Combination bortezomib and rituximab treatment affects multiple survival and death pathways to promote apoptosis in mantle cell lymphoma

GSK-J4 Inhibition of KDM6B Histone Demethylase Blocks Adhesion of Mantle Cell Lymphoma Cells to Stromal Cells by Modulating NF-κB Signaling

Multiple signaling pathways facilitate the survival and drug resistance of malignant B-cells by regulating their migration and adhesion to microenvironmental niches. NF-κB pathways are commonly dysregulated in mantle cell lymphoma (MCL), but the exact underlying mechanisms are not well understood. Here, using a co-culture model system, we show that the adhesion of MCL cells to stromal cells is associated with elevated levels of KDM6B histone demethylase mRNA in adherent cells. The inhibition of KDM6B activity, using either a selective inhibitor (GSK-J4) or siRNA-mediated knockdown, reduces MCL adhesion to stromal cells. We showed that KDM6B is required both for the removal of repressive chromatin marks (H3K27me3) at the promoter region of NF-κB encoding genes and for inducing the expression of NF-κB genes in adherent MCL cells. GSK-J4 reduced protein levels of the RELA NF-κB subunit and impaired its nuclear localization. We further demonstrated that some adhesion-induced target genes require both induced NF-κB and KDM6B activity for their induction (e.g., IL-10 cytokine gene), while others require induction of NF-κB but not KDM6B (e.g., CCR7 chemokine gene). In conclusion, KDM6B induces the NF-κB pathway at different levels in MCL, thereby facilitating MCL cell adhesion, survival, and drug resistance. KDM6B represents a novel potential therapeutic target for MCL.

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

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

NF-κB signaling promotes castration-resistant prostate cancer initiation and progression

Prostate Cancer (PCa) is the second leading cause of cancer-related death in men. Adenocarcinoma of the prostate is primarily composed of Androgen Receptor-positive (AR⁺) luminal cells that require AR transcriptional activity for survival and proliferation. As a consequence, androgen deprivation and anti-androgens are used to treat PCa patients whose disease progresses following attempted surgical or radiation interventions. Unfortunately, patients with advanced PCa can develop incurable castration-resistant PCa (CRPCa) due to mutated, variant, or overexpressed AR. Conversely, low or no AR accumulation or activity can also underlie castration resistance. Whether CRPCa is due to aberrant AR activity or AR independence, NF-κB signaling is also implicated in the initiation and maintenance of CRPCa and, thus, the NF-κB pathway may be a promising alternative therapeutic target. In this review, we present evidence that NF-κB signaling promotes CRPCa initiation and progression, describe the dichotomic role of NF-κB in the regulation of AR expression and activity and outline studies that explore NF-κB inhibitors as PCa therapies.

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 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.

Proteasome Inhibitors in Waldenström Macroglobulinemia

Waldenström macroglobulinemia (WM) remains an incurable B-cell lymphoproliferative disorder, yet therapy is only considered for patients with symptomatic disease. Primary therapy options for WM include combinations based on anti-CD20 monoclonal antibodies, mainly rituximab. However, proteasome inhibitors have become an important part of WM therapy both as primary therapy and as salvage option. Bortezomib is the proteasome inhibitor most studied and with extensive clinical experience, but new proteasome inhibitors (carfilzomib, ixazomib, oprozomib), with different toxicity profiles, routes of administration, and probably with preserved or improved activity, have become available and may also find their way into WM therapy.

