Nektar Offers Data on Target-Specific Biomarkers from Circulating Tumor Cell Sub-Study of Phase 3 BEACON Study of NKTR-102

Nektar Therapeutics

today presented biomarker data from a sub-study of the Phase 3 BEACON study of etirinotecan pegol (NKTR-102) which collected and analyzed circulating tumor cell (CTC) samples from patients in the study. A total of 80% of the 852 patients enrolled in the BEACON trial participated in the CTC sub-study. Among the 627 patients who participated and had evaluable baseline samples, CTCs were detected in 97% of these samples. For the 611 evaluable baseline patient samples which yielded CTCs, potential NKTR-102 target-specific pharmacodynamic biomarkers (Top1, Top2, and Ki67) were detected in the majority of samples. The pharmacodynamic biomarkers assessed in the CTC sub-study were chosen because of their potential ability to predict response to topoisomerase 1 inhibition as well as to measure chemo-sensitivity in metastatic cancer patients.^1,2,3,4 "We were encouraged to find that the CTC sub-study confirmed the presence of several potential target-specific pharmacodynamic biomarkers, such as topoisomerase 1, in the patients enrolled in our study," said Ivan Gergel, MD, senior vice president drug development and chief medical officer of Nektar Therapeutics. "The analysis from the BEACON CTC sub-study could help us better understand which additional patient populations would benefit from NKTR-102. We expect topline results from the BEACON study to be available in the first quarter of 2015." The data were presented during the 2014 San Antonio Breast Cancer Symposium (SABCS) in San Antonio. NKTR-102 is the first long-acting topoisomerase 1 inhibitor with an extended half-life and a unique molecular structure that is designed to concentrate the drug in tumors. It is currently being evaluated in the Phase 3 BEACON (BrEAst Cancer Outcomes with NKTR-102) study in patients with locally recurrent or metastatic breast cancer who previously have been treated with anthracycline, taxane or capecitabine (ATC). CTCs are cancer cells shed from either the primary tumor or its metastases that circulate in the peripheral blood. CTCs are emerging tumor biomarkers, collected through a minimally invasive blood draw, providing a "liquid" biopsy sample and allowing for post-treatment monitoring of patients. Study Design and Results In this CTC sub-study of the BEACON study, 7.5 mL whole blood samples from patients were drawn and analyzed for the number of CTCs, the percent of cells staining positive for a given biomarker, and the mean fluorescence intensity, reflecting the normalized intensity of the specific biomarker in the biomarker positive CTCs. Results showed that CTCs were detected in 97 percent of 627 evaluable baseline samples. The median number of CTCs per 7.5 mL blood draw was 472, which permitted evaluation of biomarkers at baseline and over the course of treatment. Poster Presentation Details Details of the NKTR-102 poster presentation follow. o Poster Title: Etirinotecan Pegol (NKTR-102) Target-specific Pharmacodynamic Biomarkers in Circulating Tumor Cells from Patients with Metastatic Breast Cancer, Dr. Edith Perez, et al. o Poster Number: P3-10-03 o Session Title/Track: Treatment: Advanced Chemotherapy o Date and Time: Thursday, December 11, 2014, 5:00-7:00 p.m. Central Time, o Location: Henry B. Gonzalez Convention Center, Exhibit Halls A-B