Jennifer E Amengual

HDAC inhibitors and decitabine are highly synergistic and associated with unique gene-expression and epigenetic profiles in models of DLBCL.

Interactions between histone deacetylase inhibitors (HDACIs) and decitabine were investigated in models of diffuse large B-cell lymphoma (DLBCL). A number of cell lines representing both germinal center B-like and activated B-cell like DLBCL, patient-derived tumor cells and a murine xenograft model were used to study the effects of HDACIs and decitabine in this system. All explored HDACIs in combination with decitabine produced a synergistic effect in growth inhibition and induction of apoptosis in DLBCL cells. This effect was time dependent, mediated via caspase-3 activation, and resulted in increased levels of acetylated histones. Synergy in inducing apoptosis was confirmed in patient-derived primary tumor cells treated with panobinostat and decitabine. Xenografting experiments confirmed the in vitro activity and tolerability of the combination. We analyzed the molecular basis for this synergistic effect by evaluating gene-expression and methylation patterns using microarrays, with validation by bisulfite sequencing. These analyses revealed differentially expressed genes and networks identified by each of the single treatment conditions and by the combination therapy to be unique with few overlapping genes. Among the genes uniquely altered by the combination of panobinostat and decitabine were VHL, TCEB1, WT1, and DIRAS3.

Dual Targeting of Protein Degradation Pathways with the Selective HDAC6 Inhibitor ACY-1215 and Bortezomib Is Synergistic in Lymphoma

Purpose: Pan-class histone deacetylase (HDAC) inhibitors are effective treatments for select lymphomas. Isoform-selective HDAC inhibitors are emerging as potentially more targeted agents. HDAC6 is a class IIb deacetylase that facilitates misfolded protein transport to the aggresome for degradation. We investigated the mechanism and therapeutic impact of the selective HDAC6 inhibitor ACY-1215 alone and in combination with bortezomib in preclinical models of lymphoma. Experimental Design: Concentration–effect relationships were defined for ACY-1215 across 16 lymphoma cell lines and for synergy with bortezomib. Mechanism was interrogated by immunoblot and flow cytometry. An in vivo xenograft model of DLBCL was used to confirm in vitro findings. A collection of primary lymphoma samples were surveyed for markers of the unfolded protein response (UPR). Results: Concentration–effect relationships defined maximal cytotoxicity at 48 hours with IC50 values ranging from 0.9 to 4.7 μmol/L. Strong synergy was observed in combination with bortezomib. Treatment with ACY-1215 led to inhibition of the aggresome evidenced by acetylated α-tubulin and accumulated polyubiquitinated proteins and upregulation of the UPR. All pharmacodynamic effects were enhanced with the addition of bortezomib. Findings were validated in vivo where mice treated with the combination demonstrated significant tumor growth delay and prolonged overall survival. Evaluation of a collection of primary lymphoma samples for markers of the UPR revealed increased HDAC6, GRP78, and XBP-1 expression as compared with reactive lymphoid tissue. Conclusions: These data are the first results to demonstrate that dual targeting of protein degradation pathways represents an innovative and rational approach for the treatment of lymphoma. Clin Cancer Res; 21(20); 4663–75. ©2015 AACR.

Preclinical Pharmacologic Evaluation of Pralatrexate and Romidepsin Confirms Potent Synergy of the Combination in a Murine Model of Human T-cell Lymphoma

Purpose: T-cell lymphomas (TCL) are aggressive diseases, which carry a poor prognosis. The emergence of new drugs for TCL has created a need to survey these agents in a rapid and reproducible fashion, to prioritize combinations which should be prioritized for clinical study. Mouse models of TCL that can be used for screening novel agents and their combinations are lacking. Developments in noninvasive imaging modalities, such as surface bioluminescence (SBL) and three-dimensional ultrasound (3D-US), are challenging conventional approaches in xenograft modeling relying on caliper measurements. The recent approval of pralatrexate and romidepsin creates an obvious combination that could produce meaningful activity in TCL, which is yet to be studied in combination. Experimental Design: High-throughput screening and multimodality imaging approach of SBL and 3D-US in a xenograft NOG mouse model of TCL were used to explore the in vitro and in vivo activity of pralatrexate and romidepsin in combination. Corresponding mass spectrometry–based pharmacokinetic and immunohistochemistry-based pharmacodynamic analyses of xenograft tumors were performed to better understand a mechanistic basis for the drug:drug interaction. Results: In vitro, pralatrexate and romidepsin exhibited concentration-dependent synergism in combination against a panel of TCL cell lines. In a NOG murine model of TCL, the combination of pralatrexate and romidepsin exhibited enhanced efficacy compared with either drug alone across a spectrum of tumors using complementary imaging modalities, such as SBL and 3D-US. Conclusions: Collectively, these data strongly suggest that the combination of pralatrexate and romidepsin merits clinical study in patients with TCLs. Clin Cancer Res; 21(9); 2096–106. ©2015 AACR.