Targeting IκappaB kinases for cancer therapy

The inhibitory kappa B kinases (IKKs) and IKK related kinases are crucial regulators of the pro-inflammatory transcription factor, nuclear factor kappa B (NF-κB). The dysregulation in the activities of these kinases has been reported in several cancer types. These kinases are known to regulate survival, proliferation, invasion, angiogenesis, and metastasis of cancer cells. Thus, IKK and IKK related kinases have emerged as an attractive target for the development of cancer therapeutics. Several IKK inhibitors have been developed, few of which have advanced to the clinic. These inhibitors target IKK either directly or indirectly by modulating the activities of other signaling molecules. Some inhibitors suppress IKK activity by disrupting the protein-protein interaction in the IKK complex. The inhibition of IKK has also been shown to enhance the efficacy of conventional chemotherapeutic agents. Because IKK and NF-κB are the key components of innate immunity, suppressing IKK is associated with the risk of immune suppression. Furthermore, IKK inhibitors may hit other signaling molecules and thus may produce off-target effects. Recent studies suggest that multiple cytoplasmic and nuclear proteins distinct from NF-κB and inhibitory κB are also substrates of IKK. In this review, we discuss the utility of IKK inhibitors for cancer therapy. The limitations associated with the intervention of IKK are also discussed.

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 in mantle cell lymphoma: comparative therapeutic outcomes

Mantle cell lymphoma (MCL) is an incurable, typically aggressive subtype of non-Hodgkin lymphoma, accounting for 4%–7% of newly diagnosed non-Hodgkin lymphoma cases. Chemoresistance commonly ensues in MCL, and patients with this heterogeneous disease invariably relapse, underscoring the unmet need for better therapies. Over the past few years, several novel agents with promising activity and unique mechanisms of action have been deemed effective in MCL. Bortezomib is a reversible proteasome inhibitor, approved as a single agent for patients with relapsed/refractory MCL who have received at least one prior line of therapy. Addition of bortezomib to chemoimmunotherapies has demonstrated good tolerability and superior efficacy, both in the upfront and salvage settings, and recently one such combination of bortezomib plus rituximab, cyclophosphamide, doxorubicin, and prednisone was approved as a frontline regimen in untreated patients with MCL. This review examines the role of bortezomib in a multitude of clinical settings and ongoing clinical trials designed to optimize its integration in the current treatment paradigms of MCL.

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.

Roles of F-box proteins in human digestive system tumors (Review)

F-box proteins (FBPs), the substrate-recognition subunit of E3 ubiquitin (Ub) ligase, are the important components of Ub proteasome system (UPS). FBPs are involved in multiple cellular processes through ubiquitylation and subsequent degradation of their target proteins. Many studies have described the roles of FBPs in human cancers. Digestive system tumors account for a large proportion of all the tumors, and their mortality is very high. This review summarizes for the first time the roles of FBPs in digestive system tumorige-nesis and tumor progression, aiming at finding new routes for the rational design of targeted anticancer therapies in digestive system tumors.

Genetic validation of the protein arginine methyltransferase PRMT5 as a candidate therapeutic target in glioblastoma

Glioblastoma is the most common and aggressive histologic subtype of brain cancer with poor outcomes and limited treatment options. Here, we report the selective overexpression of the protein arginine methyltransferase PRMT5 as a novel candidate theranostic target in this disease. PRMT5 silences the transcription of regulatory genes by catalyzing symmetric dimethylation of arginine residues on histone tails. PRMT5 overexpression in patient-derived primary tumors and cell lines correlated with cell line growth rate and inversely with overall patient survival. Genetic attenuation of PRMT5 led to cell-cycle arrest, apoptosis, and loss of cell migratory activity. Cell death was p53-independent but caspase-dependent and enhanced with temozolomide, a chemotherapeutic agent used as a present standard of care. Global gene profiling and chromatin immunoprecipitation identified the tumor suppressor ST7 as a key gene silenced by PRMT5. Diminished ST7 expression was associated with reduced patient survival. PRMT5 attenuation limited PRMT5 recruitment to the ST7 promoter, led to restored expression of ST7 and cell growth inhibition. Finally, PRMT5 attenuation enhanced glioblastoma cell survival in a mouse xenograft model of aggressive glioblastoma. Together, our findings defined PRMT5 as a candidate prognostic factor and therapeutic target in glioblastoma, offering a preclinical justification for targeting PRMT5-driven oncogenic pathways in this deadly disease.

