Rational testing for gene fusion in colorectal cancer: MSI and RAS-BRAF wild-type metastatic colorectal cancer as target population for systematic screening

Exploring ALK fusion in colorectal cancer: a case series and comprehensive analysis

Anaplastic lymphoma kinase (ALK) fusion-positive colorectal cancer (CRC) is a rare and chemotherapy-refractory subtype that lacks established and effective treatment strategies. Additionally, the efficacy and safety of ALK inhibitors (ALKi) in CRC remain undetermined. Herein, we examined a series of ALK-positive CRC patients who underwent various lines of ALKi treatment. Notably, we detected an ALK 1196M resistance mutation in a CRC patient who received multiple lines of chemotherapy and ALKi treatment. Importantly, we found that Brigatinib and Lorlatinib demonstrated some efficacy in managing this patient, although the observed effectiveness was not as pronounced as in non-small cell lung cancer cases. Furthermore, based on our preliminary analyses, we surmise that ALK-positive CRC patients are likely to exhibit inner resistance to Cetuximab. Taken together, our findings have important implications for the treatment of ALK-positive CRC patients.

Incidence and clinical significance of 491 known fusion genes in a large cohort of Japanese patients with colorectal cancer

BACKGROUND

The clinical significance of fusion genes in colorectal cancer remains unclear. The purpose of this study was to determine the incidence of fusion genes in colorectal cancer and explore their clinical significance by screening for common fusion genes in a large Japanese cohort.

METHODS

This study involved 1588 patients. The incidence of 491 fusion genes was examined using a designed fusion panel. In addition, the patients were classified into two groups (RSPO fusion-positive or -negative) according to the presence of RSPO fusions, and the clinicopathological and genetic characteristics of both groups were compared. Long-term outcomes were analyzed in patients without distant metastases.

RESULTS

Fusion genes were detected in 2% (31/1588) of colorectal cancers. The incidence of RSPO fusions (such as PTPRK-RSPO3 and EIF3E-RSPO2) was 1.5% (24/1588), making them the most common fusions, whereas the incidence of other fusion genes was extremely low. The distribution of consensus molecular subtypes and frequency of APC mutations were significantly different between the RSPO fusion-positive and -negative groups. The 3-year cumulative incidence rate of recurrence was higher in the RSPO fusion-positive group than in the RSPO fusion-negative group (positive, 31.2% vs. negative, 13.5%, hazard ratio = 2.357; p = 0.040).

CONCLUSION

Broad screening for fusion genes showed that RSPO fusions were the most common in colorectal cancer, with an incidence of 1.5%. RSPO fusions may be clinically significant in identifying patients at a high risk of recurrence who would be responsive to specific treatments.