Alisertib (MLN8237) an investigational agent suppresses Aurora A and B activity, inhibits proliferation, promotes endo-reduplication and induces apoptosis in T-NHL cell lines supporting its importance in PTCL treatment

Challenges in nodal peripheral T-cell lymphomas: from biological advances to clinical applicability

T cell lymphomas are a heterogenous group with varying biological and clinical features that tend to have poor outcomes with a few exceptions. They account for 10-15% of all non-Hodgkin lymphomas (NHL), and 20% of aggressive NHL. There has been little change in the overall prognosis of T cell lymphomas over the last 2 decades. Most subtypes carry an inferior prognosis when compared to the B cell lymphomas, with a 5-year OS of 30%. Gene expression profiling and other molecular techniques has enabled a deeper understanding of these differences in the various subtypes as reflected in the latest 5th WHO and ICC classification of T cell lymphomas. It is becoming increasingly clear that therapeutic approaches that target specific cellular pathways are needed to improve the clinical outcomes of T cell lymphomas. This review will focus on nodal T cell lymphomas and describe novel treatments and their applicability to the various subtypes.

Molecularly targeted therapies for relapsed and refractory peripheral T-cell lymphomas

The advent of molecularly targeted agents for patients with peripheral T-cell lymphomas (PTCL) has begun to change the therapeutic landscape in these diseases, especially for patients with relapsed or refractory disease. These agents, grounded in targeting numerous pathways or alterations related to disease pathogenesis, have shown promise across many PTCL subhistologies. Aided by significant advances in experimental techniques related to molecular biology, epigenetics, and immunology, more recent studies have begun elucidating mediators of resistance, both intrinsic and acquired, to inform future therapeutic advances. Defining and targeting these escape mechanisms through rational combination approaches will likely be important to continue to build on these promising advances and further improve clinical outcomes for patients facing PTCL.

Advances in the pharmacotherapeutic options for primary nodal peripheral T-cell lymphoma

INTRODUCTION

Peripheral T cell lymphomas (PTCL) are a group of heterogenous hematologic malignancies derived from post-thymic T lymphocytes and mature NK cells. Conventional chemotherapy does not guarantee a good outcome.

AREAS COVERED

The article summarizes recent investigational therapies and their mechanism of action, as well as the pharmacological properties, clinical activity, and toxicity of new agents in the treatment of primary nodal PTCLs. The review scrutinized papers included in the MEDLINE (PubMed) database between 2010 and October 2020. These were supplemented with a manual search of conference proceedings from the previous five years of the American Society of Hematology, European Hematology Association, and American Society of Clinical Oncology. Further relevant publications were obtained by reviewing the references from the chosen articles.

EXPERT OPINION

PTCLs have proved difficult to treat and investigate because of their rarity. Studies of aggressive lymphoma, including a small proportion of T-cell lymphomas, found that any benefit from intensified traditional chemotherapy in patients with PTCL is accompanied by increased toxicity. However, the management of PTCL is beginning to change dramatically, thanks to the use of more sophisticated agents targeting the mechanisms of disease development.

A Novel Aurora Kinase Inhibitor Attenuates Leukemic Cell Proliferation Induced by Mesenchymal Stem Cells

Acute myeloid leukemia (AML) mesenchymal stem cells (MSCs) play an essential role in protecting leukemic cells from chemotherapeutic agents through activating a wide range of adhesion molecules and cytokines. Thus, more attention should be paid to attenuate the protection of leukemic cells by MSCs. By examining the gene expression files of MSCs from healthy donors and AML patients through high-throughput microarrays, we found that interleukin (IL)-6 was an important cytokine secreted by AML MSCs to protect leukemic cells, contributing to disease progression. Strikingly, Aurora A (AURKA) was activated by IL-6, offering a new target to interfere with leukemia. Importantly, a novel AURKA inhibitor, PW21, showed excellent AURKA kinase inhibitory activities and attenuated the interaction of leukemic cells and the microenvironment. PW21 inhibited MSC-induced cell proliferation, colony formation, and migration, and it induced cell apoptosis. Mechanically, PW21 could inhibit IL-6 secreted by MSCs. Moreover, we found that PW21 displayed a strong anti-leukemia effect on non-obese diabetic (NOD)-severe combined immunodeficiency (SCID) and murine MLL-AF9 leukemic models. PW21 significantly prolonged the survival of leukemic mice and eliminated the leukemic progenitor cells. AURKA inhibitor PW21 could provide a new approach for treatment of leukemia through blocking the protection by the leukemic microenvironment in clinical application.

Discovery of thalicthuberine as a novel antimitotic agent from nature that disrupts microtubule dynamics and induces apoptosis in prostate cancer cells

We report for the first time the mechanism of action of the natural product thalicthuberine (TH) in prostate and cervical cancer cells. TH induced a strong accumulation of LNCaP cells in mitosis, severe mitotic spindle defects, and asymmetric cell divisions, ultimately leading to mitotic catastrophe accompanied by cell death through apoptosis. However, unlike microtubule-binding drugs (vinblastine and paclitaxel), TH did not directly inhibit tubulin polymerization when tested in a cell-free system, whereas it reduced cellular microtubule polymer mass in LNCaP cells. This suggests that TH indirectly targets microtubule dynamics through inhibition of a critical regulator or tubulin-associated protein. Furthermore, TH is not a major substrate for P-glycoprotein (Pgp), which is responsible for multidrug resistance in numerous cancers, providing a rationale to further study TH in cancers with Pgp-mediated treatment resistance. The identification of TH's molecular target in future studies will be of great value to the development of TH as potential treatment of multidrug-resistant tumors.

Axitinib overcomes multiple imatinib resistant cKIT mutations including the gatekeeper mutation T670I in gastrointestinal stromal tumors

Background

cKIT kinase overexpression and gain-of-function mutations are the critical pathogenesis of gastrointestinal stromal tumors (GISTs). Although the multiple kinase inhibitors such as imatinib, sunitinib, and regorafenib have been approved for GISTs, the acquisition of polyclonal secondary resistance mutations in KIT is still a limitation for GIST treatment. Here we explored the KIT inhibitory activity of axitinib in preclinical models and describe initial characterization of its activity in GIST patient-derived primary cells.

