ALK-Fusion Gastric Cancer Responds to Alectinib Before Progression

What happened, in summary

A 58-year-old woman developed cough, reduced appetite, and mild weight loss. Imaging showed a gastric tumor with extensive lymph-node involvement and bone disease, including a lesion in the lumbar spine, establishing Stage IV gastric cancer. Biopsy showed poorly differentiated carcinoma. She first received 5 cycles of capecitabine and oxaliplatin with sintilimab, but the bone metastases continued to worsen. She then received albumin-bound paclitaxel with limited benefit. Broader genomic testing identified a rare DCTN1–ALK fusion, along with an ATM alteration and CDK6 amplification. In May 2023, she began the ALK inhibitor alectinib. She also received strontium-89 to help control painful bone metastases. Imaging showed thinning of the stomach wall and improvement in the previously destructive lumbar lesion, with a partial response lasting about 11.5 months. In early 2024, tumor markers rose and the lumbar metastasis caused epidural spinal cord compression. She received palliative radiation to the affected lumbar area. Blood-based genomic testing at progression no longer detected the original DCTN1–ALK fusion and instead found new KRAS amplification. Her cancer then progressed rapidly throughout the body. She ultimately died from uncontrollable gastrointestinal bleeding.