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).
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.
Southern blot hybridization analysis failed to show evidence of bcl-1, bcl-2, c-myc proto-oncogene or retinoblastoma (Rb) tumor-suppressor gene rearrangements in these six cases of Richter's syndrome.
FISH studies using LSI bcl-2/IgH probe allowed quantifying the clonal cell population with this rearrangement (4% and 6.6% of cells at diagnosis and RT, respectively).
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.
We identified a novel t(10;14)(p12;q32)/IGH-BMI1 rearrangement and its IGL variant in six cases of chronic lymphocytic leukemia (CLL) and found that these aberrations were consistently acquired at time of disease progression and high grade transformation of leukemia (Richter syndrome).
Finally, sequencing data confirm initial reports associating mutations in BTK and PLCG2 with progression and clearly show that CLL progressions are associated with these mutations, while RT is likely not.
Reversible BTK inhibition is a promising strategy to combat progressive CLL, and multikinase inhibition demonstrates superior efficacy to targeted ibrutinib therapy in the setting of Richter transformation.<i>Cancer Discov; 8(10); 1300-15.
We discuss novel agents in development with a focus on the second-generation Bruton tyrosine kinase inhibitor acalabrutinib, checkpoint inhibition and the potential role of precision medicine in future trials of RS.
In conclusion, the bcl-1 locus rearranges in only about 4% of B-cell CLLs and NHLs, is predominantly rearranged in low-grade B-cell neoplasms, and does not appear to be preferentially associated with those occasional CLLs and low-grade NHLs displaying clinical aggressiveness, advanced clinical stage, or large cell transformation (Richter's syndrome).
Additionally, our results suggest a possible implication of moderate/strong p21(Waf1) expression, loss of p27 expression, and cyclin D1 overexpression in the Richter's transformation of CLL.
Southern blot hybridization analysis failed to show evidence of bcl-1, bcl-2, c-myc proto-oncogene or retinoblastoma (Rb) tumor-suppressor gene rearrangements in these six cases of Richter's syndrome.
PD-L1 expression was observed on the neoplastic B cells in rare DLBCL-RT and other DLBCL cases (1/15 vs. 1/26; P>0.05) as well as background histiocytes and dendritic cells.
Importantly, although some risk factors predict both CLL progression and transformation to RS, others (CD38 genotype, absence of del13q14, IGHV4-39 usage, stereotyped B-cell receptor) appear to specifically predict RS.
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.
A combination of germline genetic characteristics, clinical features (eg, advanced Rai stage), biologic (ζ-associated protein-70(+), CD38(+), CD49d(+)) and somatic genetic (del17p13.1 or del11q23.1) characteristics of CLL B cells, and certain CLL therapies are associated with higher risk of RS.