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Bavituximab/Sorafenib Combo Shows Promise in Liver Cancer Trial
Promising clinical data related to the investigational immunotherapy drug candidate bavituximab were presented January 16 at the American Society of Clinical Oncology (ASCO) Gastrointestinal Cancers Symposium, held in San Francisco, California.
In a phase II, single-arm, open-label trial, 38 patients with advanced hepatocellular carcinoma received bavituximab (3 mg/kg) weekly and sorafenib (400 mg) twice daily until disease progression or toxicity occurred.
The data showed that the combination of bavituximab and sorafenib was associated with an improved time to progression of 6.7 months; disease-specific survival of 8.7 months; a disease control rate of 58% (22 of 38 patients); and 4-month progression-free survival of 62%. Two patients (5%) achieved a partial response, as determined by Response Evaluation Criteria in Solid Tumors (RECIST). Median overall survival (a secondary endpoint) was 6.2 months.
Translational data from six patients indicated that half of the patients had experienced an increase in tumor-fighting immune cells after one cycle of bavituximab, similar to what has been shown for phosphatidylserine-targeting antibodies in numerous preclinical cancer models, according to the drug’s developer (Peregrine Pharmaceuticals). In addition, the increase in immune response was associated with patients who remained on study treatment for longer periods, suggesting the possibility of a clinically meaningful anti-tumor immune response.
Three of the six patients evaluated also had increased infiltration of activated tumor-fighting T-cells (CD8) into the tumor microenvironment, which correlated with a prolonged time to disease progression. In addition, these responding patients initially expressed lower levels of programmed cell death protein-1 (PD-1)-positive cells, an established marker of T-cell activation and disease outcome, before the initiation of therapy, which was followed by a measurable increase after bavituximab treatment.
Source: Peregrine Pharmaceuticals; January 16, 2015.