Interim results from Seattle Genetics’ ADCETRIS phase II trial on CTCL

Seattle Genetics, Inc. (Nasdaq: SGEN) today announced that interim results from an investigator-sponsored phase II clinical trial of ADCETRIS (brentuximab vedotin) in patients with relapsed cutaneous T-cell lymphoma (CTCL) were presented at the Society for Investigative Dermatology annual meeting being held May 9-12, 2012 in Raleigh, NC. ADCETRIS is an antibody-drug conjugate (ADC) directed to CD30. ADCETRIS has not been approved for use in CTCL.

The trial enrolled CTCL patients with mycosis fungoides (MF) or Sezary syndrome. At the time of data analysis, 17 patients had been enrolled, including 16 with MF and one with Sezary syndrome. Patients had received a median of six prior therapies, including a median of four prior systemic therapies. The primary endpoint of the trial is clinical response rate. Secondary endpoints include correlation of clinical response with CD30 expression levels, duration of response, progression-free survival and safety. The study is led by principal investigator Dr. Youn H. Kim, Professor, Department of Dermatology, and Director, Multidisciplinary Cutaneous Lymphoma Program at Stanford University School of Medicine in Stanford, CA. Key findings include:

• Twelve of 16 evaluable patients (75 percent) achieved a partial remission. Three patients had stable disease and one patient had progressive disease. One patient was not yet evaluable for response.
• Median CD30 expression on lymphoid cells in biopsies of skin lesions was 15 percent. Clinical activity was not dependent on CD30 expression levels.
• Sixty-eight percent of patients maintained response at week 25. Median duration of response had not yet been reached.
• Adverse events were mostly Grade 1 or 2, with the most common related events being peripheral neuropathy (76 percent), fatigue (65 percent), decreased appetite (30 percent) and generalized skin eruption (30 percent). The most common event of Grade 3 or higher was generalized skin eruption (18 percent). One patient experienced Grade 4 peripheral neuropathy. There was one patient death due to respiratory failure presumably secondary to pneumonia.

This is the second data set reported with ADCETRIS in CTCL patients. At the T-Cell Lymphoma Forum in January 2012, interim data were presented from a phase II investigator-sponsored trial in CD30-positive CTCL patients, including lymphomatoid papulosis, primary cutaneous anaplastic large cell lymphoma (pcALCL) or MF. In the trial, which is being conducted by Dr. Madeleine Duvic at The University of Texas MD Anderson Cancer Center, 11 of 17 evaluable patients (65 percent) achieved an objective response, including seven complete remissions (CRs) and four partial remissions (PRs). The most common adverse events were Grade 1, including diarrhea, chest tightness, alopecia, nausea, elevated liver enzymes and peripheral neuropathy.

Seattle Genetics and Millennium: The Takeda Oncology Company recently initiated a randomized phase III clinical trial of ADCETRIS for relapsed CD30-positive CTCL patients. The trial will assess ADCETRIS versus investigator's choice of methotrexate or bexarotene in patients with CD30-positive CTCL, including those with pcALCL or MF. The primary endpoint of the study is overall response rate lasting at least 4 months. Approximately 124 patients will be enrolled in the pivotal trial. The phase III trial is being conducted under a Special Protocol Assessment agreement from the U.S. Food and Drug Administration (FDA). The study also received European Medicines Agency scientific advice.