Contributions
Abstract: EP542
Type: E-Poster Presentation
Session title: Aggressive Non-Hodgkin lymphoma - Clinical
Background
Double/triple hit lymphoma (DHL/THL) is classified as high-grade B-cell lymphoma (HGBL) and is known to have a poor prognosis. These lymphomas present with concurrent rearrangements (R) of MYC and BCL2 and/or BCL6, detected by fluorescence in situ hybridization (FISH) (Swerdlow, 2017; Li, 2015; Riedell, 2018). However, little is known about other genetic alterations (e.g. gain (G) or amplification (A)) in these genes and their impact on protein over-expression detected by immunohistochemistry (IHC) and overall survival (OS).
Over-expression of MYC, BCL2 and BCL6 is currently analyzed by IHC and entities with concurrent MYC and BCL2/BCL6 over-expression are called ‘double/triple expressor lymphomas’ (DEL/TEL) and are classified as DLBCL according to WHO (Swerdlow, 2017). Nevertheless, IHC is subjective and definition of positivity is not universally standardized.
Aims
The aim of this study was is to analyze whether genetic alterations of MYC/BCL2/BCL6 genes other than rearrangements (e.g. gain/amplification) detected by FISH, contribute to the identification of a new subtype of DHL/THL and if these gains/amplifications are correlated with IHC over-expression.
Methods
FISH results from 166 samples between 2011 and 2021 were retrospectively collected and categorized into several groups: ‘DHL/THL’ (n=29), ‘Alternative DHL/THL’ (concurrent MYC R and BCL2 and/or BCL6 G/A or concurrent MYC G/A and BCL2 and/or BCL6 R; n=22), ‘Lymphomas with concurrent MYC G/A and BCL2 and/or BCL6 G/A’ (n=25), ‘single BCL2 and/or BCL6 alterations’ (R or G/A; n=35) and ‘No alterations’ (n=55). Available IHC results from these samples (DHL/THL samples excluded; n=82) were divided into ‘DEL/TEL’ (n=39) and ‘No DEL/TEL’ (n=43). FISH and IHC results were compared and correlated with OS.
All statistical analyses were performed using MedCalc windows (MedCalc Software, Ostend, Belgium). OS was estimated according to Kaplan-Meier and compared by the log-rank test. FISH and IHC results were compared using the Chi-squared test. P values < 0.05 were considered significant.
Results
According to FISH results, patients with ‘DHL/THL’ and ‘Alternative DHL/THL’ had significantly worse overall survival while this was not the case for the other groups (Fig. 1A). On the contrary, ‘DEL/TEL’ determined by IHC had no significant difference in outcome in comparison with samples without double expression (Fig 1B).
There was a significant correlation between BCL2 G/A detected by FISH and protein over-expression detected by IHC (p=0.0212). On the other hand, no statistically significant correlation was seen between MYC/BLC6 FISH G/A detected by FISH and protein over-expression detected by IHC (p=0.5518 resp. p=0.6627).
Conclusion
In the present study, the previously reported adverse prognosis of DEL/TEL (Li, 2015; Riedell, 2019; Huang, 2019; Amrallah, 2019; Ting 2019) could not be confirmed. FISH results, on the other hand, showed that only ‘DHL/THL’ and ‘Alternative DHL/THL’, which both carry MYC and BCL2/BCL6 alterations with at least one R, showed worse prognosis. Taken together, samples with only G/A in MYC and BCL/BCL6 are not correlated with adverse outcome. In addition, IHC does not effectively predict the MYC, BCL2 and BCL6 G/A detected by FISH.
In conclusion, FISH remains the golden standard and should always be performed when a HGBL is suspected in order to identify entities with poor outcome, such as ‘DHL/THL’ and ‘Alternative DHL/THL’.