Primary therapy of Waldenstrom macroglobulinemia (WM) with weekly bortezomib, low-dose dexamethasone, and rituximab (BDR): long-term results of a phase 2 study of the European Myeloma Network (EMN)

In this phase 2 multicenter trial, we evaluated the activity of bortezomib, dexamethasone, and rituximab (BDR) combination in previously untreated symptomatic patients with Waldenström macroglobulinemia (WM). To prevent immunoglobulin M (IgM) "flare," single agent bortezomib (1.3 mg/m(2) IV days 1, 4, 8, and 11; 21-day cycle), was followed by weekly IV bortezomib (1.6 mg/m(2) days 1, 8, 15, and 22) every 35 days for 4 additional cycles, followed by IV dexamethasone (40 mg) and IV rituximab (375 mg/m(2)) in cycles 2 and 5. Fifty-nine patients were treated; 45.5% and 40% were high and intermediate risk per the International Prognostic Scoring System for WM. On intent to treat, 85% responded (3% complete response, 7% very good partial response, 58% partial response [PR]). In 11% of patients, an increase of IgM ≥25% was observed after rituximab; no patient required plasmapheresis. After a minimum follow-up of 32 months, median progression-free survival was 42 months, 3-year duration of response for patients with ≥PR was 70%, and 3-year survival was 81%. Peripheral neuropathy occurred in 46% (grade ≥3 in 7%); only 8% discontinued bortezomib due to neuropathy. BDR is rapidly acting, well tolerated, and nonmyelotoxic, inducing durable responses in previously untreated WM.

Combined administration of rituximab and on 013105 induces apoptosis in mantle cell lymphoma cells and reduces tumor burden in a mouse model of mantle cell lymphoma

PURPOSE

Mantle cell lymphoma (MCL) is an incurable B-cell lymphoma, and new therapeutic strategies are urgently needed.

EXPERIMENTAL DESIGN

The effects of ON 013105, a novel benzylstyryl sulfone kinase inhibitor, alone or with doxorubicin or rituximab, were examined in Granta 519 and Z138C cells. For in vivo studies, CB17/SCID mice were implanted subcutaneously with Z138C cells and treated with various combinations of ON 013105, doxorubicin, and rituximab. Tumor burden and body weight were monitored for 28 days.

RESULTS

ON 013105 induced mitochondria-mediated apoptosis in MCL cells. Death was preceded by translocation of tBid to the mitochondria and cytochrome c release. In addition, ON 013105-treated cells exhibited reduced levels of cyclin D1, c-Myc, Mcl-1, and Bcl-xL. Using nuclear magnetic resonance (NMR) spectroscopy, we showed specific binding of ON 013105 to eIF4E, a critical factor for the initiation of protein translation. We proffer that this drug-protein interaction preferentially prevents the translation of the aforementioned proteins and may be the mechanism by which ON 013105 induces apoptosis in MCL cells. Efficacy studies in a mouse xenograft model showed that ON 013105 inhibited MCL tumor growth and that combining ON 013105 with rituximab reduced tumor burden further with negligible unwanted effects.

CONCLUSIONS

Our findings suggest that ON 013105, alone or in combination with rituximab, may be a potent therapeutic agent to treat MCLs.

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.

Inhibitory kappa B Kinases as targets for pharmacological regulation

The inhibitory kappa B kinases (IKKs) are well recognized as key regulators of the nuclear factor kappa B (NF-κB) cascade and as such represent a point of convergence for many extracellular agents that activate this pathway. The IKKs generally serve to transduce pro-inflammatory and growth stimulating signals that contribute to major cellular processes but also play a key role in the pathogenesis of a number of human diseases. Therefore, the catalytic IKKs represent attractive targets for intervention with small molecule kinase inhibitors. IKK isoforms are assembled as variable multi-subunit IKK complexes that regulate not only NF-κB dimers, but also protein substrates out-with this cascade. Consequently, close consideration of how these individual complexes transduce extracellular signals and more importantly what impact small molecule inhibitors of the IKKs have on functional outcomes are demanded. A number of adenosine triphosphate (ATP)-competitive IKKβ-selective inhibitors have been developed but have demonstrated a lack of activity against IKKα. A number of these chemicals have also exhibited detrimental outcomes such as cellular toxicity and immuno-suppression. The impact of small molecule inhibitors of IKK catalytic activity will therefore be reappraised, examining the advantages and potential disadvantages to this type of intervention strategy in the treatment of diseases such as arthritis, intestinal inflammation and cancer. Furthermore, we will outline some emerging strategies, particularly the disruption of protein-protein interactions within the IKK complex, as an alternative route towards the development of novel pharmacological agents. Whether these alternatives may negate the limitations of ATP-competitive molecules and potentially avoid the issues of toxicity will be discussed.

