Epigenetics and Lymphoma: Can We Use Epigenetics to Prime or Reset Chemoresistant Lymphoma Programs?

Non-Hodgkin lymphoma is a diverse group of lymphocyte-derived neoplasms. Although a heterogeneous group of malignancies, it has become apparent that epigenetic alterations, such as disturbances of DNA methylation and histone modification, are a common occurrence in both B cell and T cell lymphomas, contributing to lymphomagenesis. As a result, the use of epigenetic targeted therapy has been incorporated into various pre-clinical and clinical studies, demonstrating significant efficacy in lymphoma, with vorinostat becoming the first epigenetic therapy to receive FDA approval in any malignancy. The role of epigenetic drugs is evolving, with its potential use in combination therapy as well as a means of overcoming chemotherapy resistance. In this review, we discuss the epigenetic alterations in non-Hodgkin lymphomas as well as provide an overview of current epigenetic drugs and their role in clinical practice, and on-going clinical trials.

Will new drugs change the standard of care for patients with mantle cell lymphoma?

Mantle Cell lymphoma is a heterogeneous malignancy that has different subtypes with variable levels of aggressiveness. Research on the pathobiology of this disease is helping us understand the etiology for this heterogeneity and has the potential to guide future therapeutic options. The availability of the Ki67 proliferation index and the use of the MIPI score can help determine which of the numerous therapeutic options might be utilized. Minimal Residual Disease testing can act as a guide as to the potential benefit of maintenance therapy. This article discusses the current standard of care for Mantle Cell lymphoma and our current understanding of the pathobiology of the disease leading to strategies to improve patient outcomes with some of the newer targeted agents.

Emerging therapies in relapsed and refractory peripheral T-cell lymphoma

The peripheral T-cell lymphomas (PTCLs) account for 5% to 10% of all non-Hodgkin lymphomas. In the up-front setting, approximately one-quarter of patients experience a long-term remission. In the setting of relapsed and refractory disease, the median progression-free survival and overall survival are reported to be only 3.7 and 6.5 months, respectively. Unfortunately, the molecular and genetic characterization of PTCL has lagged well behind that of the B-cell lymphomas, although several recent experiences are shedding light on the remarkable molecular heterogeneity that has come to define these diverse diseases. The need to identify new active drugs for patients with PTCL has been addressed in part over the last several years, as 4 drugs have now been approved by the US Food and Drug Administration for patients with relapsed or refractory disease, and a plethora of new studies exploring novel combinations have begun to emerge. More advanced techniques in molecular biology, such as next-generation sequencing, gene expression profiling, and comparative genomic hybridization, have helped identify subtleties among subtypes and potentially identify new targets. Many of these recent clinical advances have been based on the recognition that PTCL is a disease that may be broadly characterized by gross epigenetic dysregulation with sensitivity to histone deacetylase inhibitors. In this report, we discuss emerging new therapies in relapsed and refractory PTCL and try to place these new findings in the evolving biological understanding of the disease.

Phase I Study of the Novel Investigational NEDD8-Activating Enzyme Inhibitor Pevonedistat (MLN4924) in Patients with Relapsed/Refractory Multiple Myeloma or Lymphoma

PURPOSE

Evaluate the safety, pharmacokinetic profile, pharmacodynamic effects, and antitumor activity of the first-in-class investigational NEDD8-activating enzyme (NAE) inhibitor pevonedistat (TAK-924/MLN4924) in patients with relapsed/refractory lymphoma or multiple myeloma.

EXPERIMENTAL DESIGN

Patients with relapsed/refractory myeloma (n = 17) or lymphoma (n = 27) received intravenous pevonedistat 25 to 147 mg/m(2) on days 1, 2, 8, 9 (schedule A; n = 27) or 100 to 261 mg/m(2) on days 1, 4, 8, 11 (schedule B; n = 17) of 21-day cycles.

RESULTS

Maximum tolerated doses were 110 mg/m(2) (schedule A) and 196 mg/m(2) (schedule B). Dose-limiting toxicities included febrile neutropenia, transaminase elevations, muscle cramps (schedule A), and thrombocytopenia (schedule B). Common adverse events included fatigue and nausea. Common grade ≥3 events were anemia (19%; schedule A), and neutropenia and pneumonia (12%; schedule B). Clinically significant myelosuppression was uncommon. There were no treatment-related deaths. Pevonedistat pharmacokinetics exhibited a biphasic disposition phase and approximate dose-proportional increases in systemic exposure. Consistent with the short mean elimination half-life of approximately 8.5 hours, little-to-no drug accumulation in plasma was seen after multiple dosing. Pharmacodynamic evidence of NAE inhibition included increased skin levels of CDT-1 and NRF-2 (substrates of NAE-dependent ubiquitin ligases), and increased NRF-2-regulated gene transcript levels in whole blood. Pevonedistat-NEDD8 adduct was detected in bone marrow aspirates, indicating pevonedistat target engagement in the bone marrow compartment. Three lymphoma patients had partial responses; 30 patients achieved stable disease.

