Pembrolizumab with R-CHOP in previously untreated diffuse large B-cell lymphoma: potential for biomarker driven therapy.

Tumor programmed death-ligand 1 (PD-L1) expression in diffuse large B-cell lymphoma (DLBCL) is associated with inferior outcomes. The first-line immunologically-replete setting may be an opportune time for PD-1 inhibition. We evaluated pembrolizumab in combination with R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone) in untreated patients with DLBCL. Eligible patients were age 18 or older, had adequate organ function, and had DLBCL requiring full-course therapy. Patients received pembrolizumab 200 mg/cycle with R-CHOP, primarily to assess toxicity. Response assessment utilized standard criteria, and PD-L1 staining was performed at a validated central laboratory. Among 30 patients, toxicity was comparable to standard R-CHOP but with two grade ≥3 immune related adverse events (rash, pneumonitis). The overall and complete response rate was 90% and 77%. With 25·5 months of median follow-up, 2-year progression-free survival (PFS) is 83%. PD-L1 expression was associated with non-GCB subtype, and improved PFS and survival. Pembrolizumab can safely be added to R-CHOP, and is associated with a high CR rate and 2-year PFS. Improved PFS with PR-CHOP in PD-L1 expressing tumors contradicts historical data in R-CHOP treated patients, supporting evaluation of PD-L1 as a biomarker to identify DLBCL patients who may benefit from this first-line strategy.

Mass cytometry of Hodgkin lymphoma reveals a CD4+ regulatory T-cell-rich and exhausted T-effector microenvironment.

In classical Hodgkin lymphoma (cHL), the host antitumor immune response is ineffective. Hodgkin Reed-Sternberg (HRS) cells have multifaceted mechanisms to evade the immune system, including 9p24.1/CD274(PD-L1)/PDCD1LG2(PD-L2) genetic alterations, overexpression of PD-1 ligands, and associated T-cell exhaustion and additional structural bases of aberrant antigen presentation. The clinical success of PD-1 blockade in cHL suggests that the tumor microenvironment (TME) contains reversibly exhausted T effector cells (Teffs). However, durable responses are observed in patients with ß2-microglobulin/major histocompatibility complex (MHC) class I loss on HRS cells, raising the possibility of non-CD8+ T cell-mediated mechanisms of efficacy of PD-1 blockade. These observations highlight the need for a detailed analysis of the cHL TME. Using a customized time-of-flight mass cytometry panel, we simultaneously assessed cell suspensions from diagnostic cHL biopsies and control reactive lymph node/tonsil (RLNT) samples. Precise phenotyping of immune cell subsets revealed salient differences between cHLs and RLNTs. The TME in cHL is CD4+ T-cell rich, with frequent loss of MHC class I expression on HRS cells. In cHLs, we found concomitant expansion of T helper 1 (Th1)-polarized Teffs and regulatory T cells (Tregs). The cHL Th1 Tregs expressed little or no PD-1, whereas the Th1 Teffs were PD-1+ The differential PD-1 expression and likely functional Th1-polarized CD4+ Tregs and exhausted Teffs may represent complementary mechanisms of immunosuppression in cHL.

Circulating Plasma Cells at the Time of Collection of Autologous PBSC for Transplant in Multiple Myeloma Patients is a Negative Prognostic Factor Even in the Age of Post-Transplant Maintenance Therapy.

