TRAF1-ALK Fusion Predicts Poor Prognosis for ALK Positive Anaplastic Large Cell Lymphoma Patients with Chemotherapy and ALK Inhibitor

Background: Relapsed/refractory anaplastic lymphoma kinase (ALK) positive anaplastic large cell lymphomas (ALCLs) respond to ALK inhibitors, but resistance, which bear a poor prognosis. No biomarkers were found to predict long duration of response to ALK inhibitors. The ALK gene was first identified as the fusion partner of the nucleophosmin (NPM1) gene in the recurrent t(2;5)(p23;q35) found in a subset of ALCL. However, several distinct ALK fusions which result in highly different characteristics have also been described in lymphomas.

Methods: We retrospectively reviewed seven relapsed/refractory ALK positive ALCLs who received ALK inhibitors (six with Crizotinib and one with Alectinib) at Guangdong Provincial People's Hospital from June 2007 through March 2019. We did next generation sequencing (NGS) with paraffin-embedded tissue for two patients who quickly developed resistance.

Results: Of the seven patients, four were male and three were female, with a median age of 18 years (range 15-51) old. The median line of therapies was four (range 3-7) and that of ALK inhibitor usage was three (range 2-5). The overall response rate was 7 of 7 (100%) and the median overall survival of 21.2 months (8.5-86 months). Three patients obtained complete response (CR) on Crizotinib and then received autologous stem cell transplantation, and are still CR. One patient obtained CR, but died of serious infection five months after allogeneic stem cell transplantation. One patient is in CR under continuous crizotinib administration. One patient received Crizotinib obtained CR, but three months later got progression disease, the NGS showed TNF receptor-associated factor 1 gene (TRAF1) exon 6-ALK exon 20 fusion junction. The last patient was CR on alectinib, but quickly developed resistance, with a progression free survival of 1 month, the NGS indicated TRAF1 exon 7-ALK exon 20 fusion.

Conclusions: ALK inhibitors improved survival of relapsed/refractory ALK positive ALCLs. TRAF1-ALK fusion may predict poor clinical outcome to chemotherapy and ALK inhibitors. This ALK fusion may reflect a trend to aggressive behaviour in lymphomas.