Regulation of SOX11 expression through CCND1 and STAT3 in mantle cell lymphoma.

The neural transcription factor SOX11 is usually highly expressed in typical mantle cell lymphoma (MCL), but it is absent in the more indolent form of MCL. Despite being an important diagnostic marker for this hard-to-treat malignancy, the mechanisms of aberrant SOX11 expression are largely unknown. Herein, we describe 2 modes of SOX11 regulation by the cell-cycle regulator cyclin D1 (CCND1) and the signal transducer and activator of transcription 3 (STAT3). We found that ectopic expression of CCND1 in multiple human MCL cell lines resulted in increased SOX11 transcription, which correlated with increased acetylated histones H3K9 and H3K14 (H3K9/14Ac). Increased H3K9/14Ac and SOX11 expression was also observed after histone deacetylase 1 (HDAC1) or HDAC2 was depleted by RNA interference or inhibited by the HDAC inhibitor vorinostat. Mechanistically, we showed that CCND1 interacted with and sequestered HDAC1 and HDAC2 from the SOX11 locus, leading to SOX11 upregulation. Interestingly, our data revealed a potential inverse relationship between phosphorylated Y705 STAT3 and SOX11 expression in MCL cell lines, primary tumors, and patient-derived xenografts. Functionally, inactivation of STAT3 by inhibiting the upstream Janus kinase (JAK) 1 or JAK2 or by STAT3 knockdown was found to increase SOX11 expression, whereas interleukin-21 (IL-21)-induced STAT3 activation or overexpression of the constitutively active form of STAT3 decreased SOX11 expression. In addition, targeting SOX11 directly by RNA interference or indirectly by IL-21 treatment induced toxicity in SOX11+ MCL cells. Collectively, we demonstrate the involvement of CCND1 and STAT3 in the regulation of SOX11 expression, providing new insights and therapeutic implications in MCL.

Five-year outcomes for frontline brentuximab vedotin with CHP for CD30-expressing peripheral T-cell lymphomas.

This phase 1 study evaluated frontline brentuximab vedotin in combination with cyclophosphamide, doxorubicin, and prednisone (BV+CHP; 6 cycles, then up to 10 cycles of brentuximab vedotin monotherapy) in 26 patients with CD30+ peripheral T-cell lymphoma, including 19 with systemic anaplastic large cell lymphoma. All patients (100%) achieved an objective response, with a complete remission (CR) rate of 92%; none received a consolidative stem cell transplant. After a median observation period of 59.6 months (range, 4.6-66.0) from first dose, neither the median progression-free survival (PFS) nor the median overall survival (OS) was reached. No progression or death was observed beyond 35 months. The estimated 5-year PFS and OS rates were 52% and 80%, respectively. Eighteen of 19 patients (95%) with treatment-emergent peripheral neuropathy (PN) reported resolution or improvement of symptoms. Thirteen patients (50%) remained in remission at the end of the study, with PFS ranging from 37.8+ to 66.0+ months. Eight of these 13 patients received the maximum 16 cycles of study treatment. These final results demonstrate durable remissions in 50% of patients treated with frontline BV+CHP, suggesting a potentially curative treatment option for some patients. This trial was registered at www.clinicaltrials.gov as #NCT01309789.

Long-Term Results of High-Dose Therapy and Autologous Stem Cell Transplantation for Mantle Cell Lymphoma: Effectiveness of Maintenance Rituximab.

High-dose therapy followed by autologous stem cell transplantation (ASCT) can improve outcomes for mantle cell lymphoma (MCL) but is associated with a high incidence of relapse. A retrospective study of 191 MCL patients who underwent ASCT at City of Hope was performed to examine prognostic factors for outcomes after ASCT. For all patients the 5-year overall survival (OS) was 71% (95% confidence interval [CI], 63% to 77%) and progression-free survival (PFS) was 53% (95% CI, 45% to 60%). The 5-year cumulative incidence of relapse was 41% (95% CI, 34% to 48%) with a continuous pattern of relapse events occurring at a median of 2.1 years (range, .2 to 13.4) after ASCT. In multivariate analysis, post-transplant maintenance rituximab was the factor most significantly associated with both OS (relative risk [RR], .17; 95% CI, .07 to .38) and PFS (RR, .25; 95% CI, .14 to .44). For the subset of patients who had positron emission tomography (PET) data available and were in a PET-negative first complete remission at ASCT (n = 105), maintenance rituximab was significantly associated with superior OS (RR, .17; 95% CI, .05 to .59) and PFS (RR, .20; 95% CI, .09 to .43). These results support a benefit with maintenance rituximab for all MCL patients treated with ASCT.

