A novel regimen combining high dose cytarabine and bortezomib has activity in multiply relapsed and refractory mantle cell lymphoma – long-term results of a multicenter observation study

The addition of bortezomib to rituximab, high-dose cytarabine and dexamethasone in relapsed or refractory mantle cell lymphoma-a randomized, open-label phase III trial of the European mantle cell lymphoma network

The therapy of relapsed or refractory (r/r) mantle cell lymphoma (MCL) patients remains a major clinical challenge to date. We conducted a randomized, open-label, parallel-group phase-III trial hypothesizing superior efficacy of rituximab, high-dose cytarabine and dexamethasone with bortezomib (R-HAD + B) versus without (R-HAD) in r/r MCL ineligible for or relapsed after autologous stem cell transplant (ASCT). Primary endpoint was time to treatment failure (TTF), secondary endpoints included response rates, progression free survival, overall survival, and safety. In total, 128 of 175 planned patients were randomized to R-HAD + B (n = 64) or R-HAD (n = 64). Median TTF was 12 vs. 2.6 months (p = 0.045, MIPI-adjusted HR 0.69; 95%CI 0.47-1.02). Overall and complete response rates were 63 vs. 45% (p = 0.049) and 42 vs. 19% (p = 0.0062). A significant treatment effect was seen in the subgroup of patients >65 years (aHR 0.48, 0.29-0.79) and without previous ASCT (aHR 0.52, 0.28-0.96). Toxicity was mostly hematological and attributable to the chemotherapeutic backbone. Grade ≥3 leukocytopenia and lymphocytopenia were more common in R-HAD + B without differences in severe infections between both arms. Bortezomib in combination with chemotherapy can be effective in r/r MCL and should be evaluated further as a therapeutic option, especially if therapy with BTK inhibitors is not an option. Trial registration: NCT01449344.

Mantle cell lymphoma - advances in molecular biology, prognostication and treatment approaches

Mantle cell lymphoma (MCL) is clinically characterised by its heterogenous behaviour with courses ranging from indolent cases that do not require therapy for years to highly aggressive MCL with a very limited prognosis. A better understanding of the complex biology of MCL has already led to the approval of several innovative agents, expanding the landscape of MCL therapies and improving therapeutic options especially for refractory/relapsed (R/R) disease. Nevertheless, to further optimise MCL treatment, early identification of individual risk profile and risk-adapted, patient-tailored choice of therapeutic strategy needs to be prospectively incorporated into clinical patient management. The present review highlights recent advances in deciphering the molecular background of MCL, the definition of prognostically relevant factors and the identification of potential druggable targets and summarises current treatment recommendations for primary and R/R MCL including novel targeted therapies.

The proteasome as a druggable target with multiple therapeutic potentialities: Cutting and non-cutting edges

Ubiquitin Proteasome System (UPS) is an adaptable and finely tuned system that sustains proteostasis network under a large variety of physiopathological conditions. Its dysregulation is often associated with the onset and progression of human diseases; hence, UPS modulation has emerged as a promising new avenue for the development of treatments of several relevant pathologies, such as cancer and neurodegeneration. The clinical interest in proteasome inhibition has considerably increased after the FDA approval in 2003 of bortezomib for relapsed/refractory multiple myeloma, which is now used in the front-line setting. Thereafter, two other proteasome inhibitors (carfilzomib and ixazomib), designed to overcome resistance to bortezomib, have been approved for treatment-experienced patients, and a variety of novel inhibitors are currently under preclinical and clinical investigation not only for haematological malignancies but also for solid tumours. However, since UPS collapse leads to toxic misfolded proteins accumulation, proteasome is attracting even more interest as a target for the care of neurodegenerative diseases, which are sustained by UPS impairment. Thus, conceptually, proteasome activation represents an innovative and largely unexplored target for drug development. According to a multidisciplinary approach, spanning from chemistry, biochemistry, molecular biology to pharmacology, this review will summarize the most recent available literature regarding different aspects of proteasome biology, focusing on structure, function and regulation of proteasome in physiological and pathological processes, mostly cancer and neurodegenerative diseases, connecting biochemical features and clinical studies of proteasome targeting drugs.

