Single agent bortezomib in the treatment of relapsed and refractory Hodgkin lymphoma: Cancer and leukemia Group B protocol 50206

NFkB Pathway and Hodgkin Lymphoma

The tumor cells that drive classical Hodgkin lymphoma (cHL), namely, Hodgkin and Reed-Sternberg (HRS) cells, display hallmark features that include their rareness in contrast with an extensive and rich reactive microenvironment, their loss of B-cell phenotype markers, their immune escape capacity, and the activation of several key biological pathways, including the constitutive activation of the NFkB pathway. Both canonical and alternative pathways are deregulated by genetic alterations of their components or regulators, EBV infection and interaction with the microenvironment through multiple receptors, including CD30, CD40, BAFF, RANK and BCMA. Therefore, NFkB target genes are involved in apoptosis, cell proliferation, JAK/STAT pathway activation, B-cell marker expression loss, cellular interaction and a positive NFkB feedback loop. Targeting this complex pathway directly (NIK inhibitors) or indirectly (PIM, BTK or NOTCH) remains a challenge with potential therapeutic relevance. Nodular predominant HL (NLPHL), a distinct and rare HL subtype, shows a strong NFkB activity signature because of mechanisms that differ from those observed in cHL, which is discussed in this review.

Safety and Efficacy of Brentuximab Vedotin in the Treatment of Classic Hodgkin Lymphoma

Classical Hodgkin lymphoma (cHL) is a B-cell-derived lymphoid malignancy with the most favorable prognosis among various adult malignancies. However, once it becomes refractory disease to chemotherapy or relapses after high-dose chemotherapy (HDC) with autologous stem cell transplantation (ASCT), it is difficult to manage with conventional cytotoxic chemotherapy. The introduction of brentuximab vedotin (BV) has changed the treatment landscape of cHL in the past decade. Several studies demonstrated high efficacy of BV monotherapy in heavily treated patients with cHL relapsed or refractory after HDC/ASCT. Recent studies also reported high efficacy of concurrent or sequential combination of BV and chemotherapy in patients with transplant-eligible relapsed/refractory cHL at the second-line setting. In addition, a randomized phase III trial ECHELON-1 reported a positive result of BV in combination with AVD (doxorubicin, vinblastine, and dacarbazine) in patients with newly diagnosed advanced-stage cHL. In this review, we summarize available data of BV for cHL and discuss the current and future role of BV in the management of cHL.

Combinatorial ixazomib and belinostat therapy induces NFE2L2-dependent apoptosis in Hodgkin and T-cell lymphoma

Ixazomib activity and transcriptomic analyses previously established in T cell (TCL) and Hodgkin (HL) lymphoma models predicted synergistic activity for histone deacetylase (HDAC) inhibitory combination. In this present study, we determined the mechanistic basis for ixazomib combination with the HDAC inhibitor, belinostat, in HL and TCL cells lines (ixazomib-sensitive/resistant clones) and primary tumour cells. In ixazomib-treated TCL and HL cells, transient inhibition followed by full recovery of proteasomal activity observed was accompanied by induction of proteasomal gene expression with NFE2L2 (also termed NRF2) as a prominent upstream regulator. Downregulation of both NFE2L2 and proteasomal gene expression (validated by quantitative real time polymerase chain reaction) occurred with belinostat treatment in Jurkat and L428 cells. In addition, CRISPR/Cas9 mediated knockdown of NFE2L2 in Jurkat cells resulted in a significant decrease in cell viability with ixazomib compared with untreated control cells. Using transcriptomic and proteasomal activity evaluation of ixazomib, belinostat, or ixazomib + belinostat treated cells, we observed that NFE2L2, proteasome gene expression and functional recovery were abrogated by ixazomib + belinostat combination, resulting in synergistic drug activity in ixazomib-sensitive and -resistant cell lines and primary cells. Altogether, these results suggest that the synergistic activity of ixazomib + belinostat is mediated via inhibition NFE2L2-dependent proteasomal recovery and extended proteasomal inhibition culminating in increased cell death.

Advances in the pathophysiology and treatment of relapsed/refractory Hodgkin's lymphoma with an emphasis on targeted therapies and transplantation strategies

Hodgkin’s lymphoma (HL) is highly curable with first-line therapy. However, a minority of patients present with refractory disease or experience relapse after completion of frontline treatment. These patients are treated with salvage chemotherapy followed by autologous stem cell transplantation (ASCT), which remains the standard of care with curative potential for refractory or relapsed HL. Nevertheless, a significant percentage of such patients will progress after ASCT, and allogeneic hematopoietic stem cell transplantation remains the only curative approach in that setting. Recent advances in the pathophysiology of refractory or relapsed HL have provided the rationale for the development of novel targeted therapies with potent anti-HL activity and favorable toxicity profile, in contrast to cytotoxic chemotherapy. Brentuximab vedotin and programmed cell death-1-based immunotherapy have proven efficacy in the management of refractory or relapsed HL, whereas several other agents have shown promise in early clinical trials. Several of these agents are being incorporated with transplantation strategies in order to improve the outcomes of refractory or relapsed HL. In this review we summarize the current knowledge regarding the mechanisms responsible for the development of refractory/relapsed HL and the outcomes with current treatment strategies, with an emphasis on targeted therapies and hematopoietic stem cell transplantation.

Inactivation of the putative ubiquitin-E3 ligase PDLIM2 in classical Hodgkin and anaplastic large cell lymphoma

Apart from its unique histopathological appearance with rare tumor cells embedded in an inflammatory background of bystander cells, classical Hodgkin lymphoma (cHL) is characterized by an unusual activation of a broad range of signaling pathways involved in cellular activation. This includes constitutive high-level activity of nuclear factor-κB (NF-κB), Janus kinase/signal transducer and activator of transcription (JAK/STAT), activator protein-1 (AP-1) and interferon regulatory factor (IRF) transcription factors (TFs) that are physiologically only transiently activated. Here, we demonstrate that inactivation of the putative ubiquitin E3-ligase PDLIM2 contributes to this TF activation. PDLIM2 expression is lost at the mRNA and protein levels in the majority of cHL cell lines and Hodgkin and Reed–Sternberg (HRS) cells of nearly all cHL primary samples. This loss is associated with PDLIM2 genomic alterations, promoter methylation and altered splicing. Reconstitution of PDLIM2 in HRS cell lines inhibits proliferation, blocks NF-κB transcriptional activity and contributes to cHL-specific gene expression. In non-Hodgkin B-cell lines, small interfering RNA-mediated PDLIM2 knockdown results in superactivation of TFs NF-κB and AP-1 following phorbol 12-myristate 13-acetate (PMA) stimulation. Furthermore, expression of PDLIM2 is lost in anaplastic large cell lymphoma (ALCL) that shares key biological aspects with cHL. We conclude that inactivation of PDLIM2 is a recurrent finding in cHL and ALCL, promotes activation of inflammatory signaling pathways and thereby contributes to their pathogenesis.

