Emerging Therapeutic Targets in Diffuse Large B-Cell Lymphoma

OPINION STATEMENT: The standard front-line treatment of Diffuse Large B-Cell Lymphoma (DLBCL) remains Rituximab combined with multi-agent cytotoxic chemotherapy. In spite of high response rates to this therapy, relapsed/refractory disease is observed in up to 40% of patients. It is our opinion that additional chemoimmunotherapy, followed by high-dose therapy with autologous stem cell transplant (HDT-ASCT) for responsive disease, is the optimal therapy for these patients. However, many patients cannot tolerate HDT-ASCT, or have relapsed/refractory disease in spite of it. These patients have a poor overall prognosis, and there is no clear consensus as to how these patients should be treated. Over the past decade, significant advances have been made in the understanding of the molecular genesis and subtyping of DLBCL, leading to the identification of multiple pathways and molecules that can be targeted for clinical benefit. Examples include Bcl-2, Bcl-6, cell surface markers, and myriad molecules in both the B-Cell receptor and PI3K/Akt/mTOR pathways. As agents targeting these molecules and pathways progress from preclinical models to early clinical trials, more is learned about what might predict for response to these agents, such as cell of origin classification, and/or expression of relevant molecular markers, as measured by immunohistochemistry or gene expression profiling. Both the successes and failures of these novel targeted agents promise to dramatically refine, improve, and individualize the classification and treatment of DLBCL. Therefore, it is our opinion that patients with relapsed/refractory DLBCL are an ideal population for clinical trials due to both the lack of standardized treatment, and the recent advancements in pathobiology and early-phase treatment options.

Enzastaurin hydrochloride for lymphoma: reassessing the results of clinical trials in light of recent advances in the biology of B-cell malignancies

INTRODUCTION

The B-cell receptor (BCR) is critical for the development and persistence of B-cell non-Hodgkin lymphoma (B-NHL). Protein kinase C-beta (PKC-?) has been identified as one of the key signaling hubs downstream of the BCR and constitutes a valuable target in B-NHL. As a potent PKC-? inhibitor, enzastaurin is currently being tested in Phase II/III trials.

AREAS COVERED

This review summarizes the latest results and ongoing clinical trials with enzastaurin in light of basic scientific advances in the understanding of various lymphoid cancers, including diffuse large B-cell lymphoma (DLBCL), mantle cell lymphoma (MCL), follicular lymphoma (FL), chronic lymphocytic leukemia (CLL) and Waldenstr?m's macroglobulinemia (WM).

EXPERT OPINION

While its continued clinical development is uncertain, enzastaurin should be regarded as a stepping stone for the development of future therapies; indeed, the recent research has provided valuable insight into the possible molecular mechanisms that explain its limited clinical activity especially in the treatment of DLBCL and MCL. It should be noted that there is still some interest in enzastaurin, in combination, for the treatment of WM.