Update on treatment of follicular non-Hodgkin's lymphoma: focus on potential of bortezomib

Follicular lymphoma is predominantly managed as a chronic disease, with intermittent chemo/immunotherapy reserved for symptomatic progression. It is considered incurable with conventional treatments, and current therapeutic options are associated with significant toxicities that are especially limiting in older patients. Bortezomib (PS-341; Velcade(®)), a first-in-class drug targeting the proteolytic core subunit of the 26S proteasome, has emerged as a therapeutic alternative in follicular lymphoma, with promising preclinical data and efficacy in patients with other hematological malignancies. Several clinical trials were conducted with bortezomib for the treatment of non-Hodgkin's lymphoma. As a single agent, overall responses in follicular lymphoma varied greatly (16%-41%), with weekly bortezomib showing less neurotoxicity than twice-weekly regimens, but with concern about decreased responses. Combination with rituximab was projected to improve the efficacy of bortezomib, but this resulted in increased toxicities and questionable added benefit. Although the largest Phase III study in follicular lymphoma of bortezomib plus rituximab versus rituximab alone demonstrated a significant progression-free survival difference, the absolute difference was small (12.8 months versus 11 months). Combining bortezomib with established regimens, such as rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP), rituximab, cyclophosphamide, vincristine, and prednisone (R-CVP), or rituximab-bendamustine also did not show definite benefit, and many of these studies did not meet their primary endpoint when bortezomib failed to improve responses or survival to the degree anticipated. In a disease where the goal of treatment is palliative and affected patients often have other medical and treatment-related comorbidities, decisions regarding therapies which carry risks of additional toxicities must be considered carefully. Conclusive evidence of the ability of bortezomib to improve patient outcomes meaningfully and to justify the added toxicity is lacking, but limitations in cross-trial comparisons are recognized. Large randomized trials and investigations of combinations with promising novel targeted agents will aid in determining the role of bortezomib, if any, in the future treatment of follicular lymphoma.

FTY720 increases CD74 expression and sensitizes mantle cell lymphoma cells to milatuzumab-mediated cell death

Mantle cell lymphoma (MCL) is an aggressive B-cell malignancy with a short median survival despite multimodal therapy. FTY720, an immunosuppressive drug approved for the treatment of multiple sclerosis, promotes MCL cell death concurrent with down-modulation of phospho-Akt and cyclin D1 and subsequent cell-cycle arrest. However, the mechanism of FTY720-mediated MCL cell death remains to be fully clarified. In the present study, we show features of autophagy blockage by FTY720 treatment, including accumulation of autolysosomes and increased LC3-II and p62 levels. We also show that FTY720-induced cell death is mediated by lysosomal membrane permeabilization with subsequent translocation of lysosomal hydrolases to the cytosol. FTY720-mediated disruption of the autophagic-lysosomal pathway led to increased levels of CD74, a potential therapeutic target in MCL that is degraded in the lysosomal compartment. This finding provided rationale for examining combination therapy with FTY720 and milatuzumab, an anti-CD74 mAb. Treatment of MCL cell lines and primary tumor cells with FTY720 and milatuzumab resulted in statistically significant enhanced cell death, which was synergistic in blastic variant MCL cell lines. Significant in vivo therapeutic activity of combination treatment was also demonstrated in a preclinical, in vivo model of MCL. These findings support clinical evaluation of this combination in patients with MCL.