Proteasomal Inhibition by Ixazomib Induces CHK1 and MYC-Dependent Cell Death in T-cell and Hodgkin Lymphoma

Proteasome-regulated NF-κB has been shown to be important for cell survival in T-cell lymphoma and Hodgkin lymphoma models. Several new small-molecule proteasome inhibitors are under various stages of active preclinical and clinical development. We completed a comprehensive preclinical examination of the efficacy and associated biologic effects of a second-generation proteasome inhibitor, ixazomib, in T-cell lymphoma and Hodgkin lymphoma cells and in vivo SCID mouse models. We demonstrated that ixazomib induced potent cell death in all cell lines at clinically achievable concentrations. In addition, it significantly inhibited tumor growth and improved survival in T-cell lymphoma and Hodgkin lymphoma human lymphoma xenograft models. Through global transcriptome analyses, proteasomal inhibition showed conserved overlap in downregulation of cell cycle, chromatin modification, and DNA repair processes in ixazomib-sensitive lymphoma cells. The predicted activity for tumor suppressors and oncogenes, the impact on "hallmarks of cancer," and the analysis of key significant genes from global transcriptome analysis for ixazomib strongly favored tumor inhibition via downregulation of MYC and CHK1, its target genes. Furthermore, in ixazomib-treated lymphoma cells, we identified that CHK1 was involved in the regulation of MYC expression through chromatin modification involving histone H3 acetylation via chromatin immunoprecipitation. Finally, using pharmacologic and RNA silencing of CHK1 or the associated MYC-related mechanism, we demonstrated synergistic cell death in combination with antiproteasome therapy. Altogether, ixazomib significantly downregulates MYC and induces potent cell death in T-cell lymphoma and Hodgkin lymphoma, and we identified that combinatorial therapy with anti-CHK1 treatment represents a rational and novel therapeutic approach. Cancer Res; 76(11); 3319-31. ©2016 AACR.

B-IGEV (bortezomib plus IGEV) versus IGEV before high-dose chemotherapy followed by autologous stem cell transplantation in relapsed or refractory Hodgkin lymphoma: a randomized, phase II trial of the Fondazione Italiana Linfomi (FIL)

This randomized, multicenter study evaluates the addition of bortezomib (13 mg/m(2)) to IGEV (B-IGEV) in patients with relapsed/refractory Hodgkin Lymphoma (HL). Patients received either four courses of IGEV alone (n = 40) or B-IGEV (n = 40). The primary endpoint was the complete response (CR) proportion, evaluated by FDG-PET, after induction chemotherapy. CR proportion was 39% with B-IGEV and 53% with IGEV. PFS and OS were similar between the two groups (two-year PFS: 58% vs 56%; two-year OS: 93% vs 81%). The PET-negative status after treatment was the only variable favorably influencing both PFS (two-year PFS: 77% vs 40%; p = 0.002) and OS (two-year OS: 100% vs 76%; p < 0.001). Toxicity was overall similar with the two regimens. The addition of bortezomib to IGEV does not improve response in relapsed/refractory HL patients. However, its favorable therapeutic and safety profile, and the prognostic role of pre-transplant PET negativity in patients receiving IGEV-based regimens are confirmed.

Brentuximab vedotin in relapsed/refractory Hodgkin lymphoma post-autologous transplant: meta-analysis versus historical data

OBJECTIVE

This meta-analysis evaluated the antitumor activity of brentuximab vedotin versus historical values in patients with relapsed/refractory Hodgkin lymphoma post-autologous stem cell transplantation (ASCT).

METHODS

A systematic literature review identified studies (1993-February 2013) reporting complete remission (CR) rates in patients with relapsed/refractory Hodgkin lymphoma post-ASCT. Publications reporting CR rates, identified through interrogation of multiple electronic databases and manual searches (with search terms used to capture 'relapsed', 'refractory', 'HL', and 'ASCT'), were included if they reported: ≥20 relapsed/refractory Hodgkin lymphoma patients, where ≥80% were aged ≥12 years and ≥50% had failed prior ASCT. Overall CR rate was determined using a random-effect model, and compared with that reported for brentuximab vedotin in a pivotal phase 2 trial (SG035-0003).

MAIN OUTCOME MEASURES

Across 17 evaluable studies of historical or experimental agents (n = 812), the estimated overall CR rate was 11.1% (95% confidence interval [CI] 7.0, 17.6; range, 0-38.5%) versus 33.3% (95% CI 25.3, 43.9) for brentuximab vedotin (p < 0.0001). In sensitivity analyses, the estimated overall CR rates for historical/experimental agents were 13.6% (95% CI 8.7, 21.4) when only HL trials that reported a CR rate of >0% were included (13 studies; n = 696; p = 0.0009 vs. brentuximab vedotin), and 9.0% (95% CI 4.9, 16.6) when only HL trials were included where CR definition was reported and was measured using the same criteria as in the SG035-0003 study (12 studies; n = 562; p = 0.0001 vs. brentuximab vedotin).

CONCLUSIONS

Indirect comparisons against a heterogeneous historical sample population naturally limit our ability to draw comparisons, yet the results from this quantitative meta-analysis suggest that the antitumor activity of brentuximab vedotin may exceed that of other therapies used to treat patients with relapsed/refractory Hodgkin lymphoma post-ASCT.

Meta-analysis of incidence and risk of peripheral neuropathy associated with intravenous bortezomib

BACKGROUND

Bortezomib is a proteasome inhibitor which has demonstrated activity against recurrent or newly diagnosed multiple myeloma (MM) and mantle cell lymphoma. Peripheral neuropathy has been described with this agent, although the overall incidence and relative risk remain unclear. We performed a meta-analysis to calculate the incidence of peripheral neuropathy associated with the use of intravenous bortezomib in MM and lymphoma and to compare the relative risk compared with placebo.

