CNS involvement by North American-ATLL (NA-ATLL) is associated with discrete patterns and molecular profile involving XPO1 E571 and KLF2/PI3KCD in selected cases.

Abstract

8063 Background: Information on central nervous system (CNS) involvement with NA-ATLL is limited. In this study, we describe CNS involvement in ATLL patients at a tertiary hospital in New York City. Methods: We considered CNS involvement if one of the following criteria was met 1) cerebrospinal fluid (CSF) cytology or flow cytometry was positive 2) CNS imaging was positive for disease involvement or 3) Physical exam findings were compatible with neurologic involvement. Results: Of 94 NA-ATLL patients, 21 (22.3%) had CNS involvement by ATLL. CSF was involved in 13/21 and 5/21 patients at diagnosis and relapse respectively. At diagnosis, MRI showed CNS involvement in brain and spine in 5/21 (24%) and 3/ 21 (14%) cases respectively. At relapse, imaging revealed brain and spine involvement in 2 patients each. Neurological exam was abnormal in 7 (33%) and 3 (14%) cases at diagnosis and relapse respectively. Next generation exon targeted sequencing was performed in 9 cases. Table shows the mutations (mtn) and functional groups with frequencies. XPO1 E571K mutation was present in 2 patients with extensive CNS disease and refractory to conventional treatment with an overall survival (OS) of 2 months. To our knowledge, this is the first time that XPO1 E571K is reported in a T-Cell malignancy. We also describe here a second set of mutations with CNS involvement (KLF2 and PI3KCD) in 2 patients. Median OS was 8.5 months, Median RFS was 6.5 months in our series. In most cases, the lymphomatous phenotype appeared to have direct mass-like extension (5/21) with several cases of accompanying osteolytic spine or skull lesions, whereas cases with hematogenous involvement tends to spread to the CSF by traversing the brain blood barrier. Conclusions: In this report we describe patterns of CNS involvement in ATLL and the associated mtns. We also describe two unique cases of XPO1E571K mtn in a TCL. [Table: see text]