Bortezomib for the Treatment of Hematologic Malignancies: 15 Years Later

Bortezomib is a dipeptidyl boronic acid that selectively inhibits the ubiquitin proteasome pathway, which plays a role in the degradation of many intracellular proteins. It is the first-in-class selective and reversible inhibitor of the 26S proteasome, with antiproliferative and antitumor activity. It exerts its anti-neoplastic action mainly via the inhibition of the nuclear factor-κB pathway components associated with cell proliferation, apoptosis, and angiogenesis. The drug has revolutionized the treatment of multiple myeloma and, more recently, mantle cell lymphoma. In 2003, bortezomib received accelerated approval from the US Food and Drug Administration for the treatment of relapsed/refractory multiple myeloma and in 2008 for patients with previously untreated multiple myeloma. In 2006, bortezomib was approved for the treatment of refractory/relapsed mantle cell lymphoma and, in 2014, for previously untreated mantle cell lymphoma. Bortezomib has also demonstrated clinical efficacy both as a single drug and in combination with other agents in light chain amyloidosis, lymphoplasmacytic lymphoma/Waldenstrom macroglobulinemia, and peripheral T-cell lymphomas. Furthermore, continued clinical studies are required to confirm its value for patients with indolent and aggressive B-cell non-Hodgkin lymphomas and acute leukemias.

Therapeutic Targeting of Notch Signaling Pathway in Hematological Malignancies

The Notch pathway plays a key role in several processes, including stem-cell self-renewal, proliferation, and cell differentiation. Several studies identified recurrent mutations in hematological malignancies making Notch one of the most desirable targets in leukemia and lymphoma. The Notch signaling mediates resistance to therapy and controls cancer stem cells supporting the development of on-target therapeutic strategies to improve patients’ outcome. In this brief review, we outline the therapeutic potential of targeting Notch pathway in T-cell acute jlymphoblastic leukemia, chronic lymphocytic leukemia, and mantle cell lymphoma.

Bortezomib prevents cytarabine resistance in MCL, which is characterized by down-regulation of dCK and up-regulation of SPIB resulting in high NF-κB activity

Background

The addition of high-dose cytarabine to the treatment of mantle cell lymphoma (MCL) has significantly prolonged survival of patients, but relapses are common and are normally associated with increased resistance. To elucidate the mechanisms responsible for cytarabine resistance, and to create a tool for drug discovery investigations, we established a unique and molecularly reproducible cytarabine resistant model from the Z138 MCL cell line.

Methods

Effects of different substances on cytarabine-sensitive and resistant cells were evaluated by assessment of cell proliferation using [methyl-14C]-thymidine incorporation and molecular changes were investigated by protein and gene expression analyses.

Results

Gene expression profiling revealed that major transcriptional changes occur during the initial phase of adaptation to cellular growth in cytarabine containing media, and only few key genes, including SPIB, are deregulated upon the later development of resistance. Resistance was shown to be mediated by down-regulation of the deoxycytidine kinase (dCK) protein, responsible for activation of nucleoside analogue prodrugs. This key event, emphasized by cross-resistance to other nucleoside analogues, did not only effect resistance but also levels of SPIB and NF-κB, as assessed through forced overexpression in resistant cells. Thus, for the first time we show that regulation of drug resistance through prevention of conversion of pro-drug into active drug are closely linked to increased proliferation and resistance to apoptosis in MCL. Using drug libraries, we identify several substances with growth reducing effect on cytarabine resistant cells. We further hypothesized that co-treatment with bortezomib could prevent resistance development. This was confirmed and show that the dCK levels are retained upon co-treatment, indicating a clinical use for bortezomib treatment in combination with cytarabine to avoid development of resistance. The possibility to predict cytarabine resistance in diagnostic samples was assessed, but analysis show that a majority of patients have moderate to high expression of dCK at diagnosis, corresponding well to the initial clinical response to cytarabine treatment.

Conclusion

We show that cytarabine resistance potentially can be avoided or at least delayed through co-treatment with bortezomib, and that down-regulation of dCK and up-regulation of SPIB and NF-κB are the main molecular events driving cytarabine resistance development.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4346-1) contains supplementary material, which is available to authorized users.