Methods

The activities of axitinib against mutant KIT were evaluated using protein-based assay and a panel of engineered and GIST-derived cell lines. The binding modes of axitinib-KIT/KIT mutants were analyzed. Four primary cells derived from GIST patients were also used to assess the drug response of axitinib.

Results

Axitinib exhibited potent activities against a variety of cKIT associated primary and secondary mutations. It displayed better activity against cKIT wild-type, cKIT V559D/A/G, and L576P primary gain-of-function mutations than imatinib, sunitinib, and regorafenib. In addition, it could inhibit imatinib resistant cKIT T670I and V654A mutants in vitro and in vivo GIST preclinical models.

Conclusion

Our results provide the basis for extending the application of axitinib to GISTs patients who are unresponsive or intolerant to the current therapies.

The role of aurora A and polo-like kinases in high-risk lymphomas

High-risk lymphomas (HRLs) are associated with dismal outcomes and remain a therapeutic challenge. Recurrent genetic and molecular alterations, including c-myc expression and aurora A kinase (AAK) and polo-like kinase-1 (PLK1) activation, promote cell proliferation and contribute to the highly aggressive natural history associated with these lymphoproliferative disorders. In addition to its canonical targets regulating mitosis, the AAK/PLK1 axis directly regulates noncanonical targets, including c-myc. Recent studies demonstrate that HRLs, including T-cell lymphomas and many highly aggressive B-cell lymphomas, are dependent upon the AAK/PLK1 axis. Therefore, the AAK/PLK1 axis has emerged as an attractive therapeutic target in these lymphomas. In addition to reviewing these recent findings, we summarize the rationale for targeting AAK/PLK1 in high-risk and c-myc-driven lymphoproliferative disorders.

Randomized Phase III Study of Alisertib or Investigator's Choice (Selected Single Agent) in Patients With Relapsed or Refractory Peripheral T-Cell Lymphoma

PURPOSE

The aim of this open-label, first-in-setting, randomized phase III trial was to evaluate the efficacy of alisertib, an investigational Aurora A kinase inhibitor, in patients with relapsed/refractory peripheral T-cell lymphoma (PTCL).

PATIENTS AND METHODS

Adult patients with relapsed/refractory PTCL—one or more prior therapy—were randomly assigned 1:1 to receive oral alisertib 50 mg two times per day (days 1 to 7; 21-day cycle) or investigator-selected single-agent comparator, including intravenous pralatrexate 30 mg/m² (once per week for 6 weeks; 7-week cycle), or intravenous gemcitabine 1,000 mg/m² or intravenous romidepsin 14 mg/m² (days 1, 8, and 15; 28-day cycle). Tumor tissue (disease subtype) and imaging were assessed by independent central review. Primary outcomes were overall response rate and progression-free survival (PFS). Two interim analyses and one final analysis were planned.

RESULTS

Between May 2012 and October 2014, 271 patients were randomly assigned (alisertib, n = 138; comparator, n = 133). Enrollment was stopped early on the recommendation of the independent data monitoring committee as a result of the low probability of alisertib achieving PFS superiority with full enrollment. Centrally assessed overall response rate was 33% for alisertib and 45% for the comparator arm (odds ratio, 0.60; 95% CI, 0.33 to 1.08). Median PFS was 115 days for alisertib and 104 days for the comparator arm (hazard ratio, 0.87; 95% CI, 0.637 to 1.178). The most common adverse events were anemia (53% of alisertib-treated patients v 34% of comparator-treated patients) and neutropenia (47% v 31%, respectively). A lower percentage of patients who received alisertib (9%) compared with the comparator (14%) experienced events that led to study drug discontinuation. Of 26 on-study deaths, five were considered treatment related (alisertib, n = 3 of 11; comparator, n = 2 of 15). Two-year overall survival was 35% for each arm.

CONCLUSION

In patients with relapsed/refractory PTCL, alisertib was not statistically significantly superior to the comparator arm.

The Aurora kinase A inhibitor TC-A2317 disrupts mitotic progression and inhibits cancer cell proliferation

Mitotic progression is crucial for the maintenance of chromosomal stability. A proper progression is ensured by the activities of multiple kinases. One of these enzymes, the serine/threonine kinase Aurora A, is required for proper mitosis through the regulation of centrosome and spindle assembly. In this study, we functionally characterized a newly developed Aurora kinase A inhibitor, TC-A2317. In human lung cancer cells, TC-A2317 slowed proliferation by causing aberrant formation of centrosome and microtubule spindles and prolonging the duration of mitosis. Abnormal mitotic progression led to accumulation of cells containing micronuclei or multinuclei. Furthermore, TC-A2317–treated cells underwent apoptosis, autophagy or senescence depending on cell type. In addition, TC-A2317 inactivated the spindle assembly checkpoint triggered by paclitaxel, thereby exacerbating mitotic catastrophe. Consistent with this, the expression level of Aurora A in tumors was inversely correlated with survival in lung cancer patients. Collectively, these data suggest that inhibition of Aurora kinase A using TC-A2317 is a promising target for anti-cancer therapeutics.

