Novel therapies in peripheral T-cell lymphomas

Peripheral T-cell lymphomas (PTCLs) are a rare and heterogeneous group of disorders associated with a very poor prognosis. Historically, treatment protocols have been largely based on regimens used to treat aggressive B-cell lymphomas; unfortunately, the efficacy of these regimens has been suboptimal, with most patients experiencing relapse after initial therapy. An improved understanding of the molecular biology, pathogenesis, and progression of these disorders has led to the development of a variety of novel targeted agents that may improve outcomes in patients with PTCLs. The purpose of this review is to focus on these novel agents and the various treatment approaches that are currently being evaluated in PTCLs.

Pralatrexate is synergistic with the proteasome inhibitor bortezomib in in vitro and in vivo models of T-cell lymphoid malignancies

PURPOSE

Pralatrexate (10-propargyl-10-deazaaminopterin) is an antifolate with improved cellular uptake and retention due to greater affinity for the reduced folate carrier (RFC-1) and folyl-polyglutamyl synthase. Based on the PROPEL data, pralatrexate was the first drug approved for patients with relapsed and refractory peripheral T-cell lymphoma. Bortezomib is a proteasome inhibitor that has shown some activity in patients with T-cell lymphoma.

EXPERIMENTAL DESIGN

Assays for cytotoxicity including mathematical analysis for synergism, flow cytometry, immunoblotting, and a xenograft severe combined immunodeficient-beige mouse model were used to explore the in vitro and in vivo activities of pralatrexate alone and in combination with bortezomib in T-cell lymphoid malignancies.

RESULTS

In vitro, pralatrexate and bortezomib exhibited concentration- and time-dependent cytotoxicity against a broad panel of T-lymphoma cell lines. Pralatrexate showed synergism when combined with bortezomib in all cell lines studied. Pralatrexate also induced potent apoptosis and caspase activation when combined with bortezomib across the panel. Cytotoxicity studies on normal peripheral blood mononuclear cells showed that the combination was not more toxic than the single agents. Western blot assays for proteins involved in broad growth and survival pathways showed that p27, NOXA, HH3, and RFC-1 were all significantly modulated by the combination. In a severe combined immunodeficient-beige mouse model of transformed cutaneous T-cell lymphoma, the addition of pralatrexate to bortezomib enhanced efficacy compared with either drug alone.

CONCLUSION

Collectively, these data suggest that pralatrexate in combination with bortezomib represents a novel and potentially important platform for the treatment of T-cell malignancies.

Novel therapies in peripheral T-cell lymphomas

Peripheral T-cell lymphomas (PTCLs) are a rare and heterogeneous group of disorders associated with a very poor prognosis. Historically, treatment protocols have been largely based on regimens used to treat aggressive B-cell lymphomas; unfortunately, the efficacy of these regimens has been suboptimal, with most patients experiencing relapse after initial therapy. An improved understanding of the molecular biology, pathogenesis, and progression of these disorders has led to the development of a variety of novel targeted agents that may improve outcomes in patients with PTCLs. The purpose of this review is to focus on these novel agents and the various treatment approaches that are currently being evaluated in PTCLs.

Novel Therapies and Role of Transplant in the Treatment of Peripheral T-Cell Lymphomas

Peripheral T-cell lymphomas (PTCL) are an uncommon, heterogeneous group of non-Hodgkin lymphomas that carry a much poorer prognosis than their more common B-cell counterparts. The most commonly used treatment is CHOP or its variations. However, while the results with CHOP are inadequate, there is little compelling data to suggest a preferred alternate strategy. Many of these alternate strategies have been assembled from retrospective data, small case series, subset analyses, phase II studies and individual experience. The greatest experience with alternative treatments has been with the use of high-dose therapy as consolidation. These approaches are promising, but most of the studies are retrospective and include patients with diverse prognoses, making interpretation difficult. Preliminary results of prospective trials in PTCL are only recently being reported. Perhaps more exciting have been the increasing numbers of new therapies being studied for patients with PTCL. The activities of new drugs are being described in studies specifically for PTCL, and attempts at novel combinations are beginning.