RB but not R-HCVAD is a feasible induction regimen prior to auto-HCT in frontline MCL: results of SWOG Study S1106.

Aggressive induction chemotherapy followed by autologous haematopoietic stem cell transplant (auto-HCT) is effective for younger patients with mantle cell lymphoma (MCL). However, the optimal induction regimen is widely debated. The Southwestern Oncology Group S1106 trial was designed to assess rituximab plus hyperCVAD/MTX/ARAC (hyperfractionated cyclophosphamide, vincristine, doxorubicin and dexamethasone, alternating with high dose cytarabine and methotrexate) (RH) versus rituximab plus bendamustine (RB) in a randomized phase II trial to select a pre-transplant induction regimen for future development. Patients had previously untreated stage III, IV, or bulky stage II MCL and received either 4 cycles of RH or 6 cycles of RB, followed by auto-HCT. Fifty-three of a planned 160 patients were accrued; an unacceptably high mobilization failure rate (29%) on the RH arm prompted premature study closure. The estimated 2-year progression-free survival (PFS) was 81% vs. 82% and overall survival (OS) was 87% vs. 88% for RB and RH, respectively. RH is not an ideal platform for future multi-centre transplant trials in MCL. RB achieved a 2-year PFS of 81% and a 78% MRD negative rate. Premature closure of the study limited the sample size and the precision of PFS estimates and MRD rates. However, RB can achieve a deep remission and could be a platform for future trials in MCL.

Managing Risk in Hodgkin Lymphoma.

Approximately 90% of patients with limited-stage Hodgkin lymphoma are cured. The cure rate in advanced-stage Hodgkin lymphoma is dramatically better than it once was, but it is still lower than the rate in patients with limited disease. The choice of treatment is based on several factors, including symptoms, disease stage, extent of tumor burden, and prognosis. Positron emission tomography scanning can be used to assess the patient's stage of disease, which can allow further individualization of therapy. Traditional frontline treatment options include doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD) and, for high-risk patients, bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone (BEACOPP). Autologous stem cell transplantation cures approximately 50% of patients. The antibody-drug conjugate brentuximab vedotin is very active in relapsed/refractory Hodgkin lymphoma. Data presented at the 2014 meeting of the American Society of Hematology (ASH) showed that brentuximab vedotin was beneficial in several settings, including as consolidation therapy posttransplant in patients at high risk for relapse, as first-line salvage therapy in relapsed/refractory Hodgkin lymphoma prior to autologous hematopoietic cell transplantation, and in combination with bendamustine in relapsed/refractory disease. The ASH meeting also offered promising data on novel agents, such as the programmed cell death 1 (PD-1) inhibitors. In this monograph, 4 experts in the management of Hodgkin lymphoma discuss various aspects of the disease and provide their perspectives on the new data presented at the ASH meeting.

Dose-finding study of ibrutinib and venetoclax in relapsed or refractory mantle cell lymphoma.

Relapsed Mantle cell lymphoma (MCL) is often treated with Bruton's tyrosine kinase inhibitors (BTKi); however, post-BTKi relapse can be challenging. Adding venetoclax (VEN) to ibrutinib (IBR) has shown synergy in preclinical MCL models. Prior MCL studies of the combination show promising efficacy but have conducted limited dose finding. We sought to identify the optimal dosing combination, based on efficacy and toxicity, utilizing a continual reassessment method of 6 combinations of IBR (280 mg, 420 mg, and 560 mg by mouth daily) and VEN (max dose of 200 mg and 400 mg by mouth daily). Eligible participants were not previously exposed to BTKi and not high risk for tumor lysis syndrome (TLS). VEN, initiated first at 100 mg, then at 20 mg by mouth daily after a TLS event, was started prior to adding IBR and ramped-up based on the dose level assigned. Combination treatment continued for six 28-day cycles. Thirty-five participants were enrolled and treated. One TLS event occurred with starting dose of 100 mg VEN; no TLS was seen with 20 mg. The optimal dosing combination was considered to be VEN 200 mg and IBR 420 mg with an overall response rate (ORR) of 93.8% (95% CI: 73.6% to 99.7%) and DLT incidence of 6.2% (95% CI: 0.3% to 26.4%). ORR for all arms was 82.3% (28/34; 95% CI: 65.5% to 93.2%) with a complete response (CR) rate of 42.4% (14/33; 95% CI: 25.5% to 60.8%). A participant was not allocated to IBR 560 mg and VEN 400 mg. ORR benefit was not seen with higher dosing combinations and toxicity was higher; a comparison made within the limitations of small cohorts. Resistance was seen in nearly all arms. This trial was registered at www.clinicaltrials.gov #NCT02419560.

