Subclonal evolution of a classical Hodgkin lymphoma from a germinal center B‐cell‐derived mantle cell lymphoma

Composite lymphomas (CL) represent the occurrence of two distinct lymphomas in the same patient. Often, CL share a common cellular origin, thus representing a unique model to investigate the multistep genetic path leading to lymphomagenesis in general and to the specific development of each distinct lymphoma component in particular. Here, we present the molecular analysis of a case consisting of an unusual Hodgkin lymphoma (HL) and a mantle cell lymphoma (MCL), intimately admixed within one another in lymph nodes and bone marrow yet phenotypically distinct, in a patient who first presented with splenic/leukemic MCL two years earlier. MCL and Hodgkin and Reed/Sternberg (HRS) cells harbored identical immunoglobulin (Ig) V_H gene rearrangements with shared somatic mutations, proving their common clonal origin from a (post‐)germinal center (GC) B cell. This also demonstrates the (post‐)GC origin of MCL with mutated IgV genes. Both lymphomas carried the same CCND1/IGH translocation and, unexpectedly for HL, expressed cyclin D1 and OCT2. Thus, HRS cells are able to preserve IGH locus activity (otherwise usually silenced in HL) to promote expression of an oncogene translocated into this locus. Both lymphoma populations further showed an identical TP53 function‐impairing mutation, and later acquired a TP53 heterozygous deletion independently from one another (convergent evolution). The surprisingly close genetic relationship of the lymphomas, together with their histological intermingling and the clinical history of the patient, suggests subclonal evolution of HL from MCL as a plausible pathway in alternative to that so far described in CL, i.e. separate development from a common precursor.     

Expanding control of the tumor cell cycle with a CDK2/4/6 inhibitor

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Mechanisms of therapeutic CDK4/6 inhibition in breast cancer

Cyclin dependent kinase (CDK) 4/6 inhibitors have advanced the treatment of metastatic breast cancer by targeting the cell cycle machinery, interrupting intracellular and mitogenic hormone signals that stimulate proliferation of malignant cells. Preclinical evidence demonstrated that derangements of cyclin D1, CDK4/6, and retinoblastoma expression are common in breast cancer, and suggested a therapeutic benefit from interrupting this axis required for cell cycle progression. Studies of cell lines and animal models of breast cancer have demonstrated the complex interplay between the cell cycle and estrogen receptor and human epidermal growth receptor 2 signaling, which informs our understanding of synergistic use of CDK4/6 inhibitors with endocrine therapy, as well as mechanisms of resistance to endocrine therapy. Interestingly, estrogen receptor activity leads to upregulation of cyclin D1 expression, but the estrogen receptor is also in turn activated by cyclin D1, independent of estrogen binding. Early CDK inhibitors were nonspecific and limited by systemic toxicities, while the current generation of CDK4/6 inhibitors have shown promise in the treatment of hormone receptor-positive breast cancer. Preclinical investigations of the three CDK4/6 inhibitors approved by the US Food and Drug Administration (palbociclib, ribociclib, and abemaciclib) lend further insight into their mechanism of action, which will hopefully inform the future use and refinement of these therapies. Finally, we summarize evidence for additional novel CDK4/6 inhibitors currently in development.     

A CDK4/6 inhibitor enhances cytotoxicity of paclitaxel in lung adenocarcinoma cells harboring mutant KRAS as well as wild-type KRAS

The KRAS gain-of-function mutation confers intrinsic resistance to targeted anti-cancer drugs and cytotoxic chemotherapeutic agents, ultimately leading to treatment failure. KRAS mutation frequency in lung adenocarcinoma is ~15–30%. Novel therapeutic strategies should be developed to improve clinical outcomes in these cases. Deregulation of the p16/cyclin-dependent kinase (CDK) 4/retinoblastoma (Rb) pathway is frequently observed in various cancers and it represents an attractive therapeutic target. We compared the anti-tumor efficacy of genetically knocked-down CDK4 and a pharmacological inhibitor of CDK4/6, CINK4, in KRAS mutation-positive lung adenocarcinoma cells. We also investigated changes in anti-proliferative activity and downstream molecules with these treatments in combination with paclitaxel. CDK4 short interfering RNA (siRNA) significantly increased paclitaxel sensitivity in KRAS mutation-positive H23 cells. CINK4 demonstrated concentration- and time-dependent anti-proliferative activity in 5 adenocarcinoma lines. CINK4 induced G₁ arrest by downregulating the p16/cyclin D1/Rb pathway, resulting in apoptotic induction via increased expression of cleaved caspase3, cleaved PARP and Bax. Combined CINK4 and paclitaxel produced synergistic anti-proliferative activity and increased apoptosis through reduced cyclin D1 and Bcl-2 in KRAS mutation-positive cancer cells. These data suggest CDK4 is a promising target for development of anti-cancer drugs and CINK4 combined with paclitaxel may be an effective therapeutic strategy for enhancing anti-tumor efficacy in KRAS mutation-positive lung adenocarcinoma.     