The preclinical discovery and development of bortezomib for the treatment of mantle cell lymphoma

INTRODUCTION

Mantle cell lymphoma (MCL) is an incurable, often aggressive B-cell malignancy. Bortezomib (BTZ), the 20S proteasome inhibitor was originally developed and approved for treatment of relapsed refractory multiple myeloma, and subsequently approved for treatment of MCL. BTZ's single-agent activity induces clinical responses in approximately one-third of relapsed MCL patients. BTZ-containing combination therapies have further improved the quality and duration of clinical responses compared to standard chemotherapies in previously untreated MCL patients. Areas covered: This review summarizes the discovery, mechanisms of -action and resistance, preclinical- clinical-developments, and FDA approval of BTZ for treatments of MCL. Expert opinion: Preclinical MCL models demonstrated the apoptotic effect of BTZ through multiple mechanisms, as well as synergistic anti-MCL activity between BTZ and other chemotherapeutics. Single-agent and combinational clinical trials have validated the therapeutic potential of targeting the ubiquitin proteasome system (UPS) in MCL. However, inherent and acquired drug resistance remains a significant clinical problem and multiple potential mechanisms have been identified. Next-generation proteasome inhibitors with different pharmacodynamic properties from BTZ may partially address the issue of inherent resistance, with increased response rates noted in some diseases. In addition, upstream UPS components, e.g., E3 ligases or deubiquitinating enzymes, may also be targetable in MCL.

Bortezomib for the treatment of mantle cell lymphoma: an update

Bortezomib is a first in class proteasome inhibitor, initially approved by the US Food and Drug Administration for the treatment of plasma cell myeloma. Bortezomib has been approved for the treatment of relapsed and refractory mantle cell lymphoma (MCL) and, more recently, in the upfront setting as well. Treatment algorithms for MCL have rapidly evolved over the past two decades, and the optimal regimen remains to be defined. The choice of treatment regimen is based on disease risk stratification models, the expected toxicity of antineoplastic agents, the perceived patient ability to tolerate the planned treatments and the availability of novel agents. As new drugs with novel mechanisms of action and variable toxicity profiles come into use, treatment decisions for a given patient have become increasingly complex. This article provides an overview of the evolving use of bortezomib in the rapidly changing management landscape of MCL.

The role of targeted treatment in mantle cell lymphoma: is transplant dead or alive?

Based on the profound biological insights of the last years into the molecular pathogenesis of mantle cell lymphoma and the clinical introduction of new targeted drugs, with high efficacy and a good safety profile, the therapeutic scenario for this tumor has been shown to be thoroughly favourable. No longer characterized by a uniformly dismal prognosis, mantle cell lymphoma has been revealed as a spectrum of different diseases, ranging from very indolent cases to highly aggressive and refractory ones. Thus, there is an urgent need to adapt therapy to accommodate the diverse presentations of the disease. High-dose chemotherapy, followed by autologous stem cell transplantation is the current standard of care for younger patients, generally providing high responses and long survival rates, but hampered by acute and long-term toxicity. In addition, some patients may be overtreated, while others could benefit from targeted approaches, based on the new, molecular-directed compounds. Such a personalized treatment based on the specific characteristics of individual patients may be guided by validated prognostic tools, such as the Mantle Cell Lymphoma International Prognostic Index and the Ki-67 Proliferative Index, as well as by early predictors of treatment response, like minimal residual disease analysis. Moreover, mutation screening of distinctive genomic alterations may provide new, predictive biomarkers, with an additional impact on clinical practice. Only after tailoring treatment according to the clinical and biological heterogeneity of the disease the role of transplantation and modern therapeutic options will be redefined in mantle cell lymphoma.

Mantle cell lymphoma: biology, clinical presentation, and therapeutic approaches

Mantle cell lymphoma is molecularly characterized by the chromosomal translocation t(11;14) (q13;q32) that results in a constitutional overexpression of the cell cycle regulator protein cyclin D1. Generally, the disease is characterized by rapid relapses and poor long-term outcome. However, a subset of patients with indolent disease has been identified. Randomized trials have demonstrated the superiority of dose intensified, cytarabine-containing induction with or without autologous stem cell transplantation in younger patients. In elderly patients, a rituximab-based maintenance has significantly prolonged progression-free and overall survival after treatment with rituximab, cyclophosphamide, doxorubicin hydrochloride, vincristine, and prednisone (R-CHOP). Unfortunately, the vast majority of patients will eventually relapse. Numerous molecular targeting strategies (bortezomib, lenalidomide, temsirolimus, and especially inhibitors of the B-cell receptor pathway) have achieved high response rates in phase II studies and should be strongly considered in relapsed disease.