Concurrent Inhibition of Neurosphere and Monolayer Cells of Pediatric Glioblastoma by Aurora A Inhibitor MLN8237 Predicted Survival Extension in PDOX Models

Purpose: Pediatric glioblastoma multiforme (pGBM) is a highly aggressive tumor in need of novel therapies. Our objective was to demonstrate the therapeutic efficacy of MLN8237 (alisertib), an orally available selective inhibitor of Aurora A kinase (AURKA), and to evaluate which in vitro model system (monolayer or neurosphere) can predict therapeutic efficacy in vivoExperimental Design: AURKA mRNA expressions were screened with qRT-PCR. In vitro antitumor effects were examined in three matching pairs of monolayer and neurosphere lines established from patient-derived orthotopic xenograft (PDOX) models of the untreated (IC-4687GBM), recurrent (IC-3752GBM), and terminal (IC-R0315GBM) tumors, and in vivo therapeutic efficacy through log rank analysis of survival times in two models (IC-4687GBM and IC-R0315GBM) following MLN8237 treatment (30 mg/kg/day, orally, 12 days). Drug concentrations in vivo and mechanism of action and resistance were also investigated.Results: AURKA mRNA overexpression was detected in 14 pGBM tumors, 10 PDOX models, and 6 cultured pGBM lines as compared with 11 low-grade gliomas and normal brains. MLN8237 penetrated into pGBM xenografts in mouse brains. Significant extension of survival times were achieved in IC-4687GBM of which both neurosphere and monolayer were inhibited in vitro, but not in IC-R0315GBM of which only neurosphere cells responded (similar to IC-3752GBM). Apoptosis-mediated MLN8237 induced cell death, and the presence of AURKA-negative and CD133⁺ cells appears to have contributed to in vivo therapy resistance.Conclusions: MLN8237 successfully targeted AURKA in a subset of pGBMs. Our data suggest that combination therapy should aim at AURKA-negative and/or CD133⁺ pGBM cells to prevent tumor recurrence. Clin Cancer Res; 24(9); 2159-70. ©2018 AACR.

Alisertib: a review of pharmacokinetics, efficacy and toxicity in patients with hematologic malignancies and solid tumors

INTRODUCTION

Aurora kinases are essential mediators in cell mitosis. Amplification of these kinases can lead to the development of malignancy and may be associated with inferior survival. Alisertib is an oral aurora kinase inhibitor which has been shown to induce cell-cycle arrest and apoptosis in preclinical studies. It is currently under investigation for a wide variety of malignancies including hematologic (specifically Non-Hodgkin's lymphoma) and solid tumors. Areas covered: A PubMed search was performed to identify clinical studies reporting outcomes with alisertib. Promising results are notable in patients with peripheral T cell lymphoma in particular, forming the basis for the first phase 3 randomized trial of alisertib. Although it did show encouraging response rates, it failed to demonstrate superiority over the comparator arm at an interim analysis, halting further enrollment. Expert opinion: Despite disappointing early results, alisertib remains under investigation in a number of cancer types both as monotherapy and in combination with traditional cytotoxic chemotherapy, with encouraging results. Most common toxicities in early trials include myelosuppression alopecia, mucositis and fatigue. The relatively manageable toxicity profile of alisertib along with ease of dosing may allow it to be combined with other oral agents or traditional chemotherapy across a wide variety of malignancy types.

MLN-8237: A dual inhibitor of aurora A and B in soft tissue sarcomas

Aurora kinases have become an attractive target in cancer therapy due to their deregulated expression in human tumors. Liposarcoma, a type of soft tissue sarcoma in adults, account for approximately 20% of all adult soft tissue sarcomas. There are no effective chemotherapies for majority of these tumors. Efforts made to define the molecular basis of liposarcomas lead to the finding that besides the amplifications of CDK4 and MDM2, Aurora Kinase A, also was shown to be overexpressed. Based on these as well as mathematic modeling, we have carried out a successful preclinical study using CDK4 and IGF1R inhibitors in liposarcoma. MLN8237 has been shown to be a potent and selective inhibitor of Aurora A. MLN-8237, as per our results, induces a differential inhibition of Aurora A and B in a dose dependent manner. At a low nanomolar dose, cellular effects such as induction of phospho-Histone H3 (Ser10) mimicked as that of the inhibition of Aurora kinase A followed by apoptosis. However, micromolar dose of MLN-8237 induced polyploidy, a hallmark effect of Aurora B inhibition. The dose dependent selectivity of inhibition was further confirmed by using siRNA specific inhibition of Aurora A and B. This was further tested by time lapse microscopy of GFP-H2B labelled cells treated with MLN-8237. LS141 xenograft model at a dose of 30 mg/kg also showed efficient growth suppression by selective inhibition of Aurora Kinase A. Based on our data, a dose that can target only Aurora A will be more beneficial in tumor suppression.

Co-targeting aurora kinase with PD-L1 and PI3K abrogates immune checkpoint mediated proliferation in peripheral T-cell lymphoma: a novel therapeutic strategy

Peripheral T-cell non-Hodgkin lymphoma (PTCL) are heterogeneous, rare, and aggressive diseases mostly incurable with current cell cycle therapies. Aurora kinases (AKs) are key regulators of mitosis that drive PTCL proliferation. Alisertib (AK inhibitor) has a response rate ∼30% in relapsed and refractory PTCL (SWOG1108). Since PTCL are derived from CD4⁺/CD8⁺ cells, we hypothesized that Program Death Ligand-1 (PD-L1) expression is essential for uncontrolled proliferation. Combination of alisertib with PI3Kα (MLN1117) or pan-PI3K inhibition (PF-04691502) or vincristine (VCR) was highly synergistic in PTCL cells. Expression of PD-L1 relative to PD-1 is high in PTCL biopsies (∼9-fold higher) and cell lines. Combination of alisertib with pan-PI3K inhibition or VCR significantly reduced PD-L1, NF-κB expression and inhibited phosphorylation of AKT, ERK1/2 and AK with enhanced apoptosis. In a SCID PTCL xenograft mouse model, alisertib displayed high synergism with MLN1117. In a syngeneic PTCL mouse xenograft model alisertib demonstrated tumor growth inhibition (TGI) ∼30%, whilst anti-PD-L1 therapy alone was ineffective. Alisertib + anti-PD-L1 resulted in TGI >90% indicative of a synthetic lethal interaction. PF-04691502 + alisertib + anti-PD-L1 + VCR resulted in TGI 100%. Overall, mice tolerated the treatments well. Co-targeting AK, PI3K and PD-L1 is a rational and novel therapeutic strategy for PTCL.

Critical risk-benefit assessment of the novel anti-cancer aurora a kinase inhibitor alisertib (MLN8237): A comprehensive review of the clinical data

BACKGROUND

Many current anticancer chemotherapeutics suffer from significant side effects, which have led to the exploration of more targeted therapies. This resulted in the exploration of inhibitors of Aurora A kinase as a potential anti-cancer treatment. Alisertib (MLN8237) has proven to be a potent Aurora A kinase inhibitor that had the highest safety profile among its therapeutic family. Phase I/II/III clinical trials with Alisertib have been carried out and reported promising efficacy, yet serious side effects. This article attempts to assess the clinical effect of Alisertib administration in various cancer phenotypes while describing the reported side effects.

