Sascha Roth and the Trial Where Every Tumor Vanished (2022)

Sascha Roth was packing. It was a Friday evening, and she was racing around her home to get to New York, where she was scheduled to begin weeks of radiation for rectal cancer. Then her doctor called. A team at Memorial Sloan Kettering Cancer Center had looked at her scans and could not find any cancer. There was no reason to put her through radiation.

Roth, then 38, who helps run a family home-furnishings business in the Bethesda, Maryland area, was the first patient enrolled in a small trial of an immunotherapy drug called dostarlimab. When her own result held, the researchers worried she might be a fluke. She was not.

The Trial

The trial, led by Dr. Andrea Cercek and Dr. Luis Diaz Jr., enrolled patients with a specific subtype of rectal cancer: mismatch repair-deficient (sometimes written MMRd, or microsatellite-instability-high), stage II or III. That subtype is about 5 to 10 percent of rectal cancers and tends to do badly on chemotherapy. Patients got dostarlimab, an anti-PD-1 antibody, intravenously every three weeks for six months. The plan was that anyone whose cancer did not respond would move on to the standard treatment — surgery, radiation, chemotherapy.

In the results published in the New England Journal of Medicine on June 23, 2022, all 12 patients who had finished treatment with at least six months of follow-up showed a clinical complete response. No tumor was detectable on physical exam, endoscopy, PET, or MRI. None of them needed surgery, radiation, or chemotherapy. There were no severe side effects. Diaz told the New York Times, 'I believe this is the first time this has happened in the history of cancer.'

The field's own caution came in the same week. Dr. Hanna Sanoff of the University of North Carolina, writing separately, noted that a clinical complete response 'is not a surrogate' for a long-term cure, and that the cohort was small and the follow-up short.

The Mechanism

Most of the catalog's healing entries are Mode A claims — a Mode A claim is one that would have no natural explanation if the facts held. This case is the inverse, and that is the point of including it. The facts are not in doubt; they are peer-reviewed. And the explanation is not missing; it is known. Checkpoint-inhibitor drugs take the brakes off the immune system, letting it see and attack tumors it had been ignoring. Mismatch repair-deficient tumors carry a very high number of mutations, which makes them unusually visible to that unleashed immune response. A 100 percent response is a stunning effect size. It is still a drug doing a thing drugs are understood to do, in a cohort selected precisely because their tumors were the kind most likely to respond. The program has since expanded into larger trials, and the drug drew an FDA breakthrough-therapy designation in December 2024.

Assessment

We score the probability that this exceeded a natural account near the floor of the scale, with high confidence. That is not a verdict on the result, which is one of the more remarkable things modern oncology has produced. It is a verdict on the category: there is no suspension of natural law here and no improbable timing, only a mechanism that worked. We keep the case as the science anchor. When a remission that followed prayer is offered as a miracle, this is the comparison to make first — a documented drug, a named cohort, an understood mechanism, and an effect medicine can explain and set out to repeat. The honest question for any unexplained remission is how far short of this standard of explanation it falls, and why.