GSK reports positive trial results for gynaecological cancer drug Mo-Rez

GSK has revealed positive results for a treatment for gynaecological cancers as its chief executive, Luke Miels, seeks to speed up drug development at the group.

The company said that in an early-stage trial Mocertatug Rezetecan, known as Mo-Rez, shrank or eliminated tumours in 62% of patients with ovarian cancer where chemotherapy had failed, and in 67% of those with endometrial cancer.

Based in London, GSK has recently gained plaudits for its work on tackling superbugs, becoming one of just three big pharma companies globally that continue to invest in anti-microbial research.

However, commercially GSK has been eclipsed in recent years by its bigger British rival AstraZeneca, which last year outstripped GSK’s near-£33bn turnover by more than £10bn and whose market value is more than twice as high.

GSK acquired the Mo-Rez cancer treatment, an antibody-drug conjugate (ADC), from China’s Hansoh Pharma in late 2023, and has trialled it in 224 patients around the world, including the UK, over the past year. Only a few patients needed to stop treatment because of side-effects, the most common being nausea. It is administered every three weeks via intravenous infusion.

Combined with data from a separate, intermediate trial in China, these results give the British drugmaker the confidence to go straight to late-stage trials, with five clinical studies planned globally in the next few months, including on patients in the UK.

Presenting the results at the Society of Gynecologic Oncology’s annual meeting on women’s cancer in Puerto Rico, Hesham Abdullah, GSK’s global head of cancer research and development, said: “Treatment of gynaecological cancers remains a major challenge, with a pressing need for new therapies that offer improved response rates. With Mo-Rez we now have compelling evidence of a promising clinical profile.”

Endometrial cancer affects 1.6 million women globally, with 417,000 new cases each year. Ovarian cancer affects 843,000 people, with 240,000 new cases annually.

Speaking to journalists before the conference, Abdullah described Mo-Rez as a “key asset” in the company’s growing cancer portfolio. It is expected to be a blockbuster drug, with peak annual sales of more than £2bn, which GSK hopes will help it to achieve its 2031 sales target of £40bn.

Miels, an Australian who was brought in by his predecessor, Emma Walmsley, from AstraZeneca in 2017 and worked for Roche and Sanofi-Aventis, has announced several deals since taking the helm at GSK on 1 January, and vowed to show “scientific courage”.

Abdullah said Miels, with whom he previously worked at AstraZeneca, had stepped up the pace of drug development. “The entire organisation is certainly really enjoying following this pace, the agility, and having the scientific courage.

“His leadership style, the engagement, the strategic insight, the drug development expertise … you’re also seeing some of that come to life through the development programmes.”

It has been less than a decade since GSK moved back into oncology under Walmsley, after GSK sold its cancer portfolio to Novartis in 2015 in a swap for the Swiss company’s vaccines business.

A few years ago GSK did not have any cancer drugs on the market but it now has four approved medicines and 13 in clinical development. Last year, oncology generated nearly £2bn in sales, up 43% from 2024, with sales of its endometrial cancer drug Jemperli soaring 89%.