METHODS

We searched PubMed, Embase, Cochrane databases, and meeting proceedings from the American Society of Clinical Oncology (ASCO) for relevant clinical trials. Eligible studies included prospective phase 2 and 3 clinical trials with toxicity profile on peripheral neuropathy associated with intravenous bortezomib in patients with MM and lymphoma. Statistical analyses were done to calculate summary incidences, relative risks (RRs), and 95 % confidence intervals (CIs), employing fixed- or random-effects models depending on the heterogeneity of the included studies.

RESULTS

Altogether, 34 clinical trials were selected for the meta-analysis, yielding a total of 6492 patients. The incidence of peripheral neuropathy (all grades) was 33.9 % (95 % CI, 29.9-38.5 %) and that of high-grade events was 8.1 % (95 % CI, 6.9-9.4 %). The relative risks of bortezomib-induced peripheral neuropathy compared to placebo were increased for all-grade (RR = 4.89; 95 % CI, 2.52-9.51) and high-grade (RR = 4.53; 95 % CI, 2.04-10.07) peripheral neuropathy (for randomized controlled trials only). Our analysis was also stratified by different underlying diseases, and patients with lymphoma had an increased incidence of all-grade peripheral neuropathy than those with MM when treated with intravenous bortezomib.

CONCLUSIONS

Treatment with intravenous bortezomib is associated with an increased risk of developing peripheral neuropathy.

Brentuximab vedotin compared with other therapies in relapsed/refractory Hodgkin lymphoma post autologous stem cell transplant: median overall survival meta-analysis

OBJECTIVE

This meta-analysis compared the median overall survival (mOS) of brentuximab vedotin reported in the pivotal phase 2 study with published results of other therapies for the treatment of relapsed/refractory (R/R) Hodgkin lymphoma (HL) post autologous stem cell transplant (ASCT).

RESEARCH DESIGN AND METHODS

A systematic literature review identified studies that reported survival outcomes following conventional/experimental therapies in R/R HL patients, with ≥50% having failed ≥1 ASCT. Kaplan-Meier curves were used to reconstruct individual patient level survival data. Patients were grouped by treatment type and reconstructed data were used to estimate the mOS. Censored median regression modeling was used to compare mOS in each group with the mOS in the pivotal brentuximab vedotin trial. All patients in the pivotal trial had undergone ASCT, therefore a sensitivity analysis was conducted among studies with a 100% post-ASCT patient population.

RESULTS

The mOS reported for brentuximab vedotin was 40.5 (95% CI 30.8-NA) compared with 26.4 months (95% CI 23.5-28.5) across all 40 studies identified (n = 2518 excluding the brentuximab vedotin trial) (p < 0.0001). The difference in mOS between brentuximab vedotin and chemotherapy, allogeneic stem cell transplant (allo-SCT), and other therapies, was 17.7 (95% CI 10.6-24.7; p < 0.0001), 12.5 (95% CI 8.2-16.9; p < 0.0001), and 15.2 months (95% CI 4.9-25.5; p = 0.0037), respectively. For the 11 studies reporting a 100% prior-ASCT rate (n = 662 excluding the brentuximab vedotin trial), the mOS was 28.1 months (95% CI 23.9-34.5), and the difference in mOS between brentuximab vedotin, chemotherapy, allo-SCT, and other therapies was 19.0 (95% CI 12.9-25.1; p < 0.0001), 9.4 (p > 0.05), and 6.8 months (95% CI 1.2-12.5; p = 0.0018), respectively.

CONCLUSIONS

While some selection bias may occur when comparing trials with heterogeneous eligibility criteria, in the absence of randomized controlled trial data these results suggest brentuximab vedotin improves long-term survival and is associated with longer mOS in R/R HL post-ASCT compared with other therapies.

Update on salvage options in relapsed/refractory hodgkin lymphoma after autotransplant

Despite a high clinical success, relapse in Hodgkin lymphoma occurs in 10–30% of cases and 5–10% patients are nonresponsive to initial chemotherapy. The standard management of these patients includes high-dose chemotherapy followed by autologous stem cell transplant. However, 50% of patients ultimately relapse after autotransplant which poses a big challenge. Allogeneic stem cell transplantation offers the only chance of cure in these patients. For patients who are not candidates for allogeneic stem cell transplantation, achieving cure with other possible options is highly unlikely, and thus the treatment plan becomes noncurative. Various novel agents have shown promising results but the duration of response is short lived. A standard approach to deliver the most effective treatment for these patients is still lacking. This review focuses on the treatment options currently available for relapsed and refractory disease after autotransplant.

Customized targeted therapy in Hodgkin lymphoma: hype or hope?

Although most patients with Hodgkin lymphoma (HL) are cured with primary therapy, patients with primary refractory disease or relapse after initial treatment have poor outcomes and represent an unmet medical need. Recent advances in unraveling the biology of HL have yielded a plethora of novel targeted therapies. This review provides an overview of the data behind the hype generated by these advances and addresses the question of whether or not clinically these targeted therapies offer hope for patients with HL.

Overview of proteasome inhibitor-based anti-cancer therapies: perspective on bortezomib and second generation proteasome inhibitors versus future generation inhibitors of ubiquitin-proteasome system

Over the past ten years, proteasome inhibition has emerged as an effective therapeutic strategy for treating multiple myeloma (MM) and some lymphomas. In 2003, Bortezomib (BTZ) became the first proteasome inhibitor approved by the U.S. Food and Drug Administration (FDA). BTZ-based therapies have become a staple for the treatment of MM at all stages of the disease. The survival rate of MM patients has improved significantly since clinical introduction of BTZ and other immunomodulatory drugs. However, BTZ has several limitations. Not all patients respond to BTZ based therapies and relapse occurs in many patients who initially responded. Solid tumors, in particular, are often resistant to BTZ. Furthermore, BTZ can induce dose-limiting peripheral neuropathy (PN). The second generation proteasome inhibitor Carfizomib (CFZ; U.S. FDA approved in August 2012) induces responses in a minority of MM patients relapsed from or refractory to BTZ. There is less PN compared to BTZ. Four other second-generation proteasome inhibitors (Ixazomib, Delanzomib, Oprozomib and Marizomib) with different pharmacologic properties and broader anticancer activities, have also shown some clinical activity in bortezomib-resistant cancers. While the mechanism of resistance to bortezomib in human cancers still remains to be fully understood, targeting the immunoproteasome, ubiquitin E3 ligases, the 19S proteasome and deubiquitinases in pre-clinical studies represents possible directions for future generation inhibitors of ubiquitin-proteasome system in the treatment of MM and other cancers.

