TUSTIN, CA 02/13/13 — Peregrine Pharmaceuticals announced results from its 70 patient open-label, randomized Phase II clinical trial of bavituximab used in combination with gemcitabine in patients with previously untreated, advanced Stage IV pancreatic cancer. The trial included the enrollment of patients with advanced metastatic disease including significant liver involvement and poor performance status associated with rapid disease progression. Results showed that the combination of bavituximab and gemcitabine resulted in more than a doubling of overall response rates (ORR) and an improvement in overall survival (OS) when compared with gemcitabine alone (control arm). In the trial, patients treated with a combination of bavituximab and gemcitabine had a 28% tumor response rate as compared to 13% in the control arm. Median OS, the primary endpoint of the trial, was 5.6 months for the bavituximab plus gemcitabine arm and 5.2 months for the control arm (hazard ratio = 0.75).
Bavituximab binds to phosphatidylserine which is exposed on the surface of certain atypical animal cells, including tumour cells and cells infected with any of six different families of virus. These viral families contain the viruses hepatitis C, influenza A and B, HIV 1 and 2, measles, respiratory syncytial virus and pichinde virus, which is a model for the deadly Lassa virus. Other cells are not affected since phosphatidylserine normally is only intracellular.
These target aminophospholipids, usually residing only on the inner leaflet of the plasma membrane of cells, become exposed in virally infected, damaged or malignant cells, and more generally in most cells undergoing the process of apoptosis.
The antibody’s binding to phospholipids alerts the body’s immune system to attack the tumor endothelial cells, thrombosing the tumor’s vascular network and/or attacking free floating virally infected and metastatic cells while potentially minimizing side effects in healthy tissues.
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