SPH3643: A novel cyclin‐dependent kinase 4/6 inhibitor with good anticancer efficacy and strong blood‐brain barrier permeability

The cyclin‐dependent kinase (CDK)4/6‐cyclin D1‐Rb‐p16/ink4a pathway is responsible for regulating cell progression past the G₁ restriction point during the cell cycle. The development of a majority of human tumors is associated with dysregulation of this pathway, resulting in increased cancer cell proliferation. Both CDK4 and CDK6, well‐validated cancer drug targets, function primarily as catalytic enzymes that mediate the phosphorylation of retinoblastoma protein (Rb). Here, we determined that SPH3643 is a novel potent antiproliferative agent that inhibits CDK4/6 kinase activity. In biochemical assays, SPH3643 showed more potent inhibition of both CDK4 and CDK6 than did 2 published CDK4/6 inhibitors, LY2835219 and palbociclib, and had better selectivity than LY2835219. Further in vitro study revealed that SPH3643 blocked Cdk/Rb signaling by inhibiting the phosphorylation of Rb^Ser780 and arrested the MCF‐7 cancer cells at G₀/G₁ phase, resulting in marked inhibition of the proliferation of Rb‐positive cancer cell lines. In vivo SPH3643 treatment in mice bearing xenograft tumor models of breast cancer, colon cancer, acute myelocytic leukemia, and glioblastoma resulted in significant decreases in tumor growth. SPH3643 was able to particularly strongly inhibit glioblastoma (U87‐MG) cell growth in the brains of orthotopic carcinoma xenograft mice due to its high degree of intracerebral penetration and significant persistence in this setting. Together these results revealed that SPH3643 is a potent, orally active small‐molecule inhibitor of CDK4/6 with robust anticancer efficacy and a high degree of blood‐brain barrier permeability.     

MYC translocation and/or BCL 2 protein expression are associated with poor prognosis in diffuse large B‐cell lymphoma

Genomic alterations and protein expression levels have been established as prognostic factors for survival in patients with diffuse large B‐cell lymphoma (DLBCL). In particular, double‐hit DLBCL (DHL), which exhibits translocations in MYC and BCL2 and/or BCL6, is known to be associated with a poor prognosis. However, the clinical significance of gene alterations and protein expression levels for MYC, B‐cell lymphoma (BCL)2, and BCL6 are unclear. In this study, we analyzed 61 adult patients diagnosed with DLBCL without DHL, who were treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisolone, or similar regimens. There were no differences in the distribution of MYC expression rates among the different MYC gene statuses. In log–rank tests, MYC translocation was a prognostic factor for overall survival (OS; P = 0.011), whereas BCL2 and BCL6 translocation were not prognostic indicators (P = 0.999 and P = 0.925, respectively). Although the expression levels of MYC and BCL6 were not significantly associated with OS, the expression of BCL2 was a prognostic factor for OS (P = 0.027). Furthermore, copy number gains in the MYC, BCL2, and BCL6 genes did not affect OS. MYC translocation (hazard ratio, 4.769; range, 1.518–14.98; P = 0.007) and BCL2 protein expression (hazard ratio, 3.072; range, 1.002–9.413; P = 0.049) were independent prognostic factors for survival in multivariate analyses. In conclusion, MYC translocation and BCL2 expression may need to be investigated at the initial diagnosis to predict prognosis in patients with DLBCL.     

