Attygalle, Ayoma D.

Abstract Angioimmunoblastic T-cell Lymphoma (AITL) is a rare Peripheral T-cell lymphoma that primarily affects the elderly, presenting as advanced disease characterized by aggressive behaviour and very poor outcome. Despite the unfavourable prognosis, the best approach for treating patients with AITL is still unknown. We report a retrospective multicentre study of 64 AITL patients (37 male, 27 female) who were diagnosed as AITL in our institution based on typical histology and molecular clonality analysis between 1995 and 2004. The median age at diagnosis was 60 years (range 25 to 87). Fifty-two patients (81%) presented with advanced stage III–IV disease, 41 (64%) had B symptoms and 49 (76%) elevated LDH. ECOG performance status was 1 for 40%, 2 for 53% and 3 for 9% of the patients. Based on IPI risk factors 12% of the patients were classified as low risk, 17% low intermediate, 29% high intermediate and 42% as high risk. Six patients developed autoimmune haemolytic anaemia. Therapeutic approach varied from no treatment to high dose therapy (HDT). The majority of the patients had received CHOP chemotherapy. Overall 19 patients (30%) had received 1 treatment line, 20 (31%) had 2, 19 (30%) 3, 4 patients (6%) were treated with ≥4 and 2 (3%) were not eligible for any treatment. Twenty patients (31%) proceeded to an autologous and 2 to allogeneic transplantation after achieving CR (n=12), PR (n=7) while 3 had progressive disease. Following first line therapy 37 patients (58%) achieved CR, 15 (23%) PR and 10 (16%) had primary refractory disease. Median time to relapse or progression was 6 months (1 to 89). Interestingly three patients relapsed as EBV driven DLBCL, 1as DLBCL and 2 as EBV driven Hodgkin’s lymphoma. With a median follow-up of 19 months (1 to 119) twenty-six patients (41%) were alive. Eighteen (28%) of these patients were in CR, and 8 in PR (13%). Thirty-seven patients (58%) died, 29 (45%) from disease progression. Twelve patients developed toxic complications -infectious complications (n=8), haemorrhage (n=1), thrombosis (n=1) myocardial infarction (n=2). The estimated PFS rates at 1 and 2 years were 33% and 27% respectively. Overall survival rates were estimated at 55% and 28% at 2 and 4 years. By univariate and multivariate analyses, no response to first line therapy (p=0.035) and male sex (p=0.0161), were significantly associated with higher relapse rate. Application of HDT resulted to significantly superior PFS (p=0.002). Poor performance status at presentation was the only factor found to be significant for the OS (p= 0.0317). In conclusion analysis of the results of this large cohort of AITL patients showed that although the initial overall response rate was 73% this was short lived. It is estimated that less than 30% of the patients will survive and remain disease free at 4 years. Considering the dismal outcome with current therapeutic approaches, new strategies using novel agents to improve further and most importantly maintain initial response are needed. The role of frontline HDT either autologous or allogeneic for eligible AITL patients is worth exploring in prospective collaborative studies.

Abstract Peripheral T- and NK-cell lymphomas (PTCLs) are fatal in the majority of patients, and conventional chemotherapy is minimally effective. Targeted inhibition of tyrosine kinases (TKs) might be a useful treatment strategy, but TK overexpression by PTCLs has not been well characterized (except ALK). Recently a novel translocation t(5;9) fusing the ITK and SYK genes was reported in a subset of unspecified-type PTCLs, associated with high SYK gene expression and Syk protein positivity. Syk is a non-receptor TK important in immunoreceptor signal transduction, providing proliferation and survival signals in a variety of hematopoietic cells. Syk is absent or expressed at very low levels in most normal post-thymic T cells, where this signal transduction role is fulfilled by ZAP70. Since Syk TK inhibitors are now in clinical trials for other diseases, we sought to determine the incidence of t(5;9) and Syk overexpression in PTCL. Tissue microarrays were constructed using triplicate cores from paraffin-embedded tissue blocks. Cases were studied using fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC). Additional studies were performed using flow cytometry and Western blot. There were 141 PTCLs, including 35 angioimmunoblastic, 66 unspecified, 21 anaplastic large cell, 2 enteropathy-associated, 5 hepatosplenic, 5 extranodal NK/T, and 7 other. No evidence of t(5;9) was identified by FISH in 86 informative cases. Normal T-cell subsets from peripheral blood, spleen, and lymph node were negative for Syk by IHC, flow cytometry, and Western blot. Syk was positive by immunohistochemistry in 133 of 141 (94%) PTCLs. All 8 Syk negative cases were extranodal, cytotoxic PTCLs. Western blot on frozen tissue correlated with IHC results in paraffin. All 4 Syk-positive cases tested showed phosphorylation of tyrosine residues 525/526, known to be required for Syk activation. We conclude that Syk is overexpressed in most PTCLs, including the vast majority of nodal cases. Syk may substitute for ZAP70 in these tumors and provide ongoing proliferation and survival signaling. The overexpression of Syk and phosphorylation of its Y525/526 residues suggest Syk may be a suitable target for pharmacologic TK inhibition as a treatment option for patients with PTCL.