Seattle Genetics reports SGN-75 phase I clinical trial data

Seattle Genetics, Inc. (Nasdaq:SGEN) today reported data from a phase I clinical trial of SGN-75 in patients with non-Hodgkin lymphoma or renal cell carcinoma (RCC). Preliminary results demonstrate tolerability and antitumor activity, including two objective responses in the first 16 patients treated. Dose-escalation is continuing. SGN-75 is an antibody-drug conjugate (ADC) targeted to CD70. The data were presented at the 35th European Society for Medical Oncology (ESMO) Congress being held in Milan, Italy.

“We are continuing to dose escalate in this trial to further assess the safety and activity of SGN-75, as well as to establish the optimal dosing regimen for future clinical trials.”

"These preliminary data are encouraging, and show initial evidence of antitumor activity with SGN-75 in patients with relapsed/refractory non-Hodgkin lymphoma or metastatic RCC," said Jonathan Drachman, M.D., Senior Vice President, Research and Translational Medicine of Seattle Genetics. "We are continuing to dose escalate in this trial to further assess the safety and activity of SGN-75, as well as to establish the optimal dosing regimen for future clinical trials."

Data were reported from 16 patients in the open-label phase I clinical trial, including seven with non-Hodgkin lymphoma and nine with RCC. Cohorts of patients received SGN-75 either every three weeks at doses ranging from 0.3 to 2.0 milligrams per kilogram (mg/kg) or on a weekly basis at a dose of 0.3 mg/kg. Enrolled patients in each indication had received a median of three prior systemic therapies.

Best clinical response among non-Hodgkin lymphoma patients included one patient with a complete remission, four patients with stable disease, one patient with progressive disease and one patient who was not evaluable. Best clinical response among RCC patients included one patient with a partial response, three patients with stable disease and five patients with progressive disease. The most common adverse events were fatigue, nausea and peripheral edema (swelling). A maximum tolerated dose has not been established with either dosing schedule and dose escalation continues. (Abstract #532P)

The single-agent phase I study of SGN-75 was initiated in November 2009 and is designed to enroll up to approximately 80 patients at multiple centers in the United States. The trial is evaluating the safety, tolerability, pharmacokinetic profile and antitumor activity of SGN-75. Patients enrolled in the trial must have received at least one prior therapy and have confirmed CD70 expression.

SGN-75 is an ADC comprising an anti-CD70 antibody attached to a potent, synthetic cell-killing agent, monomethyl auristatin F (MMAF), using Seattle Genetics' proprietary technology. The ADC is designed to be stable in the bloodstream, and to release its cell-killing agent upon internalization into CD70-expressing tumor cells. This approach is intended to spare non-targeted cells and thus reduce many of the toxic effects of traditional chemotherapy while enhancing the antitumor activity.