Castellar, Edgardo R. Parrilla

Abstract Background: Peripheral T-cell lymphomas (PTCLs) represent a heterogeneous group of generally aggressive malignancies, with 5-year overall survival (OS) rates of ∼35%. Only ALK translocations, which define ALK-positive anaplastic large T-cell lymphoma (ALCL), have emerged as a genetic biomarker predicting favorable outcome following conventional chemotherapy (e.g. CHOP). Using next-generation sequencing, we discovered additional recurrent chromosomal translocations in PTCLs involving either the DUSP22 locus on 6p25.3 or TP63 on 3q28. The purpose of this study was to evaluate the prognostic utility of combined testing for both these events in PTCL patients. Methods: We examined the clinicopathologic features of 134 systemic PTCLs using WHO criteria, including 49 ALCLs, 23 angioimmunoblastic PTCLs, 50 PTCLs of “not otherwise specified” type, and 12 PTCLs of other subtypes. Immunohistochemistry was used to determine ALK expression, an established surrogate for ALK translocations in ALCL. Fluorescent in situ hybridization (FISH) was performed to detect translocations of DUSP22 or TP63 in all cases. OS was plotted using the Kaplan-Meier method. Comparisons were made using the log-rank test. Results: There were 83 males and 51 females, with a mean age of 58 years (range, 6 to 90 years). Median OS for all patients was 22 months (5-year OS, 36%) with a median follow-up of 24 months (range, 0.1 to 354 months). Translocations of DUSP22, TP63, and ALK were mutually exclusive. Patients with ALK-positive ALCL (n=17) had a median OS of 176 months (median follow-up, 68 months; 5-year OS, 69%). Despite being ALK-negative, cases with translocations of DUSP22 or TP63 shared pathologic features with ALCL. Median OS was not reached in patients with DUSP22 translocations (n=7; median follow-up, 88 months; 5-year OS, 100%). Patients with tumors harboring TP63 translocations (n=9) had a median OS of 13 months (all dead at 76 months; 5-year OS, 11%). Patients with none of these abnormalities (n=101) had a median OS of 17 months (median follow-up, 13 months; 5-year OS, 29%). Differences in OS among these groups were highly significant (p=0.0002). Conclusions: PTCLs with DUSP22 translocations had a favorable prognosis similar to ALK-positive ALCLs. In contrast, TP63 were associated with very poor prognosis. FISH for these biomarkers is a promising tool for risk stratification, particularly since both translocations occurred in cases with overlapping pathologic features. PTCLs with DUSP22 translocations may represent a genetically defined subset of ALK-negative ALCLs. Like patients with ALK-positive ALCLs, these patients may not derive additional benefit from intensified up-front strategies such as early transplantation. Patients with none of these abnormalities comprised 75% of patients studied and had an intermediate prognosis, indicating the need for additional biomarkers in this group to improve risk stratification. Citation Format: Edgardo R. Parrilla Castellar, George Vasmatzis, Ryan A. Knudson, Rhett P. Ketterling, Karen L. Grogg, William R. Macon, Mark E. Law, Stephen M. Ansell, Ahmet Dogan, Andrew L. Feldman. Genetic biomarkers for risk stratification of patients with peripheral T-cell lymphoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3538. doi:10.1158/1538-7445.AM2013-3538

Key Points ALK-negative ALCLs have chromosomal rearrangements of DUSP22 or TP63 in 30% and 8% of cases, respectively. DUSP22-rearranged cases have favorable outcomes similar to ALK-positive ALCLs, whereas other genetic subtypes have inferior outcomes.