Phase I Study of the CD47 Blocker TTI-621 in Patients with Relapsed or Refractory Hematologic Malignancies.

PURPOSE: TTI-621 (SIRPα-IgG1 Fc) is a novel checkpoint inhibitor that activates antitumor activity by blocking the CD47 "don't eat me" signal. This first-in-human phase I study (NCT02663518) evaluated the safety and activity of TTI-621 in relapsed/refractory (R/R) hematologic malignancies. PATIENTS AND METHODS: Patients with R/R lymphoma received escalating weekly intravenous TTI-621 to determine the maximum tolerated dose (MTD). During expansion, patients with various malignancies received weekly single-agent TTI-621 at the MTD; TTI-621 was combined with rituximab in patients with B-cell non-Hodgkin lymphoma (B-NHL) or with nivolumab in patients with Hodgkin lymphoma. The primary endpoint was the incidence/severity of adverse events (AEs). Secondary endpoint included overall response rate (ORR). RESULTS: Overall, 164 patients received TTI-621: 18 in escalation and 146 in expansion (rituximab combination, n = 35 and nivolumab combination, n = 4). On the basis of transient grade 4 thrombocytopenia, the MTD was determined as 0.2 mg/kg; 0.1 mg/kg was evaluated in combination cohorts. AEs included infusion-related reactions, thrombocytopenia, chills, and fatigue. Thrombocytopenia (20%, grade ≥3) was reversible between doses and not associated with bleeding. Transient thrombocytopenia that determined the initial MTD may not have been dose limiting. The ORR for all patients was 13%. The ORR was 29% (2/7) for diffuse large B-cell lymphoma (DLBCL) and 25% (8/32) for T-cell NHL (T-NHL) with TTI-621 monotherapy and was 21% (5/24) for DLBCL with TTI-621 plus rituximab. Further dose optimization is ongoing. CONCLUSIONS: TTI-621 was well-tolerated and demonstrated activity as monotherapy in patients with R/R B-NHL and T-NHL and combined with rituximab in patients with R/R B-NHL.

Truncation in CCND1 mRNA alters miR-16-1 regulation in mantle cell lymphoma.

Cyclin D1 (CCND1) is a well-known regulator of cell-cycle progression. It is overexpressed in several types of cancer including breast, lung, squamous, neuroblastoma, and lymphomas. The most well-known mechanism of overexpression is the t(11;14)(q13;q32) translocation found in mantle cell lymphoma (MCL). It has previously been shown that truncated CCND1 mRNA in MCL correlates with poor prognosis. We hypothesized that truncations of the CCND1 mRNA alter its ability to be down-regulated by microRNAs in MCL. MicroRNAs are a new class of abundant small RNAs that play important regulatory roles at the posttranscriptional level by binding to the 3' untranslated region (UTR) of mRNAs blocking either their translation or initiating their degradation. In this study, we have identified the truncation in CCND1 mRNA in MCL cell lines. We also found that truncated CCND1 mRNA leads to increased CCND1 protein expression and increased S-phase cell fraction. Furthermore, we demonstrated that this truncation alters miR-16-1 binding sites, and through the use of reporter constructs, we were able to show that miR-16-1 regulates CCND1 mRNA expression. This study introduces the role of miR-16-1 in the regulation of CCND1 in MCL.

New and emerging Bruton tyrosine kinase inhibitors for treating mantle cell lymphoma - where do they fit in?

