The epigenetics of mantle cell lymphoma

Overcoming nucleoside analog chemoresistance of pancreatic cancer: a therapeutic challenge

Clinical refractoriness to nucleoside analogs (e.g., gemcitabine, capecitabine) is a major scientific problem and is one of the main reasons underlying the extremely poor prognostic state of pancreatic cancer. The drugs' effects are suboptimal partly due to cellular mechanisms limiting their transport, activation, and overall efficacy. Nonetheless, novel therapeutic approaches are presently under study to circumvent nucleoside analog resistance in pancreatic cancer. With these new approaches come additional challenges to be addressed. This review describes the determinants of chemoresistance in the gemcitabine cytotoxicity pathways, provides an overview of investigational approaches for overcoming chemoresistance, and discusses new challenges presented. Understanding the future directions of the field may assist in the successful development of novel treatment strategies for enhancing chemotherapeutic efficacy in pancreatic cancer.

Flipping the cyclin D1 switch in mantle cell lymphoma

Mantle cell lymphoma (MCL) is a rare, aggressive subtype of B cell NHL for which there is no standard of care. It is characterized by the t(11;14) translocation, implicating cyclin D1 (CCND1) in its pathogenesis. Cyclin D1 is one of a family of 3 unlinked D type cyclin genes, CCND1, 2, 3. CCND1 is not expressed in normal B cells. Deregulated expression occurs as a result of juxtaposition of cis IgH enhancer elements, Eμ and 3' Cα, to the cyclin D1 gene. These enhancer elements and regions upstream of the CCND1 gene are hypomethylated on the translocated allele. Histones surrounding the translocation have shown hyperacetylation as well, a hallmark of transcriptionally active chromatin. The t(11;14) translocation is an epigenetic event, leading to cyclin D1 deregulated transcription. These findings provide the rationale for the use of epigenetic and targeted cyclin D1 therapies to overcome resistance and induce durable remissions in MCL.

Mantle cell lymphoma: report of the 2010 Mantle Cell Lymphoma Consortium Workshop

Mantle cell lymphoma (MCL) is an aggressive B-cell non-Hodgkin lymphoma typically characterized by cyclin D1 overexpression as result of the t(11;14) translocation. MCL is biologically and clinically heterogeneous and frequently involves extranodal dissemination. Although MCL is incurable with current therapies, with the exception of allogeneic stem cell transplant, recent advances are improving long-term outcomes in MCL. Intensive research has continued to focus on elucidating biological mechanisms of MCL, identifying new molecular targets, and optimizing existing therapies. Most recently, researchers have begun focusing on new areas such as epigenetics and microRNAs and their potential applications to MCL therapy. Advances across a broad spectrum of MCL research were presented at a recent MCL Workshop. This report provides an overview of the scientific highlights from the meeting and a framework for future research.

Cladribine: not just another purine analogue?

Cladribine was synthesized as a purine analogue drug that inhibited adenosine deaminase. It received FDA approval in the 1980s for treatment of hairy cell leukemia. Given its toxicity towards lymphocytes and its corresponding immunosuppressive effects, it has been studied and found efficacious in a variety of hematologic malignancies and autoimmune conditions, most recently multiple sclerosis. This review highlights pharmacological, toxicological and clinical data for the use of cladribine. It also discusses existing and new mechanisms that may contribute to its unique clinical activity. Emerging data show that in addition to its known purine nucleoside analogue activity, cladribine possesses epigenetic properties, inhibiting S-adenosylhomocysteine hydrolase and DNA methylation. This may contribute to its efficacy and highlights the importance of studying combination therapy with other epigenetic or targeted agents. Clinical trials are underway in a variety of malignant and nonmalignant conditions.

Mantle cell lymphoma: advances in biology and therapy

PURPOSE OF REVIEW

Mantle cell lymphoma is characterized by dysregulation of cyclin D1, but this is not sufficient for lymphoma development. It is a difficult disease to treat, being incurable with standard chemotherapy and having a median survival of approximately 5 years. The purpose of this review is to update recent advances in mantle cell lymphoma biology with prognostic and potentially therapeutic implications, and mantle cell lymphoma treatment approaches and new agents.

RECENT FINDINGS

Genetic alterations that cooperate with cyclin D1 have been described that alter proliferation, in particular p27Kip and p16INK4, or apoptosis. Biological factors such as high-proliferation signature defined by gene expression profiles, loss of p27 and presence of mutant p53 confer poor prognosis. Proliferative rate also predicts patient outcome. Clinical criteria such as the international prognostic index, follicular lymphoma international prognostic index or a formula using age, performance status, white blood cell count and lactate dehydrogenase, separate prognostic groups. Not all patients require therapy at diagnosis. Although the best reported results have been with rituximab-hyperfractionated cyclophosphamide-vincristine-doxorubicin-dexamethasone-methotrexate/cytarabine, a cooperative group study of this regimen appears not quite as successful. Consolidation of remission after rituximab-cyclophosphamide-doxorubicin-vincristine-prednisone with high-dose therapy/stem-cell support prolongs remission and consolidation with radioimmunotherapy shows promise. Intensifying induction by alternating intensified rituximab-cyclophosphamide-doxorubicin-vincristine-prednisone with rituximab and high-dose cytarabine, followed by high-dose therapy appears quite promising. Novel agents active in relapsed disease include bortezomib, mammalian target of rapamycin inhibitors, immunomodulatory agents, antibodies and cyclin pathway-directed agents such as flavopiridol and cyclin-dependent kinase inhibitors.

SUMMARY

New insights into mantle cell lymphoma biology may lead to targeted therapy. Meanwhile, combinations of existing therapeutic approaches seem to have improved outcomes.