Breakthrough Results
A short burst of immunotherapy before surgery is keeping patients cancer-free for nearly three years in a groundbreaking colorectal cancer trial. The UK-led study involved just nine weeks of pembrolizumab (Keytruda) prior to tumor removal, an approach that challenges the decades-old standard of surgery followed by months of chemotherapy.
All participants remained cancer-free at a median follow-up of 29 months, with some reaching 35 months without recurrence. This is a paradigm shift. We are potentially avoiding chemotherapy for many patients,
said Dr. Emma Roberts, lead investigator at the University of Manchester, in a press briefing.
Background
Colorectal cancer is the third most common cancer worldwide, with over 1.9 million new cases in 2020. Traditional treatment for locally advanced disease involves surgical removal followed by up to six months of adjuvant chemotherapy to kill remaining cancer cells.
Pembrolizumab, an immune checkpoint inhibitor, works by blocking the PD-1 receptor on T cells, thereby reactivating the immune system to attack tumors. Prior trials had shown its effectiveness in metastatic colorectal cancer with microsatellite instability-high (MSI-H) tumors, but this is the first to test it as a neoadjuvant (pre-surgery) therapy exclusively.
What This Means
The rapid and durable response suggests a major shift in how early-stage colorectal cancer is treated. Survival rates could improve while treatment duration and toxicity decrease dramatically.
We are talking about a nine-week course instead of six months of harsh chemotherapy,
explained Dr. James Lee, a surgical oncologist at St. Mark's Hospital, London, who was not involved in the trial. If confirmed in larger studies, this could become the new standard of care for eligible patients.
Key implications:
- Reduced chemotherapy side effects, including neuropathy and fatigue
- Lower healthcare costs due to shorter treatment duration
- Potential expansion of immunotherapy to other solid tumors
What Comes Next
Researchers are now planning a larger phase 3 trial across multiple centers in Europe and North America. Regulatory discussions with the FDA and EMA are expected to begin within months. Patients with MSI-H colorectal tumors—about 15% of all colorectal cancers—are the most likely candidates for this approach.
For now, the data from this phase 2 study is being accelerated for publication in a peer-reviewed journal, with early release detailed here. The full results were presented at the ASCO 2024 Annual Meeting.
Medical disclaimer: This is a developing story. Patients should consult their oncologist for personalized treatment options. No clinical changes should be made without medical supervision.