Bortezomib in the treatment of mantle cell lymphoma

Mantle cell lymphoma (MCL) is a hematological malignancy with unfavorable prognosis. Bortezomib, a potent, selective and reversible inhibitor of the 26S proteasome, was shown to be active in MCL and is currently implemented in therapeutic combinations. Single-agent bortezomib has demonstrated clinical efficacy in relapsed and refractory MCL with objective response in up to 47% of the patients. However, complete remission rates are low and duration of response is relatively short. In previously untreated patients, the addition of bortezomib to induction chemotherapy is also promising. Further evaluation of bortezomib alone or in combination with other drugs for the treatment of MCL is warranted to improve the quality of life and survival of patients. This review explores bortezomib as therapy in patients with MCL.

Mantle cell lymphoma: evolving management strategies

Mantle cell lymphoma (MCL) is a rare and aggressive form of non-Hodgkin's lymphoma that generally affects older individuals and continues to have one of the worst outcomes of all the lymphomas. Over the last decade, there has been a widespread adoption of cytarabine-based therapy in younger patients, and the incorporation of rituximab into chemotherapeutic regimens has become an evidence-based standard of care. However MCL remains a largely incurable disease, and following relapse, it can be a challenge to manage. Although it is possible to define prognosis reliably, there are, as yet, no clear diagnostic or response-adjusted parameters that can help to guide therapeutic decisions. However, there are a number of highly active targeted therapies that are moving into the clinic that are set to transform the therapeutic paradigm for this disease in the very near future. This review will explore the molecular pathogenesis of MCL and the current and evolving therapeutic strategies for this disease.

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.

Management of mantle cell lymphoma in the elderly patient

Mantle cell lymphoma is a relatively rare B-cell lymphoma with a specific genetic lesion and a typical immunophenotypic profile. The median age is 65 years. There is no curative treatment, except allogeneic stem cell transplantation for a selected group of patients. For the majority of patients, especially the elderly, the aim of therapy should therefore be a long progression-free survival. Age and comorbidity may hamper the use of the most active treatment regimen, such as high dose cytarabine and autologous stem cell transplantation. Therefore, it is a challenge to select the most appropriate therapy for an elderly patient. Studies specifically designed for elderly patients are rare. A recently performed large randomized study for elderly patients, however, has shown that R-CHOP (rituximab with cyclophosphamide, doxorubicin, vincristine, and prednisone) chemotherapy followed by maintenance rituximab can result in a long progression-free survival. For patients too frail for R-CHOP chemotherapy, a treatment should be offered that benefits the patient in reducing the symptoms of the disease without causing too many side effects. Progression or relapse will occur in all patients sooner or later. Second-line treatment should again be carefully selected. Several options are mentioned. New drugs are being developed, and new combinations are investigated. Further improvement in the outcome of patients with mantle cell lymphoma is expected. Participation in well-designed clinical trials, also by elderly patients, is important to find the real benefit that can be achieved, and to get information on the tolerability of these treatments in this age group.

ESMO Consensus conferences: guidelines on malignant lymphoma. part 2: marginal zone lymphoma, mantle cell lymphoma, peripheral T-cell lymphoma

To complement the existing treatment guidelines for all tumour types, ESMO organizes consensus conferences to focus on specific issues in each type of tumour. In this setting, a consensus conference on the management of lymphoma was held on 18 June 2011 in Lugano, next to the 11th International Conference on Malignant Lymphoma. The conference convened ∼30 experts from all around Europe, and selected six lymphoma entities to be addressed; for each of them, three to five open questions were to be addressed by the experts. For each question, a recommendation should be given by the panel, referring to the strength of the recommendation based on the level of evidence. This consensus report focuses on the three less common lymphoproliferative malignancies: marginal zone lymphoma, mantle cell lymphoma, and peripheral T-cell lymphomas. A first report had focused on diffuse large B-cell lymphoma, follicular lymphoma, and chronic lymphocytic leukaemia.