Novel therapy for Hodgkin lymphoma

The treatment of Hodgkin lymphoma (HL) relies on multimodality treatment with standard chemotherapy, radiation therapy, and autologous or allogeneic stem cell transplantation in cases of relapsed disease. Genomic advances in HL provided insights into deregulation of key nodal signaling pathways, including the PI3K, NF-κB, and JAK/STAT pathways, which are amenable to small-molecule targeting. Understanding how HL cells interact and depend on their microenvironment for survival signals and immune protection may uncover other such pathways. Small-molecule targeting has the potential to dramatically improve treatment outcomes, especially in patients with highly refractory disease and those with poor tolerance to existing chemotherapies. As novel therapies continue to be developed for HL, the challenge will be to address the needs of high-risk groups, reduce long-term therapy-related morbidity, position current established treatments with novel therapies, and concurrently develop biomarkers to aid in patient selection. Brentuximab vedotin, which was approved in 2011, is already shifting the treatment paradigm of HL. Undoubtedly, other novel therapeutics in the pipeline will affect positively the landscape of treatment in HL.

New drugs and targeted treatments in Hodgkin's lymphoma

New drugs are being developed in recent years that may change the handling of relapsed and refractory Hodgkin's lymphoma patients. Brentuximab vedotin treatment has already been approved by the FDA; and other drugs are promising, such as histone deacetylase inhibitors, bendamustine, lenalidomide and m-TOR inhibitors.

New strategies in Hodgkin lymphoma: better risk profiling and novel treatments

Recent advances in Hodgkin lymphoma research are expected to prelude a promising new treatment era for patients and their treating physicians. Scientific investigations over the last few years have provided new insights into risk stratification, and, simultaneously, a plethora of novel targeted therapies are emerging for patients with relapsed and refractory disease. These novel therapies will be tested primarily in high-risk patients because 75% of the patients are cured with conventional therapies. The challenges, as Hodgkin lymphoma therapy moves forward, will be using these biologic insights to identify the patients who may benefit earlier in treatment from these novel agents, and tailoring the therapy to the tumor biology of the patient. These dual aims are intertwined; as our therapeutic arsenal increases, these biologic determinants of risk may themselves inform the design of therapies and the choice of treatments for high-risk patients.

Novel CD20 monoclonal antibodies for lymphoma therapy

Rituximab (RTX), a monoclonal antibody (mAb) against CD20, has been widely used for lymphoma therapy. RTX in combination with cyclophosphamide /doxorubicin /vincristine /prednisone (R-CHOP) remains the standard frontline regimen for diffuse large B-cell lymphoma. However, suboptimal response and /or resistance to rituximab have remained a challenge in the therapy of B-cell non-Hodgkin's lymphoma (NHL). Novel agents are under active clinical trials. This review will summarize the latest development in new mAbs against CD20, which include second-generation mAbs, ofatumumab, veltuzumab (IMMU-106), ocrelizumab (PRO70769), and third-generation mAbs, AME-133v (ocaratuzumab), PRO131921 and GA101 (obinutumumab).

Hodgkin's lymphoma in adults

Management of Hodgkin's lymphoma continues to develop. Outcomes for patients with favourable-risk, early-stage disease are excellent, and serial reductions in intensity of treatment have been made to retain the excellent prognosis while reducing the late effects of treatment. Prognosis is also very good in advanced-stage disease but the rate of relapse is higher than in early-stage disease, and the optimum first-line treatment is unclear. Workers are investigating the role of functional imaging to assess whether treatment can be tailored according to response, with the most intensive therapies reserved for patients predicted to have poor outcomes. In this Seminar we critically appraise the management of Hodgkin's lymphoma in early-stage disease, advanced-stage disease, and at relapse, with a focus on late effects of treatment.

Rad knockdown induces mitochondrial apoptosis in bortezomib resistant leukemia and lymphoma cells

To understand the molecular mechanism(s) underlying bortezomib resistance, we sought to identify potential target genes that were differentially expressed in bortezomib-resistant leukemia cells versus parental controls. Microarray analysis revealed that the mRNA levels of Rad (Ras associated with diabetes) were higher in the bortezomib-resistant Jurkat (Jurkat-R) cells than in the parental control cells. The importance of Rad for bortezomib resistance was supported by three observations. First, Rad knockdown overcame bortezomib resistance and induced mitochondrial apoptosis via Noxa/Bcl-2 modulation. Second, Rad decreased cell death in response to bortezomib. Third, leukemia and lymphoma cell lines (K-562, Raji, IM-9 and Jurkat-R) with elevated Rad expression levels showed higher degrees of bortezomib resistance versus those (Sup-B15, JVM-2, U266 and Jurkat) with low Rad expression levels (r=0.48, P=0.0004). Thus, Rad over expression could be a molecular target to improve bortezomib sensitivity in human leukemia and lymphoma.

Treatment of newly diagnosed advanced stage Hodgkin lymphoma

ABVD continues to be the standard of care for patients with advanced stage Hodgkin Lymphoma (HL) although escalated BEACOPP has improved survival in one randomized controlled trial (RCT). More intensive regimens have higher rates of acute and late toxicities and this poses significant issues for patients. Consolidation strategies such as radiation or autologous stem cell transplantation (ASCT) have not demonstrated an improvement in overall survival in RCTs. Novel technology and therapeutics are leading us to investigate new questions. Interim FDG-PET scanning is now being tested in prospective studies. Small, typically retrospective trials suggest that interim PET scans are independent markers of outcome and current trials are piloting the use of PET-adapted therapy. Targeted therapeutics have been evaluated in the relapsed and refractory setting and now show promising single agent activity. Agents including brentuximab vedotin (a conjugated anti-CD30 monoclonal antibody) and the histone deacetylase inhibitor panabinostat have reported encouraging single agent activity and a large study of brentuximab vedotin maintenance post ASCT is underway. Combination and maintenance trials are planned or ongoing in the primary treatment setting that will hopefully improve on the treatment standards of the past decade. This review will discuss the current standard of care in advanced stage HL, summarize some of the current data regarding interim FDG-PET scans and will conclude with some issues related to the development of new agents that are likely to be involved in the future standard of therapy.