The HB22.7 Anti-CD22 monoclonal antibody enhances bortezomib-mediated lymphomacidal activity in a sequence dependent manner

Most non-Hodgkin's lymphomas (NHL) initially respond to chemotherapy, but relapse is common and treatment is often limited by chemotherapy-related toxicity. Bortezomib, is a highly selective proteasome inhibitor with anti-NHL activity; it is currently FDA approved for second-line treatment of mantle cell lymphoma (MCL). Bortezomib exerts its activity in part through the generation of reactive oxygen species (ROS) and also by the induction of apoptosis.We previously validated CD22 as a potential target in treating NHL and have shown that the anti-CD22 ligand blocking antibody, HB22.7, has significant independent lymphomacidal properties in NHL xenograft models. We sought to determine whether or not these agents would work synergistically to enhance cytotoxicity. Our results indicate that treatment of NHL cell lines with HB22.7 six hours prior to bortezomib significantly diminished cell viability. These effects were not seen when the agents were administered alone or when bortezomib was administered prior to HB22.7. Additionally, HB22.7 treatment prior to bortezomib increased apoptosis in part through enhanced ROS generation. Finally, in a mouse xenograft model, administration of HB22.7 followed 24 hours later by bortezomib resulted in 23% smaller tumor volumes and 20% enhanced survival compared to treatment with the reverse sequence. Despite the increased efficacy of HB22.7 treatment followed by bortezomib, there was no corresponding decrease in peripheral blood cell counts, indicating no increase in toxicity. Our results suggest that pre-treatment with HB22.7 increases bortezomib cytotoxicity, in part through increased reactive oxygen species and apoptosis, and that this sequential treatment combination has robust efficacy in vivo.

Cancer Tissue Engineering: A Novel 3D Polystyrene Scaffold for In Vitro Isolation and Amplification of Lymphoma Cancer Cells from Heterogeneous Cell Mixtures

Isolation and amplification of primary lymphoma cells in vitro setting is technically and biologically challenging task. To optimize culture environment and mimic in vivo conditions, lymphoma cell lines were used as a test case and were grown in 3-dimension (3D) using a novel 3D tissue culture polystyrene scaffold with neonatal stromal cells to represent a lymphoma microenvironment. In this model, the cell proliferation was enhanced more than 200-fold or 20,000% neoplastic surplus in 7 days when less than 1% lymphoma cells were cocultured with 100-fold excess of neonatal stroma cells, representing 3.2-fold higher proliferative rate than 2D coculture model. The lymphoma cells grew and aggregated to form clusters during 3D coculture and did not maintained the parental phenotype to grow in single-cell suspension. The cluster size was over 5-fold bigger in the 3D coculture by day 4 than 2D coculture system and contained less than 0.00001% of neonatal fibroblast trace. This preliminary data indicate that novel 3D scaffold geometry and coculturing environment can be customized to amplify primary cancer cells from blood or tissues related to hematological cancer and subsequently used for personalized drug screening procedures.

Bortezomib plus rituximab versus rituximab alone in patients with relapsed, rituximab-naive or rituximab-sensitive, follicular lymphoma: a randomised phase 3 trial

BACKGROUND

Bortezomib and rituximab have shown additive activity in preclinical models of lymphoma, and have been shown to be active and generally well tolerated in a randomised phase 2 study in patients with follicular and marginal zone lymphoma. We compared the efficacy and safety of rituximab alone or combined with bortezomib in patients with relapsed or refractory follicular lymphoma in a phase 3 setting.

METHODS

In this multicentre phase 3 trial, rituximab-naive or rituximab-sensitive patients aged 18 years or older with relapsed grade 1 or 2 follicular lymphoma were randomly assigned (1:1) to receive five 35-day cycles consisting of intravenous infusions of rituximab 375 mg/m(2) on days 1, 8, 15, and 22 of cycle 1, and on day 1 of cycles 2-5, either alone or with bortezomib 1·6 mg/m(2), administered by intravenous injection on days 1, 8, 15, and 22 of all cycles. Randomisation was stratified by FLIPI score, previous use of rituximab, time since last therapy, and region. Treatment assignment was based on a computer-generated randomisation schedule prepared by the sponsor. Patients and treating physicians were not masked to treatment allocation. The primary endpoint was progression-free survival analysed by intention to treat. This trial has been completed and is registered with ClinicalTrials.gov, number NCT00312845.

