Colorectal Cancer Research: MSI/MMR, KRAS, EGFR & Immunotherapy Reagents

Colorectal cancer (CRC) is the third most common cancer globally. Molecular profiling of CRC has become essential for treatment selection, with microsatellite instability (MSI) status, RAS/BRAF mutation status, and HER2 amplification guiding therapy decisions. For a broader view of all oncology reagent categories, see our Cancer Research Reagents hub.

Key Targets and Biomarkers

MSI/MMR IHC panel: MLH1, MSH2, MSH6, and PMS2 antibodies detect mismatch repair protein expression on FFPE tissue. Loss of any MMR protein indicates MSI-high (dMMR) status, which predicts response to PD-1 checkpoint immunotherapy (pembrolizumab, nivolumab) and identifies Lynch syndrome carriers. For guidance on building diagnostic IHC panels, see our IHC Panel Design guide.

RAS mutations (KRAS exon 2/3/4, NRAS exon 2/3/4) predict resistance to anti-EGFR antibodies (cetuximab, panitumumab) in metastatic CRC. Only RAS wild-type patients benefit from EGFR-targeted therapy. Anti-KRAS antibodies and mutation-specific reagents are used in expression and functional studies.

BRAF V600E mutation occurs in ~8–10% of CRC and indicates aggressive biology with poor prognosis. Anti-BRAF V600E antibodies (clone VE1) detect the mutant protein by IHC, providing a rapid mutation screening tool complementary to molecular testing.

CEA (CEACAM5) is the classic CRC serum biomarker, used for post-surgical surveillance. Anti-CEA antibodies and recombinant CEA proteins support ELISA development and IHC studies. CEA-targeted ADCs and bispecific T cell engagers are in clinical development.

CDX2, CK20, and CK7 antibodies form the standard IHC panel for confirming colorectal origin in metastatic carcinoma of unknown primary. Anti-VEGF (bevacizumab) remains a backbone of metastatic CRC treatment, with research biosimilar versions available for preclinical and PK/ADA studies.

References

1. Dekker E, Tanis PJ, Vleugels JLA, Kasi PM, Wallace MB. Colorectal cancer. Lancet. 2019;394(10207):1467-1480. doi: 10.1016/S0140-6736(19)32319-0

2. Pardoll DM. The blockade of immune checkpoints in cancer immunotherapy. Nat Rev Cancer. 2012;12(4):252-264. doi: 10.1038/nrc3239

3. Hanahan D. Hallmarks of cancer: new dimensions. Cancer Discov. 2022;12(1):31-46. doi: 10.1158/2159-8290.CD-21-1059

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