Bortezomib added to daunorubicin and cytarabine during induction therapy and to intermediate-dose cytarabine for consolidation in patients with previously untreated acute myeloid leukemia age 60 to 75 years: CALGB (Alliance) study 10502

PURPOSE

The purpose of this study was to determine remission induction frequency when bortezomib was combined with daunorubicin and cytarabine in previously untreated older adults with acute myeloid leukemia (AML) and safety of bortezomib in combination with consolidation chemotherapy consisting of intermediate-dose cytarabine (Int-DAC).

PATIENTS AND METHODS

Ninety-five adults (age 60 to 75 years; median, 67 years) with previously untreated AML (including therapy-related and previous myelodysplastic syndrome) received bortezomib 1.3 mg/m(2) intravenously (IV) on days 1, 4, 8, and 11 with daunorubicin 60 mg/m(2) on days 1 through 3 and cytarabine 100 mg/m(2) by continuous IV infusion on days 1 through 7. Patients who achieved complete remission (CR) received up to two courses of consolidation chemotherapy with cytarabine 2 gm/m(2) on days 1 through 5 with bortezomib. Three cohorts with escalating dose levels of bortezomib were tested (0.7, 1.0, and 1.3 mg/m(2)). Dose-limiting toxicities were assessed during the first cycle of consolidation. The relationship between cell surface expression of CD74 and clinical outcome was assessed.

RESULTS

Frequency of CR was 65% (62 of 95), and 4% of patients (four of 95) achieved CR with incomplete platelet recovery (CRp). Eleven patients developed grade 3 sensory neuropathy. Bortezomib plus Int-DAC proved tolerable at the highest dose tested. Lower CD74 expression was associated with CR/CRp (P = .04) but not with disease-free or overall survival.

CONCLUSION

The addition of bortezomib to standard 3 + 7 daunorubicin and cytarabine induction chemotherapy for AML resulted in an encouraging remission rate. The maximum tested dose of bortezomib administered in combination with Int-DAC for remission consolidation was 1.3 mg/m(2) and proved tolerable. Further testing of this regimen is planned.

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).

Current treatment of mantle cell lymphoma: results of a national survey and consensus meeting

In most patients, mantle cell lymphoma (MCL) shows an aggressive clinical course with a continuous relapse pattern and a median survival of only 3-5 years. In the current study generation of the European MCL Network, the addition of high-dose Ara-C to R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone)-like regimen followed by myeloablative consolidation achieved a significant improvement of progression-free survival in younger patients. In elderly patients, rituximab maintenance led to a marked prolongation of remission duration. Emerging strategies include mammalian target of rapamycin (mTOR) inhibitors, proteasome inhibitors, immune modulatory drugs, Bruton's tyrosine kinase inhibitors and others, all based on the dysregulated control of cell cycle machinery and impairment of several apoptotic pathways. Combination strategies are currently being investigated in numerous trials, but their introduction into clinical practice and current treatment algorithms remains a challenge. In the current survey, the application of the molecular targeted compounds were collected and evaluated by a representative national network of 14 haematological institutions. Optimised strategies are recommended for clinical routine. Future studies will apply individualised approaches according to the molecular risk profile of the patient.

Treatment of older patients with mantle-cell lymphoma

BACKGROUND

The long-term prognosis for older patients with mantle-cell lymphoma is poor. Chemoimmunotherapy results in low rates of complete remission, and most patients have a relapse. We investigated whether a fludarabine-containing induction regimen improved the complete-remission rate and whether maintenance therapy with rituximab prolonged remission.

METHODS

We randomly assigned patients 60 years of age or older with mantle-cell lymphoma, stage II to IV, who were not eligible for high-dose therapy to six cycles of rituximab, fludarabine, and cyclophosphamide (R-FC) every 28 days or to eight cycles of rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) every 21 days. Patients who had a response underwent a second randomization to maintenance therapy with rituximab or interferon alfa, each given until progression.

