Diffuse Large B-Cell Lymphoma in Kenya: MYC, BCL2, and the Cell of Origin

PURPOSE

Diffuse large B-cell lymphoma (DLBCL) is the most commonly diagnosed non-Hodgkin lymphoma in adults in Kenya. Cell of origin (COO) and double expression of MYC and BCL2 are two important prognostic factors for DLBCL. A small subset (5% to 10%) of DLBCL cases show positivity for CD5 and are associated with poor prognosis, whereas CD30 antigen, seen in up to 10% of cases, may be a useful target for therapy. We sought to determine the prevalence of MYC/BCL2 double expression, COO, and proportion of Epstein-Barr virus positivity among patients with DLBCL diagnosed at a tertiary referral laboratory in Kenya.

PATIENTS AND METHODS

All cases of DLBCL diagnosed from 2012 through 2015 in our pathology department were analyzed. Tumor tissue microarray sections were stained with CD20, CD3, CD5, CD30, BCL2, BCL6, CD10, MUM1, MYC, and Ki67, classified for COO on the basis of the Hans algorithm, and subjected to Epstein-Barr virus-encoded small RNAs in situ hybridization.

RESULTS

Among 165 DLBCL cases, the median age was 50 years, and there was no sex predilection. Only 18 (10.9%) cases showed double expression for MYC and BCL2. Germinal center B (GCB)-cell type DLBCL accounted for 67 cases (40.6%) and 97 cases (59.4%) were classified as non-GCB. The mean Ki67 proliferation index was significantly higher in the double-expressing (45%) and non-GCB groups (36%) compared with the non-double-expressing group (29%) and GCB group (26%). Sixteen cases (9.7%) were Epstein-Barr virus-encoded small RNAs positive, 12 (75%) of which were non-GCB.

CONCLUSION

DLBCL in Kenya is seen in much younger patients with the poor prognostic non-GCB-type accounting for 59.4% of cases. MYC and BCL2 double expression was seen in fewer tumors than reported in the literature and in significantly older patients.

Management of diffuse large B-cell lymphoma (DLBCL)

Diffuse large B-cell lymphoma (DLBCL) is the most common non-Hodgkin lymphoma. While CHOP was the standard combination chemotherapy for 25 years, the incorporation of the CD20 antibody rituximab at the beginning of this century has considerably improved the outcome of all patients with DLBCL: Depending on the prognostic subgroup, only half to one-third of the patients die of their DLBCL compared to pre-rituximab era. Treatment is usually tailored according to the individual risk profile of a DLBCL patient according to the International Prognostic Index (IPI). Assignment of DLBCL according to the gene expression profile into DLBLC originating from a germinal center B cell (GC type) or from an activated B cell (ABC type) has provided novel insights into the pathogenesis of the respective DLBCL, identified molecules which are indispensable for the survival of the lymphoma cells and provided targets for novel "targeted therapies" drugs. Incorporating these new drugs into combination immunochemotherapy or substituting single drugs in the R-CHOP combination will result in even higher cure rates of and/or less toxicity for patients with DLBCL in the decade to come.

[Diagnosis and treatment in patients with B-cell lymphoma unclassified that is intermediate between diffuse large B-cell lymphoma and Burkitt's lymphoma]

AIM

To characterize a group of patients with B-cell lymphoma (BCLU) unclassified that is intermediate between diffuse large B-cell lymphoma and Burkitt's lymphoma, to identify poor prognostic factors, and to evaluate therapeutic efficiency in patients with BCLU.

SUBJECTS AND METHODS

Twenty-five patients with BCLU were examined. Double-hit lymphoma (DHL) was diagnosed in 8 (32%) patients. According to the Ann-Arbor classification of lymphoma, its stages II, III, and IV were diagnosed in 3 (12%), 2 (8%), and 20 (80%) patients, respectively. MYC rearrangement was observed in 11 (48%) out of 23 patients: single-hit lymphoma in 3 patients and DHL in 8 (BCL2+/MYC+ in 6 cases and BCL6+/MYC+ in 2). The expression of с-MYC (cut off ≥40%) was revealed in 17 (74%) out of 23 patients; that of BCL2 (cut off ≥50%) was detected in 14 (58%) out of 24 patients; coexpression of both proteins was seen in 12 (52%) out of 23 patients. The DHL group showed a correlation between the rearrangement of the BCL2+/MYC+ genes and the expression of MYC and BCL2 proteins in 5 out of 6 patients. Taking into account the heterogeneity of the entire patient group, DHL and non-DHL subgroups were considered separately. Both subgroups were comparable by clinical characteristics. BCLU patients younger than 60 years of age received treatment according to the LB-M-04 ± rituximab; those aged 60 or older had CHOP-like regimens ± rituximab. Autologous stem cell transplantation (auto-SCT) was performed in 5 patients belonging to a high-risk group.

