This was a small study, with only 18 patients with rectal cancer, each taking the same medicine.
But the results were amazing. The cancer disappeared in each individual patient, undetectable on physical examination, endoscopy, PET scan or MRI scan.
Dr Louis A. Diaz Jr. of the Sloan Memorial Cancer Catering Center, author of an article published Sunday in the New England Journal of Medicine describing results sponsored by pharmaceutical company GlaxoSmithKline, said he was unaware of another study in which treatment completely eradicated cancer in each patient.
“I believe this is the first time this has happened in the history of cancer,” said Dr. Diaz.
Dr Alan P. Venook, a colorectal cancer specialist at the University of California, San Francisco, who was not involved in the study, said he also thought it was his first time.
Complete remission in each patient is “unheard of,” he said.
These patients with rectal cancer have faced grueling treatments – chemotherapy, radiation and most likely life-changing surgery, which can lead to intestinal, urinary and sexual dysfunction. Some will need colostomy bags.
They entered the study thinking that when it was over, they would have to undergo these procedures because no one expected their tumors to disappear.
But they were surprised: no additional treatment was needed.
“There were many happy tears,” said Dr. Andrea Cercek, an oncologist at Memorial Sloan Kettering Cancer Center and co-author of the paper, which was presented Sunday at the annual meeting of the American Society of Clinical Oncology.
Another surprise, Dr. Venook added, was that none of the patients had clinically significant complications.
On average, one in five patients has an adverse reaction to medicines such as the one that patients have taken, dostarlimab, known as checkpoint inhibitors. The drug is given every three weeks for six months and costs about $ 11,000 per dose. It unmasks cancer cells, allowing the immune system to identify and destroy them.
While most side effects are easily managed, up to 3% to 5% of patients taking checkpoint inhibitors have more severe complications, which in some cases lead to muscle weakness and difficulty swallowing and chewing.
The lack of significant side effects, Dr. Venook said, means “either they haven’t treated enough patients, or in some ways these cancers are just different.”
In an editorial accompanying the paper, Dr. Hannah K. Sanoff of the University of North Carolina for the Lineberger Comprehensive Cancer Center, who was not involved in the study, called it “small but convincing.” She added, however, that it was unclear whether the patients had been cured.
“Very little is known about the length of time it takes to understand whether a clinical complete response to dostarlimab equals a cure,” Dr Sanoff said in an editorial.
Dr Kimi Ng, a colorectal cancer expert at Harvard Medical School, said that while the results were “remarkable” and “unprecedented”, they would have to be repeated.
The inspiration for the rectal cancer study came from a 2017 clinical trial led by Dr. Diaz, which Merck, a drugmaker, funded. It involves 86 people with metastatic cancer that originates in different parts of their bodies. But all cancers share a gene mutation that prevents cells from repairing DNA damage. These mutations occur in 4 percent of all cancer patients.
Patients in this study received a Merck checkpoint inhibitor, pembrolizumab, for up to two years. Tumors shrink or stabilize in about one-third to one-half of patients, and they live longer. Tumors disappeared in 10 percent of study participants.
This prompted Dr. Chercek and Dr. Diaz to ask: What would happen if the drug was used much earlier in the course of the disease before the cancer had a chance to spread?
They focused on a study of patients with locally advanced rectal cancer – tumors that have spread to the rectum and sometimes to the lymph nodes, but not to other organs. Dr. Chercek noted that chemotherapy did not help some patients who had the same mutations that affected patients in the 2017 study. Instead of shrinking during treatment, their rectal tumors grew.
Perhaps, Dr. Cercek and Dr. Diaz speculate, checkpoint inhibitor immunotherapy would allow such patients to avoid chemotherapy, radiation, and surgery.
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Dr. Diaz began asking companies that make checkpoint inhibitors if they would sponsor a little experience. They refused, saying the process was too risky. He and Dr. Chercek wanted to give the medicine to patients who could be cured with standard treatments. What the researchers suggest may allow cancers to grow beyond the point where they can be cured.
“It is very difficult to change the standard of care,” said Dr. Diaz. “All the standard care equipment wants to do the operation.
Finally, a small biotech company, Tesaro, agreed to sponsor the study. Tesaro was bought by GlaxoSmithKline, and Dr. Diaz said he should remind the larger company that they were doing the research – the company’s executives had almost forgotten about the little test.
Their first patient was Sasha Roth, then 38 years old. She first noticed rectal bleeding in 2019, but otherwise felt good – she is a runner and helps run a family furniture store in Bethesda, Maryland.
During sigmoidoscopy, she recalls, her gastroenterologist said, “Oh, no. I was not expecting that! “
The next day the doctor called Mrs. Roth. He did a biopsy of his tumor. “It’s definitely cancer,” he told her.
“I completely melted,” she said.
She was soon to begin chemotherapy at Georgetown University, but a friend insisted on seeing Dr. Philip Patty at the Sloan Catering Memorial first. Dr. Patti told her that he was almost certain that her cancer involved a mutation that made her unlikely to respond well to chemotherapy. However, it turned out that Ms. Roth was eligible to participate in the clinical trial. If she had started chemotherapy, she wouldn’t have.
Not expecting a full response to dostarlimab, Ms. Roth planned to move to New York for radiation, chemotherapy and possibly surgery after the trial. To maintain her fertility after the expected radiation treatment, she removed her ovaries and placed them back under her ribs.
After the trial, Dr. Chercek told her the news.
“We looked at your scans,” she said. “There is absolutely no cancer.” She did not need additional treatment.
“I told my family,” Ms. Roth said. “They didn’t believe me.”
But two years later, she still has no sign of cancer.