Ribociclib,a CDK 4/6 inhibitor,plus endocrine therapy in Asian women with advanced breast cancer

The ongoing, Phase Ib MONALEESASIA study is evaluating the efficacy and safety of ribociclib plus endocrine therapy in Asian patients with hormone receptor‐positive, human epidermal growth factor receptor 2‐negative advanced breast cancer. Eligible patients from Japan, Hong Kong, and Singapore were enrolled in this 2‐phase study consisting of a dose‐escalation phase to determine the maximum‐tolerated dose and the recommended Phase II dose of ribociclib plus letrozole, and a dose‐expansion phase to evaluate safety and tolerability of ribociclib plus letrozole, fulvestrant, or tamoxifen. An exploratory biomarker analysis evaluating expression of target genes was also conducted. In the dose‐escalation phase, the maximum‐tolerated/recommended Phase II doses of ribociclib were lower in Japanese patients (300 mg) than in Asian non‐Japanese patients (600 mg). Ribociclib plus endocrine therapy at the recommended Phase II dose had a manageable safety profile, with neutropenia and elevated liver transaminases being the most common adverse events leading to dose modifications or discontinuations, and it demonstrated evidence of clinical activity in both Japanese and Asian non‐Japanese patients. Preliminary efficacy in Asian populations is similar to that observed in White populations studied in previous ribociclib (MONALEESA) trials. Biomarker analysis demonstrated suppression of pharmacodynamic biomarker gene expression, indicating inhibition of target genes by ribociclib combined with endocrine therapy. Results from the ongoing study support the use of ribociclib in combination with letrozole in Asian non‐Japanese patients at the same dose (600 mg) as White patients. In Japanese patients, a lower dose of ribociclib (300 mg) should be considered. Clinicaltrials.gov: NCT02333370.     

Preclinical characterization of SHR6390, a novel CDK 4/6 inhibitor,in vitro and in human tumor xenograft models

Inhibition of the cyclin‐dependent kinase (CDK) 4/6‐retinoblastoma (RB) pathway is an effective therapeutic strategy against cancer. Here, we performed a preclinical investigation of the antitumor activity of SHR6390, a novel CDK4/6 inhibitor. SHR6390 exhibited potent antiproliferative activity against a wide range of human RB‐positive tumor cells in vitro, and exclusively induced G₁ arrest as well as cellular senescence, with a concomitant reduction in the levels of Ser780‐phosphorylated RB protein. Compared with the well‐known CDK4/6 inhibitor palbociclib, orally administered SHR6390 led to equivalent or improved tumor efficacy against a panel of carcinoma xenografts, and produced marked tumor regression in some models, in association with sustained target inhibition in tumor tissues. Furthermore, SHR6390 overcame resistance to endocrine therapy and HER2‐targeting antibody in ER‐positive and HER2‐positive breast cancer, respectively. Moreover, SHR6390 combined with endocrine therapy exerted remarkable synergistic antitumor activity in ER‐positive breast cancer. Taken together, our findings indicate that SHR6390 is a novel CDK4/6 inhibitor with favorable pharmaceutical properties for use as an anticancer agent.     

BCL6 gene rearrangement and protein expression are associated with large cell presentation of extranodal marginal zone B‐cell lymphoma of mucosa‐associated lymphoid tissue

Extranodal marginal zone B‐cell lymphoma of mucosa‐associated lymphoid tissue (MALT lymphoma) is an indolent B‐cell lymphoma, which is often localized in the stomach. It is characterized by typical morphology, immunology, cytogenetics and expression profile. The coexistence of a large B‐cell lymphoma and a MALT lymphoma in the gastrointestinal tract is defined as a composite lymphoma (ComL) and, as we have previously shown, is almost always the consequence of secondary transformation of MALT lymphoma. Here, we have analyzed a panel of seven MALT lymphomas, seven ComL and thirteen large cell variants of marginal zone B‐cell lymphomas (MZBL) using FISH for the detection of rearrangements of IGH, MALT1, BCL6, BCL10 and FOXP1 and immunohistochemistry for Bcl6, Bcl10 and FoxP1. Translocations involving IGH were found in 10/27 lymphomas including two cases with IGH‐BCL6 fusion and one with IGH‐BCL10 fusion; in 7/10 cases, the translocation partner was not identified. Bcl10 and FoxP1 protein expression was heterogeneous throughout the series. Genetic rearrangements of BCL6 and Bcl6 protein expression were found almost exclusively in the large cell components of the ComL and the large cell extranodal MZBL (p = 0.2093 and p = 0.0261, respectively). These findings suggest Bcl6 as a marker for transformation of MALT lymphoma.     

