Pre-surgery immunotherapy kept bowel cancer patients cancer-free for nearly three years

Overview

Updated Oct 11

A short course of immunotherapy before surgery kept every patient with a specific form of bowel cancer free of recurrence for nearly three years. In the NEOPRISM-CRC trial, 32 patients with MMR-deficient bowel cancer received pembrolizumab for up to nine weeks before surgery, instead of the usual post-operative chemotherapy.

None of the 32 relapsed in 33 months. That includes patients who still had traces of cancer after treatment; those remnants did not grow or spread. Standard surgery-plus-chemotherapy carries about a 25% three-year relapse rate for this group.

Why it matters

If confirmed, pre-surgery immunotherapy could replace post-operative chemotherapy for thousands of UK bowel cancer patients and cut their three-year relapse risk.

Questions about this story

Free account needed to ask — your question is kept and asked for you right after sign-up. Answers are public.

No questions yet — be the first to ask.

Key Indicators

Cancer recurrences

None of 32 NEOPRISM-CRC patients relapsed in 33 months of follow-up. At the March 31, 2026 data cutoff, 31 patients were in the relapse analysis.

Trial patients so far

Stage 2-3 MMR-deficient bowel cancer patients treated at five UK hospitals. Recruitment continues toward a target of 78.

59%

No detectable cancer after treatment

Share of patients with no cancer detectable after immunotherapy and surgery.

32.9

Median follow-up (months)

Median follow-up at the March 31, 2026 data cutoff, ranging from 26.4 to 41.4 months.

6.2%

Grade 3-4 immune-related side effects

Two of 32 patients had serious immune-related adverse events from pembrolizumab.

~25%

Standard-care 3-year relapse rate

Expected relapse rate for surgery followed by chemotherapy, used as the trial comparison.

Voices

Curated perspectives — historical figures and your fellow readers.

People Involved

Christopher (surname not reported)

NEOPRISM-CRC trial participant, stage 3 bowel cancer

Cancer-free more than three years after treatment

Yanrong Jiang

Lead study author, NEOPRISM-CRC trial

Presented the trial's 33-month follow-up results at the AACR 2026 annual meeting

Organizations Involved

University College London (UCL)

University and research institution

Lead institution for the NEOPRISM-CRC trial

UCL researchers led the trial and presented its updated results at the AACR annual meeting in April 2026.

University College London Hospitals NHS Foundation Trust

NHS hospital trust

Co-lead and treating center for the NEOPRISM-CRC trial

UCLH partnered with UCL to run the trial and provided clinical care for study patients.

American Association for Cancer Research (AACR)

Professional association of cancer researchers

Venue for presenting the trial's updated results

The NEOPRISM-CRC team presented its zero-relapse follow-up at the AACR annual meeting in April 2026.

Timeline

2023 October 2026

4 events Latest: October 10th, 2026 · 1 month ago

Tap a bar to jump to that date

October 2026
ScienceDaily reports the durable outcomes
Latest Coverage

ScienceDaily publishes report on zero recurrences, including patients with residual disease.
October 10th, 2026
April 2026
Zero relapses presented at AACR meeting
Results

Researchers report none of 32 patients relapsed after 33 months of follow-up.
April 2026
May 2023
Christopher's surgery marks tumor response
Treatment

Patient undergoes surgery after nine weeks of pembrolizumab; doctors say cancer melted away.
May 2023
2023
NEOPRISM-CRC trial enrolls 32 patients
Trial

Patients with MMR-deficient stage 2-3 bowel cancer join the trial at five UK hospitals.
2023

Scenarios

NHS approves pre-surgery pembrolizumab for MMR-deficient bowel cancer

Likely Resolves by Q2 2028

Discussed by: UCL and UCLH researchers, BBC News reporting on hopes the treatment reaches the NHS in coming years

NICE appraises neoadjuvant pembrolizumab for MMR-deficient stage 2-3 bowel cancer. If approved, pre-surgery immunotherapy becomes the standard first step, replacing surgery-then-chemo for this patient group. UCL and UCLH researchers said they hope it reaches the NHS in the coming years.

Larger trial confirms the durable benefit

Possible Resolves by End of 2029

Discussed by: Researchers cautioning the current trial is small with a short follow-up; Prof Jim Khan on the need for tailored approaches

A phase 3 trial with more patients and longer follow-up reports recurrence or survival outcomes. Results either confirm the zero-relapse finding or narrow it once a larger, more diverse group is studied. Researchers say the current evidence needs validation at scale.

Immunotherapy benefit stays limited to MMR-deficient patients

Possible Resolves by End of 2028

Discussed by: BBC News reporting on patient Elise Sargent with a different mutation; Prof Jim Khan on tailoring treatment to tumor biology

The zero-relapse result applies only to the 10-15% of stage 2-3 bowel cancer patients with MMR-deficient tumors. National guidelines keep pre-surgery immunotherapy limited to this group, and patients with other genetic profiles continue with standard chemotherapy options.

Blood tests steer some patients past surgery entirely

Possible

Discussed by: NEOPRISM-CRC lead author Yanrong Jiang, presenting at the AACR 2026 annual meeting

Researchers found that ctDNA clearance from blood and baseline T-cell receptor clonality predicted pathological response. Jiang proposed using these markers to pick 'super responders' for nonoperative management, avoiding surgery, and to decide who needs adjuvant therapy. She called for prospective, adaptive, biomarker-informed trials to test the approach.

Historical Context

2 moments from history that rhyme with this story — and how they unfolded.

May 2017

FDA approves pembrolizumab for MSI-high cancers (2017)

The US Food and Drug Administration approved pembrolizumab for any solid tumor with microsatellite instability-high or mismatch-repair-deficient features. It was the first approval tied to a genetic marker rather than tumor location.

Then

Patients with these mutations gained a drug effective across multiple cancer types, not just one.

Now

Established MMR deficiency as a predictive biomarker for immunotherapy, laying the foundation for trials like NEOPRISM-CRC.

Why this matters now

The same genetic profile selected patients for this bowel cancer trial — the marker predicted who would respond to the drug.

May 2022

CheckMate 816 neoadjuvant lung cancer trial (2022)

A phase 3 trial showed nivolumab plus chemotherapy before surgery improved event-free survival in resectable non-small-cell lung cancer, versus chemotherapy alone.

Then

Became a new standard option for resectable lung cancer patients.

Now

Encouraged pre-surgical immunotherapy across tumor types, including the design NEOPRISM-CRC later tested in bowel cancer.

Why this matters now

Provided the precedent for giving immunotherapy before surgery rather than after — the approach this trial applied to MMR-deficient bowel cancer.