Circulating plasma cells (CPCs) have been detected in patients with multiple myeloma (MM) at various stages of disease and associated with worse outcomes. Little data exist regarding the impact of CPCs at the time of autologous peripheral blood stem cell (PBSC) collection on outcomes, and the impact of maintenance therapy after autologous stem cell transplantation (ASCT) on prognosis in patients with CPC-containing collections. All patients with MM who underwent first ASCT at Fred Hutchinson Cancer Research Center from 2012 to 2015 and had evaluation for CPCs at the time of PBSC collection were included in our analysis. Seven-color flow cytometry was used to detect the presence of CPCs. Kaplan-Meier estimates were used to generate overall survival (OS) and progression-free survival (PFS) rates from the time of ASCT. A multivariate analysis, including receipt of maintenance therapy post-ASCT, high-risk cytogenetics, and international staging system (ISS) stage, was included in a Cox proportional hazards regression model for associations with OS and PFS. We identified 227 patients with MM who underwent ASCT; of these, 144 (63.4%) patients had routine assessment of CPCs at the time of PBSC collection. One hundred seventeen (81.3%) patients did not have CPCs and 27 (18.8%) did have CPCs. The presence of CPCs was highly associated with poorer PFS (P = .031 by log-rank analysis), but did not affect OS. The median PFS for those patients without CPCs was 39.4 months (95% confidence interval [CI], 31.1 to not reached), while the median PFS for those patients with CPCs was 16.5 months (95% CI, 13.7 to not reached). A subgroup analysis of patients achieving very good partial response (VGPR) or better at time of collection, showed the median PFS for patients without CPCs was 38.3 months (95% CI, 29 to not reached), as compared with those patients with CPCs, where it was only 16.5 months (95% CI, 12 months to not reached; P = .02). There was no statistically significant difference in PFS or OS among those patients achieving partial response at the time of collection. In a Cox proportional hazards model, adjusting for post-ASCT maintenance therapy, high-risk cytogenetics, and ISS stage at time of initial diagnosis, there was a 43% higher risk of progression or death among the patients with CPCs (P = .04). The presence of CPCs at the time of autologous PBSC collection is a negative prognostic factor for risk of early relapse or death despite the advent of novel agents and maintenance strategies. The impact of CPCs was most significant among patients achieving a VGPR or better at time of collection. The presence of CPCs denotes a unique group of high-risk MM patients for whom alternative treatment strategies are needed to overcome resistance to current standard therapies.

Characterization and Purification of Neoplastic Cells of Nodular Lymphocyte Predominant Hodgkin Lymphoma from Lymph Nodes by Flow Cytometry and Flow Cytometric Cell Sorting.

We report the flow cytometric (FC) identification and characterization of lymphocyte predominant (LP) cells from tissues involved by nodular lymphocyte predominant Hodgkin lymphoma (NLPHL). First, we immunophenotyped the NLPHL cell line (DEV) confirming a germinal center immunophenotype, lack of expression of CD32 and CD58, and expression of CD54. Nineteen of 26 lymph nodes involved by NLPHL demonstrated a population with an LP immunophenotype (73%), which included expression of germinal center markers (CD75/Bcl-6-positive, CD32-weak/negative without CD10), a B-cell immunophenotype (CD19/CD20/CD40+), IgD and/or IgM expression (67%), and lack of programmed death-ligand 1/ligand 2. The LP cells demonstrated an adhesion macromolecule expression pattern distinct from Hodgkin and Reed-Sternberg cells of classical Hodgkin lymphoma (CHL) (uniform CD50 and variable CD58 for NLPHL; minimal CD50, bright CD58 expression for CHL). A two-tube consensus assay identified LP cells in all seven NLPHL cases examined and only one non-NLPHL case (94 cases evaluated). Finally, FC cell sorting studies confirm that FC-defined populations have an LP cytomorphology. Taken together, these findings demonstrate a two-tube consensus assay can be used to immunophenotype NLHPL with high specificity and sensitivity and rapidly purify LP cells for genetic studies. This study also confirms aneuploidy in LP cells, provides antigens that may be helpful in distinguishing NLPHL from CHL, and suggests that T cells interact less avidly with LP cells than with Hodgkin and Reed-Sternberg cells.

The first report of human primary thoracic spine mast cell sarcoma: a case report.

