GSK’s Cancer Comeback Just Passed Another Important Test

GSK and Hansoh Pharmaceutical’s experimental drug Ris-Rez has met the main goal of a late-stage trial in patients with relapsed or treatment-resistant osteosarcoma. The result could support a future regulatory application while strengthening GSK’s wider effort to rebuild its cancer business around targeted treatments capable of working across several tumour types.

GSK’s effort to rebuild its cancer business has received another boost after an experimental treatment succeeded in a late-stage trial for one of the most aggressive forms of bone cancer.

Risvutatug rezetecan, known as Ris-Rez, met the main goal of a Phase 3 trial involving patients with osteosarcoma whose cancer had returned or stopped responding to previous treatments.

The study found that patients receiving Ris-Rez lived longer without their cancer worsening than those given the treatment against which it was tested. This measurement, known as progression-free survival, is commonly used to determine whether an experimental cancer drug is delaying the disease.

The full trial results have not yet been released, meaning the size of the improvement and complete safety findings remain unknown. However, reaching the main goal of a late-stage study gives GSK and its partner, Hansoh Pharmaceutical, an important piece of evidence as they consider the drug’s path towards regulators.

Osteosarcoma is a rare bone cancer that primarily affects children, teenagers and young adults. Surgery and chemotherapy can be effective when the disease is found early, but treatment options become much more limited if the cancer returns or spreads.

That makes Ris-Rez medically important, even if osteosarcoma alone represents a relatively small commercial market.

The treatment belongs to a rapidly developing category of medicines called antibody-drug conjugates, or ADCs. These drugs combine an antibody capable of recognising cancer cells with a powerful cancer-killing substance. The aim is to deliver treatment more directly to the tumour while reducing unnecessary exposure to healthy tissue.

Ris-Rez targets B7-H3, a protein found at high levels on several types of solid tumours. That gives the drug potential beyond bone cancer and helps explain why GSK has made it an important part of its growing oncology pipeline.

The company is already studying the treatment in lung cancer, prostate cancer and other solid tumours. Earlier in July, Ris-Rez also produced positive late-stage results in China for advanced or relapsed small-cell lung cancer.

That wider development programme is where the larger investment opportunity lies. A successful treatment for one rare cancer can be valuable, but a drug that works across several tumour types could become a much more meaningful source of future revenue.

Hansoh originally developed Ris-Rez and retains its commercial rights in China. GSK licensed rights across most international markets in 2023 as part of its attempt to gain access to promising cancer drugs before their potential is fully established.

The partnership reflects a wider shift in the pharmaceutical industry. Large drugmakers are increasingly turning to smaller biotechnology companies, particularly in China, for experimental treatments that can strengthen their pipelines more quickly than relying entirely on internal research.

For GSK, the urgency is particularly clear. The company sold much of its oncology business to Novartis in 2015 but has since returned to the sector, building a new portfolio through licensing agreements, acquisitions and internal development.

That rebuilding effort is intended to provide new growth as older medicines eventually lose patent protection. It also places GSK in one of the pharmaceutical industry’s most competitive markets, where successful cancer drugs can generate billions of dollars in annual sales but development failures remain common.

Ris-Rez is not yet an approved treatment, and this trial does not guarantee that it will reach patients worldwide. Hansoh plans to begin the process of seeking approval in China, while GSK must continue producing evidence through its own international development programme.

Regulators will also need to examine the complete safety results. ADCs are designed to target tumours more precisely than conventional chemotherapy, but they can still cause serious side effects because of the powerful drugs they carry.

The latest trial therefore represents progress rather than a finished success story.

Still, Ris-Rez is beginning to provide something GSK badly needs from its cancer pipeline: repeated evidence that one of its most important experimental drugs may work across more than one difficult-to-treat disease.

One successful trial cannot complete GSK’s oncology comeback. But with positive late-stage results now emerging in both bone and lung cancer, that comeback is starting to look more credible.