Anaplastic Lymphoma Kinase (ALK) Inhibitors Show Activity in Colorectal Cancer With ALK Rearrangements: Case Series and Literature Review

Anaplastic lymphoma kinase (ALK) rearrangement is a well-known driver oncogene detected in approximately 5% of non-small cell lung cancer. However, ALK rearrangement is much less frequent in other solid tumors outside the lungs, such as colorectal cancer (CRC); thus, the optimal management of CRC with ALK rearrangements has yet to be established. In this report, we describe 2 cases of ALK-positive CRC, both of which benefited from ALK tyrosine kinase inhibitor (ALK-TKI) therapy. Case 1 was a postoperative patient with poorly differentiated colon adenocarcinoma, who was diagnosed with metastatic relapse shortly after surgery. Both fluorouracil, leucovorin, and oxaliplatin (FOLFOX) and bevacizumab combined with 5-fluorouracil, l-leucovorin, and irinotecan (FOLFIRI) proved ineffective against the disease. The patient was then treated with ensartinib, as the CAD-ALK fusion gene was detected by genomic analysis. The patient was initially treated with ensartinib monotherapy for 9 months, then with ensartinib combined with local radiotherapy and fruquintinib for another 4 months for isolated hilar hepatic lymph node metastasis. The patient experienced disease progression with an acquired ALK G1202R resistance mutation that responded well to lorlatinib. Case 2 involved a 72-year-old man with advanced colon cancer (pT4bN2aM1b, stage IV) harboring an EML4-ALK fusion. The patient underwent resection of the right colon tumor due to intestinal obstruction, but the disease continued to progress after 12 courses of FOLFIRI and bevacizumab chemotherapy. However, the patient responded remarkably well to alectinib. Our report emphasizes the importance of gene detection in the treatment of malignant tumors, and the significance of ALK mutations in CRC.