‘The tumors just disappeared’: New cancer treatment shocks scientists in clinical trial
All patients with advanced rectal cancer who entered phase two of a small clinical trial in the US are now remission.
The new immunotherapy tested in the trial has “almost no toxicity,” Its 100 percent success rate gives scientists new hope.
Watch the video above to see the study’s lead author explain how the treatment works.
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The small study, published Sunday in The New England Journal of Medicine, successfully eradicated advanced rectal cancer in all 12 participants in six months.
“What’s so remarkable here is that it eliminated cancer. The tumors just disappeared,” said study author and oncologist at Memorial Sloan Kettering Cancer Center, Dr. Andrea Cercek.
The trial was designed to follow the study drug, dostarlimab, with standard chemoradiotherapy and surgery in participants who did not have a clinically complete response — yet all 12 participants were tumor-free under MRI even after six months of follow-up.
“It’s really what cancer doctors’ dreams are made of, to see a response like that,” Cercek said.
Longer follow-up of participants in remission is needed to assess the duration of a successful response.
The results are just phase two of the ongoing study that began in 2019.
The full study will test the drug on 30 participants, with final data expected in 2023 and completed by 2025.
Dostarlimab, under the product name Jemperli, was approved by the Therapeutic Goods Administration in February 2022 to treat adult patients with recurrent or advanced mismatch repair-deficient endometrial cancer.
How it works
The standard treatment for advanced rectal cancer is “chemotherapy and radiation followed by surgical resection of the rectum,” the study claims. Cercek says traditional therapies for rectal cancer are “really quite toxic.”
That’s why the “incredible efficacy” of the study drug “with really almost no toxicity” is such a breakthrough.
“It’s an immunotherapy, and it works by unlocking the body’s natural immune system to fight cancer,” Cercek said.
“Normally, when this is used in patients with advanced disease, it happens in about 10 percent of patients, and here it’s 100 percent, so that’s the most notable part.”
“This kind of therapy works in specific cancer cells in colorectal cancer cells that have a mismatch repair deficiency, so they’re missing a gene that allows them to repair their DNA,”
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Mismatch repair-deficient cells usually have a series of mutations that can lead to cancer, which the immune system must try to recognize as foreign.
Some tumors express an inhibitory receptor known as the “programmed cell death protein (PD-1),” which downregulates the immune system and stops white blood cells from doing their job.
The drug being tested, dostarlimab, is an anti-PD-1 monoclonal antibody — meaning it blocks the PD-1 receptor so that an immune response can be triggered.
It was administered to participants with mismatch-repair-deficient stage II or III rectal adenocarcinoma every three weeks during the six-month trial.
“When we give immunotherapy like dostarlimab, it just boosts the immune system, so it sees cancer and gets it.
The future of immunotherapy
Cercek’s goal is to extend the new technology as a treatment for advanced disease to early-stage disease and other solid tumors and cancers deficient for mismatch repair.
“We see increased sensitivity when the tumors are in the early stages when they’re in the organ where they start,” she said.
“Our goal is to replicate this in other solid tumors such as stomach, pancreatic, and bladder cancer, which have a mismatch repair deficiency, where they have this potential susceptibility to immunotherapy.”
“Maybe we can also achieve that in patients with gastric cancer where surgery may not be necessary if they have the same kind of remarkable response.”