In a phase I dose-escalation study, 45 patients received doses of brentuximab vedotin every three weeks, ranging from 0.1 milligrams per kilogram (mg/kg) to 3.6 mg/kg. Among 28 evaluable Hodgkin lymphoma and systemic ALCL patients treated at doses of 1.2 mg/kg and higher, the overall response rate was 54 percent based on investigator assessment, compared to 57 percent based on independent review. At the higher dose levels, 39 percent of patients achieved a complete response based on investigator assessment, compared to 32 percent based on independent review. The median duration of response was at least 7.3 months.

The company is also conducting an ongoing phase I dose-escalation trial of brentuximab vedotin administered weekly to patients with Hodgkin lymphoma or systemic ALCL. Interim data have shown that out of 20 evaluable patients treated at doses of 0.8 mg/kg and higher, 60 percent achieved an objective response, including 50 percent with complete responses. Across all dose levels, 81 percent of patients achieved tumor reductions.

In both phase I clinical trials, brentuximab vedotin has been generally well tolerated. The majority of adverse events were Grade 1 and 2, with the most common being fatigue, fever, peripheral neuropathy, diarrhea and nausea.

About Brentuximab Vedotin

Brentuximab vedotin is an ADC comprising an anti-CD30 antibody attached by an enzyme cleavable linker to a potent, synthetic drug payload, monomethyl auristatin E (MMAE), using Seattle Genetics ™ proprietary technology. The ADC is designed to be stable in the bloodstream, but to release MMAE upon internalization into CD30-expressing tumor cells, resulting in targeted cell-killing.

Seattle Genetics is also conducting a single-agent phase II study of brentuximab vedotin in relapsed and refractory systemic ALCL, as well as a phase II study evaluating the potential for retreatment with brentuximab vedotin in patients who have relapsed after discontinuing previous brentuximab vedotin therapy.

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