CONCLUSIONS

Pevonedistat demonstrated anticipated pharmacodynamic effects in the clinical setting, a tolerable safety profile, and some preliminary evidence that may be suggestive of the potential for activity in relapsed/refractory lymphoma.

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.

Belinostat in patients with refractory or relapsed peripheral T-cell lymphoma: a perspective review

Peripheral T-cell lymphoma (PTCL) is a disease with poor prognosis and limited treatment options. Recent advances in cancer biology suggest that PTCL may be characterized by gross epigenetic dysregulation, which may help explain its sensitivity to histone deacetylase (HDAC) inhibitors. HDAC inhibitors have demonstrated significant activity in T-cell neoplasms and recently, the BELIEF trial evaluated belinostat leading to its approval in the US. This review discusses the development of belinostat, its mechanism of action, pivotal clinical trials, drug toxicity and its recent approval for patients with relapsed or refractory PTCL. Key clinical trials covered include phase I/II evaluation of belinostat in hematologic malignancies, cutaneous T-cell lymphoma (CTCL) and PTCL. In addition, the BELIEF trial in PTCL leading to FDA approval of belinostat is reviewed in detail.

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.

Putting the clinical and biological heterogeneity of non-hodgkin lymphoma into context

The lymphomas represent one of the most heterogeneous groups of malignancies in all of cancer medicine. Whether one attempts to understand these diseases in the context of their complicated ontogeny, unique biologic features, or clinical presentation, this heterogeneity has been a mixed blessing. On the one hand, it has created an ever-changing way to classify these diseases, as classification schemes have been compelled to reflect the rapidly emerging information that seems to split the disease into smaller and smaller subtypes. On the other hand, the biologic and clinical dissection of these diseases has allowed for the identification of unique biologic features-features that have led to novel targets and generated a plethora of new drugs. Virtually every subtype of non-Hodgkin lymphoma has benefited from these efforts to understand the biology of the different subtypes. This paradigm has led to new clinical trials that tailor novel drug regimens to specific biologic disease subtypes. As a prelude to this CCR Focus section, we attempt to put this evolving heterogeneity into context, bridging historical and modern-day views of classification of these diseases. Then, some of the world's leading lymphoma researchers share their perspectives on how to formulate new concepts of care in this era of biologic discovery. Over a relatively short time, the advances in lymphoma research have been nothing short of stunning. There now seems to be little doubt that these recent breakthroughs will redound favorably on the majority of patients diagnosed with a lymphoproliferative malignancy. See all articles in this CCR Focus section, "Paradigm Shifts in Lymphoma."

Changing the paradigms of treatment in peripheral T-cell lymphoma: from biology to clinical practice

Despite enormous advances in our understanding of aggressive lymphomas, it is clear that progress in the peripheral T-cell lymphomas (PTCL) has lagged well behind other B-cell malignancies. Although there are many reasons for this, the one commonly cited notes that the paradigms for diffuse large B-cell lymphoma (DLBCL) were merely applied to all patients with PTCL, the classic "one-size-fits-all" approach. Despite these challenges, progress is being made. Recently, the FDA has approved four drugs for patients with relapsed/refractory PTCL over the past 5 years, and if one counts the recent Japanese approval of the anti-CCR4 monoclonal antibody for patients with adult T-cell leukemia/lymphoma, five drugs have been approved worldwide. These efforts have led to the initiation of no fewer than four randomized clinical studies exploring the integration of these new agents into standard CHOP (cyclophosphamide-Adriamycin-vincristine-prednisone)-based chemotherapy regimens for patients with newly diagnosed PTCL. In addition, a new wave of studies are exploring the merits of novel drug combinations in the disease, an effort to build on the obvious single-agent successes. What has emerged most recently is the recognition that the PTCL may be a disease-characterized by epigenetic dysregulation, which may help explain its sensitivity to histone deacetylase (HDAC) inhibitors, and open the door for even more creative combination approaches. Nonetheless, advances made over a relatively short period of time are changing how we now view these diseases and, hopefully, have poised us to finally improve its prognosis. See all articles in this CCR Focus section, "Paradigm Shifts in Lymphoma."