RESULTS

Of the 560 patients enrolled, 532 were included in the intention-to-treat analysis for response, and 485 in the primary analysis for response. The median age was 70 years. Although complete-remission rates were similar with R-FC and R-CHOP (40% and 34%, respectively; P=0.10), progressive disease was more frequent with R-FC (14%, vs. 5% with R-CHOP). Overall survival was significantly shorter with R-FC than with R-CHOP (4-year survival rate, 47% vs. 62%; P=0.005), and more patients in the R-FC group died during the first remission (10% vs. 4%). Hematologic toxic effects occurred more frequently in the R-FC group than in the R-CHOP group, but the frequency of grade 3 or 4 infections was balanced (17% and 14%, respectively). In 274 of the 316 patients who were randomly assigned to maintenance therapy, rituximab reduced the risk of progression or death by 45% (in remission after 4 years, 58%, vs. 29% with interferon alfa; hazard ratio for progression or death, 0.55; 95% confidence interval, 0.36 to 0.87; P=0.01). Among patients who had a response to R-CHOP, maintenance therapy with rituximab significantly improved overall survival (4-year survival rate, 87%, vs. 63% with interferon alfa; P=0.005).

CONCLUSIONS

R-CHOP induction followed by maintenance therapy with rituximab is effective for older patients with mantle-cell lymphoma. (Funded by the European Commission and others; ClinicalTrials.gov number, NCT00209209.).

Proteasome inhibitors in mantle cell lymphoma

Mantle cell lymphoma (MCL) represents a subtype of non-Hodgkin's lymphoma (NHL) which has a relatively poor prognosis compared to other forms of NHL. Despite multiple options for cytotoxic chemotherapy, attempts to prolong the survival of patients with this disease have not yet met with success. Consequently, the development of targeted approaches to therapy which minimize toxicities has potentially important implications for MCL. Proteasome inhibitors preferentially kill transformed cells through diverse mechanisms. The proteasome inhibitor bortezomib was initially approved for patients with relapsed or refractory multiple myeloma and now has been approved for relapsed or refractory MCL. The introduction of newer proteasome inhibitors with activity in bortezomib-resistant disease and reduced toxicity profiles may yield further benefits. Multiple ongoing studies are building on the known efficacy of proteasome inhibitors in MCL by evaluating combination regimens involving either cytotoxic or targeted therapies, with the ultimate goal of prolonging survival in this patient population.

Proteasome inhibition and combination therapy for non-Hodgkin's lymphoma: from bench to bedside

Although patients with B-cell non-Hodgkin's lymphoma (NHL) usually respond to initial conventional chemotherapy, they often relapse and mortality has continued to increase over the last three decades in spite of salvage therapy or high dose therapy and stem cell transplantation. Outcomes vary by subtype, but there continues to be a need for novel options that can help overcome chemotherapy resistance, offer new options as consolidation or maintenance therapy postinduction, and offer potentially less toxic combinations, especially in the elderly population. The bulk of these emerging novel agents for cancer treatment target important biological cellular processes. Bortezomib is the first in the class of proteasome inhibitors (PIs), which target the critical process of intracellular protein degradation or recycling and editing through the proteasome. Bortezomib is approved for the treatment of relapsed or refractory mantle cell lymphoma. The mechanisms of proteasome inhibition are very complex by nature (because they affect many pathways) and not fully understood. However, mechanisms of action shared by bortezomib and investigational PIs such as carfilzomib, marizomib, ONX-0912, and MLN9708 are distinct from those of other NHL treatments, making them attractive options for combination therapy. Preclinical evidence suggests that the PIs have additive and/or synergistic activity with a large number of agents both in vitro and in vivo, from cytotoxics to new biologicals, supporting a growing number of combination studies currently underway in NHL patients, as reviewed in this article. The results of these studies will help our understanding about how to best integrate proteasome inhibition in the management of NHL and continue to improve patient outcomes.

The proteasome inhibitor bortezomib targets cell cycle and apoptosis and acts synergistically in a sequence-dependent way with chemotherapeutic agents in mantle cell lymphoma

Single-agent bortezomib, a potent, selective, and reversible inhibitor of the 26S proteasome, has demonstrated clinical efficacy in relapsed and refractory mantle cell lymphoma (MCL). Objective response is achieved in up to 45% of the MCL patients; however, complete remission rates are low and duration of response proved to be relatively short. These limitations may be overcome by combining proteasome inhibition with conventional chemotherapy. Rational combination treatment and schedules require profound knowledge of underlying molecular mechanisms. Here we show that single-agent bortezomib treatment of MCL cell lines leads to G2/M arrest and induction of apoptosis accompanied by downregulation of EIF4E and CCND1 mRNA but upregulation of p15(INK4B) and p21 mRNA. We further present synergistic efficacy of bortezomib combined with cytarabine in MCL cell lines. Interestingly this sequence-dependent synergistic effect was seen almost exclusively in combination with AraC, indicating that pretreatment with cytarabine, followed by proteasome inhibition, may be the preferred approach.

