A 42-year-old woman had no evidence of cancer after receiving the drug dostarlimab which is still in early trials for treatment of a rare form of colorectal cancer.
Carrie Downey, a single mother to a 17-year-old son, was diagnosed with bowel cancer a year ago but now, after just six months of treatment with a new cancer drug, she’s been given the all-clear.
The drug, dostarlimab, is still being trialled and targets a specific variant of colorectal cancer where the cells have genetic abnormalities. The patients all have a specific mismatch repair (MMR) gene mutation.
The gene defect is present for between 3.5 per cent to 5 per cent of rectal cancers, according to the Swansea Bay University Health Board.
Downey, who is 42 years old, was told that because of the location of her cancer, she could be left with a permanent stoma - an opening in the abdomen to get rid of your body’s waste, which is collected in a small bag worn outside the body.
She was referred to oncologist Dr Craig Barrington on behalf of the South West Wales Cancer Centre.
“He said something along the lines of, ‘What would you do if I said we could get the same result, no evidence of cancer, without having a permanent stoma and major surgery?” Downey said in a statement.
“He had checked my biopsies and knew I had this rare mutation. He said there had been trials, and he was confident he could get the funding because I met the criteria. He asked if I would like to go ahead with it”.
Downey received three intravenous (IV) treatments of the drug a week for six months with each treatment taking around 30 minutes.
“I got tired and had a rash here and there, but nothing compared to chemotherapy, radiotherapy or surgery,” she said.
The tumour shrunk during treatment at by the end of the time period, there was no evidence left of the disease.
“We are now the first UK nation and joint first globally with Italy to have it as routine as an option for treatment,” Barrington said in a statement.
“It doesn't mean the patient has to have it. It's an additional tool in our toolbox, as it were. But when you've got a trial showing 100 per cent complete response it’s difficult to argue against it”.
Medicine still being trialled, with limited data
Ten patients have been prescribed dostarlimab in Wales but its use for treatment of these rare cases of rectal cancer is still being analysed.
The drug, which is marketed by GlaxoSmithKline (GSK) under the name Jemperli, was first approved in the European Union in 2021 for the treatment of endometrial cancer that is advanced and has the same gene abnormality.
A small clinical trial of 12 patients with rectal cancer in the United States, which was published in the New England Journal of Medicine in 2022, found that there was a clinical complete response in all patients.
The study concluded that this type of rectal cancer (known as mismatch repair-deficient/microsatellite instability-high (dMMR/MSI-H)) was “highly sensitive” to the drug but said that “longer follow-up is needed to assess the duration of the response”.
There are additional ongoing trials in the US, but these are “single-arm trials” and thus not randomised, which was noted as a cause of concern for US authorities back in February.
Despite that, a US Food and Drug Administration (FDA) committee voted that the data from two single-arm trials would be “sufficient to characterise the benefits and risks” of using the medicine to treat advanced rectal cancer with gene abnormalities.