METHODS

Alisertib clinical data were systematically retrieved from Medline, CINAHL, PubMed, and Cochrane Central Register of Controlled Trials and analyzed for quality, relevance, and originality in three stages prior to inclusion.

RESULTS

Overall, seven studies met inclusion criteria and enrolled a total of 630 patients. The reported "potential" clinical effect of Alisertib in various tumours is promising as it improved time to disease progression, progression-free survival, and the duration of disease stability. The achieved improvement therefore rationalizes its further investigation as a novel anticancer therapy. However, the administration of the drug was associated with serious haematological disturbances in a relatively high percentage of patients.

CONCLUSION

The evidence of the anti-tumour effect of Alisertib administration is compelling in various types of malignancies. The reported side effects were serious but manageable in many cases. Topical or more targeted routes of administration are suggested when possible to overcome off-target events with systematic administration of the drug.

Disruption of Aneuploidy and Senescence Induced by Aurora Inhibition Promotes Intrinsic Apoptosis in Double Hit or Double Expressor Diffuse Large B-cell Lymphomas

Double hit (DH) or double expressor (DE) diffuse large B-cell lymphomas (DLBCL) are aggressive non-Hodgkin's lymphomas (NHL) with translocations and/or overexpressions of MYC and BCL-2, which are difficult to treat. Aurora kinase (AK) inhibition with alisertib in DH/DE-DLBCL induces cell death in ∼30%, while ∼70% are aneuploid and senescent cells (AASC), a mitotic escape mechanism contributing to drug resistance. These AASCs elaborated a high metabolic rate by increased AKT/mTOR and ERK/MAPK activity via BTK signaling through the chronic active B-cell receptor (BCR) pathway. Combinations of alisertib + ibrutinib or alisertib + ibrutinib + rituximab significantly reduced AASCs with enhanced intrinsic cell death. Inhibition of AK + BTK reduced phosphorylation of AKT/mTOR and ERK-1/2, upregulated phospho-H2A-X and Chk-2 (DNA damage), reduced Bcl-6, and decreased Bcl-2 and Bcl-xL and induced apoptosis by PARP cleavage. In a DE-DLBCL SCID mouse xenograft model, ibrutinib alone was inactive, while alisertib + ibrutinib was additive with a tumor growth inhibition (TGI) rate of ∼25%. However, TGI for ibrutinib + rituximab was ∼50% to 60%. In contrast, triple therapy showed a TGI rate of >90%. Kaplan-Meier survival analysis showed that 67% of mice were alive at day 89 with triple therapy versus 20% with ibrutinib + rituximab. All treatments were well tolerated with no changes in body weights. A novel triple therapy consisting of alisertib + ibrutinib + rituximab inhibits AASCs induced by AK inhibition in DH/DE-DLBCL leading to a significant antiproliferative signal, enhanced intrinsic apoptosis and may be of therapeutic potential in these lymphomas. Mol Cancer Ther; 16(10); 2083-93. ©2017 AACR.

Aurora-A Kinase: A Potent Oncogene and Target for Cancer Therapy

The Aurora kinase family is comprised of three serine/threonine kinases, Aurora-A, Aurora-B, and Aurora-C. Among these, Aurora-A and Aurora-B play central roles in mitosis, whereas Aurora-C executes unique roles in meiosis. Overexpression or gene amplification of Aurora kinases has been reported in a broad range of human malignancies, pointing to their role as potent oncogenes in tumorigenesis. Aurora kinases therefore represent promising targets for anticancer therapeutics. A number of Aurora kinase inhibitors (AKIs) have been generated; some of which are currently undergoing clinical evaluation. Recent studies have unveiled novel unexpected functions of Aurora kinases during cancer development and the mechanisms underlying the anticancer actions of AKIs. In this review, we discuss the most recent advances in Aurora-A kinase research and targeted cancer therapy, focusing on the oncogenic roles and signaling pathways of Aurora-A kinases in promoting tumorigenesis, the recent preclinical and clinical AKI data, and potential alternative routes for Aurora-A kinase inhibition.

Alisertib induces apoptosis and autophagy through targeting the AKT/mTOR/AMPK/p38 pathway in leukemic cells

Alisertib, a potent and selective Aurora kinase A inhibitor, has been demonstrated to exert potent anti-cancer effects in pre-clinical and clinical studies. However, mechanisms of action of alisertib, including the molecular pathways involved in alisertib-induced apoptosis and autophagy of leukemic cells, have remained elusive. The aim of the present study was to investigate the effects of alisertib on cell growth, apoptosis and autophagy and to delineate the possible molecular mechanisms in leukemic cells. Acid phosphatase, MTT and Annexin V/propidium iodide staining assays as well as immunostaining for light chain 3B showed that treatment of the REH leukemia cell line with alisertib exerted potent growth inhibitory effects, and induced apoptosis and autophagy in a dose‑dependent manner. Western blot analysis indicated that these effects may be attributed to the suppression of the activity of the Akt/mammalian target of rapamycin/5'-AMP-dependent kinase/p38 mitogen-activated protein kinase signaling pathways in REH cells. The present study confirmed that alisertib may represent a promising autophagy-inducing drug for the treatment of leukemia and shed light on its molecular mechanism of action.