In this report, we present a 53-year-old woman with primary mast cell sarcoma of the thoracic spine vertebrae. Mast cell sarcoma is an aggressive and rare cancer. To date, no cases of primary mast cell sarcoma have been reported in the spinal vertebrae. The patient initially presented with a 1-month history of pelvic and abdominal pain. Inconclusive gynecological evaluation resulted in a CT of the abdomen and pelvis, demonstrating a destructive lesion centered at the 11th thoracic vertebral body. The patient underwent a two-stage spine operation for T11 corpectomy and T7-L3 posterior spinal fusion. Histopathological, immunohistochemical, and flow cytometry studies of the resection specimens showed the tumor to be mostly composed of CD117-positive and mast cell tryptase-positive cells with features consistent with mast cell sarcoma. This is the first reported case of primary vertebral mast cell sarcoma, which may mimic other destructive lesions of the spine including osteomyelitis, vertebral tuberculosis, or plasmacytoma.
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Recurrent somatic loss of TNFRSF14 in classical Hodgkin lymphoma.

Investigation of the genetic lesions underlying classical Hodgkin lymphoma (CHL) has been challenging due to the rarity of Hodgkin and Reed-Sternberg (HRS) cells, the pathognomonic neoplastic cells of CHL. In an effort to catalog more comprehensively recurrent copy number alterations occurring during oncogenesis, we investigated somatic alterations involved in CHL using whole-genome sequencing-mediated copy number analysis of purified HRS cells. We performed low-coverage sequencing of small numbers of intact HRS cells and paired non-neoplastic B lymphocytes isolated by flow cytometric cell sorting from 19 primary cases, as well as two commonly used HRS-derived cell lines (KM-H2 and L1236). We found that HRS cells contain strikingly fewer copy number abnormalities than CHL cell lines. A subset of cases displayed nonintegral chromosomal copy number states, suggesting internal heterogeneity within the HRS cell population. Recurrent somatic copy number alterations involving known factors in CHL pathogenesis were identified (REL, the PD-1 pathway, and TNFAIP3). In eight cases (42%) we observed recurrent copy number loss of chr1:2,352,236-4,574,271, a region containing the candidate tumor suppressor TNFRSF14. Using flow cytometry, we demonstrated reduced TNFRSF14 expression in HRS cells from 5 of 22 additional cases (23%) and in two of three CHL cell lines. These studies suggest that TNFRSF14 dysregulation may contribute to the pathobiology of CHL in a subset of cases.

Pretransplantation Minimal Residual Disease Predicts Survival in Patients with Mantle Cell Lymphoma Undergoing Autologous Stem Cell Transplantation in Complete Remission.

Autologous stem cell transplantation (ASCT) is standard therapy for mantle cell lymphoma (MCL) in remission after induction chemotherapy, with the best results for patients in complete remission (CR). We hypothesized that evaluation of minimal residual disease (MRD) before ASCT could further stratify outcomes for these patients. Patients with MCL who underwent ASCT in clinical CR between 1996 and 2011 with pretransplantation MRD testing were eligible. Presence of a clonal IgH rearrangement, t(11; 14) by PCR or positive flow cytometry from blood or bone marrow, was considered positive. An adjusted proportional hazards model for associations with progression-free (PFS) and overall survival (OS) was performed. Of 75 MCL patients in CR, 8 (11%) were MRD positive. MRD positivity was associated with shorter OS and PFS. The median OS for MRD-negative patients was not reached, with 82% survival at 5 years, whereas for the MRD-positive patients, median OS was 3.01 years (hazard ratio [HR], 4.04; P = .009), with a median follow-up of 5.1 years. The median PFS for MRD-negative patients was not reached with 75% PFS at 5 years, whereas for MRD-positive patients, it was 2.38 years (HR, 3.69; P = .002). MRD positivity is independently associated with poor outcomes after ASCT for MCL patients in CR.

A Distributed Network for Intensive Longitudinal Monitoring in Metastatic Triple-Negative Breast Cancer.

