Experimental cancer drugs found to help some patients avoid surgery

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The results from an ambitious cancer study are giving hope that immunotherapy drugs alone can treat some gastrointestinal tumours, eliminating the need for severe, life-altering surgeries and other harsh therapies.

For as long as cancer treatment has existed, “cutting it out has been the best way to cure it,” said Luis Diaz, a gastrointestinal medical oncologist at Memorial Sloan Kettering Cancer Center in New York and one of the coleaders of the study, along with Andrea Cercek, also a gastrointestinal medical oncologist with MSK. “This is a complete paradigm shift.”

The approach “gives patients more agency in determining how they want to approach their treatment based on chances of survivorship, but also quality of life and side effects,” said Karen Knudsen, CEO of the Parker Institute for Cancer Immunotherapy at the University of California at San Francisco.

The study enrolled 103 patients with hard tumours from gastrointestinal cancers affecting organs such as the stomach, bladder and intestines that normally would be treated with surgery. All had tumours with mutations, called mismatch repair deficiencies, that prevent cells from fixing DNA damage. These types of mutations occur in 2 to 3 percent of all cancers.

Eighty percent of patients treated with an immunotherapy drug, dostarlimab, did not require chemotherapy, radiation or surgery, including organ removal, the trial found. That included all 49 patients with rectal cancers, who saw their tumours disappear completely after six months of treatment, with no recurrence at five years. Thirty-five of 54 patients with tumours in places such as the colon, bladder, esophagus and stomach saw their cancer disappear.

Diaz and his team shared the results Sunday at the annual meeting of the American Association for Cancer Research and published them in the New England Journal of Medicine. The trial results build on the groundbreaking first phase of the study, which debuted at the same conference in 2022.

During Phase 1, which was conducted in 2020, a tiny sample of 14 patients with early-stage rectal cancer were given dostarlimab. The tumours in all 14 patients vanished after six months of the experimental treatment.

The second phase of the trial added patients with solid, non-rectal tumours. Patients received a 500 mg dose of dostarlimab intravenously every three weeks, for a total of nine treatments. Almost 40 percent of patients had no side effects at all, Diaz said; some patients experienced mild rashes or itching, while a smaller number experienced more serious lung infections and encephalitis.

Diaz is hopeful dostarlimab will become an available option for the small number of cancer patients with mismatch repair mutations – and that it becomes eligible for insurance reimbursement. (The drug costs about $11,500 a vial, and nine doses are required). The Food and Drug Administration in December gave pharmaceutical company GSK’s dostarlimab drug Jemperli a breakthrough therapy designation, which aims to accelerate development and review of drugs that could represent a significant step forward.

For patients, especially younger ones, the value of being able to treat these types of tumours without surgery is immense, Diaz said.

“Imagine being in your 20s and having to lose an organ in your body that will change how you interact with the world, change your fertility, change sexual function or change just your quality of life in general,” he said. “People can adapt, but it’s certainly a very different outlook.”

In 2020, Kelly Spill was initially unsure what her choices – or even prognosis – would be when she was diagnosed with Stage 3 colorectal cancer at 28 years old. She had given birth to her son eight months earlier and was planning her wedding with her now-husband when she learned she was among the growing cohort of young people developing cancer.

“I never really dreamed of having a big wedding, I never dreamed of just having that white dress. But I always dreamed of having a family,” said Spill, now 33. Going the route of oral radiation and chemotherapy treatment would not only destroy her fertility, it would also impair sexual function, and she would need to wear a colostomy bag for the rest of her life.

“Hearing that at 28 years old is just so scary,” Spill said.

When a research nurse told Spill that her test results indicated she might have other options, Spill looked at her mother, who encouraged her to try the experimental route, and became the fourth patient to enroll in Phase 1 of the trial. She later continued into Phase 2.

Spill began immunotherapy the following week. By her ninth treatment, her tumour had completely disappeared.

After her treatment, Spill was still slated for radiation until she had her radiation doctor check her records.

“When he called back, he said: ‘I mean this in the nicest possible way, but I hope to never speak to you again. You do not need any radiation,'” Spill said. “That was the true celebration. Because I knew that that just changed my whole entire life.”

Today, Spill remains cancer-free. She gave birth to her second child, and in just a few weeks she and her husband will welcome a third.

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