The Aurora-A inhibitor MLN8237 affects multiple mitotic processes and induces dose-dependent mitotic abnormalities and aneuploidy

Inhibition of Aurora kinase activity by small molecules is being actively investigated as a potential anti-cancer strategy. A successful therapeutic use of Aurora inhibitors relies on a comprehensive understanding of the effects of inactivating Aurora kinases on cell division, a challenging aim given the pleiotropic roles of those kinases during mitosis. Here we have used the Aurora-A inhibitor MLN8237, currently under phase-I/III clinical trials, in dose-response assays in U2OS human cancer cells synchronously proceeding towards mitosis. By following the behaviour and fate of single Aurora-inhibited cells in mitosis by live microscopy, we show that MLN8237 treatment affects multiple processes that are differentially sensitive to the loss of Aurora-A function. A role of Aurora-A in controlling the orientation of cell division emerges. MLN8237 treatment, even in high doses, fails to induce efficient elimination of dividing cells, or of their progeny, while inducing significant aneuploidy in daughter cells. The results of single-cell analyses show a complex cellular response to MLN8237 and evidence that its effects are strongly dose-dependent: these issues deserve consideration in the light of the design of strategies to kill cancer cells via inhibition of Aurora kinases.

Recent advances in the development of Aurora kinases inhibitors in hematological malignancies

Over the last two decades, since the discovery of Drosophila mutants in 1995, much effort has been made to understand Aurora kinase biology. Three mammalian subtypes have been identified thus far which include the Aurora A, B and C kinases. These regulatory proteins specifically work at the cytoskeleton and chromosomal structures between the kinetochores and have vital functions in the early phases of the mitotic cell cycle. Today, there are multiple phase I and phase II clinical trials as well as numerous preclinical studies taking place looking at Aurora kinase inhibitors in both hematologic and solid malignancies. This review focuses on the preclinical and clinical development of Aurora kinase inhibitors in hematological malignancy and discusses their therapeutic potential.

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.

The role of alisertib in treatment of peripheral T-cell lymphomas

Peripheral T-cell lymphomas are aggressive lymphomas with poor outcomes for which novel treatments are urgently needed. Alisertib (MLN8237) is a second-generation oral Aurora A kinase inhibitor. Treatment with alisertib results in an accumulation of cells with abnormal mitotic spindles, leading to decreased proliferation and apoptosis in a range of human tumor cell lines. Alisertib has shown single-agent antitumor activity in animal xenograft models and promising antitumor activity alone or in combination with other agents in patients with solid and hematologic cancers, and T-cell lymphomas in particular. It is currently being tested in randomized controlled Phase III trials in relapsed/refractory peripheral T-cell lymphoma.

Phase 1 dose escalation trial of ilorasertib, a dual Aurora/VEGF receptor kinase inhibitor, in patients with hematologic malignancies

BACKGROUND

Ilorasertib (ABT-348) is a novel inhibitor of Aurora kinase, vascular endothelial growth factor (VEGF) and platelet-derived growth factor receptors, and the Src families of tyrosine kinases. Ilorasertib alone or in combination with azacitidine demonstrated activity in preclinical models in various hematological malignancies, indicating that pan-Aurora kinase and multiple kinase inhibition may have preferential antileukemic activity. This phase 1 trial determined the safety, pharmacokinetics, and preliminary antitumor activity of ilorasertib alone or combined with azacitidine in advanced hematologic malignancies.

PATIENTS AND METHODS

Fifty-two patients (median age, 67 years; 35 % with >4 prior regimens) with acute myelogenous leukaemia (AML; n = 38), myelodysplastic syndrome (n = 12), or chronic myelomonocytic leukaemia (n = 2) received 3 or 6 doses of ilorasertib per 28-day cycle and were assigned to arm A (once-weekly oral), B (twice-weekly oral), C (once-weekly oral plus azacitidine), or D (once-weekly intravenous) treatment.

RESULTS

Maximum tolerated doses were not determined; the recommended phase 2 oral monotherapy doses were 540 mg once weekly and 480 mg twice weekly. The most common grade 3/4 adverse events were hypertension (28.8 %), hypokalemia (15.4 %), anemia (13.5 %), and hypophosphatemia (11.5 %). Oral ilorasertib pharmacokinetics appeared dose proportional, with a 15-hour half-life and no interaction with azacitidine. Ilorasertib inhibited biomarkers for Aurora kinase and VEGF receptors, and demonstrated clinical responses in 3 AML patients.

CONCLUSIONS

Ilorasertib exhibited acceptable safety and pharmacokinetics at or below the recommended phase 2 dose, displayed evidence of dual Aurora kinase and VEGF receptor kinase inhibition, and activity in AML.

Phase 1 study of the investigational Aurora A kinase inhibitor alisertib (MLN8237) in East Asian cancer patients: pharmacokinetics and recommended phase 2 dose

PURPOSE

This phase 1 study assessed the pharmacokinetics (PK), maximum tolerated dose (MTD)/recommended phase 2 dose (RP2D), safety, and preliminary efficacy of the investigational Aurora A kinase inhibitor, alisertib, in East Asian patients with advanced solid tumors or lymphomas.

PATIENTS AND METHODS

Patients received alisertib twice-daily (BID) for 7 days in 21-day cycles. Doses were escalated (3 + 3) from 30 mg BID based on cycle 1 dose-limiting toxicities (DLTs) until the MTD, followed by expansion for PK/safety characterization.

RESULTS

Thirty-six patients (61 % Chinese, 36 % Korean, 3 % Malay) received alisertib (30 mg BID, n = 30; 40 mg BID, n = 6; median, 2.5 cycles). Alisertib exposures increased approximately dose proportionally, and mean half-life was 16 h. Geometric mean apparent oral clearance (2.65 L/h) was 40 % lower than previous estimates in Western patients, resulting in approximately 70 % higher mean dose-normalized, steady-state exposures (735 nM*h/mg) in East Asian patients. Two patients experienced DLTs at 40 mg BID (grade 3 stomatitis; grade 4 neutropenia); the MTD/RP2D was 30 mg BID. Common toxicities (grade ≥3 at RP2D) were neutropenia (50 %), diarrhea (13 %), and stomatitis (10 %). One patient with extranodal T-/NK-cell lymphoma (nasal type) achieved a partial response and 18 (51 %) had stable disease.

CONCLUSION

The MTD/RP2D of alisertib in East Asian patients (30 mg BID) was lower than in Western patients (50 mg BID), consistent with higher systemic exposures in the East Asian population. Alisertib was generally well tolerated and showed signs of antitumor activity in East Asian cancer patients.