Mast cells promote the growth of Hodgkin's lymphoma cell tumor by modifying the tumor microenvironment that can be perturbed by bortezomib

Hodgkin's lymphoma is frequently associated with mast cell infiltration that correlates directly with disease severity, but the mechanisms underlying this relationship remain unclear. Here, we report that mast cells promote the growth of Hodgkin's tumor by modifying the tumor microenvironment. A transplantation assay shows that primary murine mast cells accelerate tumor growth by established Hodgkin's cell lines, and promote marked neovascularization and fibrosis. Both mast cells and Hodgkin's cells were sensitive to bortezomib, but mast cells were more resistant to bortezomib. However, bortezomib inhibited degranulation, PGE(2)-induced rapid release of CCL2, and continuous release of vascular endothelial growth factor-A from mast cells even at the concentration that did not induce cell death. Bortezomib-treated mast cells lost the ability to induce neovasculization and fibrosis, and did not promote the growth of Hodgkin tumor in vivo. These results provide further evidence supporting causal relationships between inflammation and tumor growth, and demonstrate that bortezomib can target the tumor microenvironment.

Advances in the treatment of relapsed or refractory Hodgkin's lymphoma

Hodgkin's lymphoma (HL) is diagnosed in 20,000 men and women annually in North America and Europe. Despite treatment advancements for HL resulting in an overall survival rate of 80%, patients with advanced stage disease continue to have suboptimal outcomes, with relapse rates of 30%-40%. An additional 10%-15% of patients present with primary refractory disease. For patients who relapse after initial treatment, salvage chemotherapy followed by autologous stem cell transplant in those with chemotherapy-sensitive disease is the standard of care. Patients who relapse after second-line therapy have a median survival time in the range of 6-36 months, and the optimal management of these patients remains unclear. Unfortunately, there have been no new agents approved for relapsed HL treatment since the 1970s. Consequently, clinical decision making in this population is difficult. Recently however, several agents have emerged that have shown clinical promise in this poor-risk population. This review discusses the management of these patients and also discusses several newer agents showing clinical promise in the treatment of HL.

Quantifying nuclear p65 as a parameter for NF-κB activation: Correlation between ImageStream cytometry, microscopy, and Western blot

The nuclear factor kappa B (NF-κB) pathway, which regulates many cellular processes including proliferation, apoptosis, and survival, has emerged as an important therapeutic target in cancer. Activation of the NF-κB transcription factor is associated with nuclear translocation of the p65 component of the complex. Conventional methods employed to determine nuclear translocation of NF-κB either lack statistical robustness (microscopy) or the ability to discern heterogeneity within the sampled populations (Western blotting and Gel Shift assays). The ImageStream platform combines the high image content information of microscopy with the high throughput and multiparameter analysis of flow cytometry which overcomes the aforementioned limitations of conventional assays. It is demonstrated that ImageStream assessment of receptor-mediated (TNFα) and drug (Daunorubicin, DNR)-induced NF-κB translocation in leukemic cell lines correlates well with microscopy analysis and Western blot analysis. It is further demonstrated that ImageStream cytometry enables quantitative assessment of p65 translocation in immunophenotypically defined subpopulations; and that this assessment is highly reproducible. It is also demonstrated that, quantitatively, the DNR-induced nuclear translocation of NF-κB correlates well with a biological response (apoptosis). We conclude that the ImageStream has the potential to be a powerful tool to evaluate NF-κB /p65 activity as a determinant of response to therapies designed to target aberrant NF-κB signaling activities.

Molecular Pathogenesis of Hodgkin's Lymphoma: Increasing Evidence of the Importance of the Microenvironment

Hodgkin's lymphoma (HL) represents the most common subtype of malignant lymphoma in young people in the Western world. Most patients can be cured with modern treatment strategies, although approximately 20% will die after relapse or progressive disease. The histologic hallmark of the disease is the presence of the characteristic Hodgkin Reed-Sternberg (HRS) cells in classical HL and so-called lymphocyte-predominant (LP) cells in nodular lymphocyte-predominant HL. HL is unique among all cancers because malignant cells are greatly outnumbered by reactive cells in the tumor microenvironment and make up only approximately 1% of the tumor. Expression of a variety of cytokines and chemokines by the HRS and LP cells is believed to be the driving force for an abnormal immune response, perpetuated by additional factors secreted by reactive cells in the microenvironment that help maintain the inflammatory milieu. The malignant HRS and LP cells manipulate the microenvironment, permitting them to develop their malignant phenotype fully and evade host immune attack. Gene expression signatures derived from non-neoplastic cells correlate well with response to initial and subsequent therapies, reflecting their functional relevance. Recent biomarker studies have added texture to clinical outcome predictors, and their incorporation into prognostic models may improve our understanding of the biologic correlates of treatment failure. Moreover, recent preclinical and clinical studies have demonstrated that the tumor microenvironment represents a promising therapeutic target, raising hope that novel treatment strategies focused on the interface between malignant and reactive cells will soon emerge.

The Management of Classical Hodgkin's Lymphoma: Past, Present, and Future

The management of classical Hodgkin's lymphoma (CHL) is a success story of modern multi-agent haemato-oncology. Prior to the middle of the twentieth century CHL was fatal in the majority of cases. Introduction of single agent radiotherapy (RT) demonstrated for the first time that these patients could be cured. Developments in chemotherapy including the mechlorethamine, vincristine, procarbazine and prednisolone (MOPP) and Adriamycin, bleomycin, vinblastine and dacarbazine (ABVD) regimens have resulted in cure rates of over 80%. Even in relapse, CHL patients can be salvaged with high dose chemotherapy and autologous haematopoietic stem cell transplantation (ASCT). Challenges remain, however, in finding new strategies to manage the small number of patients who continue to relapse or progress. In addition, the young age of many Hodgkin's patients forces difficult decisions in balancing the benefit of early disease control against the survival disadvantage of late toxicity. In this article we aim to summarise past trials, define the current standard of care and appraise future developments in the management of CHL.

