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Published on: August 19, 2014
Disruption of BIRC3 associates with fludarabine chemorefractoriness in TP53 wild-type chronic lymphocytic leukemia
Davide Rossi1, Marco Fangazio, Silvia Rasi
1Division of Hematology, Department of Translational Medicine, Amedeo Avogadro University of Eastern Piedmont, Novara, Italy. rossidav@med.unipmn.it
Abstract:
The genetic lesions identified to date do not fully recapitulate the molecular pathogenesis of chronic lymphocytic leukemia (CLL) and do not entirely explain the development of severe complications such as chemorefractoriness. In the present study, BIRC3, a negative regulator of noncanonical NF-κB signaling, was investigated in different CLL clinical phases. BIRC3 lesions were absent in monoclonal B-cell lymphocytosis (0 of 63) and were rare in CLL at diagnosis (13 of 306, 4%). Conversely, BIRC3 disruption selectively affected 12 of 49 (24%) fludarabine-refractory CLL cases by inactivating mutations and/or gene deletions that distributed in a mutually exclusive fashion with TP53 abnormalities. In contrast to fludarabine-refractory CLL, progressive but fludarabine-sensitive patients were consistently devoid of BIRC3 abnormalities, suggesting that BIRC3 genetic lesions associate specifically with a chemorefractory phenotype. By actuarial analysis in newly diagnosed CLL (n = 306), BIRC3 disruption identified patients with a poor outcome similar to that associated with TP53 abnormalities and exerted a prognostic role that was independent of widely accepted clinical and genetic risk factors. Consistent with the role of BIRC3 as a negative regulator of NF-κB, biochemical studies revealed the presence of constitutive noncanonical NF-κB activation in fludarabine-refractory CLL patients harboring molecular lesions of BIRC3. These data identify BIRC3 disruption as a recurrent genetic lesion of high-risk CLL devoid of TP53 abnormalities.
Insights
Genetic lesions in BIRC3 are linked to poor outcomes in chronic lymphocytic leukemia (CLL) and chemorefractoriness. This finding identifies BIRC3 as a key factor in high-risk CLL, independent of TP53 abnormalities.
Area of Science:
- Oncology
- Genetics
- Molecular Biology
Background:
- Genetic mutations in chronic lymphocytic leukemia (CLL) do not fully explain its pathogenesis or complications like chemorefractoriness.
- BIRC3, a regulator of noncanonical NF-κB signaling, has not been fully characterized in different CLL clinical phases.
Purpose of the Study:
- To investigate the role of BIRC3 genetic lesions in chronic lymphocytic leukemia (CLL) progression and chemorefractoriness.
- To determine if BIRC3 disruption is associated with a specific clinical phenotype and patient outcome.
Main Methods:
- Analysis of BIRC3 lesions (mutations and deletions) in various CLL clinical phases, including monoclonal B-cell lymphocytosis, newly diagnosed CLL, and fludarabine-refractory CLL.
- Comparison of BIRC3 disruption frequency between fludarabine-refractory and fludarabine-sensitive CLL cases.
- Actuarial analysis to assess the prognostic role of BIRC3 disruption in newly diagnosed CLL.
- Biochemical studies to investigate NF-κB signaling activation in CLL patients with BIRC3 lesions.
Main Results:
- BIRC3 lesions were absent in monoclonal B-cell lymphocytosis and rare in newly diagnosed CLL (4%).
- BIRC3 disruption was found in 24% of fludarabine-refractory CLL cases, occurring mutually exclusively with TP53 abnormalities.
- Patients with progressive but fludarabine-sensitive CLL lacked BIRC3 abnormalities, suggesting a link to chemorefractoriness.
- BIRC3 disruption identified patients with poor outcomes in newly diagnosed CLL, independent of other risk factors.
- Constitutive noncanonical NF-κB activation was observed in fludarabine-refractory CLL with BIRC3 lesions.
Conclusions:
- BIRC3 disruption is a recurrent genetic lesion specifically associated with chemorefractory chronic lymphocytic leukemia (CLL).
- BIRC3 lesions identify a subset of high-risk CLL patients lacking TP53 abnormalities, offering a new prognostic marker.
- The findings implicate BIRC3 inactivation and subsequent noncanonical NF-κB activation in the pathogenesis of aggressive CLL.
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