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.

Belinostat in Patients With Relapsed or Refractory Peripheral T-Cell Lymphoma: Results of the Pivotal Phase II BELIEF (CLN-19) Study

PURPOSE

Peripheral T-cell lymphomas (PTCLs) represent a diverse group of non-Hodgkin lymphomas with a poor prognosis and no accepted standard of care for patients with relapsed or refractory disease. This study evaluated the efficacy and tolerability of belinostat, a novel histone deacetylase inhibitor, as a single agent in relapsed or refractory PTCL.

PATIENTS AND METHODS

Patients with confirmed PTCL who experienced progression after ≥ one prior therapy received belinostat 1,000 mg/m(2) as daily 30-minute infusions on days 1 to 5 every 21 days. Central assessment of response used International Working Group criteria. Primary end point was overall response rate. Secondary end points included duration of response (DoR) and progression-free and overall survival.

RESULTS

A total of 129 patients were enrolled, with a median of two prior systemic therapies. Overall response rate in the 120 evaluable patients was 25.8% (31 of 120), including 13 complete (10.8%) and 18 partial responses (15%). Median DoR by International Working Group criteria was 13.6 months, with the longest ongoing patient at ≥ 36 months. Median progression-free and overall survival were 1.6 and 7.9 months, respectively. Twelve of the enrolled patients underwent stem-cell transplantation after belinostat monotherapy. The most common grade 3 to 4 adverse events were anemia (10.8%), thrombocytopenia (7%), dyspnea (6.2%), and neutropenia (6.2%).

CONCLUSION

Monotherapy with belinostat produced complete and durable responses with manageable toxicity in patients with relapsed or refractory PTCL across the major subtypes, irrespective of number or type of prior therapies. These results have led to US Food and Drug Administration approval of belinostat for this indication.

The novel kinesin spindle protein (KSP) inhibitor SB-743921 exhibits marked activity in in vivo and in vitro models of aggressive large B-cell lymphoma

The kinesin spindle protein (KSP) is a mitotic protein essential for cell cycle control and motility. SB-743921 (hereafter SB-921) is an inhibitor that selectively targets the ATP-binding domain of the KSP. The preclinical activity of SB-921 was evaluated in models of diffuse large B-cell lymphoma (DLBCL). The cytotoxicity of SB-921 was evaluated in a series of germinal center (GC-DLBCL) and post-germinal center (ABC-DLBCL) DLBCL cell lines and a murine lymphoma xenograft model. GC-DLBCL lines generally demonstrated greater sensitivity to SB-921. IC50 values ranged between 1 nM and 900 nM for GC-DLBCL compared to 1 nM to 10 μM for ABC lines. SB-921 demonstrated marked activity in a xenograft model of Ly-1 (GC-DLBCL). While SB-921 was relatively more active in GC derived cell lines, ABC-derived lines still underwent apoptosis at higher concentrations. These results demonstrate that SB-921 inhibits proliferation and induces apoptosis in both GC-DLBCL and ABC-DLBCL.

The novel IKK2 inhibitor LY2409881 potently synergizes with histone deacetylase inhibitors in preclinical models of lymphoma through the downregulation of NF-κB

PURPOSE

To evaluate the pharmacologic activity of a novel inhibitor of IκB kinase β (IKK2), LY2409881, in preclinical models of B- and T-cell lymphoma, as a single agent and in combination with histone deacetylase (HDAC) inhibitors.

EXPERIMENTAL DESIGN

The in vitro activity of LY2409881 was determined using an ATP-based growth inhibition assay and flow cytometric assay of apoptosis in lymphoma cell lines. The in vivo activity of LY2409881 was determined using SCID-beige xenograft mouse model. The mechanism of action was determined using immunoblotting, immuofluorescence, and electrophoretic mobility shift assay. Synergy of LY2409881 with other drugs active in lymphoma was determined by calculating relative risk ratio (RRR) and combination index (CI).

RESULTS

LY2409881 inhibited constitutively activated NF-κB, and caused concentration- and time-dependent growth inhibition and apoptosis in lymphoma cells. In models of diffuse large B-cell lymphoma (DLBCL), the cytotoxicity of LY2409881 correlated with the overall activation status of NF-κB, but not simply in a pattern predicted by the cell-of-origin classification of these cell lines. LY2409881 was safe to mice at three dose levels, 50, 100, and 200 mg/kg, all of which caused significant inhibition of tumor growth. LY2409881 suppressed the activity of the NF-κB subunit p65 in lymphoma cells treated by the HDAC inhibitor romidepsin, underlying a potential mechanism of the marked synergy observed of these two drugs.