Phase II Intergroup Trial of Alisertib in Relapsed and Refractory Peripheral T-Cell Lymphoma and Transformed Mycosis Fungoides: SWOG 1108

PURPOSE

Aurora A kinase (AAK) is upregulated in highly proliferative lymphomas, suggesting its potential as a therapeutic target. Alisertib is a novel oral AAK inhibitor without adverse safety signals in early-phase studies that demonstrated preliminary activity in T-cell lymphoma. This phase II study was conducted to further investigate the efficacy of alisertib in relapsed or refractory peripheral T-cell non-Hodgkin lymphoma (PTCL).

PATIENTS AND METHODS

Eligible patients with histologically confirmed relapsed/refractory PTCL or transformed Mycosis fungoides (tMF) received alisertib 50 mg twice a day for 7 days on 21-day cycles.

RESULTS

Of 37 eligible patients, the histologic subtypes enrolled included PTCL not otherwise specified (n = 13), angioimmunoblastic T-cell lymphoma (n = 9), tMF (n = 7), adult T-cell lymphoma/leukemia (n = 4), anaplastic large-cell lymphoma (n = 2), and extranodal natural killer/T-cell lymphoma (n = 2). Grade 3 and 4 adverse events in ≥ 5% of patients included neutropenia (32%), anemia (30%), thrombocytopenia (24%), febrile neutropenia (14%), mucositis (11%), and rash (5%). Treatment was discontinued most commonly for disease progression. Among the PTCL subtypes, the overall response rate was 30%, whereas no responses were observed in tMF. Aurora B kinase was more commonly overexpressed than AAK in tumor specimens. Analysis of AAK, Aurora B kinase, MYC, BCL-2, phosphatidylinositol 3-kinase γ, and Notch1 expression revealed no association with response.

CONCLUSION

Alisertib has antitumor activity in PTCL, including heavily pretreated patients. These promising results are being further investigated in an ongoing international, randomized phase III trial comparing alisertib with investigator's choice in PTCL.

Dual Aurora A and JAK2 kinase blockade effectively suppresses malignant transformation

Aurora A and JAK2 kinases are involved in cell division and tumor cell survival, respectively. Here we demonstrate that ectopic expression of Aurora A and JAK2 together is more effective than each alone at inducing non-transformed cells to grow in an anchorage-independent manner and to invade. Furthermore, siRNA silencing or pharmacological inhibition of Aurora A and JAK2 with Alisertib and Ruxolitinib, respectively, is more effective than blocking each kinase alone at suppressing anchorage-dependent and –independent growth and invasion as well as at inducing apoptosis. Importantly, we have developed dual Aurora and JAK inhibitors, AJI-214 and AJI-100, which potently inhibit Aurora A, Aurora B and JAK2 in vitro. In human cancer cells, these dual inhibitors block the auto-phosphorylation of Aurora A (Thr-288) and the phosphorylation of the Aurora B substrate histone H3 (Ser-10) and the JAK2 substrate STAT3 (Tyr-705). Furthermore, AJI-214 and AJI-100 inhibit anchorage dependent and independent cell growth and invasion and induce G2/M cell cycle accumulation and apoptosis. Finally, AJI-100 caused regression of human tumor xenografts in mice. Taken together, our genetic and pharmacological studies indicate that targeting Aurora A and JAK2 together is a more effective approach than each kinase alone at inhibiting malignant transformation and warrant further advanced pre clinical investigations of dual Aurora A/JAK2 inhibitors as potential anti tumor agents.

Gene expression profiling in non-Hodgkin lymphomas

Although the current WHO classification (Swerdlow et al. WHO classification of tumours of haematopoietic and lymphoid tissues. International Agency for Research on Cancer, Lyon, 2008 [1]) for hematolymphoid neoplasms has delineated lymphomas based on the combined morphologic, immunophenotypic, and genotypic findings, further refinement is necessary especially in regard to therapeutics and prognostic implications. High-throughput gene expression profiling (GEP) using microarray technology (Schena et al. Science 270:467-470, 1995 [2]; Augenlicht et al. Proc Natl Acad Sci USA 88:3286-3289, 1991 [3]) was developed about 20 years ago, and further refinement of the technology and analytical approaches has enabled us to routinely evaluate practically the entire transcriptome at a time. GEP has helped to improve the classification and prognostication of non-Hodgkin lymphomas (NHL) as well as improved our understanding of their pathophysiology and response to new therapeutics. In this paper, we will briefly review how this revolutionary tool has transformed our understanding of lymphomas and given us insight into targeted therapeutics. We will also discuss the current efforts in adapting the findings to routine clinical practice, the evolution of the research technology and directions in the future.

Current management of peripheral T-cell lymphomas

Peripheral T-cell lymphomas (PTCLs) are an uncommon group of lymphoproliferative disorders accounting for approximately 10-15 % of all non-Hodgkin lymphomas (NHL) in Western countries. Although PTCLs are associated with poor prognosis, outcomes vary with disease subtype. The standard of care has been anthracycline-based induction combination chemotherapy, however, with the exception of low-risk ALK-positive anaplastic large cell lymphoma, relapse rates are high. Therefore, consolidation with autologous stem cell transplantation is usually recommended for patients deemed candidates, and with aggressive subtypes. In recent years, a number of novel agents including pralatrexate, histone deacetylase inhibitors, immunotoxins, proteasome inhibitors, aurora kinase inhibitors and the CD30 antibody-drug conjugate brentuximab vedotin, have shown promise in the treatment of PTCLs. Studies are underway to explore the activity of these newer agents used in the frontline setting.

Issues in interpreting the in vivo activity of Aurora-A

INTRODUCTION

Based on its role as a mitotic regulatory kinase, overexpressed and associated with aneuploidy in cancer, small-molecule inhibitors have been developed for Aurora-A (AURKA) kinase. In preclinical and clinical assessments, these agents have shown efficacy in inducing stable disease or therapeutic response. In optimizing the use of Aurora-A inhibitors, it is critical to have robust capacity to measure the kinase activity of Aurora-A in tumors.