Accelerating cancer research is expected to require new types of clinical trials. This report describes the Intensive Trial of OMics in Cancer (ITOMIC) and a participant with triple-negative breast cancer metastatic to bone, who had markedly elevated circulating tumor cells (CTCs) that were monitored 48 times over 9 months. A total of 32 researchers from 14 institutions were engaged in the patient's evaluation; 20 researchers had no prior involvement in patient care and 18 were recruited specifically for this patient. Whole-exome sequencing of 3 bone marrow samples demonstrated a novel ROS1 variant that was estimated to be present in most or all tumor cells. After an initial response to cisplatin, a hypothesis of crizotinib sensitivity was disproven. Leukapheresis followed by partial CTC enrichment allowed for the development of a differential high-throughput drug screen and demonstrated sensitivity to investigational BH3-mimetic inhibitors of BCL-2 that could not be tested in the patient because requests to the pharmaceutical sponsors were denied. The number and size of CTC clusters correlated with clinical status and eventually death. Focusing the expertise of a distributed network of investigators on an intensively monitored patient with cancer can generate high-resolution views of the natural history of cancer and suggest new opportunities for therapy. Optimization requires access to investigational drugs.

Detection of minimal residual disease in NPM1-mutated acute myeloid leukemia by next-generation sequencing.

Detection of minimal residual disease predicts adverse outcome in patients with acute myeloid leukemia. Currently, minimal residual disease may be detected by RQ-PCR or flow cytometry, both of which have practical and diagnostic limitations. Here, we describe a next-generation sequencing assay for minimal residual disease detection in NPM1-mutated acute myeloid leukemia, which encompasses ∼60% of patients with normal karyotype acute myeloid leukemia. Exon 12 of NPM1 was PCR amplified using sequencing adaptor-linked primers and deep sequenced to enable detection of low-prevalence, acute myeloid leukemia-specific activating mutations. We benchmarked our results against flow cytometry, the standard of care for acute myeloid leukemia minimal residual disease diagnosis at our institution. The performance of both approaches was evaluated using defined dilutions of an NPM1 mutation-positive cell line and longitudinal clinical samples from acute myeloid leukemia patients. Using defined control material, we found this assay sensitive to approximately 0.001% mutant cells, outperforming flow cytometry by an order of magnitude. Next-generation sequencing was precise and semiquantitative over four orders of magnitude. In 22 longitudinal samples from six acute myeloid leukemia patients, next-generation sequencing detected minimal residual disease in all samples deemed negative by flow cytometry. Further, in one-third of patients, sequencing detected alternate NPM1 mutations in addition to the patient's index mutation, consistent with tumor heterogeneity. Next-generation sequencing provides information without prior knowledge of NPM1 mutation subtype or validation of allele-specific probes as required for RQ-PCR assays, and without generation and interpretation of complex multidimensional flow cytometry data. This approach may complement current technologies to enhance patient-specific clinical decision-making.

CD46 and CD59 inhibitors enhance complement-dependent cytotoxicity of anti-CD38 monoclonal antibodies daratumumab and isatuximab in multiple myeloma and other B-cell malignancy cells.

Multiple myeloma (MM) is an incurable malignancy of the B-cell lineage. Remarkable progress has been made in the treatment of MM with anti-CD38 monoclonal antibodies such as daratumumab and isatuximab, which can kill MM cells by inducing complement-dependent cytotoxicity (CDC). We showed that the CDC efficacy of daratumumab and isatuximab is limited by membrane complement inhibitors, including CD46 and CD59, which are upregulated in MM cells. We recently developed a small recombinant protein, Ad35K++, which is capable of transiently removing CD46 from the cell surface. We also produced a peptide inhibitor of CD59 (rILYd4). In this study, we tested Ad35K++ and rILYd4 in combination with daratumumab and isatuximab in MM cells as well as in cells from two other B-cell malignancies. We showed that Ad35K++ and rILYd4 increased CDC triggered by daratumumab and isatuximab. The combination of both inhibitors had an additive effect in vitro in primary MM cells as well as in vivo in a mouse xenograft model of MM. Daratumumab and isatuximab treatment of MM lines (without Ad35K++ or rILYd4) resulted in the upregulation of CD46/CD59 and/or survival of CD46high/CD59high MM cells that escaped the second round of daratumumab and isatuximab treatment. The escape in the second treatment cycle was prevented by the pretreatment of cells with Ad35K++. Overall, our data demonstrate that Ad35K++ and rILYd4 are efficient co-therapeutics of daratumumab and isatuximab, specifically in multi-cycle treatment regimens, and could be used to improve treatment of multiple myeloma.

