A research paper published in the New England Journal of Medicine on June 23, 2022, reported that 12 patients with rectal cancer treated with the immunotherapy drug dostarlimab have all achieved complete remission – the cancers vanished or are undetectable after the treatment. 

Doctors followed up with these 12 patients for 6 to 25 months after the treatment, and the results from all patients are remarkable: 

• The tumor is undetectable on MRI scan and endoscopic examination;
• No progression or recurrence had been reported during the follow-up period;
• No severe adverse events have been reported for all patients since the treatment.

This type of outstanding treatment outcome has not happened before.

Genetic Testing Played a Critical Role 

This unprecedented treatment outcome proved that developing genetic testing technology and applying it to cancer treatment is worth its decade-long research efforts. 

All patients received genetic testing before being selected for the clinical trial. These 12 patients were recruited for the trial because they tested positive for a genetic instability called mismatch repair deficiency (MMR-d). Research has shown that patients with MMR-d may respond better to dostarlimab treatment than patients without it.

The genetic testing on MMR-d played a critical role in successfully treating this cohort of patients. Actually, the combination of genetic-testing-based patient selection and immunotherapy led to the complete remission of all patients in this clinical trial.