboration on combination cancer treatments. The aim is to combine Summit's ivonescimab with several of AstraZeneca's antibody–drug conjugates (ADCs), starting with Sone-Ve for gastrointestinal cancers. On October 2, Daiichi Sankyo joined a separate collaboration to evaluate ivonescimab with Datroway. AstraZeneca announcement ↗ Datroway collaboration ↗

ADCs use an antibody to deliver a cytotoxic drug. Ivonescimab, by contrast, targets PD-1 and VEGF, acting on immune responses and blood-vessel formation. The development strategy is to improve treatment outcomes by combining different mechanisms.

What distinguishes this deal is the substantial equity investment alongside the joint trials. Each company retains development and commercial rights to its own drug while sharing trial supplies and costs. Rather than buying the partner's drug, AstraZeneca is building a relationship in which progress on that drug can advance its own. Agreement overview ↗

An established development model in oncology

Cross-company combination development is no longer unusual. Regeneron says that, alongside its collaboration with BioNTech, more than 12 supply and clinical collaborations involving its PD-1 inhibitor are under way. One drug can become a partner for candidates from several companies. Regeneron collaborations ↗

Some combinations have already reached approval. In June 2026, the FDA approved Gilead's ADC Trodelvy with Merck's immune checkpoint inhibitor Keytruda as a first-line treatment for certain patients with PD-L1-positive advanced triple-negative breast cancer. Datroway's developers are therefore competing to establish a difference in a market where ADC–immunotherapy combinations are beginning to enter clinical practice. FDA approval announcement ↗

Outside cancer, combinations serve different purposes

In HIV, Gilead and Merck are jointly developing lenacapavir and islatravir as a once-weekly oral treatment. The plan draws on the long-acting properties of two drugs that target different parts of the viral life cycle. Their agreement covers not just trials, but joint development, commercialisation and revenue sharing. Gilead–Merck agreement ↗

In June 2026, the companies reported that two Phase 3 studies in people whose virus was already suppressed met their primary endpoints, demonstrating non-inferiority to existing daily treatment at week 48. The intended benefit is not only virological control, but less frequent dosing. Phase 3 topline results ↗

Imlifidase, marketed as Idefirix, is an enzyme drug that cleaves IgG antibodies already present in the body. In the EU, it is used before kidney transplantation in certain adults whose antibodies against a donor make transplantation difficult. It temporarily reduces antibody-mediated rejection to make transplantation possible; patients still require standard immunosuppressive treatment afterwards. EMA overview ↗

It does not selectively cleave only anti-AAV antibodies: it also acts on IgG involved in defence against infection. Antibodies subsequently rise again. Its proposed use in gene therapy seeks to exploit this temporary period of reduced antibody activity to make AAV-mediated gene transfer possible. Product information ↗ Gene-therapy development agreement ↗

In its agreement with Sarepta, Hansa arranged to receive not only revenue from its own drug, but also royalties on gene therapies made accessible through the pretreatment. Without owning the gene therapy itself, Hansa linked its enabling role to the partner's sales. Hansa–Sarepta agreement ↗

This development effort has not, however, established success. In three Duchenne muscular dystrophy cases reported in 2025, antibody reduction allowed treatment to be administered, but expression of the protein encoded by the delivered gene was lower than in other studies. Sarepta now lists the trial as terminated. Removing a barrier to administration did not necessarily deliver sufficient benefit beyond it. Hansa report ↗ Sarepta clinical trial list ↗

Combinations of cell therapies and drugs are also being explored in autoimmune disease. Artiva is combining its investigational NK-cell product AlloNK with the anti-CD20 antibody rituximab to deplete B cells in rheumatoid arthritis and other conditions. The antibody recognises the target and NK cells help eliminate it. In May 2026, the company outlined a randomised trial comparing the combination with rituximab alone. This is an example of combining therapeutic technologies, not evidence of a commercial partnership with the antibody manufacturer. Artiva development plans ↗

Collaboration is likely to continue, but not in a single form

There are reasons for these programmes to continue. It is difficult for one company to hold the best option across antibodies, nucleic acids, cells and delivery technologies. The intended gains also differ: greater efficacy, fewer doses or the ability to treat more patients.

The business structures therefore differ too. Do the companies each sell their own drug, share revenue from a joint product, or receive royalties on a partner's sales? The scientific contribution each makes is reflected in the contract.

AstraZeneca's investment can be read as a decision to extend this complementary relationship across several of its drugs rather than confine it to one trial. Supporting its partner's development capacity may expand the scope of its own programmes. It committed $2 billion to that relationship.