FINDINGS

Between April 10, 2006, and Aug 12, 2008, 676 patients were randomised to receive rituximab (n=340) or bortezomib plus rituximab (n=336). After a median follow-up of 33·9 months (IQR 26·4-39·7), median progression-free survival was 11·0 months (95% CI 9·1-12·0) in the rituximab group and 12·8 months (11·5-15·0) in the bortezomib plus rituximab group (hazard ratio 0·82, 95% CI 0·68-0·99; p=0·039). The magnitude of clinical benefit was not as large as the anticipated prespecified improvement of 33% in progression-free survival. Patients in both groups received a median of five treatment cycles (range 1-5); 245 of 339 (72%) and 237 of 334 (71%) patients in the rituximab and bortezomib plus rituximab groups, respectively, completed five cycles. Of patients who did not complete five cycles, most discontinued early because of disease progression (77 [23%] patients in the rituximab group, and 56 [17%] patients in the bortezomib plus rituximab group). Rates of adverse events of grade 3 or higher (70 [21%] of 339 rituximab-treated patients vs 152 [46%] of 334 bortezomib plus rituximab treated patients), and serious adverse events (37 [11%] patients vs 59 [18%] patients) were lower in the rituximab group than in the combination group. The most common adverse events of grade 3 or higher were neutropenia (15 [4%] patients in the rituximab group and 37 [11%] patients in the bortezomib plus rituximab group), infection (15 [4%] patients and 36 [11%] patients, respectively), diarrhoea (no patients and 25 [7%] patients, respectively), herpes zoster (one [<1%] patient and 12 [4%] patients, respectively), nausea or vomiting (two [<1%] patients and 10 [3%] patients, respectively) and thrombocytopenia (two [<1%] patients and 10 [3%] patients, respectively). No individual serious adverse event was reported by more than three patients in the rituximab group; in the bortezomib plus rituximab group, only pneumonia (seven patients [2%]) and pyrexia (six patients [2%]) were reported in more than five patients. In the bortezomib plus rituximab group 57 (17%) of 334 patients had peripheral neuropathy (including sensory, motor, and sensorimotor neuropathy), including nine (3%) with grade 3 or higher, compared with three (1%) of 339 patients in the rituximab group (no events of grade ≥3). No patients in the rituximab group but three (1%) patients in the bortezomib plus rituximab group died of adverse events considered at least possibly related to treatment.

INTERPRETATION

Although a regimen of bortezomib plus rituximab is feasible, the improvement in progression-free survival provided by this regimen versus rituximab alone was not as great as expected. The regimen might represent a useful addition to the armamentarium, particularly for some subgroups of patients.

FUNDING

Johnson & Johnson Pharmaceutical Research & Development and Millennium Pharmaceuticals, Inc.

Combination anti-CD74 (milatuzumab) and anti-CD20 (rituximab) monoclonal antibody therapy has in vitro and in vivo activity in mantle cell lymphoma

Mantle cell lymphoma (MCL) is an aggressive B-cell malignancy with a median survival of 3 years despite chemoimmunotherapy. Rituximab, a chimeric anti-CD20 monoclonal antibody (mAb), has shown only modest activity as single agent in MCL. The humanized mAb milatuzumab targets CD74, an integral membrane protein linked with promotion of B-cell growth and survival, and has shown preclinical activity against B-cell malignancies. Because rituximab and milatuzumab target distinct antigens and potentially signal through different pathways, we explored a preclinical combination strategy in MCL. Treatment of MCL cell lines and primary tumor cells with immobilized milatuzumab and rituximab resulted in rapid cell death, radical oxygen species generation, and loss of mitochondrial membrane potential. Cytoskeletal distrupting agents significantly reduced formation of CD20/CD74 aggregates, cell adhesion, and cell death, highlighting the importance of actin microfilaments in rituximab/milatuzumab-mediated cell death. Cell death was independent of caspase activation, Bcl-2 family proteins or modulation of autophagy. Maximal inhibition of p65 nuclear translocation was observed with combination treatment, indicating disruption of the NF-κB pathway. Significant in vivo therapeutic activity of combination rituximab and milatuzumab was demonstrated in a preclinical model of MCL. These data support clinical evaluation of combination milatuzumab and rituximab therapy in MCL.

