Correction: Bidirectional linkage between the B-cell receptor and NOTCH1 in chronic lymphocytic leukemia and in Richter's syndrome: therapeutic implications.
In addition to clinical prognostic features such lactate dehydrogenase level, platelet count, and performance status, important predictors of poor outcome in RT are TP53 disruption and clonal relationship of DLBCL to underlying CLL.
While nodal RS has been extensively investigated in literature, pathogenesis and prognosis of cutaneous RS are still partially unknown, even if a role of Epstein-Barr virus infection and p53 disruption has been suggested.
Molecular lesions of regulators of tumor suppression (TP53), cell cycle (CDKN2A), and cell proliferation (NOTCH1, MYC) overall account for ~90% of RS and may be responsible for the aggressive clinical phenotype observed in this disease because of the combined effect of chemoresistance and rapid disease kinetics.
Molecular lesions of tumor suppression regulators (TP53), cell cycle (CDKN2A) and cell proliferation (NOTCH1, MYC) overall account for ∼90% of RS and may be responsible for its aggressive clinical phenotype.
Molecular lesions of regulators of tumor suppression (TP53), cell cycle (CDKN2A), and cell proliferation (NOTCH1, MYC) overall account for ~90% of RS and may be responsible for the aggressive clinical phenotype observed in this disease because of the combined effect of chemoresistance and rapid disease kinetics.
Molecular lesions of tumor suppression regulators (TP53), cell cycle (CDKN2A) and cell proliferation (NOTCH1, MYC) overall account for ∼90% of RS and may be responsible for its aggressive clinical phenotype.
Patients with chronic lymphocytic leukemia (CLL) carrying deletion of 17p (17p-) or mutations of TP53 have a uniquely poor prognosis related to increased propensities to progress to symptomatic disease, poor responses to chemo(immuno)therapy and high rates of Richter transformation.
Recent studies have also identified the crucial role of CDKN2A loss, TP53 disruption, C-MYC activation, and NOTCH1 mutations in the transformation from CLL to RS.
There was a significantly higher risk for Richter's syndrome (RS) transformation in patients with NOTCH1 or FBXW7 mutations, with four of the seven (57%) patients developing RS and characterized at least by one of the two abnormalities.
RS lesions are heterogeneous in terms of load and spectrum among patients, and include those involved in CLL progression and chemorefractoriness (TP53 disruption and NOTCH1 activation) as well as some not previously implicated in CLL or RS pathogenesis.
RS lesions are heterogeneous in terms of load and spectrum among patients, and include those involved in CLL progression and chemorefractoriness (TP53 disruption and NOTCH1 activation) as well as some not previously implicated in CLL or RS pathogenesis.
On the contrary, NOTCH1, SF3B1 and BIRC3 mutations appear to have a specific significance, the clinical value of which is currently being validated, i.e. association to Richter syndrome transformation for NOTCH1 mutations, and short progression-free survival after treatment for SF3B1 mutations.
Patient proportions with TP53 defects at diagnosis or before first therapy were reported within the range 5-15 %, but they increase dramatically in pretreated cohorts (reported up to 44 %), and also in patients with Richter transformation (50 % harbor TP53 defects).
The poor prognosis conferred by NOTCH1 mutations was attributable, at least in part, to shorter treatment-free survival and higher risk of Richter transformation.
Specific risk factors for the development of Richter's transformation in a patient with CLL have yet to be identified; however, TP53 disruption, c-MYCabnormalities, unmutated immunoglobulin heavy chain (IGHV) < 2%, non-del13q cytogenetics, CD38 gene polymorphisms, stereotypy, and VH4-39 gene usage may predispose to Richter's transformation.
Accordingly, most (9/11, 81.1%) clonally related RS harbored a genetic lesion disrupting TP53 that was already present, though at subclonal levels, in 5/11 (45.5%) samples of the paired CLL phase.
Although most of these genes were affected at low frequency in an expanded CLL screening cohort, mutational activation of NOTCH1, observed in 8.3% of CLL at diagnosis, was detected at significantly higher frequency during disease progression toward Richter transformation (31.0%), as well as in chemorefractory CLL (20.8%).
RS that were clonally unrelated to the paired chronic lymphocytic leukemia phase were clinically and biologically different from clonally related RS because of significantly longer survival (median, 62.5 months vs 14.2 months; P = .017) and lower prevalence of TP53 disruption (23.1% vs 60.0%; P = .018) and B-cell receptor stereotypy (7.6% vs 50.0%; P = .009).
Using a laser-capture microdissection we analyzed small and large leukemic bone marrow cells from 19 patients with RS for loss of heterozygosity (LOH) on chromosome 11 (D11S2179 at the ATM gene), 17 (D17S938 and D17S1852 at the TP53 site), and 20 (Plc1, D20S96, D20S110, and D20S119).
Four immunohistochemical patterns of p53 and p21(Waf1) expression were observed: (1) p53-/p21- in 10 of 15 CLL (67%), but only in two of six RS (33%); (2) p53+/p21+ in three CLL (20%) and two RS (33%); (3) p53-/p21+ in one RS; and (4) p53++/p21- in two CLL and one RS.Two p53+/p21+ CLL evolved into RS. p53 mutations clustered around the p53++/p21- (two CLL and one RS) and p53-/p21- (one CLL and one RS) tumors.
At diagnosis, B-cell chronic lymphocytic leukemia frequently display deletions of 13q14, trisomy 12 and alterations of the ATM gene, whereas evolution to Richter's syndrome is associated with disruption of p53.