Glembatumumab vedotin is a fully-human monoclonal antibody-drug conjugate (ADC) that targets glycoprotein NMB (gpNMB). gpNMB is a protein overexpressed by multiple tumor types, including breast cancer and melanoma. gpNMB has been shown to be associated with the ability of the cancer cell to invade and metastasize and to correlate with reduced time to progression and survival in breast cancer. The gpNMB-targeting antibody, CR011, is linked to a potent cytotoxic, monomethyl auristatin E (MMAE), using Seattle Genetics’ proprietary technology. Glembatumumab vedotin is designed to be stable in the bloodstream, but to release MMAE upon internalization into gpNMB-expressing tumor cells, resulting in a targeted cell-killing effect. Glembatumumab vedotin is in development for the treatment of locally advanced or metastatic breast cancer—with an initial focus in triple negative disease. This program is also in development for the treatment of Stage III and IV melanoma.
Breast Cancers Expressing gpNMB
In late 2012, Celldex completed the Phase 2 EMERGE study in metastatic breast cancer. This exploratory study was prospectively designed to enable the Company to analyze if potential clinical benefit could be linked back to gpNMB expression levels. Final data from the study were presented at the 2012 San Antonio Breast Cancer Symposium and supported a clinical benefit in heavily pre-treated breast cancer patients with tumors that over-express gpNMB, quantified as expression in greater than 25% of tumor cells.
EMERGE: Overall Response Rate and Disease Control Data in Breast Cancer
EMERGE: Overall Survival and Progression Free Survival Data in Breast Cancer
The METRIC Study in Triple Negative Breast Cancer
In December 2013, Celldex initiated a randomized study, called METRIC, evaluating glembatumumab vedotin in patients with gpNMB over-expressing triple negative breast cancer. Patients are currently being screened in up to 100 sites in the United States, Canada and Australia. Approximately 300 patients are being randomized (2 to 1) with metastatic triple negative breast cancers that over-express gpNMB and who have received standard therapies, including anthracycline, if clinically indicated, and taxane treatments. The study is a direct comparison of glembatumumab vedotin versus capecitabine, also known by the trade name Xeloda®. The primary endpoint for this study is progression free survival. Please visit www.MetricStudy.com or clinicaltrials.gov for more information on this trial.
For more information on the glembatumumab vedotin program, view recent scientific presentations and publications.
Xeloda is a registered trademark of Genentech, a member of the Roche Group.
Melanomas Expressing gpNMB
More than 85% of patients with metastatic melanoma express gpNMB, making it an attractive target for study of glembatumumab vedotin. In 2010, data from a Phase 2 study of glembatumumab vedotin were presented at the American Society of Clinical Oncology Annual Meeting which demonstrated significant activity in advanced melanoma patients. In the study, the primary activity endpoint of overall response rate (ORR) was achieved with an ORR of 15% (5/34). Median progression free survival (PFS) was 3.9 months. More frequent dosing schedules were evaluated in two additional, parallel dose-escalation arms in which patients received glembatumumab vedotin weekly or twice every three weeks. At the maximum tolerated doses in these schedules, the response rate was observed to be 20% (n=15) and 33% (n=6), respectively. Preliminary data suggest an increase in PFS in patients with high tumoral gpNMB expression. The subset of seven patients, whose tumors were found to express high amounts of gpNMB, and who were treated at the maximum tolerated doses across all dosing schedules, demonstrated a median PFS of 4.9 months. In December 2014, the Company initiated an open-label Phase 2 study of glembatumumab vedotin in patients with unresectable Stage III or IV melanoma.
In addition to triple negative breast cancer and metastatic melanoma, Celldex plans to evaluate glembatumumab vedotin in other indications in which gpNMB is highly expressed, including squamous cell lung cancer, osteosarcoma, uveal melanoma and pediatric sarcoma.