RESULTS

The 3-year overall survival (OS) was 62% and the 3-year event-free survival (EFS) was 51%. The 3-year OS was lower for the DHL group than that for the non-DHL group (43 and 75%, respectively).

CONCLUSION

In the DHL group, both OS and EFS are significantly lower (the risk of poor outcome, including death, is higher) than those in the non-DHL group. It is conceivable that intensified chemotherapy with auto-SCT increases treatment results in patients with BCLU; however, a larger number of observations are needed to obtain valid data.

Prognostic factors for diffuse large B-cell lymphoma in the R(X)CHOP era

BACKGROUND

The introduction of rituximab (R) to conventional CHOP chemotherapy for newly diagnosed diffuse large B-cell lymphoma (DLBCL) led to an unequivocal improvement in survival, establishing RCHOP as the standard of care. Still, nearly 40% of DLBCL patients will eventually die of relapsed disease. Efforts to improve outcomes by addition of new biologic agents (X) to the RCHOP backbone are underway. In this era of R(X)CHOP, it is imperative to develop prognostic and predictive markers, not only to identify patients who will suffer a particularly aggressive course, but also to accurately select patients for clinical trials from which they will most benefit.

DESIGN

The following review was undertaken to describe prognostic factors in DLBCL, with emphasis on markers that are accurate, relatively available, and clinically applicable in 2014.

RESULTS

The International Prognostic Index retains its validity in the era of RCHOP, although with limited ability to predict those with <50% chance of long-term survival. Gene expression profiling has provided novel insights into the biology of DLBCL and led to the development of immunohistochemistry (IHC) algorithms that are in routine practice. Identification of a 'double-hit' (DH) lymphoma by fluorescent in situ hybridization with aberrations involving MYC and/or BCL2 and BCL6 genes has important implications due to its extremely dismal prognosis with RCHOP. Other markers such as the absolute lymphocyte count (ALC), serum immunoglobulin free light chains, vitamin D levels, serum cytokines/chemokines, and imaging with positron emission tomography (PET) have all shown promise as future predictive/prognostic tests.

CONCLUSIONS

The future for new treatment options in DLBCL is promising with current clinical trials testing novel targeted agents such as bortezomib, lenalidomide, and ibrutinib as the 'X' in R(X)CHOP. Predictive factors are required to select and randomize patients appropriately for these trials. We envision the day when 'X' will be chosen based on the biological characteristics of the tumor.

Double hit lymphoma - a case of unusual response after sequential aggressive chemotherapy and review of the literature

Lymphomas with recurrent chromosomal breakpoints activating multiple oncogenes, including MYC, BCL2, and BCL6 are often referred to as "Dual Hit" or "Double Hit" lymphomas (DHL). In the updated classification for malignant lymphomas by the World Health Organization (WHO), the novel category of "B-cell lymphoma unclassifiable with features intermediate between diffuse large B-cell lymphoma (DLBCL) and Burkitt's lymphoma (BL)" was proposed in an attempt to create a (temporary) container for aggressive mature B-cell lymphomas that should not be diagnosed as either BL or DLBCL. DHL make up an important part of this novel WHO category, the other part representing heterogeneous cases of aggressive B-cell lymphoma that have features of BL. DHL are highly aggressive lymphomas with generally poor response to first line and salvage treatment. Limited data is available to guide therapeutic decisions, and despite aggressive measures including high dose (HD) chemotherapy followed by autologous hematopoietic cell transplantation (AHCT), outcome is unsatisfyingly poor. Herein, we report a case of a patient with DHL and review the relevant literature.

Transformation of follicular lymphoma to double hit B-cell lymphoma causing hypercalcemia in a 69-year-old female: a case report and review of the literature

Double hit B-cell lymphomas are rare tumors that are defined by a chromosomal breakpoint affecting the MYC/8q24 locus in combination with another recurrent breakpoint, mainly a t(14;18)(q32;q21) involving BCL2. These tumors mostly occur in adults and carry a very poor prognosis. Double hit lymphomas can occur de novo, or arise from transformation of follicular lymphoma. We report a case of a 69-year-old female with abdominal distention and progressively worsening weakness over six months. Patient presented with severe hypercalcemia and multiple intra-abdominal/pelvic masses. Histopathology results of the abdominal mass were compatible with a double hit B-cell lymphoma. However, bone marrow biopsy results showed a low grade follicular lymphoma, thus suggesting peripheral transformation of follicular lymphoma to double hit B-cell lymphoma. Patient was transferred to a tertiary care center and was started on combination chemotherapy (EPOCH: doxorubicin, etoposide, vincristine, cyclophosphamide, and prednisone). Our paper highlights not only transformation of follicular lymphoma to double hit B-cell lymphoma and the challenges encountered in diagnosing and treating these aggressive tumors, but also the association of new onset/worsening hypercalcemia in such patients.

