A clinical trial assessing the efficacy of drug, Dostarlimab, on a subtype of colorectal cancer was shown to be effective in eliminating cancer in all of the trial’s patients. (Credit: Dr_Microbe, Getty Images/iStockphoto)
A study reporting on a phase II clinical trial consisting of 12 patients revealed that all of its patient’s were in remission following the use of immunotherapy drug, Dostarlimab, also sold under the brand name, Jemperli.
The clincal trial participants all had a particular type rectal cancer, specifically, mismatch repair–deficient (MMRd) stage II or III rectal adenocarcinoma. None of the participating patients had undergone chemoradiotherapy or surgical treatments.
Dr. Luis Diaz, an oncologist and member of the clinical trial team, explained to MSK News, “An MMRd tumor develops a defect in its ability to repair certain types of mutations that occur in cells. When those mutations accumulate in the tumor, they stimulate the immune system, which attacks the mutation-ridden cancer cells.”
Dr. Andrea Cercek, one of the study’s investigators, explained the immunotherapy drug’s mechanism of action, by explain how it enables immune cells to be more effective. She said, “When the brakes are taken off the immune cells, MMRd cells look especially strange because they have so many mutations. So the immune cells attack with much more force.”
The study’s results state, “All 12 patients (100%; 95% confidence interval, 74 to 100) had a clinical complete response, with no evidence of tumor on magnetic resonance imaging (MRI), 18F-fluorodeoxyglucose–positron-emission tomography (PET), endoscopic evaluation, digital rectal examination, or biopsy.”
Along with the impressive outcome, no grade 3 adverse effects were reported. Grade 3 adverse effects include serious adverse events that require immediate intervention, often requiring hospitalization.
Despite the unprecedented results, the clinical trial team remains cautiously optimistic. The trial only consisted of 18 patients, most of which have only been monitored for 6-25 months following the use of the drug, therefore the long-term efficacy of the drug is still yet to be known.
Dr. Diaz concluded by stating, “it’s the tip of the iceberg…. we are investigating if this same method may help other cancers where the treatments are often life-altering and tumors can be MMRd. We are currently enrolling patients with gastric (stomach), prostate, and pancreatic cancers.”
For more information on this clinical trial, read more about it at www.clinicaltrials.gov.
The study was published in The New England Journal of Medicine on June 5th, 2022.
Abstract. Background. Neoadjuvant chemotherapy and radiation followed by surgical resection of the rectum is a standard treatment for locally advanced rectal cancer. A subset of rectal cancer is caused by a deficiency in mismatch repair. Because mismatch repair–deficient colorectal cancer is responsive to programmed death 1 (PD-1) blockade in the context of metastatic disease, it was hypothesized that checkpoint blockade could be effective in patients with mismatch repair–deficient, locally advanced rectal cancer. Methods. We initiated a prospective phase 2 study in which single-agent dostarlimab, an anti–PD-1 monoclonal antibody, was administered every 3 weeks for 6 months in patients with mismatch repair–deficient stage II or III rectal adenocarcinoma. This treatment was to be followed by standard chemoradiotherapy and surgery. Patients who had a clinical complete response after completion of dostarlimab therapy would proceed without chemoradiotherapy and surgery. The primary end points are sustained clinical complete response 12 months after completion of dostarlimab therapy or pathological complete response after completion of dostarlimab therapy with or without chemoradiotherapy and overall response to neoadjuvant dostarlimab therapy with or without chemoradiotherapy. Results. A total of 12 patients have completed treatment with dostarlimab and have undergone at least 6 months of follow-up. All 12 patients (100%; 95% confidence interval, 74 to 100) had a clinical complete response, with no evidence of tumor on magnetic resonance imaging, 18F-fluorodeoxyglucose–positron-emission tomography, endoscopic evaluation, digital rectal examination, or biopsy. 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). No adverse events of grade 3 or higher have been reported. Conclusion. Mismatch repair–deficient, locally advanced rectal cancer was highly sensitive to single-agent PD-1 blockade. Longer follow-up is needed to assess the duration of response.
Cercek A, Lumish M, Sinopoli J, Weiss J, Shia J, Lamendola-Essel M, El Dika IH, Segal N, Shcherba M, Sugarman R, Stadler Z, Yaeger R, Smith JJ, Rousseau B, Argiles G, Patel M, Desai A, Saltz LB, Widmar M, Iyer K, Zhang J, Gianino N, Crane C, Romesser PB, Pappou EP, Paty P, Garcia-Aguilar J, Gonen M, Gollub M, Weiser MR, Schalper KA, Diaz LA Jr. PD-1 Blockade in Mismatch Repair-Deficient, Locally Advanced Rectal Cancer. N Engl J Med. 2022 Jun 5. doi: 10.1056/NEJMoa2201445. Epub ahead of print. PMID: 35660797.
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