The NEOPRISM-CRC trial, led by researchers from University College London and University College London Hospitals NHS Trust, focused on 32 patients with stage two or three bowel cancer who had a specific genetic profile known as MMR-deficient or MSI-high. These patients were given up to nine weeks of the immunotherapy drug pembrolizumab before surgery, instead of the normal method of surgery followed by three to six months of chemotherapy. Early results showed the treatment led to tumour shrinkage, with 59% of patients having no detectable signs of cancer after their operation. After 33 months of follow-up, none of the patients saw their cancer return, according to major media reports. This outcome is particularly notable because roughly a quarter of patients receiving standard surgery and post-operative chemotherapy would normally be expected to relapse within three years.
The complete response included those whose cancer had completely disappeared and those who still had tiny amounts remaining after surgery, which did not grow or spread. Researchers believe this proves that pre-surgery immunotherapy may be an effective treatment method for bowel cancer, and the findings have been hailed as extremely encouraging.
Bowel cancer is the fourth-most common type of the disease in Britain, responsible for around 46,600 new cancer cases every year and 17,700 deaths. The deadly disease is also on the rise in young people, with the number of bowel cancer patients aged 25 to 49-year-olds rising by around 50% since the early 1990s. In February, Dawson's Creek star James Van Der Beek died after a two year battle with bowel cancer, aged 48, highlighting the disease's impact across age groups.
Christopher Burston, 73, was one of 32 patients recruited for the study. He was diagnosed with stage three bowel cancer in February 2023 after completing a screening kit. According to Daily Express - Health, Burston described the cancer as a very obvious lump high up in his bowel and said he was told it was at stage three, later learning it could have been growing for years, which came as a real shock. He had been warned that the operation in May 2023 might leave him needing a temporary or permanent stoma, but this was not necessary in the end. According to Daily Express - Health, Burston described how, over tea and biscuits after the colonoscopy, nurses did their best to reassure him that treatment was possible and the outcome could be good. He now has regular blood tests, CT scans and colonoscopies, plus six-monthly check-ins with his doctors.
According to Daily Express - Health, Burston described understanding the trial as aiming to destroy the cancer using his immune system, activated by a drug tuned to the genetic makeup of the cancer, which would reduce or even eliminate the need for chemotherapy after surgery. After the operation, he was told by Dr Shiu that the cancer had effectively melted away, which was a wonderful relief and gave him hope that the cancer would not return and that further treatment would not be needed. According to Daily Express - Health, Burston described feeling little effect from the treatment or surgery, feeling very lucky that his main problem is age rather than cancer, and being able to play guitar, tend his garden and walk the dog as before, looking forward to spending time with friends and family.
Key unknowns remain, including the long-term side effects of pembrolizumab in this pre-surgery context and how the cost of this immunotherapy treatment compares to standard chemotherapy. It is also unclear when this treatment might become widely available for patients outside clinical trials or if there are specific patient groups for whom it is less effective or unsafe.