Addition of lenalidomide to rituximab, ifosfamide, carboplatin, etoposide (RICER) in first-relapse/primary refractory diffuse large B-cell lymphoma

Relapsed/refractory diffuse large B-cell lymphoma (DLBCL) is associated with a poor prognosis. Outcomes are particularly poor following immunochemotherapy failure or relapse within 12 months of induction. We conducted a Phase I/II trial of lenalidomide plus RICE (rituximab, ifosfamide, carboplatin, and etoposide) (RICER) as a salvage regimen for first-relapse or primary refractory DLBCL. Dose-escalated lenalidomide was combined with RICE every 14 d. After three cycles of RICER, patients with chemosensitive disease underwent stem cell collection and consolidation with BEAM [BCNU (carmustine), etoposide, cytarabine, melphalan] followed by autologous stem cell transplantation (autoSCT). Patients who recovered from autoSCT toxicities within 90 d initiated maintenance treatment with lenalidomide 25 mg daily for 21 d every 28 d for 12 months. No dose-limiting or unexpected toxicities occurred with lenalidomide 25 mg plus RICE. Grade 3/4 haematological toxicities resolved appropriately, and planned dose density and dose intensity of RICER were preserved. No lenalidomide or RICE dose reductions were required in any of the three cycles. After two cycles of RICER, nine of 15 patients (60%) achieved a complete response, and two achieved a partial response (13%). Combining lenalidomide with RICE is feasible, and results in promising response rates (particularly complete response rates) in high-risk DLBCL patients.

Both c-Myc and Ki-67 expression are predictive markers in patients with extranodal NK/T-cell lymphoma, nasal type: a retrospective study in China

Extranodal natural killer (NK)/T-cell lymphoma, nasal type (ENKTL) is an increasingly recognized disease entity of aggressive tumor progression. The objective of this study was to investigate the clinical and prognostic significance of c-Myc and Ki-67 expression in ENKTL. Immunohistochemistry for c-Myc and Ki-67 was performed on tissue sections from 53 patients diagnosed with ENKTL, and their correlation with clinicopathologic variables was assessed. We also made a comparison between c-Myc positive and negative ENKTL on proliferation index (PI); and analyzed relationship between expression of c-Myc and Ki-67 index. The survival was analyzed by Kaplan-Meier product-limit method. Positive expression of c-Myc was shown in 64.2% of the patients, and high expression of Ki-67 was found in 66%. The PI in c-Myc-positive tumor cell was significantly higher than that in c-Myc-negative ones (P=0.005). The positive correlation between c-Myc expression and Ki-67 index was also found (r=0.454, P=0.001). Patients of c-Myc expression were shown to be associated with unfavorable overall survival (OS) and decreased progression free survival (PFS) (P=0.000 and 0.013, respectively). High expression of Ki-67 was also shown to be correlated with worse OS and PFS (P=0.014 and 0.016, respectively). And patients expression of c-Myc+/Ki-67 high had the worst OS and PFS (P=0.002 and 0.027, respectively). c-Myc may play an important role in the carcinogenesis of NK/T cell lymphoma by promoting cell proliferation. Both c-Myc expression and Ki-67 high expression in ENKTL patients may be valuable indicators for predicting the survival of ENKTL patients.

U-2932: two clones in one cell line, a tool for the study of clonal evolution

Genetic heterogeneity is common in tumors, explicable by the development of subclones with distinct genetic and epigenetic alterations. We describe an in vitro model for cancer heterogeneity, comprising the diffuse large B-cell lymphoma cell line U-2932 which expresses two sets of cell surface markers representing twin populations flow-sorted by CD20 vs CD38 expression. U-2932 populations were traced to subclones of the original tumor with clone-specific immunoglobulin IgVH4-39 hypermutation patterns. BCL6 was overexpressed in one subpopulation (R1), MYC in the other (R2), both clones overexpressed BCL2. According to the combined results of immunoglobulin hypermutation and cytogenetic analysis, R1 and R2 derive from a mother clone with genomic BCL2 amplification, which acquired secondary rearrangements leading to the overexpression of BCL6 (R1) or MYC (R2). Some 200 genes were differentially expressed in R1/R2 microarrays including transcriptional targets of the aberrantly expressed oncogenes. Other genes were regulated by epigenetic means as shown by DNA methylation analysis. Ectopic expression of BCL6 in R2 variously modulated new candidate target genes, confirming dual silencing and activating functions. In summary, stable retention of genetically distinct subclones in U-2932 models tumor heterogeneity in vitro permitting functional analysis of oncogenes against a syngenic background.