A phase II study of bortezomib and gemcitabine in relapsed mantle cell lymphoma from the National Cancer Institute of Canada Clinical Trials Group (IND 172)

Bortezomib and gemcitabine have each shown activity as single agents in mantle cell lymphoma (MCL), which is incurable. The purpose of this phase II study was to determine the efficacy and safety of the previously unstudied combination of bortezomib and gemcitabine in patients with relapsed or refractory MCL. Patients were eligible if they had relapsed MCL with 1-3 prior therapies. Patients were treated with gemcitabine 1000 mg/m(2) on days 1 and 8 and bortezomib 1.0 mg/m(2) IV on days 1, 4, 8, and 11, on a 21-day schedule. Twenty-six patients were evaluable for toxicity and 25 for response. The overall response rate was 60% and the median progression free survival was 11.4 months. The main adverse effects were hematological, with 40% and 48% of patients experiencing grade 3/4 thrombocytopenia and granulocytopenia, respectively. Bortezomib and gemcitabine is an active combination in relapsed and refractory MCL with clinically meaningful results. It offers a chemotherapy backbone to which other agents, less myelosuppressive, may be added.

Mantle cell lymphoma

MCL is a well-characterized clinically aggressive lymphoma with a poor prognosis. Recent research findings have slightly improved the outcome of this neoplasm. The addition of rituximab to conventional chemotherapy has increased overall response rates, but it does not improve overall survival with respect to chemotherapy alone. The use of intensive frontline therapies including rituximab and consolidated by ASCT ameliorates response rate and prolongs progression-free survival, but any impact on survival remains to be proven. Furthermore, the optimal timing, cytoreductive regimen and conditioning regimen, and the clinical implications of achieving a disease remission even at molecular level remain to be elucidated. The development of targeted therapies as the consequence of better dissection of pathogenetic pathways in MCL might improve the outcome of conventional chemotherapy in most patients and spare the toxicity of intense therapy in a minority of MCL patients characterized by a relatively indolent disease. Patients not eligible for intensive regimens, such as hyperC-VAD, may be considered for less demanding therapies, such as the combination of rituximab either with CHOP or with purine analogues, or bendamustine. Allogeneic SCT can be an effective option for relapsed disease in patients who are fit enough and have a compatible donor. Maintenance rituximab may be considered after response to immunochemotherapy for relapsed disease, although there are currently no data to recommend this approach as the first-line strategy. As the optimal approach to the management of MCL is still evolving, it is critical that these patients be enrolled in clinical trials to identify better treatment options.

Bortezomib combined with rituximab and dexamethasone is an active regimen for patients with relapsed and chemotherapy-refractory mantle cell lymphoma

BACKGROUND

Bortezomib belongs to a new class of anti-cancer agents, the proteasome inhibitors, and has documented activity in multiple myeloma and mantle cell lymphoma. Preclinical studies suggest that bortezomib has synergistic activity with rituximab, which provides a rationale for the exploration of treatment combinations.

DESIGN AND METHODS

The activity and safety of bortezomib in combination with rituximab and dexamethasone were investigated in patients with relapsed or chemotherapy-refractory mantle cell lymphoma. A treatment cycle consisted of bortezomib (1.3 mg/m² on days 1, 4, 8, and 11; six 21-day cycles), rituximab (375 mg/m², day 1) and dexamethasone (40 mg orally, days 1 to 4). Responding patients received four consolidating doses of rituximab. Sixteen patients with progressive mantle cell lymphoma after a median of three prior lines of therapy were enrolled.

RESULTS

The overall response rate was 81.3% (13 patients), with seven patients achieving a complete response (43.8%). Six of these patients were also negative for disease activity by positron emission tomography scanning. The median progression-free survival and overall survival were 12.1 and 38.6 months, respectively. In patients achieving a complete response, the median progression-free survival and overall survival have not yet been reached. Adverse events (greater than grade II) included thrombocytopenia (37.5%), fatigue (18.8%) and peripheral neuropathy (12.5%). Two patients discontinued bortezomib because of grade III neuropathy.

