Results of a pivotal clinical trial with of single-agent brentuximab vedotin (SGN-35), an antibody-drug conjugate (ADC) targeted to CD30 shows that the trial drug achieved in positive results in the treatment of relapsed and refractory Hodgkin lymphoma (HL).

Hodgkin lymphoma (HL) is distinguished from other types of lymphoma by the presence of one characteristic type of cell, known as the Reed-Sternberg cell. A defining attribute of the Reed-Sternberg cell is its expression of the CD30 antigen.

According to the American Cancer Society, approximately 8,500 cases of Hodgkin lymphoma will be diagnosed in the United States during 2010 and more than 1,300 will die from the disease. Globally, there are more than 30,000 cases of Hodgkin lymphoma diagnosed each year. Although front-line combination chemotherapy can result in durable response rates, up to 30% of these patients relapse or are refractory to front-line treatment and have few therapeutic options beyond ASCT.

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The single-arm pivotal trial assessed efficacy and safety of single-agent brentuximab vedotin in relapsed or refractory, post-autologous stem cell transplant (ASCT) HL patients. Patients received 1.8 milligrams per kilogram of brentuximab vedotin every three weeks for up to 16 total doses. The primary endpoint of the trial was objective response rate as assessed by an independent review facility. Response assessments were based on the rigorous and internationally established Revised Response Criteria for Malignant Lymphoma (Cheson, 2007). Secondary endpoints included complete response rate, duration of response, progression-free survival, overall survival and tolerability. The trial was conducted under a Special Protocol Assessment (SPA) with the FDA and was discussed with the EMA during the process of obtaining EU Centralized Scientific Advice on the brentuximab vedotin development program. Brentuximab vedotin has been granted orphan drug designation by the FDA and EMA for the treatment of HL and ALCL and has been granted fast track designation by the FDA for HL.

The trial was conducted in 102 relapsed or refractory HL patients.

Trial Results
Seventy-five percent of patients in the pivotal trial achieved an objective response as assessed by an independent central review, the primary endpoint of the trial. The median duration of response was greater than six months. The safety profile of brentuximab vedotin in this trial was generally consistent with prior clinical trial experience. A more complete data set will be presented at an upcoming scientific meeting.

“We are extremely excited with the top-line results, as they move us one step closer to our goal of bringing brentuximab vedotin to patients with relapsed or refractory Hodgkin lymphoma,” said Clay B. Siegall, Ph.D., President and Chief Executive Officer of Seattle Genetics. “We are positioned for a Biologics License Application (BLA) submission to the U.S. Food and Drug Administration (FDA) in the first half of 2011. In addition, we plan to report top-line data from our phase II trial of brentuximab vedotin in patients with relapsed or refractory systemic anaplastic large cell lymphoma (ALCL) within the next few weeks.”

“The lack of adequate therapies for the treatment of relapsed and refractory Hodgkin lymphoma represents a substantial unmet medical need worldwide, with almost a third of the 30,000 newly diagnosed patients relapsing or becoming refractory to front-line therapy annually,” said Nancy Simonian, M.D., Chief Medical Officer of Millennium Pharmaceuticals. “These data have the potential to provide an important advance in therapy for Hodgkin lymphoma. We intend to discuss these results with European regulators to support our goal of submitting a Marketing Authorization Application to the European Medicines Agency (EMA) in 2011.”

Brentuximab vedotin is an ADC comprising an anti-CD30 monoclonal antibody attached by an enzyme cleavable linker to a potent, synthetic drug payload, monomethyl auristatin E (MMAE) utilizing Seattle Genetics’ proprietary technology. The ADC employs a novel linker system that is designed to be stable in the bloodstream but to release MMAE upon internalization into CD30-expressing tumor cells. This approach is intended to spare non-targeted cells and thus may help minimize the potential toxic effects of traditional chemotherapy while allowing for the selective targeting of CD30-expressing cancer cells, thus potentially enhancing the antitumor activity.

In addition to the pivotal HL trial, Seattle Genetics and Millennium are conducting a phase II trial for relapsed and refractory systemic ALCL, a phase III clinical trial AETHERA trial) for patients at high risk of residual HL following autologous stem cell transplant, a phase II retreatment trial for relapsed patients who previously responded to brentuximab vedotin, and a phase I combination trial for front-line treatment of HL.


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