Noxa/Bcl-2 protein interactions contribute to bortezomib resistance in human lymphoid cells

Previous studies have suggested that the BH3 domain of the proapoptotic Bcl-2 family member Noxa only interacts with the anti-apoptotic proteins Mcl-1 and A1 but not Bcl-2. In view of the similarity of the BH3 binding domains of these anti-apoptotic proteins as well as recent evidence that studies of isolated BH3 domains can potentially underestimate the binding between full-length Bcl-2 family members, we examined the interaction of full-length human Noxa with anti-apoptotic human Bcl-2 family members. Surface plasmon resonance using bacterially expressed proteins demonstrated that Noxa binds with mean dissociation constants (K(D)) of 3.4 nm for Mcl-1, 70 nm for Bcl-x(L), and 250 nm for wild type human Bcl-2, demonstrating selectivity but not absolute specificity of Noxa for Mcl-1. Further analysis showed that the Noxa/Bcl-2 interaction reflected binding between the Noxa BH3 domain and the Bcl-2 BH3 binding groove. Analysis of proteins expressed in vivo demonstrated that Noxa and Bcl-2 can be pulled down together from a variety of cells. Moreover, when compared with wild type Bcl-2, certain lymphoma-derived Bcl-2 mutants bound Noxa up to 20-fold more tightly in vitro, pulled down more Noxa from cells, and protected cells against killing by transfected Noxa to a greater extent. When killing by bortezomib (an agent whose cytotoxicity in Jurkat T-cell leukemia cells is dependent on Noxa) was examined, apoptosis was enhanced by the Bcl-2/Bcl-x(L) antagonist ABT-737 or by Bcl-2 down-regulation and diminished by Bcl-2 overexpression. Collectively, these observations not only establish the ability of Noxa and Bcl-2 to interact but also identify Bcl-2 overexpression as a potential mechanism of bortezomib resistance.

Beyond chemotherapy: new agents for targeted treatment of lymphoma

An improved understanding of the molecular biology of cancer cell growth and survival and the role of the microenvironment in supporting the survival of cancer cells, including lymphoma cells, has led to the identification of a number of potential therapeutic targets. Despite these advances, drug development for lymphoma remains slow, inefficient, and frequently unfocused. Future work should focus on identifying 'driver' molecular defects of oncogenic pathways that can be targeted therapeutically, discovering predictive biomarkers for treatment response, and prioritizing promising drugs to accelerate their approval. This Review summarizes the current development status of novel agents for lymphoma and discusses strategies to move the field forward.

Targeted therapy in lymphoma

Discovery of new treatments for lymphoma that prolong survival and are less toxic than currently available agents represents an urgent unmet need. We now have a better understanding of the molecular pathogenesis of lymphoma, such as aberrant signal transduction pathways, which have led to the discovery and development of targeted therapeutics. The ubiquitin-proteasome and the Akt/mammalian target of rapamycin (mTOR) pathways are examples of pathological mechanisms that are being targeted in drug development efforts. Bortezomib (a small molecule protease inhibitor) and the mTOR inhibitors temsirolimus, everolimus, and ridaforolimus are some of the targeted therapies currently being studied in the treatment of aggressive, relapsed/refractory lymphoma. This review will discuss the rationale for and summarize the reported findings of initial and ongoing investigations of mTOR inhibitors and other small molecule targeted therapies in the treatment of lymphoma.

Novel treatment strategies for patients with relapsed classical Hodgkin lymphoma

The treatment of patients with relapsed and refractory Hodgkin lymphoma (HL), especially those who relapse after autologous stem cell transplantation, remains challenging. Patients with HL whose disease relapses after stem cell transplantation are rarely cured with current treatment modalities, and have a median survival of less than 3 years. Since no new drugs have been approved by the FDA for HL in more than three decades, there is a clear unmet medical need for drug development for this patient population. New treatment strategies that are based on targeting oncogenic signaling pathways are currently explored. This review will focus on emerging new treatment modalities that are currently under investigation for patients with relapsed classical HL.

A Phase II trial of the oral mTOR inhibitor everolimus in relapsed Hodgkin lymphoma

Everolimus is an oral antineoplastic agent that targets the raptor mammalian target of rapamycin (mTORC1). The phosphatidylinositol 3-kinase/mTOR signal transduction pathway has been demonstrated to be activated in tumor samples from patients with Hodgkin lymphoma (HL). The goal of this trial was to learn the antitumor activity and toxicity of everolimus in patients with relapsed/refractory HL. Patients were eligible if they had measurable disease, a platelet count >75,000, and an absolute neutrophil count >1,000. Patients received everolimus 10 mg PO daily. Dose reductions were allowed. Response was assessed after two and six cycles and then every three cycles until progression. Patients could remain on drug until progression or toxicity. Nineteen patients were enrolled. Median age was 37 years (range, 27-68). Patients had received a median of six prior therapies (range, 3-14) and 84% had undergone prior autologous stem cell transplant. The ORR was 47% (95% CI: 24-71%) with eight patients achieving a PR and one patient achieving a CR. The median TTP was 7.2 months. Four responders remained progression free at 12 months. Patients received a median of seven cycles of therapy. Of the 19 patients, one remains on therapy at 36 months; the others went off study because of progressive disease (16), toxicity (1), and death from infection (1). Four patients experienced a Grade 3 or higher pulmonary toxicity. Everolimus has single-agent activity in relapsed/refractory HL and provides proof-of-concept that targeting the mTOR pathway in HL is clinically relevant.