Aurora A Kinase Inhibition Selectively Synergizes with Histone Deacetylase Inhibitor through Cytokinesis Failure in T-cell Lymphoma

Purpose: Aurora A kinase (AAK) is expressed exclusively during mitosis, and plays a critical role in centrosome duplication and spindle formation. Alisertib is a highly selective AAK inhibitor that has demonstrated marked clinical activity of alisertib across a spectrum of lymphomas, though particularly in patients with T-cell lymphoma (TCL). We sought to compare and contrast the activity of alisertib in preclinical models of B-cell lymphoma (BCL) and TCL, and identify combinations worthy of clinical study. High-throughput screening of pralatrexate, the proteasome inhibitor (ixazomib), and the histone deacetylase (HDAC) inhibitor (romidepsin) revealed that only romidepsin synergized with alisertib, and only in models of TCL. We discovered that the mechanism of synergy between AAK inhibitors and HDAC inhibitors appears to be mediated through cytokinesis failure. Experimental Design: A high-throughput screening approach was used to identify drugs that were potentially synergistic in combination with alisertib. Live-cell imaging was used to explore the mechanistic basis for the drug: drug interaction between alisertib and romidepsin. An in vivo xenograft TCL model was used to confirm in vitro results. Results: In vitro, alisertib exhibited concentration-dependent cytotoxicity in BCL and TCL cell lines. Alisertib was synergistic with romidepsin in a T-cell–specific fashion that was confirmed in vivo. Live-cell imaging demonstrated that the combination treatment resulted in profound cytokinesis failure. Conclusions: These data strongly suggest that the combination of alisertib and romidepsin is highly synergistic in TCL through modulation of cytokinesis and merits clinical development. Clin Cancer Res; 21(18); 4097–109. ©2015 AACR.

The combination of hypomethylating agents and histone deacetylase inhibitors produce marked synergy in preclinical models of T-cell lymphoma

T‐cell lymphomas (TCL) are aggressive lymphomas usually treated with CHOP (cyclophsophamide, doxorubicin, vincristine, prednisolone)‐like regimens upfront. Recent data suggest that TCL are driven by epigenetic defects, potentially rendering them sensitive to epigenetic therapies. We explored the therapeutic merits of a combined epigenetic platform using histone deacetylase inhibitors (HDACIs) and DNA methyltransferase inhibitors (DNMT) in in vitro and in vivo models of TCL. The 50% inhibitory concentration (IC50) values revealed romidepsin was the most potent HDACI, with an IC50 in the low nanomolar range. The combination with a hypomethylating agent produced synergy across all cell lines, which was confirmed in cytotoxicity and apoptosis assays. An in vivo xenograft study demonstrated inhibition of tumour growth in the combination cohort compared to the single agent. Gene expression array and global methylation profiling revealed differentially expressed genes and modulated pathways for each of the single treatment conditions and the combination. Most of the effects induced by the single agent treatment were maintained in the combination group. In total, 944 unique genes were modulated by the combination treatment, supporting the hypothesis of molecular synergism. These data suggest combinations of hypomethylating agents and HDACIs are synergistic in models of TCL, which is supported at the molecular level.

Regression of HIV-related diffuse large B-cell lymphoma in response to antiviral therapy alone

To the editor: Patients with HIV on highly active antiretroviral therapy (HAART) have protection against the development of non-Hodgkin lymphoma (NHL) compared with HIV-positive patients not on HAART, and most studies have suggested that there may be improved outcomes when adding HAART to

Brentuximab vedotin plus bendamustine in relapsed or refractory Hodgkin's lymphoma: an international, multicentre, single-arm, phase 1–2 trial