CDK4/6 Inhibition as a therapeutic strategy in breast cancer: palbociclib,ribociclib, and abemaciclib

With 40,920 American women expected to die from breast cancer in 2018 and global health estimates that more than 508,000 women died in 2011 from this disease, the identification of novel therapeutic strategies for the treatment of breast cancer cannot be ignored. A breakthrough class of cancer drugs that has emerged in recent years and has had an impact in the treatment of breast cancer are the cyclin-dependent kinase 4 and 6 (CDK4/6) inhibitors, with palbociclib the first in class to have received regulatory approval for breast cancer. In this article we will compare and contrast three CDK4/6 inhibitors - palbociclib, ribociclib and abemaciclib - that have received regulatory approval for the treatment of metastatic breast cancer. Ribociclib and abemaciclib developed after the success of palbociclib represent examples of "me-too" therapies increasingly being deployed in oncology.     

CDK4/6 inhibitor plus endocrine therapy for hormone receptor‐positive,HER2‐negative metastatic breast cancer: The new standard of care

Patients presenting with hormone receptor‐positive (HR⁺), human epidermal growth factor receptor 2‐negative (HER2^–) metastatic breast cancer (MBC) are usually treated with endocrine therapy (ET), except if there is a concern about endocrine resistance or a need to achieve rapid disease control due to visceral crisis. The combination of CDK4/6 inhibitor + ET has now replaced single‐agent ET as the standard first‐line treatment; and it can also be considered a standard option in the second‐line setting. This review briefly summarizes recently reported efficacy findings from the key phase III clinical trials of CDK4/6 inhibitor + ET in patients with HR⁺/HER2^– MBC, including evidence that adding a CDK4/6 inhibitor to ET improves overall survival and does so without reducing patients’ quality of life. There is still much to learn regarding the use of CDK4/6 inhibitors and how they may be optimally integrated into clinical practice. In particular, there is a need for specific biomarkers that help predict the likelihood of response or resistance to CDK4/6 inhibitor therapy; and for data to guide treatment decisions when a patient's disease progresses on a CDK4/6 inhibitor.     

MLL/KMT2A translocations in diffuse large B‐cell lymphomas

Translocations of the histone‐lysine N‐methyltransferase 2A (KMT2A) gene, formerly known as myeloid lymphoid leukemia/mixed‐lineage leukemia gene, are commonly associated with high‐risk de novo or therapy‐associated B‐cell and T‐cell lymphoblastic leukemias and myeloid neoplasms. Rare B‐cell non‐Hodgkin lymphomas harboring KMT2A translocations have been reported, but information regarding the clinical behavior of such cases is limited. Here, we describe two extranodal diffuse large B‐cell lymphomas (DLBCLs): a primary thyroid DLBCL and a large cell transformation of a splenic marginal zone lymphoma, which displayed complex karyotypes and translocations involving chromosome 11q23 targeting the KMT2A gene. The pathological and clinical characteristics of these cases are discussed in the context of previously reported lymphomas associated with different types of KMT2A genetic aberrations. In contrast to the poor clinical outcomes of patients with acute leukemias and myeloid neoplasms associated with KMT2A translocations, patients with B‐cell non‐Hodgkin lymphomas, exhibiting similar translocations, appear to respond well to immunochemotherapy. Our findings add to the growing list of histone methyltransferase genes deregulated in DLBCL and highlight the diversity of mechanisms, altering the function of epigenetic modifier genes in lymphomas.     

Heat shock protein 90 inhibitor NVP‐AUY922 exerts potent activity against adult T‐cell leukemia–lymphoma cells