Pembrolizumab With R-CHOP in Previously Untreated DLBCL: Sustained, High Efficacy, and Safety With Long-Term Follow-Up.

BACKGROUND: While generally ineffective in relapsed diffuse large B cell lymphoma (DLBCL), immune checkpoint inhibitors (ICIs) may hold greater promise in untreated, immunocompetent patients. We previously reported safety and early efficacy of pembrolizumab plus rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (PR-CHOP) in a phase I trial of untreated DLBCL, noting responses in 90% of patients (complete response 77%) and a 2-year progression-free survival (PFS) of 83%. We herein report long-term safety and efficacy at 5-year follow up. PATIENTS AND METHODS: Adult patients with untreated DLBCL or grade 3b follicular lymphoma, intended to receive 6 cycles of R-CHOP were eligible. Patients (N = 30) were treated with pembrolizumab 200 mg IV and R-CHOP in 21-day cycles for 6 cycles. RESULTS: At median follow up of 4.8 years, 5-year PFS was 71% (CI, 54%-94%) and 5-year overall survival was 83% (CI, 71%-98%). Immune-related adverse events (IRAEs) occurred in 7 (23%) patients (10% grade 3/4). Three IRAEs (rash, thyroiditis, rheumatoid arthritis) occurred beyond 3 months of treatment completion. PD-L1 tumor expression was documented in 19 of 23 (83%) tested patients. None of the 19 patients who had any PD-L1 expression have relapsed, whereas 2 out of the 4 patients with no PD-L1 expression have relapsed. CONCLUSION: PR-CHOP has led to durable responses in most patients, with the best outcomes in PD-L1-expressing disease. Furthermore, the safety profile was manageable, with no consistent pattern of late events. These data support ongoing strategies incorporating ICIs in frontline DLBCL therapy and confirmation of predictive biomarkers including tumor PD-L1 expression.

Strategies for immunophenotyping and purifying classical Hodgkin lymphoma cells from lymph nodes by flow cytometry and flow cytometric cell sorting.

Flow cytometry is an established technique to immunophenotype hematopoietic neoplasms. While the diagnosis of classical Hodgkin lymphoma (CHL) has commonly been made using paraffin sections, we have recently demonstrated that the neoplastic Hodgkin and Reed-Sternberg (HRS) cells of CHL can be identified by flow cytometry. Using 6- and 9-color flow cytometric assays, CHL can be immunophenotyped with 85-90% sensitivity and nearly 100% specificity. Analysis of this data requires using established gating strategies to help in the identification of putative HRS cell populations. Interestingly, HRS cells bind to reactive T cells (HRS-T cell rosetting) and this phenomenon can be identified and utilized diagnostically by flow cytometry. In addition, the reactive T cells of CHL show characteristic immunophenotypic changes by flow cytometry and these changes can suggest a diagnosis of CHL. Finally, these principles can be employed to rapidly purify HRS cells using flow cytometric cell sorting. This manuscript provides experimental protocols for immunophenotyping CHL by flow cytometry as well as purifying the HRS cells via flow cytometric cell sorting.

Predictors of risk of relapse in classic Hodgkin lymphoma.

Using multiparametric flow cytometric analysis, in a cohort of 62 patients with classic Hodgkin lymphoma having a median follow-up period of 69.5 months, we found-patients who experienced primary resistance or disease relapse (DR) had lower percentage of rosetted Hodgkin Reed-Sternberg cells (HRS-cells) as compared with patients who achieved sustained complete remission (SCR) (p=0.022); patients >35 years of age had higher percentage of HRS-cells (p=0.017) and lower percentage of B cells (p=0.017) and the nodular sclerosis subtype had higher percentage of B-cells (p=0.046) and activated B-cells (p=0.03). The proportion of SCR and DR subsets did not differ by histological subtypes, disease stage or age groups.