Keyword(s): Fluorescence in situ hybridization, High-grade non-Hodgkins-lymphoma, Immunohistochemistry
Abstract: EP542
Type: E-Poster Presentation
Session title: Aggressive Non-Hodgkin lymphoma - Clinical
Background
Double/triple hit lymphoma (DHL/THL) is classified as high-grade B-cell lymphoma (HGBL) and is known to have a poor prognosis. These lymphomas present with concurrent rearrangements (R) of MYC and BCL2 and/or BCL6, detected by fluorescence in situ hybridization (FISH) (Swerdlow, 2017; Li, 2015; Riedell, 2018). However, little is known about other genetic alterations (e.g. gain (G) or amplification (A)) in these genes and their impact on protein over-expression detected by immunohistochemistry (IHC) and overall survival (OS).
Over-expression of MYC, BCL2 and BCL6 is currently analyzed by IHC and entities with concurrent MYC and BCL2/BCL6 over-expression are called ‘double/triple expressor lymphomas’ (DEL/TEL) and are classified as DLBCL according to WHO (Swerdlow, 2017). Nevertheless, IHC is subjective and definition of positivity is not universally standardized.
Aims
The aim of this study was is to analyze whether genetic alterations of MYC/BCL2/BCL6 genes other than rearrangements (e.g. gain/amplification) detected by FISH, contribute to the identification of a new subtype of DHL/THL and if these gains/amplifications are correlated with IHC over-expression.
Methods
FISH results from 166 samples between 2011 and 2021 were retrospectively collected and categorized into several groups: ‘DHL/THL’ (n=29), ‘Alternative DHL/THL’ (concurrent MYC R and BCL2 and/or BCL6 G/A or concurrent MYC G/A and BCL2 and/or BCL6 R; n=22), ‘Lymphomas with concurrent MYC G/A and BCL2 and/or BCL6 G/A’ (n=25), ‘single BCL2 and/or BCL6 alterations’ (R or G/A; n=35) and ‘No alterations’ (n=55). Available IHC results from these samples (DHL/THL samples excluded; n=82) were divided into ‘DEL/TEL’ (n=39) and ‘No DEL/TEL’ (n=43). FISH and IHC results were compared and correlated with OS.
All statistical analyses were performed using MedCalc windows (MedCalc Software, Ostend, Belgium). OS was estimated according to Kaplan-Meier and compared by the log-rank test. FISH and IHC results were compared using the Chi-squared test. P values < 0.05 were considered significant.
Results
According to FISH results, patients with ‘DHL/THL’ and ‘Alternative DHL/THL’ had significantly worse overall survival while this was not the case for the other groups (Fig. 1A). On the contrary, ‘DEL/TEL’ determined by IHC had no significant difference in outcome in comparison with samples without double expression (Fig 1B).
There was a significant correlation between BCL2 G/A detected by FISH and protein over-expression detected by IHC (p=0.0212). On the other hand, no statistically significant correlation was seen between MYC/BLC6 FISH G/A detected by FISH and protein over-expression detected by IHC (p=0.5518 resp. p=0.6627).
Conclusion
In the present study, the previously reported adverse prognosis of DEL/TEL (Li, 2015; Riedell, 2019; Huang, 2019; Amrallah, 2019; Ting 2019) could not be confirmed. FISH results, on the other hand, showed that only ‘DHL/THL’ and ‘Alternative DHL/THL’, which both carry MYC and BCL2/BCL6 alterations with at least one R, showed worse prognosis. Taken together, samples with only G/A in MYC and BCL/BCL6 are not correlated with adverse outcome. In addition, IHC does not effectively predict the MYC, BCL2 and BCL6 G/A detected by FISH.
In conclusion, FISH remains the golden standard and should always be performed when a HGBL is suspected in order to identify entities with poor outcome, such as ‘DHL/THL’ and ‘Alternative DHL/THL’.
Keyword(s): Fluorescence in situ hybridization, High-grade non-Hodgkins-lymphoma, Immunohistochemistry