WASHINGTON, DC, June 13 — It’s remarkably rare that one comes across a story about cancer that might bring on a great big smile. Nonetheless, last week it was reported that all 18 patients in a rectal cancer drug trial ended up cancer-free the first time around. The drug they were studying is called Dostarlimab. It was described as a medication that “unmasks cancer cells, allowing the immune system to identify and destroy them.” And, apparently, it did.
Oncologist Andrea Cercek at New York’s Memorial Sloan Kettering Cancer Center was the lead author of the study. Her conclusion was, “I don’t think anyone has seen this before, where every single patient has had the tumor disappear.”
According to the study report, the research team “initiated a prospective phase 2 study in which single-agent Dostarlimab, an anti-PD-1 monoclonal antibody, was administered every three weeks for six months in patients with mismatch repair-deficient stage II or III rectal adenocarcinoma…The treatment was to be followed by standard chemotherapy and surgery.” But none of the patients needed that follow-up treatment. They all “had a clinical complete response, with no evidence of tumor on magnetic resonance imaging…At the time of this report, no patients had received chemoradiotherapy or undergone surgery, and no cases of progression or recurrence had been reported during follow-up (range 6 to 25 months).”
Dr. Hanna Sanoff, the quality and innovation officer of the North Carolina Cancer Hospital and professor in the UNC School of Medicine Division of Oncology, points out that “Over 45,000 people in the United States were diagnosed with rectal cancer last year, and many of those cases were in people under the age of 65. Historical treatment of the disease has included radiation, surgery, and chemotherapy, which can be debilitating despite its curative potential, pointing to the need for better and more effective treatments that can prolong longevity while maintaining the quality of life. These initial findings of the remarkable benefit of the use of Dostarlimab are very encouraging but also need to be viewed with caution until the results can be replicated in a larger and more diverse population.”
Dr. Sanoff was not involved in the Sloan Kettering Dostarlimab study, but she published her take on its results in the New England Journal of Medicine. “Despite these uncertainties, Cercek and colleagues and their patients who agreed to forgo standard treatment for a promising but unknown future with immunotherapy have provided what may be an early glimpse of a revolutionary treatment shift,” Dr. Sanoff wrote.
In its report, the Washington Post pointed to several potential shortcomings of the study. The Post pointed out the small number of patients that participated and that the earliest patients in the trial still have years of observation ahead of them. And the report noted that “even the earliest patients in the trial still have several more years of observation to ensure that the tumors haven’t reemerged or metastasized elsewhere in the body. The results also only pertain to those who carry a specific abnormality to their rectal cancer known as mismatch repair deficiency, which impedes the body’s function to normalize or ‘repair’ abnormalities when cells divide and instead results in mutations. The deficiency occurs in roughly 5 to 10 percent of all rectal cancer patients and tends to resist chemotherapy.”
However, the Post story did point out that the drug showed it may be a way to treat a mismatch repair deficiency of the pancreas, stomach, or bladder. In fact, David Ryan, the director of clinical oncology at Massachusetts General Hospital, called the results of the Sloane Kettering trial “a game changer” for cancer patients with mismatch-repair deficiency.