Current approaches to the management of pediatric Hodgkin lymphoma

Hodgkin lymphoma is one of the few cancers that affect both adults and children. Cure rates for Hodgkin lymphoma remain among the best for pediatric cancers. However, cure is often associated with significant delayed effects of therapy, including an elevated risk for second malignancies, cardiotoxicity, pulmonary toxicity, and gonadal and non-gonadal endocrine dysfunction. Therefore, the aim of current treatment strategies is to further improve outcomes while minimizing therapy-related complications. At diagnosis, patients are classified into risk groups based on disease stage, and the presence of clinical, biologic, and serologic risk factors. In general, the most recent trials have intensified therapy in those patients with high-risk disease to improve disease control, and have limited therapy in those patients with low-risk disease to avoid secondary effects. In low-risk patients, multiple studies have been conducted to investigate limiting either radiation therapy or chemotherapy to prevent long-term side effects without affecting the excellent cure rate. In intermediate- and high-risk patients, many studies have examined intensifying therapy to improve event-free survival rates. In addition, response assessment by fluorine-18-2-fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET) may be particularly important in pediatric Hodgkin lymphoma; it may allow modification of treatment to maximize treatment efficacy and minimize late effects of chemotherapy and radiation therapy. Despite the improvements in treatment for all stages of Hodgkin lymphoma, there is still a subgroup of patients who do not enter remission with initial therapy or relapse after initial response to therapy. Unfortunately, standard-dose salvage chemotherapy for relapsed disease has disappointing results in terms of overall survival since patients have typically already received intensive therapy. While there is no standard of care in terms of salvage chemotherapy, high-dose chemotherapy with autologous stem cell transplant (ASCT) rescue has become the standard of care for the majority of children with relapsed Hodgkin lymphoma. The use of allogeneic transplantation is controversial in relapsed or refractory Hodgkin lymphoma; because of the high transplant-related mortality, allogeneic transplant has not been associated with improved overall survival over ASCT. As more has been learned about the biologic mechanisms involved in Hodgkin lymphoma, biologically-based therapies are being investigated for use in this disease, both at initial diagnosis and relapse. Both immunotherapy and small molecules are being studied as possible therapeutic agents in Hodgkin lymphoma. Unfortunately, the vast majority of investigations of novel agents have occurred exclusively in adult patients. However, since pediatric Hodgkin lymphoma and adult Hodgkin lymphoma are similar, these results may potentially be extrapolated to pediatric Hodgkin lymphoma.

Novel therapies for Hodgkin Lymphoma

In recent years, improved understanding of the biology of Hodgkin Lymphoma (HL) has uncovered many potential targets for the treatment of this disease. Clarification of the B-ceLL origin of the Hodgkin Reed Sternberg (HRS) cell and of the complex interactions between the HRS cell and the HL microenvironment have provided new insights into the pathophysiology of HL and identified extracellular and intracellular molecules which are essential for HRS survival. New agents directed at these molecules are now in early phase clinical trials.

The future of small molecule inhibitors in lymphoma

For the many patients with lymphoma that has relapsed after and/or has become refractory to existing treatments, the development of novel therapeutics is imperative. Investigation into intracellular processes that are dysregulated during lymphomagenesis has uncovered several new potential targets for anticancer agents. Although monoclonal antibodies and other immunotherapeutics have led to dramatic advances in the treatment of patients with lymphoma, the parallel development of small molecule inhibitors has been equally exciting. These agents, whose small size allows direct entry into tumor cells, can target distinct proteins or complexes, thereby disrupting molecular processes on which neoplastic cells depend for survival and growth. This review surveys the published literature on many of these new targeted molecules, focusing on some of the most promising agents for which phase 2 data currently exist. It also explores the potential for incorporating these agents into broader multidrug regimens.

Upcoming diagnostic and therapeutic developments in classical Hodgkin's lymphoma

With improvements in therapy, increasing dose intensity, early recognition of toxicity, and enhanced supportive care, current outcomes in patients with classical Hodgkin's lymphoma (HL) may be superior to disease-free and overall survival (OS) predicted by existing prognostic models, including the International Prognostic Score (IPS). The addition of biologic markers to recognized clinical prognostic factors, including those of the IPS, may to improve patient risk stratification and guide therapy in the future. However, the identification of these markers has been problematic due to the lack of large, confirmatory prospective trials, reproducibility and feasibility of the assays, and failure to improve upon already recognized clinical risk factors. One biomarker in particular, CD68, present on tumor infiltrating macrophages and detectable by immunohistochemical staining, is significantly associated with both shortened progression-free and disease-specific survivals in patients with HL at diagnosis and at relapse. In addition, less than 5% CD68+ cells correlates with a 100% disease-specific survival in patients with early-stage HL. CD68 represents just one of the many prognostic markers that could eventually be used to risk-stratify therapy. In addition, biologic markers may not only serve as prognostic markers, but also as therapeutic targets in HL. This review examines current data using the IPS to determine patient outcome, discuss several potential biologic prognostic markers, and summarize new therapies that are currently in clinical development in HL.

Novel therapies for peripheral T-cell non-Hodgkin's lymphomas

PURPOSE OF REVIEW

To review new agents under investigation for the treatment of patients with peripheral T-cell lymphoma.

RECENT FINDINGS

New agents being evaluated in these patients include histone deacetylase inhibitors (e.g. romidepsin, vorinostat, and balinostat), purine analogs and agents that interfere with the purine metabolic pathway (e.g. forodesine), immunomodulatory agents, proapoptotic small molecules (e.g. oblimersen, obatoclax, and gossypol), antifols (e.g. pralatrexate), proteasome inhibitors (e.g. bortezomib), monoclonal antibodies against T-cell antigens (e.g. CD30 and CD52), and immunotoxins (e.g. denileukin diftitox).

SUMMARY

The development of rational combinations of such agents in clinical trials will be required to improve the outcome of these patients.

Optimal treatment for relapsing patients with Hodgkin lymphoma

Relapsed or refractory classical Hodgkin lymphoma (HL) remains a therapeutic challenge. Patients with relapsed HL should be identified according to their prognostic factors at relapse (duration of remission and extranodal disease or stage). Patients with refractory disease, defined as progression during induction treatment or within 90 days after the end of treatment, have the worst prognosis. Following non-crossresistant salvage chemotherapy to achieve cytoreduction, high-dose therapy (HDT) and autologous stem cell transplantation has been shown to be better than conventional-dose chemotherapy for first-relapse/refractory HL. For patients with very unfavorable relapse or primary refractory HL, outcome remains poor with HDT. For these patients, the role of tandem HDT or allogeneic stem cell transplantation will be discussed. In this setting, novel investigational treatments will be presented.

PCI-24781 induces caspase and reactive oxygen species-dependent apoptosis through NF-kappaB mechanisms and is synergistic with bortezomib in lymphoma cells

PURPOSE

We investigated the cytotoxicity and mechanisms of cell death of the broad-spectrum histone deacetylase (HDAC) inhibitor PCI-24781, alone and combined with bortezomib in Hodgkin lymphoma and non-Hodgkin lymphoma cell lines and primary lymphoproliferative (CLL/SLL) cells.

EXPERIMENTAL DESIGN

Apoptosis, mitochondrial membrane potential, cell cycle analysis, and reactive oxygen species (ROS) were measured by flow cytometry, whereas caspase activation was determined by Western blot. Nuclear factor kappaB (NF-kappaB)-related mRNAs were quantified by reverse transcription-PCR, NF-kappaB-related proteins by Western blotting, and NF-kappaB DNA-binding activity by electromobility shift assay. Finally, gene expression profiling was analyzed.

