Results from a global clinical trial show that using a brand-new drug – currently called GRWD5769 – with an existing type of immunotherapy called cemiplimab can shrink tumours or keep them stable in people with 6six different advanced and hard-to-treat cancers.
The types of cancer included in the trial are cervical, bladder, liver, non-small cell lung cancer, squamous cell carcinoma of the head and neck and a type of bowel cancer called microsatellite stable bowel cancer.
Every patient who responded in the Phase 1/2 EMITT-1 trial had already failed treatment, and most had no conventional treatment options left after multiple lines. Crucially, immunotherapy hadn't worked or had stopped working.
Unlike many cancer treatments, GRWD5769 was well tolerated by patients, meaning that they could stay on the drug and have a better quality of life.
The results, which were generated between March 2023 and March 2026, are being presented at this year’s ASCO Annual Meeting by Professor Fiona Thistlethwaite, Consultant Medical Oncologist at The Christie NHS Foundation Trust and Principal Investigator of the trial. Fiona is the Medical Director of the National Institute for Health and Care Research Manchester Clinical Research Facility (CRF) at The Christie, one of the sites where the study was delivered.
The pill, which has been developed by Oxford-based company Greywolf Therapeutics and can be taken at home, has the potential to make immunotherapy effective where it hasn’t been.
Summary of the data to be presented at ASCO 2026
- Responses where the tumour has shrunk by at least 30% were achieved across all 6 tumour types, and deep responses of up to 95% were observed.
- The combination was most effective in the cohort of patients with bladder cancer and, critically, showed promise in those with microsatellite stable (MSS) colorectal cancer who did not have liver metastases - a tumour type where immunotherapy has shown no meaningful benefit and remains unlicensed.
- Responding to immunotherapy after having already failed it before is very rare, but the overall response rate observed across the 6 tumour types was between 13% and 36%.
- Durable clinical benefit – where the patient is living without disease progression for at least 6 months – ranged from 18% to 55%.
- In a striking difference to many experimental cancer treatments, this new drug is well tolerated with a favourable safety profile across all 6 cancers.
200 people are taking part in the trial at 28 cancer centres in 4 countries, including 6 in the UK. The trial is still ongoing, with a larger study already in planning.
Professor Fiona Thistlethwaite, Consultant Medical Oncologist at The Christie NHS Foundation Trust and Medical Director of the National Institute for Health and Care Research (NIHR) Manchester Clinical Research Facility (CRF) at The Christie, one of the sites where the study was delivered, said: “Immunotherapy has been a game-changer in the way we treat cancer, but the number of people that can benefit is still relatively low.
“What excites me about this trial is the combination of what we’re seeing - strong signals of efficacy across 6 tumour types that have shown great resistance to immunotherapy, with very few side effects. That's unusual at such an early stage when we’re usually just looking at how safe it is.
“There’s a lot more work to be done before it reaches the clinic, but for a brand-new drug to show that kind of profile so early, and in so many different types of hard-to-treat cancers, gives me genuine optimism.”
How GRWD5769 works
Immunotherapy works by enlisting T cells — the cells of the immune system that attack infections — to hunt and destroy cancer. It’s been a gamechanger for cancer treatment, but it fails in around two thirds of patients.
This is because immunotherapy struggles when tumours hide from the immune system, or when T cells become exhausted fighting the same cancer target repeatedly. These are 2 of the biggest challenges facing immunotherapy researchers.
GRWD5769 aims to tackle these problems by both making the tumour cells visible to the T cells that couldn’t previously find them and by periodically changing which T cells attack to prevent them from burning out.
It does this by inhibiting an enzyme called endoplasmic reticulum aminopeptidase 1 (ERAP1), which helps the immune system to recognise the cancer and attack it. A drug has never been clinically tested with this target before.
When used in combination with cemiplimab, which works by blocking a protein called PD-1, which stops the immune system from fighting tumours, this creates a two-pronged approach to attacking the cancer.
In terms of how treatment works, patients take 2 GRWD5769 capsules a day for 3 weeks and have one intravenous dose of cemiplimab over that period.
Then, over the next 3 weeks, they just have one intravenous dose of cemiplimab. Treatment continues in this way – three weeks on both treatments, followed by 3 weeks just on cemiplimab. The dose cycling aims to continuously refresh the pool of T cells attacking the tumour, preventing them from burning out.
The UK Chief Investigator is Professor Stefan Symeonides, Consultant Medical Oncologist at the Edinburgh Cancer Centre, NHS Lothian, and Professor of Experimental Cancer Medicine at the Institute of Genetics and Cancer, University of Edinburgh, who said: “This exciting new type of immunotherapy reveals hidden aspects of the cancer to the immune system to renew the immune response and then keep it refreshed and active.
"It is fantastic to have been able to bring this promising new immunotherapy approach through to clinical trials and to see our patients benefiting.”
How the EMITT-1 trial helped patient Pat Brogan
Pat Brogan, a 68-year-old granddad from Cowdenbeath in Fife has seen his advanced lung cancer shrink by around 30% since starting on the EMITT-1 trial in February 2025.
He has had very few side effects and is now getting ready to walk his daughter down the aisle in June. He’s also planning to go on holiday to Spain with Linda, his wife of 16 years.
“When I was first diagnosed nearly 5 years ago, I was getting ready to say my goodbyes, so to be here and to be living a relatively normal life, is a miracle,” Pat says.
Pat, who worked at Scottish Water for 35 years before retiring at 60, went to the doctor in October 2021 after losing his voice. He was referred the hospital where they found tumours in his neck that were affecting his vocal cords. He was diagnosed with stage 4 lung cancer.
“My mum, sister and dad had all died from cancer, so I thought that the run of awful luck might have ended with me. It was quite a shock when I was diagnosed. I had been singing and dancing at a music festival shortly before my diagnosis and felt fine. I almost couldn’t believe that I could be that seriously ill,” adds Pat.
Pat started chemotherapy and immunotherapy which worked for around three years before his tumours started to grow again.
It was this point that he was offered 2 choices: to start on a more intensive course of chemotherapy which might not work or to be referred to the Edinburgh Cancer Centre to find out more about the EMITT-1 trial. He chose the latter.
Pat started on the trial in February 2025. He had his first scan 6 weeks later which showed his tumours had already started to get smaller. In total, they’ve shrunk by 30% over the time he’s been on the trial.
“Being on the trial has given me my life back,” says Pat. “Not only have my tumours shrunk, but I have a good quality-of-life, something I might not have had with harsh chemotherapy. We spent a lot of time in Spain before my diagnosis, and now we’re planning to back for a holiday. My daughter is getting married in June and I’ll be able to walk her down the aisle, something I never thought I’d be able to do.”
“I have a good life. I get up every morning and look forward to the extra time I have to spend with Linda and the rest of my family, including my two grandchildren who are just starting their adult lives. We’ve also got a dog – a Bichon Frise called Seamus – who keeps me fit with his demands for daily walks.”
“I’m so grateful to Professor Stefan Symeonides and his team in Edinburgh and to all the other patients who have taken part in cancer research before me. I wouldn’t have the life I have now without them. Hopefully, by taking part in research, I can also make things better for people like me in the future,” says Pat.