INTRODUCTION: Despite recent prognostic improvements, mantle cell lymphoma (MCL) remains incurable. Bruton tyrosine kinase (BTK) is a key receptor in B-cell tumorigenesis, and the benefits of the first BTK inhibitor, ibrutinib, are becoming clear in MCL. However, off-target activities, which contribute to ibrutinib-related adverse events, suggest potential for further improvement of this drug class. Areas covered: The authors systematically interrogated ClinicalTrials.gov for trials containing keywords for BTK and MCL. Published literature for new and emerging BTK inhibitors being investigated in MCL was then identified (PubMed and Embase), summarized, and placed in the context of treatment guidelines. Expert commentary: Reduced off-target effects of new and emerging covalent, irreversible BTK inhibitors under investigation in patients with MCL offer the potential of improved safety compared with ibrutinib. Efficacy may also be favorable based on trial data for acalabrutinib, which has just been approved in the USA as second-line therapy for MCL. The role of BTK inhibitors in treating MCL will evolve substantially over the coming years as results from a number of trials become available, particularly in relation to potential upfront use and possible synergy with other targeted therapies such as B-cell lymphoma 2, phosphoinositide 3-kinase and checkpoint inhibitors.

Multi-center phase II trial of bortezomib and rituximab maintenance combination therapy in patients with mantle cell lymphoma after consolidative autologous stem cell transplantation.

BACKGROUND: Mantle cell lymphoma (MCL) is an aggressive and incurable lymphoma. Standard of care for younger patients with MCL is induction chemotherapy followed by autologous stem cell transplantation (auto-HCT). Rituximab maintenance after auto-HCT has been shown to improve progression-free survival (PFS) and overall survival (OS) in MCL. Bortezomib maintenance therapy has also been shown to be tolerable and feasible in this setting. However, the combination of bortezomib and rituximab as maintenance therapy post-auto-HCT has not been studied. METHODS: We conducted a multicenter, phase II trial of bortezomib given in combination with rituximab as maintenance in MCL patients after consolidative auto-HCT. Enrolled patients (n = 23) received bortezomib 1.3 mg/m2 subcutaneously weekly for 4 weeks every 3 months (up to 24 months) and rituximab 375 mg/m2 intravenously weekly for 4 weeks every 6 months (up to 24 months) for a total duration of 2 years. The primary study endpoint was disease-free survival (DFS). RESULTS: With a median follow-up of 35.9 months, the 2-year DFS probability was 90.2% (95% CI 66-97), and 2-year OS was 94.7% (95% CI 68-99). The most frequent grade 3/4 toxic events were neutropenia (in 74% of patients) and lymphopenia (in 35%). The incidence of peripheral neuropathy was 48% for grade 1, 9% for grade 2, and 0% for grade 3/4. We also examined the role of quantitative cyclin D1 (CCND1) mRNA in monitoring minimal residual disease. CONCLUSION: Combined bortezomib and rituximab as maintenance therapy in MCL patients following auto-HCT is an active and well-tolerated regimen. TRIAL REGISTRATION: ClinicalTrials.gov NCT01267812 , registered Dec 29, 2010.

CCND1 mutations increase protein stability and promote ibrutinib resistance in mantle cell lymphoma.

Mantle cell lymphoma (MCL) is characterized by the t(11;14) translocation, which leads to deregulated expression of the cell cycle regulatory protein cyclin D1 (CCND1). Genomic studies of MCL have also identified recurrent mutations in the coding region of CCND1. However, the functional consequence of these mutations is not known. Here, we showed that, compared to wild type (WT), single E36K, Y44D or C47S CCND1 mutations increased CCND1 protein levels in MCL cell lines. Mechanistically, these mutations stabilized CCND1 protein through attenuation of threonine-286 phosphorylation, which is important for proteolysis through the ubiquitin-proteasome pathway. In addition, the mutant proteins preferentially localized to the nucleus. Interestingly, forced expression of WT or mutant CCND1 increased resistance of MCL cell lines to ibrutinib, an FDA-approved Bruton tyrosine kinase inhibitor for MCL treatment. The Y44D mutant sustained the resistance to ibrutinib even at supraphysiologic concentrations (5-10 µM). Furthermore, primary MCL tumors with CCND1 mutations also expressed stable CCND1 protein and were resistant to ibrutinib. These findings uncover a new mechanism that is critical for the regulation of CCND1 protein levels, and is directly relevant to primary ibrutinib resistance in MCL.

Irradiated compared with nonirradiated NSG mice for the development of a human B-cell lymphoma model.