AREAS COVERED

We provide an overview of molecular mechanisms of mitotic and non-mitotic activation of Aurora-A kinase, and interaction of Aurora-A with its regulatory partners. Typically, Aurora-A activity is measured by use of phospho-antibodies targeting an autophosphorylated T288 epitope. However, recent studies have identified alternative means of Aurora-A activation control, including allosteric regulation by partners, phosphorylation on alternative activating residues (S51, S98), dephosphorylation on inhibitory sites (S342) and T288 phosphorylation by alternative kinases such as Pak enzymes. Additional work has shown that the relative abundance of Aurora-A partners can affect the activity of Aurora-A inhibitors, and that Aurora-A activation also occurs in interphase cells.

EXPERT OPINION

Taken together, this work suggests the need for comprehensive analysis of Aurora-A activity and expression of Aurora-A partners in order to stratify patients for likely therapeutic response.

Alisertib (MLN8237), a selective Aurora-A kinase inhibitor, induces apoptosis in human tongue squamous cell carcinoma cell both in vitro and in vivo

Aurora-A kinases are overexpressed in many cancer tissues and cells. Alisertib is an investigational, orally administered, selective, small-molecule Aurora-A kinase inhibitor with preclinical activity against a broad range of tumors. Our study was aimed to detect the effects of alisertib on human tongue squamous cell carcinoma (HTSCC). Treatment of a human tongue squamous cell carcinoma cell line, HSC-3, with alisertib to inhibition of Aurora-A kinases reduced proliferation and induced apoptosis, which was accompanied by activation of the ATM/Chk2/p53 pathway. In vivo, inhibition of Aurora-A kinases in established xenografted tumors decreased tumor size and weight. Kaplan-Meyer survival analysis demonstrated that the cumulative survival time of mice without Aurora-A kinases was significantly longer than those with Aurora-A kinases. Our data provide the basis for developing alisertib to treat human tongue squamous cell carcinoma.

MLN8237 ( alisertib ) and its role in peripheral T-cell lymphoma

INTRODUCTION

Peripheral T-cell lymphomas (PTCL) are a diverse group of rare non-Hodgkin lymphomas (NHL) that carry a poor prognosis and are in need of effective therapies. A greater understanding of how these tumours proliferate as well as how best to exploit these processes should lead to more durable tumour regression and better clinical outcomes for patients. New approaches include the histone deacetylase inhibitors, antifolates, fusion proteins, nucleoside analogues and agents targeting the immune system, which are being investigated either as single agents or as a combination.

AREAS COVERED

The authors review the evidence for the orally administered aurora A kinase inhibitor MLN8237 ( alisertib ) in T-cell lymphoma. No significant association between clinical response and AAK expression has been observed but inhibition of this enzyme in a Phase II study has demonstrated tumour regression in 27% of heavily pretreated B- and T-cell NHL, with 50% of PTCL patients responding and 3 of 4 patients achieving durable responses.

EXPERT OPINION

A Phase III trial in relapsed PTCL is recruiting patients comparing MLN8237 against single agent comparators. With regards to the data; the response rate of MLN8237 in refractory NHL is promising. The authors believe that further preclinical work identifying the best combinations to take through into clinical trials is important, particularly as this agent is used in earlier lines of therapy.

Past, present and future treatment strategies in peripheral T-cell lymphomas

SUMMARY 

Nodal peripheral T-cell lymphomas (PTCLs) are very aggressive tumors characterized by poor response to conventional chemotherapy and dismal prognosis. Recent evidence has indicated that, at least for patients aged less than 60 years, frontline high-dose chemotherapy followed by autologous stem cell transplantation can be an effective strategy. Unfortunately, however, a significant fraction of patients cannot benefit from this approach, due to age, poor performance status or early relapse. In addition, a percentage of transplanted patients eventually relapse. In this article, based on their experience and on the most recent literature, the authors review the current concept on PTCL treatment, focusing on the most common PTCL nodal subtypes.

Alisertib added to rituximab and vincristine is synthetic lethal and potentially curative in mice with aggressive DLBCL co-overexpressing MYC and BCL2

Pearson correlation coefficient for expression analysis of the Lymphoma/Leukemia Molecular Profiling Project (LLMPP) demonstrated Aurora A and B are highly correlated with MYC in DLBCL and mantle cell lymphoma (MCL), while both Auroras correlate with BCL2 only in DLBCL. Auroras are up-regulated by MYC dysregulation with associated aneuploidy and resistance to microtubule targeted agents such as vincristine. Myc and Bcl2 are differentially expressed in U-2932, TMD-8, OCI-Ly10 and Granta-519, but only U-2932 cells over-express mutated p53. Alisertib [MLN8237 or M], a highly selective small molecule inhibitor of Aurora A kinase, was synergistic with vincristine [VCR] and rituximab [R] for inhibition of cell proliferation, abrogation of cell cycle checkpoints and enhanced apoptosis versus single agent or doublet therapy. A DLBCL (U-2932) mouse model showed tumor growth inhibition (TGI) of ∼10–20% (p = 0.001) for M, VCR and M-VCR respectively, while R alone showed ∼50% TGI (p = 0.001). M-R and VCR-R led to tumor regression [TR], but relapsed 10 days after discontinuing therapy. In contrast, M-VCR-R demonstrated TR with no relapse >40 days after stopping therapy with a Kaplan-Meier survival of 100%. Genes that are modulated by M-VCR-R (CENP-C, Auroras) play a role in centromere-kinetochore function in an attempt to maintain mitosis in the presence of synthetic lethality. Together, our data suggest that the interaction between alisertib plus VCR plus rituximab is synergistic and synthetic lethal in Myc and Bcl-2 co-expressing DLBCL. Alisertib plus vincristine plus rituximab [M-VCR-R] may represent a new strategy for DLBCL therapy.

