Drug cures rectal cancer patients in new trial. Will this impact current course of treatment?

Patients part of the study didn't require any chemotherapy or surgery

By Taran Deol
Published: Wednesday 08 June 2022

A known drug had unprecedented results in 12 cancer patients part of a small trial, shining a ray of hope for radiation-free treatment, according to a report. 

Sascha Roth’s diagnosis of rectal cancer had left both her and her doctor in shock. She was about to move cities for treatment when her friend suggested a surgeon at the Memorial Sloan Kettering Cancer Centre in New York. 

She became the first patient in a trial where dostarlimab — a cancer drug developed by British multinational pharmaceutical company GlaxoSmithKline plc — was tested in early stages of the disease. Roth has been cancer-free for two years now. 

The findings of the small study with just 12 people were remarkable, said experts: No cancer was detected in any patient by physical exam, endoscopy, PET scans or MRI scans. 

The patients were administered dostarlimab every three weeks for six months, according to the study published in the New England Journal of Medicine on June 5, 2022. “No patients had received chemoradiotherapy or undergone surgery, and no cases of progression or recurrence had been reported during follow-up (6 to 25 months),” the authors noted.

The trial was conducted in patients diagnosed with Stage II or Stage III rectal cancer. Traditional treatment for this is radiation, followed by chemotherapy and surgery which could likely result in neuropathy, infertility, bowel, urinary and sexual dysfunction. 

While the trial was being conducted, patients were supposed to receive the last two steps of treatment after taking the six-month course of the drug. Since all 12 had no sign of cancer for a year after the treatment, there was no need for chemotherapy or surgery. 

“What’s really remarkable is this is the first time I know of in solid tumour oncology where we’ve had a 100 per cent complete response, and we’ve completely omitted the normal standard of care,” Luis Diaz, head of the division of solid tumour oncology at Memorial Sloan Kettering and one of the doctors who designed the study, was quoted as saying in Stat News.

But that is not all. No adverse events of Grade 3 or higher were reported, the study found. Grade 3 or higher typically means significant symptoms requiring hospitalisation or invasive intervention. 

This is well below the average of one out of five people having some sort of an adverse reaction to a drug like dostarlimab. Experts believe this could be a function of the small sample size of the study and perhaps not the drug entirely. 

This is another reason why Dr Hanna K Sanoff of the University of North Carolina’s Lineberger Comprehensive Cancer Center, who was not involved in the study, is wary of celebrating but calls the findings compelling.

“These results are cause for great optimism, but such an approach cannot yet supplant our current curative treatment approach. The end point presented — clinical complete response — is an imperfect surrogate for long-term cancer control,” Dr Sanoff wrote in an editorial accompanying the paper.

It remains to be seen whether the cancer will remerge. The authors noted that longer follow-up is needed to assess the duration of response. “These recurrence dynamics may (or may not) differ between immunotherapy and chemoradiotherapy and between early and late-stage disease,” wrote Dr Sanoff.

In fact, very little is known about the duration of time needed to find out whether a clinical complete response to dostarlimab equates to cure, she added.

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