BACKGROUND Brentuximab vedotin is currently approved for patients with relapsed or refractory Hodgkins lymphoma who previously received an autologous stem cell transplant or two previous multiagent chemotherapy regimens, and for patients with relapsed or refractory systemic anaplastic large-T-cell lymphoma who previously received at least one chemotherapy regimen. A high proportion of patients with CD30-expressing relapsed or refractory lymphomas have durable responses to single-agent brentuximab vedotin and show longer progression-free survival than do patients treated with chemotherapy. In patients with Hodgkins lymphoma and peripheral T-cell lymphoma, treatment with bendamustine alone only achieves modest improvements in progression-free survival compared with that for chemotherapy. The objective of this study was to explore the safety and clinical activity of the combination of brentuximab vedotin plus bendamustine in heavily pretreated patients with relapsed or refractory Hodgkins lymphoma and anaplastic large-T-cell lymphoma. METHODS In this international, multicentre, single-arm, phase 1-2 trial, eligible patients were aged 18 years or older, had histologically confirmed relapsed or refractory Hodgkins lymphoma or anaplastic large-T-cell lymphoma, had biopsy-proven CD30-positive tumours, had an Eastern Cooperative Oncology Group performance status of 2 or less, and received at least one previous multiagent chemotherapy regimen. In phase 1, patients were assigned following a 3+3 dose-escalation design to one of four cohorts to receive one dose of either 1·2 mg/kg or 1·8 mg/kg of brentuximab vedotin intravenously on day 1 of a 21 day cycle, plus one dose of bendamustine (70 mg/m2, 80 mg/m2, or 90 mg/m2) on days 1 and 2 of the treatment cycle. In phase 2, all patients were assigned to receive brentuximab vedotin plus bendamustine at the recommended phase 2 dose from phase 1. The primary endpoints were maximum tolerated dose and dose-limiting toxicity for phase 1, and the proportion of patients achieving an overall response in phase 2. For both phases 1 and 2, all patients receiving at least one dose of study drug were evaluable for toxicity and all patients completing at least one cycle of therapy were evaluable for response. The study is ongoing but no longer recruiting patients. This trial is registered with ClinicalTrials.gov, number NCT01657331. FINDINGS Between July 26, 2012, and May 31, 2017, we enrolled and assigned 65 patients to treatment (64 [98%] with Hodgkins lymphoma and one [2%] with anaplastic large-T-cell lymphoma; 28 [43%] during phase 1 and 37 [57%] during phase 2). In the phase 1 part, the maximum tolerated dose of the combination was not reached. Dose-limiting toxicities were observed in three (11%) of 28 patients, including grade 4 neutropenia at 1·8 mg/kg brentuximab vedotin plus 80 mg/m2 of bendamustine in two (7%) patients and diffuse rash at 1·2 mg/kg brentuximab vedotin plus 70 mg/m2 of bendamustine in one (4%) patient. The recommended phase 2 dose was deemed to be 1·8 mg/kg of brentuximab vedotin and 90 mg/m2 of bendamustine, which are the standard doses of the drugs when given as single agents. In the phase 2 part, an overall response was achieved in 29 (78% [95% CI 62-91]) of 37 patients. Serious adverse events included grade 3 lung infection in five (14%) of 37 patients in the phase 2, and grade 3-4 neutropenia in 16 (25%) of 65 patients across phases 1 and 2. There were no treatment-related deaths. INTERPRETATION This study shows that brentuximab vedotin plus bendamustine, with a favourable safety profile, is an active salvage regimen for heavily pretreated patients with relapsed or refractory Hodgkins lymphoma. This salvage regimen can potentially serve as an efficacious and safe alternative to platinum-based chemotherapy before autologous stem cell transplant. FUNDING Seattle Genetics, Lymphoma Research Fund of Columbia University and National Center for Advancing Translational Sciences, and National Institutes of Health.

A phase 1/2 trial of ublituximab, a novel anti-CD20 monoclonal antibody, in patients with B-cell non-Hodgkin lymphoma or chronic lymphocytic leukaemia previously exposed to rituximab

This phase 1/2 study evaluated the safety, pharmacokinetic behavior and anti‐tumour activity of ublituximab, a unique type I, chimeric, glycoengineered anti‐CD20 monoclonal antibody, in rituximab‐relapsed or ‐refractory patients with B‐cell non‐Hodgkin lymphoma (B‐NHL) or chronic lymphocytic leukaemia (CLL). Induction therapy (doses of 450–1200 mg) consisted of 4 weekly infusions in cycle 1 for NHL and 3 weekly infusions in cycles 1 and 2 for CLL. Patients received ublituximab maintenance monthly during cycles 3–5, then once every 3 months for up to 2 years. Enrolled patients with B‐NHL (n = 27) and CLL (n = 8) had a median of 3 prior therapies. No dose‐limiting toxicities or unexpected adverse events (AEs) occurred. The most common AEs were infusion‐related reactions (40%; grade 3/4, 0%); fatigue (37%; grade 3/4, 3%); pyrexia (29%; grade 3/4, 0%); and diarrhoea (26%; grade 3/4, 0%). Common haematological AEs were neutropenia (14%; grade 3/4, 14%) and anaemia (11%; grade 3/4, 6%). The overall response rate for evaluable patients (n = 31) was 45% (13% complete responses, 32% partial responses). Median duration of response and progression‐free survival were 9·2 months and 7·7 months, respectively. Ublituximab was well‐tolerated and efficacious in a heterogeneous and highly rituximab‐pre‐treated patient population.

