For patients with metastatic colorectal cancer, the sequence of treatment is often a guessing game. Doctors know that anti-EGFR therapies like cetuximab work, but they struggle to know when to stop. New data from the CAPRI-2 GOIM trial, presented at the ESMO GI Cancers Congress 2026, offers a potential solution.

Researchers used plasma ctDNA comprehensive genomic profiling to track patients in real time. They wanted to see if they could identify who would continue to benefit from cetuximab even after switching chemotherapy backbones. The results were striking.

Refining the Patient Selection

The trial focused on patients with RAS and BRAF V600E wild-type, microsatellite stable metastatic colorectal cancer. Investigators categorized patients into two groups based on their ctDNA profiles. Those without detectable pathogenic variants in a panel of resistance-related genes were labeled "negative hyperselected." Those with one or more variants were "positive hyperselected."

This distinction proved vital. In the first-line setting, the negative hyperselected group saw an objective response rate of 78 percent. The positive hyperselected group saw only 54 percent. The gap was clear.

The Case for Continuing Cetuximab

After the first round of treatment, the researchers switched the chemotherapy backbone from FOLFIRI to FOLFOX while keeping cetuximab in the mix. They wanted to see if the drug still held value. It did.

For the negative hyperselected group, the median progression-free survival reached 8.3 months. For the positive group, it was just 4.65 months. The difference was statistically significant. It suggests that for a specific subset of patients, cetuximab remains a potent tool well into the second line of therapy.

Why This Matters Now

Standard care often relies on broad markers. This trial suggests we can do better. By using serial liquid biopsies, clinicians may be able to tailor treatment sequences more precisely. It turns a blunt instrument into a scalpel.

"Plasma ctDNA CGP can help identify patients who derive meaningful benefit from continuing cetuximab by simply switching the chemo backbone," noted MV Chandrakanth following the presentation. The data supports a more dynamic approach to therapy.

Key Takeaways

  • Precision matters: Plasma ctDNA profiling identified a "negative hyperselected" group that responded significantly better to cetuximab-based therapy.
  • Sequencing success: Continuing cetuximab while switching from FOLFIRI to FOLFOX extended progression-free survival in the negative hyperselected cohort.
  • Dynamic monitoring: Serial liquid biopsies allow for real-time adjustments to treatment, moving beyond baseline testing alone.

What Experts Say

The findings from CAPRI-2 GOIM underscore a shift toward molecularly driven sequencing. While the survival benefit from the start of second-line therapy was not statistically significant, the overall survival from baseline favored the hyperselected group. Experts suggest this validates the use of ctDNA to avoid unnecessary toxicity in patients unlikely to respond. The next step for the research team is to determine if this strategy holds up in larger, randomized phase III trials. Clinicians should watch for the full publication of these results later this year to see if these criteria become part of standard clinical guidelines.