Adult T‐cell leukemia–lymphoma (ATL), an aggressive neoplasm etiologically associated with HTLV‐1, is a chemoresistant malignancy. Heat shock protein 90 (HSP90) is involved in folding and functions as a chaperone for multiple client proteins, many of which are important in tumorigenesis. In this study, we examined NVP‐AUY922 (AUY922), a second generation isoxazole‐based non‐geldanamycin HSP90 inhibitor, and confirmed its effects on survival of ATL‐related cell lines. Analysis using FACS revealed that AUY922 induced cell‐cycle arrest and apoptosis; it also inhibited the growth of primary ATL cells, but not of normal PBMCs. AUY922 caused strong upregulation of HSP70, a surrogate marker of HSP90 inhibition, and a dose‐dependent decrease in HSP90 client proteins associated with cell survival, proliferation, and cell cycle in the G₁ phase, including phospho‐Akt, Akt, IKKα, IKKβ, IKKγ, Cdk4, Cdk6, and survivin. Interestingly, AUY922 induced downregulation of the proviral integration site for Moloney murine leukemia virus (PIM) in ATL cells. The PIM family (PIM‐1, ‐2, ‐3) is made up of oncogenes that encode a serine/threonine protein kinase family. As PIM kinases have multiple functions involved in cell proliferation, survival, differentiation, apoptosis, and tumorigenesis, their downregulation could play an important role in AUY922‐induced death of ATL cells. In fact, SGI‐1776, a pan‐PIM kinase inhibitor, successfully inhibited the growth of primary ATL cells as well as ATL‐related cell lines. Our findings suggest that AUY922 is an effective therapeutic agent for ATL, and PIM kinases may be a novel therapeutic target.     

CDK4/6抑制剂联合内分泌治疗对乳腺癌细胞miRNA表达水平的影响

目的:分析CDK4/6抑制剂联合内分泌药物对人乳腺癌细胞中相关miRNA表达水平的影响。方法:培养人乳腺癌细胞MDA-MB-231、SK-BR-3、MCF-7株,使用CDK4/6抑制剂帕布昔利布和内分泌药物阿那曲唑作用于人乳腺癌细胞,MTT法检测细胞增殖情况,BD流式细胞仪检测细胞凋亡和细胞周期情况,采用RT-PCR检测相关miRNA表达情况,Western blot 检测TNF-α、Survivin蛋白表达。结果:在药物作用12 h、24 h、48 h和72 h后的MDA-MB-231研究组、SK-BR-3研究组、MCF-7研究组细胞中miRNA-1321、miRNA-574-5p、miRNA-24-3p的表达水平均较对照组有所下降,而miRNA-1246、miRNA-494-3p、miRNA-29b-3p的表达水平有所升高;MDA-MB-231研究组、SK-BR-3研究组、MCF-7研究组细胞G0/G1期、S期的比例均较对照组细胞均有所升高,而G2/M期比例与对照组相比较均有所下降;MDA-MB-231研究组、SK-BR-3研究组、MCF-7研究组细胞中TNF-α及Survivin的表达水平均较对照组有所上升。结论:CDK4/6抑制剂联合内分泌药物可以调节人乳腺癌细胞中相关miRNA表达水平,从而抑制人乳腺癌细胞增殖。     

Array comparative genomic hybridization identifies genetic regions associated with outcome in aggressive diffuse large B‐cell lymphomas

BACKGROUND:

Diffuse large B‐cell lymphomas (DLBCLs) are the most common type of non‐Hodgkin lymphomas. With chemotherapy and progenitor stem cell transplantation, about 60% of patients with DLBCL are long‐term survivors. The International Prognostic Index identifies patients with different outcomes. However, biologic characteristics also may help to discriminate different treatments groups.

METHODS:

DNA copy number changes identified by array comparative genomic hybridization (array‐CGH) were studied in 40 patients who had DLBCL with a poor prognosis and who were treated uniformly with dose‐escalated cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) and intensification before high‐dose chemotherapy with autologous stem cell transplantation.

RESULTS:

In total, 722 copy number changes were observed (median, 5 copy number changes per patient; range, 0‐75 copy number changes per patient), with a predominance of gains. Gains on 2p16 were present only in patients who failed to achieve a complete response after escalated CHOP therapy (P < .05). In univariate analysis, gains on 2p16 and losses on 17p13 (the tumor protein p53 gene TP53 gene) were associated with a poor response to the therapy. Furthermore, age >60 years and losses on 10q23.31 (the phosphatase and tensin homolog gene PTEN) or on 17p13 were associated with short survival. In multivariate analysis, only advanced age and losses on 10q23.31 retained an adverse prognostic impact.

CONCLUSIONS:

Array‐CGH identified multiple regions with common copy number changes, some of which were associated with outcome in patients with DLBCL. Cancer 2009. © 2009 American Cancer Society.