A Review of the Flow Cytometric Findings in Classic Hodgkin Lymphoma, Nodular Lymphocyte Predominant Hodgkin Lymphoma and T Cell/Histiocyte-Rich Large B Cell Lymphoma.

Classic Hodgkin lymphoma, nodular lymphocyte predominant Hodgkin lymphoma, and T cell/histiocyte-rich large B cell lymphoma form a unique set of lymphomas with similar morphologic growth patterns (occasional neoplastic cells within a prominent cellular cell background) that are pathobiologically related. Distinguishing these entities has been historically difficult by flow cytometry; however, our laboratory has developed antibody-fluorochrome combinations capable of immunophenotyping these lymphomas. Additionally, characterization of the background reactive lymphocytes can aid in narrowing the differential diagnosis. This review summarizes the immunophenotypic features and insights of the neoplastic and reactive populations found in this unique group of lymphomas.

Neutrophil to lymphocyte ratio and peripheral blood biomarkers correlate with survival outcomes but not response among head and neck and salivary cancer treated with pembrolizumab and vorinostat.

BACKGROUND: Associations between peripheral blood biomarkers and oncologic outcomes were explored in recurrent/metastatic (R/M) head and neck squamous cell carcinoma (HN) and salivary gland cancer (SGC) treated with pembrolizumab and vorinostat on a phase II trial (NCT02538510). EXPERIMENTAL DESIGN: Twenty-five HN and 25 SGCs were treated with pembrolizumab and vorinostat. Baseline peripheral blood was available in 21 HN and 20 SGCs and evaluated for associations with grade ≥3 adverse events (G ≥ 3AE) by CTCAEv4, objective response rate (ORR), overall survival (OS), and progression-free survival (PFS). RESULTS: Higher pretreatment neutrophil-to-lymphocyte ratio (NLR) and neutrophils, as well as lower pretreatment lymphocytes and T helper cells correlated with worse OS and PFS. Higher NLR further predicted increased rates of G ≥ 3AEs. No correlations with ORR were observed. CONCLUSIONS: In a prospectively evaluated cohort of HN and SGCs treated with pembrolizumab and vorinostat, we observed novel associations between peripheral blood biomarkers and oncologic outcomes and toxicities.

Peripheral lymphocytes and lactate dehydrogenase correlate with response and survival in head and neck cancers treated with immune checkpoint inhibitors.

BACKGROUND: Little is known regarding associations between peripheral blood biomarkers (PBBMs) and survival, response, and toxicity in recurrent/metastatic head and neck squamous cell carcinomas (R/M HNSCC) treated with immune checkpoint inhibitors (ICIs). METHODS: In this single-institution retrospective cohort study, a dataset of patients with R/M HNSCC treated with ICIs between 08/2012-03/2021 was established, including demographic and clinicopathologic characteristics. Pretreatment PBBMs were collected and evaluated for associations with grade ≥3 adverse events (G ≥ 3AE) by CTCAEv5, objective response (ORR) by RECIST 1.1, overall survival (OS), and progression-free survival (PFS). Multivariable models for each outcome were created using elastic net variable selection. RESULTS: Our study included 186 patients, with 51 (27%) demonstrating complete or partial response to immunotherapy. Multivariable models adjusted for ECOG performance status (PS), p16, and smoking demonstrated that pretreatment higher LDH and absolute neutrophils, as well as lower percent lymphocytes correlated with worse OS and PFS. Higher LDH and lower % lymphocytes also correlated with worse ORR. CONCLUSIONS: In the largest study to date examining PBBMs in ICI-treated R/M HNSCCs, our variable selection method revealed PBBMs prognostic for survival and response to immunotherapy. These biomarkers warrant further investigation in a prospective study along with validation with CPS biomarker.

Efficacy, safety, and molecular response predictors of oral ixazomib and short-course rituximab in untreated iNHL.