NOD.Cg-Prkdc(scid)Il2rg(tm1Wjl)/SzJ (NSG) mice are a superior strain for the engraftment of human tumors, as they provide an ideal model to explore the potency, toxicity, and dosage of therapeutic drugs. Although whole-body nonlethal irradiation is often performed to enhance engraftment, the need for irradiation to establish a human B-cell lymphoma model using the NSG strain has not been addressed. In the current study, a mouse model of B-cell lymphoma was established by intravenous injection of human B-cell lymphoma Z138 cells into mice with and without irradiation. Tumor development, signs of engraftment, survivability of engrafted mice, histopathology, and immunohistochemistry were evaluated. Potential sex-associated variations in the model were assessed also. Irradiation of NSG mice did not enhance tumor cell engraftment, and nonirradiated animals had increased survivability. Mice with irradiation survived for a median of 27 d before being euthanized due to signs of morbidity, whereas those without irradiation had a median survival of 35 d. Both irradiated and nonirradiated mice were normal in activity until 3 wk after the injection of cells. At that time, the mice started to show signs of lymphoma including ruffled fur, decreased activity, and hindlimb paralysis. There were no significant differences in evaluated parameters between male and female mice. Therefore, we conclude that a model of B-cell lymphoma can successfully be established by using Z138 cells in nonirradiated male and female NSG mice.

Brentuximab vedotin in the front-line treatment of patients with CD30+ peripheral T-cell lymphomas: results of a phase I study.

PURPOSE: Front-line treatment of peripheral T-cell lymphomas (PTCL) involves regimens such as cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP) and results in a 5-year overall survival (OS) rate of less than 50%. This phase I open-label study evaluated the safety and activity of brentuximab vedotin administered sequentially with CHOP or in combination with CHP (CHOP without vincristine) as front-line treatment in patients with CD30(+) PTCL. PATIENTS AND METHODS: Patients received sequential treatment (once every 3 weeks) with brentuximab vedotin 1.8 mg/kg (two cycles) followed by CHOP (six cycles) or brentuximab vedotin 1.8 mg/kg plus CHP (BV+CHP) for six cycles (once every 3 weeks). Responders received single-agent brentuximab vedotin for eight to 10 additional cycles (for a total of 16 cycles). The primary objective was assessment of safety; secondary end points included objective response rate, complete remission (CR) rate, progression-free survival rate (PFS), and OS. There were no prespecified comparisons of the two treatment approaches. RESULTS: After sequential treatment, 11 (85%) of 13 patients achieved an objective response (CR rate, 62%; estimated 1-year PFS rate, 77%). Grade 3/4 adverse events occurred in eight (62%) of 13 patients. At the end of combination treatment, all patients (n = 26) achieved an objective response (CR rate, 88%; estimated 1-year PFS rate, 71%). All seven patients without anaplastic large-cell lymphoma achieved CR. Grade 3/4 adverse events (≥ 10%) in the combination-treatment group were febrile neutropenia (31%), neutropenia (23%), anemia (15%), and pulmonary embolism (12%). CONCLUSION: Brentuximab vedotin, administered sequentially with CHOP or in combination with CHP, had a manageable safety profile and exhibited substantial antitumor activity in newly diagnosed patients with CD30(+) PTCL. A randomized phase III trial is under way, comparing BV+CHP with CHOP (clinical trial No. NCT01777152).

Small interfering RNAs targeting cyclin D1 and cyclin D2 enhance the cytotoxicity of chemotherapeutic agents in mantle cell lymphoma cell lines.

Cyclin D1 (CCND1) is a known cell cycle regulator whose overexpression is a hallmark of mantle cell lymphoma (MCL). Although molecular techniques have unified the diagnostic approach to MCL, no therapeutic advances have been made to target this particular pathway. The significance of CCND1 in the pathogenesis and treatment of MCL has yet to be defined. We have taken advantage of RNA interference (RNAi) to down-regulate CCND1 expression in two MCL cell lines (Granta-519 and Jeko-1) to investigate the cytotoxic effect of combining RNAi with conventional chemotherapeutic agents. We designed four small interfering RNAs (siRNAs) specific to CCND1, one specific to CCND2, and one dual-targeting siRNA that simultaneously down-regulates CCND1 and CCND2. Etoposide and doxorubicin were used as chemotherapeutics in combination with the siRNAs. The transfected siRNAs in MCL cell lines triggered 40-60% reduction in target mRNA and protein levels. Importantly, the siRNA-mediated reduction in cyclins resulted in decreased IC(50) (50% inhibitory concentration) values for both doxorubicin and etoposide. The combination of siRNA-mediated inhibition of the cyclins along with chemotherapeutic agents could potentially be used to lower the effective doses of the chemotherapeutic agents and reduce drug-related toxicities.