# CEACAM5 imaging for occult colorectal recurrence

Source: https://nuclide.cc/opportunities/opp-ceacam5-imaging-colorectal/  
Nuclide record `opp-ceacam5-imaging-colorectal` (Opportunity). Data CC BY-NC 4.0, attribute "Data from Nuclide (nuclide.cc)"; commercial use needs a licence.

## TL;DR

After bowel cancer surgery, a rising blood marker often signals that the cancer is back, but scans frequently cannot say where. The one scan ever approved for that exact problem was withdrawn from the market in 2005 and nothing has replaced it.

## Summary

The clinical scenario is specific and common: a treated colorectal cancer patient's serum CEA rises during surveillance while CT, MRI and colonoscopy are normal or equivocal. Salvage surgery or ablation can still cure oligometastatic recurrence, but only if the disease can be localised. Arcitumomab (CEA-Scan), a technetium-99m anti-CEA antibody fragment approved for precisely this indication, was withdrawn from both the US and EU markets in 2005; clinicians now fall back on FDG PET/CT off-label, which in one referred series found recurrence in 56 of 88 such patients.

Meanwhile the therapeutic side of CEACAM5 has grown: antibody-drug conjugates, T-cell engagers and CAR-T programmes target it, and the field has learned that CEA-directed therapy selection is not the same question as CEA-directed localisation. The most advanced CEACAM5-directed imaging agent in humans is not a PET tracer at all but SGM-101, a near-infrared fluorescent anti-CEA antibody for intraoperative use, now in a randomised phase 3 trial (NCT03659448, about 300 patients). For PET, the most advanced is the CEA-targeted nanobody 68Ga-HNI01 at first-in-human scale, nine patients.

The competitive picture changed independently of imaging. Tumour-informed ctDNA now detects recurrence a median of 5.9 months before radiological recurrence in GALAXY/CIRCULATE-Japan, and ctDNA-guided adjuvant therapy was non-inferior to standard management in DYNAMIC while halving chemotherapy use. ctDNA says whether and roughly when; it does not say where. That distinction is the whole of the case for a CEACAM5 tracer, and it is a stronger case now than when CEA-Scan was withdrawn, because more patients are being flagged as molecularly positive with nothing to localise.

## Fields

- Kind: Opportunity
- Last checked: 2026-09-23
- Also known as: CEA PET; CEACAM5 PET
- Tags: unmet need first; colorectal; recurrence; ctDNA

## Sources

- FDG PET/CT for occult colorectal recurrence with raised CEA: https://pmc.ncbi.nlm.nih.gov/articles/PMC5153343/
- NCT03659448: SGM-101 phase 3 in colorectal cancer: https://clinicaltrials.gov/study/NCT03659448
- GALAXY: ctDNA lead time over radiological recurrence, Nature Medicine 2024: https://www.nature.com/articles/s41591-024-03254-6
- DYNAMIC: ctDNA-guided adjuvant therapy in stage II colon cancer: https://pmc.ncbi.nlm.nih.gov/articles/PMC9701133/
- CT nodal staging accuracy meta-analysis: https://pmc.ncbi.nlm.nih.gov/articles/PMC13394594/

## Connected records

- isotopes: [Fluorine-18](https://nuclide.cc/isotopes/f-18/), [Gallium-68](https://nuclide.cc/isotopes/ga-68/), [Technetium-99m](https://nuclide.cc/isotopes/tc-99m/)
- indications: [Colorectal cancer](https://nuclide.cc/indications/colorectal-cancer/)
- technologies: [FDG PET](https://nuclide.cc/technologies/fdg-pet/), [Immuno-PET](https://nuclide.cc/technologies/immuno-pet/), [PET/CT](https://nuclide.cc/technologies/pet-ct/)
- targets: [CEACAM5](https://nuclide.cc/targets/ceacam5/)

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