Patients with indolent B-cell non-Hodgkin lymphoma (iNHL) generally require treatment but experience normal survival, emphasizing the need for simpler, safer therapies. Proteasome inhibitors target aberrant signaling pathways within iNHL and have manageable toxicities. We evaluated the oral proteasome inhibitor ixazomib as initial monotherapy, and combined with rituximab, for first-line treatment of iNHL. Treatment-naïve patients with iNHL needing therapy received oral ixazomib 4 mg weekly until progressive disease or unacceptable adverse events. A 4-week course of rituximab was added during month 7. The primary end point was overall response rate (ORR) during the ixazomib monotherapy window. Correlations included gene expression profiling and response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination. Thirty-three patients with follicular lymphoma (FL) (n = 20), marginal zone lymphoma (n = 7), and other iNHL were treated with a median follow-up of 30.3 months. During the 6-month ixazomib window, the ORR was 24%, including 35% in FL. The best ORR over the entire study period was 52% overall and 65% in FL; complete response was achieved in 33% and 45%, respectively. The median duration of response was 25.8 months (range, 0-49.7), and the 24-month progression-free and overall survival rates were 51% (95% confidence interval [CI], 32-67) and 91% (95% CI, 74-97), respectively. Ixazomib was well tolerated. Baseline downregulation of proteasome genes, PSMB9 (P = .03) and PSMB8 (P = .007), were associated with response. All evaluated patients generated anti-S antibodies to SARS-CoV-2 vaccination, with a median of 254.9 binding arbitrary unit per mL. Ixazomib demonstrated efficacy alone and with short-course rituximab in untreated iNHL while exhibiting favorable toxicity, convenience, and retention of the B-cell immune response. This trial is registered at www.clinicaltrials.gov as NCT02339922.

Mutations in a gene encoding a midbody kelch protein in familial and sporadic classical Hodgkin lymphoma lead to binucleated cells.

Classical Hodgkin lymphoma (cHL) is a malignancy of B-cell origin in which the neoplastic cells, known as "Reed-Sternberg" (RS) cells, are characteristically binucleated. Here we describe a family where multiple individuals developing cHL have inherited a reciprocal translocation between chromosomes 2 and 3. The translocation disrupts KLHDC8B, an uncharacterized gene from a region (3p21.31) previously implicated in lymphoma and related malignancies, resulting in its loss of expression. We tested KLHDC8B as a candidate gene for cHL and found that a 5'-UTR polymorphism responsible for decreasing its translational expression is associated with cHL in probands from other families with cHL and segregates with disease in those pedigrees. In one of three informative sporadic cases of cHL, we detected loss of heterozygosity (LOH) for KLHDC8B in RS cells, but not reactive T lymphocytes, purified from a malignant lymph node. KLHDC8B encodes a protein predicted to contain seven kelch repeat domains. KLHDC8B is expressed during mitosis, where it localizes to the midbody structure connecting cells about to separate during cytokinesis, and it is degraded after cell division. Depletion of KLHDC8B through RNA interference leads to an increase in binucleated cells, implicating its reduced expression in the formation of cHL's signature RS cell.

A comparison and review of the flow cytometric findings in classic Hodgkin lymphoma, nodular lymphocyte predominant Hodgkin lymphoma, T cell/histiocyte rich large B cell lymphoma, and primary mediastinal large B cell lymphoma.

The "Hodgkin-like" lymphomas including classic Hodgkin lymphoma, nodular lymphocyte predominant Hodgkin lymphoma, T cell/histiocyte rich large B cell lymphoma, and primary mediastinal large B cell lymphoma have been shown to be pathobiologically related. With the exception of primary mediastinal large B cell lymphoma, these lymphomas have similar morphologic growth patterns with occasional neoplastic cells within a prominent reactive cell background. Historically, distinguishing these entities was difficult by flow cytometry; however, over the past 15 years, our laboratory has developed antibody-fluorochrome combinations capable of accurately distinguishing these entities by their immunoprofile. Additionally, an algorithmic approach based on characterization of the background reactive B-cell and T-cell populations can aid in narrowing the differential diagnosis. This review summarizes both the morphologic and immunophenotypic features and the current flow cytometric insights of the neoplastic and reactive populations found in this unique subset of lymphomas.