Anaplastic Lymphoma Kinase Gene Rearrangement in Children and Young Adults With Mesothelioma.

Introduction: Children and young adults diagnosed with malignant mesothelioma may have unique genetic characteristics. In this study, we evaluated for the presence of the anaplastic lymphoma kinase (ALK) translocations in these patients.

Methods: In a prospective study of mesothelioma natural history (ClinicalTrials.gov number NCT01950572), we assessed for the presence of the ALK translocation in patients younger than 40 years, irrespective of the site of disease. The presence of this translocation was assessed by means of fluorescence in situ hybridization (FISH). If the patients tested positive for the ALK translocation, both immunohistochemistry and RNA sequencing were performed on the tumor specimen.

Results: Between September 2013 and December 2018, 373 patients were enrolled in the mesothelioma natural history study, of which 32 patients were 40 years old or younger at the time of their mesothelioma diagnosis. There were 25 patients with peritoneal mesothelioma, five with pleural mesothelioma, one with pericardial mesothelioma, and one with bicompartmental mesothelioma. Presence of an ALK translocation by FISH was seen in two of the 32 patients (6%) with mesothelioma. Both patients, a 14-year-old female and a 27-year-old male, had peritoneal mesothelioma and had no history of asbestos exposure, prior radiation therapy, or predisposing germline mutations. Neither had detectable ALK expression by immunohistochemistry. RNA sequencing revealed the presence of an STRN fusion partner in the female patient but failed to identify any fusion protein in the male patient.

Conclusions: Young patients with peritoneal mesothelioma should be evaluated for the presence of ALK translocations. Presence of this translocation should be assessed by FISH and these patients could potentially benefit from tyrosine kinase inhibitors targeting ALK.