CONCLUSION

Collectively, these data strongly suggest that targeting the NF-κB pathway in combination with romidepsin could represent a novel and potent regimen for the treatment of B- and T-cell lymphoma.

Development and characterization of a Mantle Cell Lymphoma Cell Bank in the American Type Culture Collection

Mantle cell lymphoma (MCL) is a rare B-cell malignancy that carries a relatively poor prognosis compared to other forms of non-Hodgkin lymphoma. Standardized preclinical tools are desperately required to hasten the discovery and translation of promising new treatments for MCL. Via an initiative organized through the Mantle Cell Lymphoma Consortium and the Lymphoma Research Foundation, we gathered MCL cell lines from laboratories around the world to create a characterized MCL Cell Bank at the American Type Culture Collection (ATCC). Initiated in 2006, this collection now contains eight cell lines, all of which have been rigorously characterized and are now stored and available for distribution to the general scientific community. We believe the awareness and use of these standardized cell lines will decrease variability between investigators, harmonize international research efforts, improve our understanding of the pathogenesis of the disease and hasten the development of novel treatment strategies.

Abstract 4296: Correlation of the apparent diffusion coefficient of water assessed by diffusion-weighted imaging with treatment outcome in refractory lymphoma patients

The contrast of MR images can be made sensitive to the average motion of water molecules (diffusivity) giving rise to diffusion-weighted imaging (DWI). Intensity maps of the apparent diffusion constant (ADC) of water can be generated from the DWI information and average ADC values of anatomical regions can be assessed. Malignant tissues generally exhibit hypercellularity, increased nucleus-to-cytoplasm ratios, and an increased amount of macromolecules resulting in decreased water diffusivity (lower ADC). Additionally, a response-related ADC increase has been demonstrated in malignancies under therapy. We previously reported that the ADC mean value (in 10-3 mm2 s-1 [SD, n]) of masses of refractory lymphoma patients prior to a new treatment was lower than the ADC mean value of lymph nodes of healthy volunteers (0.91 [0.23, 15] vs. 1.13 [0.14, 10], respectively). This difference was significant (p < 0.01) despite of a large dispersion on the ADC data from the patients. Given this dispersion, we wanted to prove if refractory lymphoma patients with lower ADC values responded differently than those with higher ADC values. Experimental Design: Under ethical review board approval, refractory lymphoma patients underwent a pretreatment MR exam. DWI was acquired using echo-planar imaging with fat suppression and b-values of 0 and 1000 s/mm2 and the ADC of water in the tumor obtained. Time to treatment failure (TTF) was defined as the time between the end of one treatment and the start of a new one. Results: ADC and TTF were obtained in 12 refractory lymphoma patients and divided into those with TTF ≤ 75 days and those with TTF > 75 days. The ADC mean value [SD, n] in patients with TTF ≤ 75 days was 0.73 [0.20, 5] while in those with TTF > 75 days was 1.04 [0.20, 7]. These mean values were significantly different (p < 0.02). Furthermore, the comparison of the ADC mean value of lymph nodes of healthy volunteers with the ADC mean value of refractory patients with TTF ≤ 75 days was highly significant (p < 0.0005) while the comparison between healthy volunteers and patients with TTF > 75 days was not. Discussion: Our results demonstrate that refractory lymphoma patients with tumor masses displaying abnormally low ADC values prior to the start of treatment have poorer treatment outcome than those patients with ADC tumor values that are comparable to those in normal lymph nodes. If low ADC is due to increased tumor cellularity in patients with poorer outcome, this could produce reduced drug availability, thus explaining the substandard outcome. Our results demonstrate an important predictive value of the ADC determination by DWI in refractory lymphoma patients. This together with the fact that DWI is a noninvasive technique and its acquisition is fairly quick makes the ADC a parameter that could become critical for the clinical examination of the patient with refractory lymphoma.

Citation Format: Fernando Arias-Mendoza, Hamed Mojahed, Ahmed Sawas, Owen A. O'Connor. Correlation of the apparent diffusion coefficient of water assessed by diffusion-weighted imaging with treatment outcome in refractory lymphoma patients. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 4296. doi:10.1158/1538-7445.AM2014-4296