HIP1-ALK fusion variant in non-small-cell lung cancer and response to crizotinib: a case report and review of the literature

Several fusion partners of ALK have been reported in patients with non-small cell lung cancer (NSCLC). Huntingtin interacting protein 1 (HIP1)-ALK is one kind of ALK fusion. We report a case of HIP1-ALK fusion variant in non-small-cell lung cancer and further review the clinical characteristics and efficacy of crizotinib to this type of fusion in NSCLC patients. The case involved a 56-year-old Chinese woman with multiple lung metastases NSCLC (T1N0M1, stage IV). Histological examination of the tumor showed lung adenocarcinoma. Ventana (D5F3) ALK IHC assay (Ventana Medical Systems, Roche, Inc) analysis of the left lung tissue revealed the presence of an ALK rearrangement. The patient then experienced a remarkable tumor response to crizotinib. By using next generation sequencing, we found that the tumor had HIP1-ALK (H21; A20) rather than the most common kind of Echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK). Considering this rare ALK fusion and remarkable response to crizotinib treatment, we conclude that the incidence of HIP1-ALK in NSCLC patients with ALK rearrangement should be attentive. NSCLC patients with HIP1-ALK fusion gene respond to treatment with ALK inhibitors. With the guidance of a precise diagnosis, attention to other rare ALK fusions could lead to novel diagnostic methods.