RESULTS

PCI-24781 induced concentration-dependent apoptosis that was associated with prominent G(0)/G(1) arrest, decreased S-phase, increased p21 protein, and increased ROS in Hodgkin lymphoma and non-Hodgkin lymphoma cell lines. Dose-dependent apoptosis with PCI-24781 was also seen among primary CLL/SLL cells. PCI-24781-induced apoptosis was shown to be ROS- and caspase-dependent. Combined PCI-24781/bortezomib treatment resulted in strong synergistic apoptosis in all non-Hodgkin lymphoma lines (combination indices, 0.19-0.6) and was additive in Hodgkin lymphoma and primary CLL/SLL cells. Further, PCI-24781/bortezomib resulted in increased caspase cleavage, mitochondrial depolarization, and histone acetylation compared with either agent alone. Gene expression profiling showed that PCI-24781 alone significantly down-regulated several antioxidant genes, proteasome components, and NF-kappaB pathway genes, effects that were enhanced further with bortezomib. Reverse transcription-PCR confirmed down-regulation of NF-kappaB1 (p105), c-Myc, and IkappaB-kinase subunits, where NF-kappaB DNA binding activity was decreased.

CONCLUSION

We show that PCI-24781 results in increased ROS and NF-kappaB inhibition, leading to caspase-dependent apoptosis. We also show that bortezomib is synergistic with PCI-24781. This combination or PCI-24781 alone has potential therapeutic value in lymphoma.

Novel treatment strategies for patients with relapsed classical Hodgkin lymphoma

Although classical Hodgkin lymphoma (HL) is considered one of the most curable human cancers, the treatment of patients with relapsed and refractory disease, especially those who relapse after autologous stem cell transplantation, remains challenging. Furthermore, because the median age of the patients is in the mid-30s, the impact of early mortality on the number of years lost from productive life is remarkable. Patients with HL whose disease relapses after stem cell transplantation are rarely cured with current treatment modalities. New drugs and novel treatment strategies that are based on our understanding of the disease biology and signaling pathways are needed to improve treatment outcome for these patients. This review will focus on emerging new treatment modalities that are currently under investigation for patients with relapsed classical HL.

The potential of proteasome inhibitors in cancer therapy

BACKGROUND

The ubiquitin-proteasome system has become a promising novel molecular target in cancer due to its critical role in cellular protein degradation, its interaction with cell cycle and apoptosis regulation and its unique mechanism of action.

OBJECTIVE

This review focuses both on preclinical results and on data from clinical trials with proteasome inhibitors in cancer.

METHODS

Results in hematological malignancies and solid tumors were included, and important data presented in abstract form were considered in this review.

RESULTS/CONCLUSION

Bortezomib as first-in-class proteasome inhibitor has proven to be highly effective in some hematological malignancies, overcomes conventional chemoresistance, directly induces cell cycle arrest and apoptosis, and also targets the tumor microenvironment. It has been granted approval by the FDA for relapsed multiple myeloma, and recently for relapsed mantle cell lymphoma. Combination chemotherapy regimens have been developed providing high remission rates and remission quality in frontline treatment or in the relapsed setting in multiple myeloma. The combination of proteasome inhibition with novel targeted therapies is an emerging field in oncology. Moreover, novel proteasome inhibitors, such as NPI-0052 and carfilzomib, have been developed. This review summarizes our knowledge of the ubiquitin-proteasome system and recent data from cancer clinical trials.

Modern treatment of Hodgkin lymphoma

PURPOSE OF REVIEW

The present review summarizes the current therapies and controversies in the management of newly diagnosed and relapsed classical and lymphocyte predominant Hodgkin lymphoma and briefly describes novel agents in development for Hodgkin lymphoma.

RECENT FINDINGS

Early restaging fluoro-2-deoxy-D-glucose-positron emission tomography scans appear to provide important prognostic information, particularly in patients with advanced stage Hodgkin lymphoma. A persistently positive scan after two cycles of chemotherapy appears to predict a very dismal outcome, whereas a negative interim scan predicts a very favorable outcome. This finding provides an opportunity to study the effect of tailoring therapy early in the course of disease, perhaps shortening therapy and avoiding radiotherapy in early stage patients with a negative interim scan and escalating therapy in those with positive scans. Recent retrospective studies show it is safe to administer the standard doxorubicin, bleomycin, vinblastine, dacarbazine chemotherapy regimen, prescribed for nearly all patients with Hodgkin lymphoma, at full dose, on schedule without growth factors, minimizing the risk of bleomycin lung toxicity and perhaps improving outcome. Several new drugs are showing promise for refractory Hodgkin lymphoma, including the immunotoxin SGN-35 and the histone deacetylase inhibitor MGCD0103. Rituximab is being studied for the treatment of both classical and lymphocyte predominant Hodgkin lymphoma.

SUMMARY

Current trials employing risk-adapted therapy on the basis of interim fluoro-2-deoxy-D-glucose-positron emission tomography scans have the potential of improving outcomes for all patients with Hodgkin lymphoma, either by improving cure rates, minimizing toxicity, or both.

Bortezomib and gemcitabine in relapsed or refractory Hodgkin's lymphoma

BACKGROUND

Given the significant activity and tolerability of gemcitabine in patients with relapsed Hodgkin's lymphoma (HL), the critical role that nuclear factor kappa B (NF-kappaB) appears to play in the pathogenesis of this tumor, the ability of bortezomib to inhibit NF-kappaB activity, and laboratory studies suggesting synergistic antitumor effects of gemcitabine and bortezomib, we hypothesized that this combination would be efficacious in patients with relapsed or refractory HL.

PATIENTS AND METHODS

A total of 18 patients participated. Patients received 3-week cycles of bortezomib 1 mg/m(2) on days 1, 4, 8, and 11 plus gemcitabine 800 mg/m(2) on days 1 and 8.

RESULTS

The overall response rate for all patients was 22% (95% confidence interval 3% to 42%). Three patients developed grade III transaminase elevation: one was removed from the study and two had doses of gemcitabine held. Almost all patients exhibited inhibition of proteasome activity with treatment.

CONCLUSIONS

The combination of gemcitabine and bortezomib is a less active and more toxic regimen in relapsed HL than other currently available treatments. It poses a risk of severe liver toxicity and should be pursued with caution in other types of cancer.