Aurora-A mitotic kinase induces endocrine resistance through down-regulation of ERα expression in initially ERα+ breast cancer cells

Development of endocrine resistance during tumor progression represents a major challenge in the management of estrogen receptor alpha (ERα) positive breast tumors and is an area under intense investigation. Although the underlying mechanisms are still poorly understood, many studies point towards the ‘cross-talk’ between ERα and MAPK signaling pathways as a key oncogenic axis responsible for the development of estrogen-independent growth of breast cancer cells that are initially ERα+ and hormone sensitive. In this study we employed a metastatic breast cancer xenograft model harboring constitutive activation of Raf-1 oncogenic signaling to investigate the mechanistic linkage between aberrant MAPK activity and development of endocrine resistance through abrogation of the ERα signaling axis. We demonstrate for the first time the causal role of the Aurora-A mitotic kinase in the development of endocrine resistance through activation of SMAD5 nuclear signaling and down-regulation of ERα expression in initially ERα+ breast cancer cells. This contribution is highly significant for the treatment of endocrine refractory breast carcinomas, because it may lead to the development of novel molecular therapies targeting the Aurora-A/SMAD5 oncogenic axis. We postulate such therapy to result in the selective eradication of endocrine resistant ERα^low/− cancer cells from the bulk tumor with consequent benefits for breast cancer patients.

Molecular genetics of peripheral T-cell lymphomas

Peripheral T-cell lymphomas (PTCL) are rare neoplasms that in most instances respond poorly to conventional chemotherapies. Four varieties--PTCL not otherwise specified (NOS), angioimmunoblastic T-cell lymphoma (AITL), ALK+ anaplastic T-cell lymphoma (ALCL), and ALK- ALCL--account for about 60 % of them. Their classification is difficult because of the wide spectrum of morphologic features and the lack of robust immunohistochemical markers. Thus, high-throughput technologies can importantly contribute to their better understanding. In particular, gene expression profiling has cleared the borders among PTCL/NOS, ALK- ALCL and AITL. In fact, gene signatures have been developed even from formalin-fixed paraffin-embedded tissue samples that definitely distinguish one tumor from the other(s). This has important practical implications: for instance on routine diagnostics PTCL/NOS expressing CD30 can be easily confused with ALK- ALCL, but has a much worse prognosis. Therefore, the clear-cut distinction between the two conditions is pivotal to understand the results of ongoing trials with Brentuximab Vedotin, targeting the CD30 molecule. Besides improving the diagnosis, molecular studies have provided the rationale for the usage of novel drugs in the setting of PTCLs, such as ALK inhibitors in ALK+ ALCL, anti-angiogenetic drugs in AITL, and tyrosine kinase inhibitors in PTCL/NOS and ALK+ and ALK- ALCLs.

Phase I study of MLN8237--investigational Aurora A kinase inhibitor--in relapsed/refractory multiple myeloma, non-Hodgkin lymphoma and chronic lymphocytic leukemia

Purpose Amplification or over-expression of the mitotic Aurora A kinase (AAK) has been reported in several heme-lymphatic malignancies. MLN8237 (alisertib) is a novel inhibitor of AAK that is being developed for the treatment of advanced malignancies. The objectives of this phase I study were to establish the safety, tolerability, and pharmacokinetic profiles of escalating doses of MLN8237 in patients with relapsed or refractory heme-lymphatic malignancies. Methods Sequential cohorts of patients received MLN8237 orally as either a powder-in-capsule (PIC) or enteric-coated tablet (ECT) formulation. Patients received MLN8237 PIC 25–90 mg for 14 or 21 consecutive days plus 14 or 7 days’ rest, respectively, or MLN8237 ECT, at a starting dose of 40 mg/day once-daily (QD) for 14 days plus 14 days’ rest, all in 28-day cycles. Subsequent cohorts received MLN8237 ECT 30–50 mg twice-daily (BID) for 7 days plus 14 days’ rest in 21-day cycles. Results Fifty-eight patients were enrolled (PIC n = 28, ECT n = 30). The most frequent grade ≥3 drug-related toxicities were neutropenia (45 %), thrombocytopenia (28 %), anemia (19 %), and leukopenia (19 %). The maximum tolerated dose on the ECT 7-day schedule was 50 mg BID. The terminal half-life of MLN8237 was approximately 19 h. Six (13 %) patients achieved partial responses and 13 (28 %) stable disease. Conclusion The recommended phase II dose of MLN8237 ECT is 50 mg BID for 7 days in 21-day cycles, which is currently being evaluated as a single agent in phase II/III trials in patients with peripheral T-cell lymphoma.

Management of relapses after hematopoietic cell transplantation in T-cell non-Hodgkin lymphomas

T-cell non-Hodgkin lymphomas (NHLs) are a heterogeneous group of malignancies that represent 10%-15% of all NHLs. The prognosis of relapsed T-cell NHL is poor, especially for those relapsing after an autologous (auto-) or allogeneic (allo-) hematopoietic cell transplantation (HCT). Disease relapse post auto-HCT is best managed on a clinical trial. In the absence of an investigational protocol, the choice of salvage therapies should take into account patient performance status, eligibility for an allo-HCT, and surface CD30 expression. CD30-directed therapies or aggressive salvage regimens can be used as a bridge to allo-HCT in medically fit patients. In the elderly or more infirm patients, single-agent therapies could be offered, aiming at palliation. Similarly, relapse after an allo-HCT is not uncommon and is a real challenge. Reduction in ongoing immune suppression or donor lymphocyte infusion are often considered in this setting to augment graft-versus-lymphoma (GVL) effects and can occasionally provide durable disease control. Clinical trials designed to investigate novel therapeutic agents with immunomodulatory properties to augment GVL effects (eg, histone deacetylase [HDAC] inhibitors, proteasome inhibitor, lenalidomide) or targeted therapies (eg, aurora A kinase inhibitors, anaplastic lymphoma kinase [ALK] inhibitors) are sorely needed to improve the dismal outcomes of T-cell NHL relapsing after an allo-HCT.

Peripheral T-cell lymphomas: a review of current approaches and hopes for the future

Peripheral T-cell lymphomas (PTCL) are a diverse group of lymphoproliferative disorders, which share a common denominator of overall poor prognosis, with few exceptions. In this article, the authors review current standard of care approaches for the treatment of PTCLs, the role of stem-cell/bone marrow transplantation, and current developments in novel targeted therapies.