A prospective phase 2 study in which the single-agent drug Dostarlimab was administered to a total of 18 patients with colorectal cancer resulted in a major surprise for medical oncology scientists.
After all these patients had at least 6 months of follow-up with the monoclonal drug that blocks the protein in immune cells, they all had a complete clinical response, with no evidence of tumor on physical examination, endoscopy, PET scans and MRI scans.
The drug was administered every 3 weeks for 6 months in patients with stage II or III rectal adenocarcinoma with cells that have mutations - or changes - in certain genes.
"I think this is the first time this has happened in the history of cancer," said Dr. Luis A. Diaz Jr, one of the authors of the study published in the scientific journal New England Journal of Medicine and led by a team at Memorial Sloan Kettering Cancer Center in New York, who said they were unaware of any other study in which a treatment had completely eliminated the cancer in all patients.
While the small study, funded by GlaxoSmithKline Pharmaceuticals and the Simon and Eve Colin Foundation, among others, which showed good response to single-agent treatment, will need prolonged follow-up and repetition to assess the duration of response and whether it amounts to a cure.
This treatment was to be followed by procedures such as standard chemo and radiotherapy, as well as surgery. However, none of this was necessary, as the tumors disappeared in their entirety, and without significant clinical complications.
According to Andrea Cercek, an oncologist at Memorial Sloan Kettering Cancer Center and co-author of the paper, "there were many tears of joy" upon seeing the results.
It should be noted that, on average, one in five patients has some adverse reaction to drugs such as the one the patients took, dostarlimab, known as immune checkpoint inhibitors.
The drug was administered every three weeks for six months and cost about $11,000 per dose, The New York Times reported.
How does the colorectal cancer drug work?
Dostarlimab, an anti-PD-1 monoclonal antibody, exposes cancer cells, allowing the immune system to identify and destroy them.
The inspiration for the rectal cancer study came from a clinical trial Diaz conducted in 2017, funded by Merck Pharmaceuticals, in which 86 people with metastatic cancer in various parts of the body participated.
But all the cancers had in common a genetic mutation that prevented the cells from repairing DNA damage - mismatch repair deficiency - which occurs in four percent of cancer patients.
In addition, Diaz is working to develop a "molecular Pap test" that can diagnose ovarian and endometrial cancer at an early stage. A crucial breakthrough that would mean being able to detect more cases of these cancers and begin treating them as quickly as possible.
The test is currently in clinical trials.
With information from The New York Times.
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