Phase 2 trial of rituximab and bortezomib in patients with relapsed or refractory mantle cell and follicular lymphoma

BACKGROUND

In vitro studies in mantle cell lymphoma (MCL) cell lines and patient-derived cells have demonstrated synergistic apoptosis with combined rituximab and bortezomib (R-bortezomib) compared with single-agent bortezomib. Therefore, the authors of this report evaluated R-bortezomib in a preclinical model and in a phase 2 clinical trial.

METHODS

A Hu-MCL-severe combined immunodeficiency (SCID) model engrafted with the Jeko cell line was treated with R-bortezomib, bortezomib, or rituximab. Twenty-five patients with relapsed follicular lymphoma (n = 11) and MCL (n = 14) received 375 mg/m(2) rituximab on Days 1 and 8 and 1.3 to 1.5 mg/m(2) bortezomib on Days 1, 4, 8, and 11 every 21 days for a median of 3 cycles (range, 1-5 cycles).

RESULTS

R-bortezomib resulted in a statistically significant improvement in overall survival in Hu-MCL-SCID mice. In the clinical trial, the overall response rate was 40% in all 25 patients, 55% in patients with follicular lymphoma, and 29% in patients with MCL. The estimated 2-year progression-free survival (PFS) rate was 24% (95% confidence interval [CI], 10%-53%) in all patients and 60% (95% CI, 20%-85%) in responding patients. Thirteen patients (52%) developed grade 3 neurotoxicity, which consisted of constipation/ileus, sensory or motor neuropathy, or orthostatic hypotension. Patients who were heterozygous for the CD32a (Fcγ receptor IIa) 131 histidine (H) to arginine (R) polymorphism had a significantly decreased PFS (P = .009) after R-bortezomib compared with HH and RR homozygotes.

CONCLUSIONS

R-bortezomib had significant activity in patients with relapsed or refractory follicular lymphoma and MCL, although an unexpectedly high incidence of grade 3 neurologic toxicity was a potential limiting factor with this combination.

Bortezomib modulates surface CD20 in B-cell malignancies and affects rituximab-mediated complement-dependent cytotoxicity

Unresponsiveness to rituximab treatment develops in many patients prompting elucidation of underlying molecular pathways. It was recently observed that rituximab-resistant lymphoma cells exhibit up-regulation of components of the ubiquitin-proteasome system (UPS). Therefore, we investigated in more detail the role of this system in the regulation of CD20 levels and the influence of proteasome inhibitors on rituximab-mediated complement-dependent cytotoxicity (R-CDC). We observed that incubation of Raji cells with rituximab leads to increased levels of ubiquitinated CD20. However, inhibition of the UPS was not associated with up-regulation of surface CD20 levels, although it significantly increased its ubiquitination. Short-term (24 hours) incubation of Raji cells with 10 or 20nM bortezomib did not change surface CD20 levels, but sensitized CD20+ lymphoma cells to R-CDC. Prolonged (48 hours) incubation with 20nM bortezomib, or incubation with 50nM bortezomib for 24 hours led to a significant decrease in surface CD20 levels as well as R-CDC. These effects were partly reversed by bafilomycin A1, an inhibitor of lysosomal/autophagosomal pathway of protein degradation. These studies indicate that CD20 levels are regulated by 2 proteolytic systems and that the use of proteasome inhibitors may be associated with unexpected negative influence on R-CDC.