Targets, Toxins, and T Cells--a Review of New Monoclonal Antibodies in the Treatment of Peripheral T Cell Lymphomas

The peripheral T cell lymphomas (PTCLs) are a heterogeneous group of neoplasms for which standardized treatment approaches remain elusive. A number of new therapeutic agents have become available, of which monoclonal antibodies (MAbs) represent a powerful tool for targeted treatment of PTCLs. Therapeutic MAbs vary in their structure, targets, and mechanisms of action. Common mechanisms of action include antibody-dependent cell-mediated cytotoxicity, complement-dependent cytotoxicity, direct apoptosis, blocking of receptors or signaling pathways, delivery of cytotoxic agents to tumor cells, and binding to and blocking biologically active molecules. This review will focus on recent published evidence for the various MAbs used in the treatment of PTCLs. The results overall have been very promising, and the future will see more trials with these antibodies alone and in various therapy combinations, as well as newer ones with novel modifications, conjugates, and targets.

Brentuximab vedotin for Hodgkin lymphoma and systemic anaplastic large cell lymphoma: a review of clinical experience and future directions

SUMMARY Brentuximab vedotin is a novel agent indicated for the treatment of relapsed and refractory Hodgkin lymphoma and systemic anaplastic large cell lymphoma. Brentuximab vedotin is an antibody–drug conjugate consisting of chimeric anti-CD30 antibody cAC10, linked to four molecules of monomethylauristatin E, a tubulin destabilizer. It was granted US FDA approval in 2011 following two pivotal Phase II studies showing objective responses of 75 and 86% in heavily pretreated relapsed and refractory Hodgkin lymphoma and systemic anaplastic large cell lymphoma, respectively. Brentuximab vedotin can be used as a bridge to more definitive stem cell transplant. There are currently over 30 open clinical studies involving the use of brentuximab vedotin used as single agent or combined with chemotherapy in both front-line and salvage settings. These studies include use in other CD30-positive B- and T-cell lymphomas, as well as in CD30-positive germ cell tumors. In clinical practice brentuximab vedotin has been associated with significant sensory and motor neuropathies and clinicians should be alert to the potential for significant neuropathy and the need for dose reduction. However, the potential for significant neuropathy must be balanced against the remarkable clinical benefit of brentuximab vedotin in patients with heavily pretreated relapsed and refractory lymphomas.

Drug conjugates such as Antibody Drug Conjugates (ADCs), immunotoxins and immunoliposomes challenge daily clinical practice

Drug conjugates have been studied extensively in preclinical in vitro and in vivo models but to date only a few compounds have progressed to the clinical setting. This situation is now changing with the publication of studies demonstrating a significant impact on clinical practice and highlighting the potential of this new class of targeted therapies. This review summarizes the pharmacological and molecular background of the main drug conjugation systems, namely antibody drug conjugates (ADCs), immunotoxins and immunoliposomes. All these compounds combine the specific targeting moiety of an antibody or similar construct with the efficacy of a toxic drug. The aim of this strategy is to target tumor cells specifically while sparing normal tissue, thus resulting in high efficacy and low toxicity. Recently, several strategies have been investigated in phase I clinical trials and some have entered phase III clinical development. This review provides a detailed overview of various strategies and critically discusses the most relevant achievements. Examples of the most advanced compounds include T-DM1 and brentuximab vedotin. However, additional promising strategies such as immunotoxins and immunoliposmes are already in clinical development. In summary, targeted drug delivery by drug conjugates is a new emerging class of anti-cancer therapy that may play a major role in the future.

Brentuximab vedotin

Brentuximab vedotin (SGN-35), an intravenously administered CD30-specific antibody-drug conjugate, has recently been approved by the U.S. Food and Drug Administration for two indications, including (i) patients with Hodgkin lymphoma relapsing after autologous stem-cell transplantation (ASCT), or after two multidrug regimens in patients with Hodgkin lymphoma who are not candidates for ASCT; and (ii) patients with systemic anaplastic large cell lymphoma (ALCL) who failed at least one prior multidrug chemotherapy regimen. Patients with Hodgkin lymphoma and ALCL treated with brentuximab vedotin showed markedly high response rates for a single agent, exceeding 70% and 80% for Hodgkin lymphoma and ALCL, respectively. The complete response rate was equally as impressive, at 34% and 57% for Hodgkin lymphoma and ALCL, respectively. Results like these and from many other upcoming clinical trials, in which brentuximab vedotin is being investigated in the frontline setting, promise to profoundly change how we manage the CD30-positive lymphoproliferative malignancies. The mechanism of action, preclinical antitumor activity, and clinical activity of brentuximab vedotin against Hodgkin lymphoma, ALCL, and other CD30-expressing lymphomas are reviewed.