Development and Characterization of a Novel CD19CherryLuciferase (CD19CL) Transgenic Mouse for the Preclinical Study of B-Cell Lymphomas

Purpose: To generate a transgenic mouse that when crossed with spontaneous mouse models of lymphoma will allow for quantitative in vivo measurement of tumor burden over the entire spectrum of the disease and or response to therapy in a “disease” or lymphoma subtype-specific manner. Experimental Design: We developed a novel genetically engineered transgenic mouse using a CherryLuciferase fusion gene targeted to the CD19 locus to achieve B-cell–restricted fluorescent bioluminescent emission in transgenic mouse models of living mice. The use of a dual function protein enables one to link the in vivo analysis via bioluminescence imaging to cell discriminating ex vivo analyses via fluorescence emission. Results: The spatiotemporal tracking of B-cell lymphoma growth and the response of an established B-cell lymphoma to a drug known to induce remission was evaluated in a double transgenic animal obtained by crossing the CD19CherryLuciferase transgenic mouse to a mouse model of an aggressive B-cell lymphoma. The observations validated the use of the CD19CherryLuciferase transgenic mouse in the assessment of an active drug routinely used in the treatment of lymphoproliferative malignancies. Conclusions: The transgenic mouse described here is the first of its kind, intended to be used to hasten translational studies of novel agents in lymphoma, with the intent that understanding the relevant pharmacology before clinical study will accelerate successful development in clinical studies. Clin Cancer Res; 18(14); 3803–11. ©2012 AACR.

Sustained, durable responses with alemtuzumab in refractory angioimmunoblastic T-cell lymphoma.

Angioimmunoblastic T-cell lymphoma (AITL) was first described in the 1970s as a clinical syndrome characterized by lymphadenopathy, hepatosplenomegaly, anemia, and hypergammaglobulinemia [1,2]. Pathological features include effacement of lymph node architecture by a polymorphic infiltrate of plasma cells, eosinophils, and histiocytes. Mediumsized lymphocytes with clear cytoplasm surround extensive vascular proliferation [3]. Immunohistochemistry demonstrates areas of CD3þ T cells with CD4þ predominance and proliferation of follicular dendritic cells. T-cell gene rearrangement demonstrates clonality. Although the etiology of AITL is uncertain, there is a clear association with Epstein–Barr virus (EBV), where EBV load correlates with histological progression and clinical severity of disease [4]. As a rare subtype of non-Hodgkin lymphoma (NHL), it represents only 2% of all such cases. It is a diagnosis of the elderly associated with a poor prognosis, with median survival less than 36 months and 5-year survival of approximately 30% [5]. Clinically, patients commonly suffer from immune dysfunction, including autoimmune disease and infections [6]. There is no standard treatment for AITL. Although most patients initially respond to steroids and high-dose combination chemotherapy, they frequently relapse within short time intervals [7]. There have been reports using cyclosporine A, fludarabine, methotrexate, thalidomide, and bevacizumab, with mixed results [8–12]. Alemtuzumab is an unconjugated, non-modulating, humanized monoclonal antibody that binds to the CD52 antigen [13]. CD52 is a cell surface glycoprotein expressed on the surface of lymphocytes, monocytes, and macrophages, but not hematopoietic stem cells. Expression occurs in higher densities on malignant T cells. The mechanism of action of alemtuzumab is not completely known, but it is hypothesized to induce cell death through complement-mediated cytolysis, antibody-dependent cellular cytotoxicity, and apoptosis [14,15]. Here we report on three patients with relapsed AITL who achieved sustained, durable responses with alemtuzumab. A 73-year-old female was noted to have abnormal lymph node and bone marrow architecture 4 years prior to her diagnosis of AITL. In 2001, she was found to have a lymph node with focal infiltrates of polyclonal plasma cells and a hypercellular bone marrow with atypical lymphocytes, with increased eosinophils and plasma cells (7%), which were polyclonal. By 2005 she had similar bone marrow findings, but lymph node evaluation revealed a predominance of T cells with prominent vascular component and positive T-cell receptor gamma chain gene rearrangement. Based on her diagnosis of AITL, she received combination chemotherapy composed of adriamycin, vincristine, cyclophosphamide, and prednisone (CHOP) (Table I), but relapsed within 7 months. She was subsequently treated with cytoxan and prednisone and then gemcitabine with prednisone from November 2006 until May 2007, with neither regimen offering a significant clinical benefit. By June 2007, she presented with fevers, weight loss, splenomegaly (11 cm6 13 cm), and lactate dehydrogenase (LDH) of 1292 U/L (313–618 U/L). She was started on alemtuzumab 30 mg infusion three times per week. The patient received antibiotic prophylaxis