CONCLUSIONS

Bortezomib combined with rituximab and dexamethasone has promising activity and manageable toxicity in patients with heavily pretreated mantle cell lymphoma. Achievement of complete response emerged as an important factor for sustained disease control. This trial was registered at www.clinicaltrials.gov as #NCT00261612.

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.

Phase I trial of bortezomib in combination with rituximab-HyperCVAD alternating with rituximab, methotrexate and cytarabine for untreated aggressive mantle cell lymphoma

Mantle cell lymphoma (MCL) outcomes have improved over the last two decades; however, late relapses occur. Bortezomib has shown single agent activity of 33% in relapsed MCL and has an additive/synergistic effect in vitro when combined with drugs currently used to treat MCL. We hypothesized that a combination of bortezomib with current intense non-transplant chemoimmunotherapy might prevent late relapses. The toxicity of bortezomib when combined with methotrexate and cytarabine is unknown. Patients aged 18-79 years with untreated aggressive MCL were treated with R-HyperCVAD (rituximab, cyclophosphamide, vincristine, doxorubicin, dexamethasone) alternating with rituximab-methotrexate/cytarabine (R-M/A). Bortezomib was added to the R-Hyper-CVAD combination as a fixed dose of 1·3 mg/m(2) IV on days 2 and 5 and was added to the R-M/A regimen after rituximab, in increasing doses of 0·7, 1, and 1·3 mg/m(2) in cohorts of three patients. Twenty patients were assessed for toxicity of the regimen. The principal toxicity was haematological and did not differ from that observed with a similar regimen without the bortezomib. In particular, there was no pulmonary or neurological dose-limiting toxicity, showing that bortezomib can be safely combined with R-HyperCVAD and R-M/A.

Mantle cell lymphoma: state-of-the-art management and future perspective

Mantle cell lymphoma (MCL) is a unique subtype of B-cell non-Hodgkin lymphomas (NHL) characterized in almost all cases by the chromosomal translocation t(11;14)(q13;q32) and nuclear cyclin D1 overexpression. Most patients present with advanced stage disease, often with extranodal dissemination, and typically pursue an aggressive clinical course. Recent improvement has been achieved by the successful introduction of monoclonal antibodies and dose-intensified approaches including autologous stem cell transplantation strategies. However, with the exception of allogeneic hematopoietic stem cell transplantation, current treatment approaches are not curative and the corresponding survival curve is characterized by a relatively steep and continuous decline, with a median survival of about 4 years and <15% long-term survivors. Despite its rarity, MCL is of particular clinical and scientific interest by providing a paradigm for neoplasms with dysregulated control of cell cycle machinery and impaired apoptotic pathways. Recently gained insights into underlying pathobiology unravel numerous promising molecular targeting strategies, however their introduction into clinical practice and current treatment algorithms remains a challenge. This article will provide relevant information for decision making in clinical practice and give a perspective on upcoming management strategies.

Current treatment standards and emerging strategies in mantle cell lymphoma

Mantle cell lymphoma (MCL) is a unique subtype of B-cell non-Hodgkin lymphomas characterized by the chromosomal translocation t(11;14)(q13;q32) and nuclear cyclin D1 overexpression in the vast majority of cases. Most patients present with advanced stage disease, often with extranodal dissemination, and pursue an aggressive clinical course in the majority of cases. Recent improvement has been achieved by the successful introduction of monoclonal antibodies and dose-intensified approaches including autologous stem cell transplantation (ASCT) strategies. With the exception of allogeneic hematopoietic stem cell transplantation, current treatment approaches are non-curative and the corresponding survival curves are characterized by a delayed, but continuous decline and a median survival of 4 to 6 years. However, recently a subset (15%) of long-term survivors have been identified with a rather indolent clinical course even after conventional treatment strategies only. Emerging strategies such as proteasome inhibitors, IMIDs, mTOR inhibitors and others are based on the dysregulated control of cell cycle machinery and impaired apoptotic pathways. Monotherapy of these compounds achieves efficacy comparable to conventional chemotherapy in relapsed MCL, and combination strategies are currently being investigated in numerous trials; however, their introduction into clinical practice and current treatment algorithms remains a challenge.