R-CHOP and consolidation radiotherapy for limited-stage and low-IPI high-grade b-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements: A single-center case series and review of literature

@#High-Grade B-Cell Lymphoma (HGBCL) with gene rearrangements in MYC and BCL2 and/or BCL6 is an aggressive malignancy usually presenting in advanced stages. Current recommendations suggest the use of regimens more intensive than R-CHOP (rituximab, cyclophosphamide, vincristine, doxorubicin, prednisone), which are based on retrospective studies and single-arm prospective trials that included patients who are mostly in the advanced stage, and did not receive consolidation radiotherapy. The optimal approach and treatment of HGBCL, whether limited-stage (LS) or advanced-stage, remains to be determined. Here we describe the promising outcomes of three patients with LS and low IPI HGBCL with the use of R-CHOP as induction chemotherapy regimen, which was followed by consolidation radiotherapy. Three women, 54-, 60-, and 64-years of age diagnosed to have HGBCL with MYC, and BCL2 and/or BCL6 rearrangements, with Ann Arbor stages I-IIE were included in this case series. All three patients had complete metabolic response to 6 cycles of R-CHOP and was subsequently treated with consolidation involved site radiotherapy (ISRT; total dose 30-36 Gy). Chemotherapy and radiotherapy were tolerated very well. All patients remain to be in remission, with the longest being at 23 months. Outcomes of patients with HGBCL generally remain to be poor, but this may not be the case for patients with limited-stage disease and favorable clinicopathologic risk profile. Nevertheless, the treatment of HGBCL is currently evolving and more studies are needed to determine the ideal approach and preferred chemotherapy regimen. Also, more studies are needed to elucidate the potential role of consolidation radiotherapy in patients with limited-stage HGBCL to improve survival outcomes. Findings of this case series suggest that patients with LS HGBCL may still derive benefit from R-CHOP followed by consolidation ISRT, but prospective trials are needed to confirm this.

Prognostic Value of Histone Modifying Enzyme EZH2 in RCHOP-Treated Diffuse Large B-Cell Lymphoma and High Grade B-Cell Lymphoma.

BACKGROUND: DLBCL represent a heterogeneous group of aggressive diseases. High grade B-cell lymphomas (HGBCL) were recently individualized from DLBCL as a discrete diagnostic entity due to their worse prognosis. Currently, although most patients are successfully treated with RCHOP regimens, 1/3 will either not respond or ultimately relapse. Alterations in histone modifying enzymes have emerged as the most common alterations in DLBCL, but their role as prognostic biomarkers is controversial. We aimed to ascertain the prognostic value of EZH2 immunoexpression in RCHOP-treated DLBCL and HGBCL. RESULTS: We performed a retrospective cohort study including 125 patients with RCHOP-treated DLBCL or HGBCL. EZH2 expression levels did not differ between diagnostic groups or between DLBCL-NOS molecular groups. We found no associations between EZH2 expression levels and outcome, including in the subgroup analysis (GC versus non-GC). Nonetheless, EZH2/BCL2 co-expression was significantly associated with worse outcome (event free survival and overall survival). CONCLUSION: Although EZH2 mutations are almost exclusively found in GC-DLBCL, we found similar EZH2 expression levels in both DLBCL-NOS molecular groups, suggesting non-mutational mechanisms of EZH2 deregulation. These findings suggest that the use of EZH2 antagonists might be extended to non-GC DLBCL patients with clinical benefit. EZH2/BCL2 co-expression was associated with a worse outcome.

XPO1 expression worsens the prognosis of unfavorable DLBCL that can be effectively targeted by selinexor in the absence of mutant p53.

The XPO1 inhibitor selinexor was recently approved in relapsed/refractory DLBCL patients but only demonstrated modest anti-DLBCL efficacy, prompting us to investigate the prognostic effect of XPO1 in DLBCL patients and the rational combination therapies in high-risk DLBCL. High XPO1 expression (XPO1high) showed significant adverse prognostic impact in 544 studied DLBCL patients, especially in those with BCL2 overexpression. Therapeutic study in 30 DLBCL cell lines with various molecular and genetic background found robust cytotoxicity of selinexor, especially in cells with BCL2-rearranged (BCL2-R+) DLBCL or high-grade B-cell lymphoma with MYC/BCL2 double-hit (HGBCL-DH). However, expression of mutant (Mut) p53 significantly reduced the cytotoxicity of selinexor in overall cell lines and the BCL2-R and HGBCL-DH subsets, consistent with the favorable impact of XPO1high observed in Mut-p53-expressing patients. The therapeutic effect of selinexor in HGBCL-DH cells was significantly enhanced when combined with a BET inhibitor INCB057643, overcoming the drug resistance in Mut-p53-expressing cells. Collectively, these data suggest that XPO1 worsens the survival of DLBCL patients with unfavorable prognostic factors such as BCL2 overexpression and double-hit, in line with the higher efficacy of selinexor demonstrated in BCL2-R+ DLBCL and HGBCL-DH cell lines. Expression of Mut-p53 confers resistance to selinexor treatment, which can be overcome by combined INCB057643 treatment in HGBCL-DH cells. This study provides insight into the XPO1 significance and selinexor efficacy in DLBCL, important for developing combination therapy for relapsed/refractory DLBCL and HGBCL-DH.

Unexpected favorable outcome in a patient with high grade B-cell lymphoma with abnormalities of MYC, BCL6 and BCL2 loci.

High grade B-cell lymphoma (HGBCL) by WHO 2016 classification requires rearrangements of MYC and BCL2 and/or BCL6, practically covering the so called "double-hit" or "triple hit" lymphomas. We report a case of HGBCL "triple-hit" lymphoma in a 64-year old female. Cytogenetic and fluorescence in situ hybridization (FISH) studies revealed complex karyotype including rearrangement of MYC to a novel, non-IG partner on chromosome 18, and rearrangement of BCL2, BCL6 and IGH as well as ins(3)(q21q27.3q25.1) among other abnormalities. FISH studies showed five copies of MYC and 3-8 copies of BCL2. Gene expression analysis by RNA sequencing showed that MYC, BCL2 and MECOM genes were overexpressed whereas BCL6 was under-expressed. BCL6 was fused to MBNL1 gene due to complex structural rearrangement. MYC was expressed in >70% of cells and BCL2 was diffusely but highly expressed by immunohistochemistry. No pathogenic mutations were identified by sequencing a 26-gene panel including TP53. The patient has unexpectedly been in complete remission for 12 months after diagnosis after intensive chemotherapy including DA-EPOCH regimen despite having HGBCL. The prognostication of HGBCL patients may further be improved by the sub-categorization of these lymphomas on the basis of more detailed genomic markers than merely the WHO 2016 classification.