Preliminary results from an ongoing Phase 1b/2 clinical trial assessing TRACON Pharmaceuticals' (TCON -6.6%) lead candidate TRC105, combined with Bayer's NEXAVAR (sorafenib), in patients with advanced hepatocellular carcinoma (HCC) demonstrated a treatment effect compared to NEXAVAR alone. The data were presented at the ASCO-GI Symposium in San Francisco.
Partial responses were observed in 25% (n=2/8) of patients while 38% (n=3/8) showed at least a 50% reduction in an HCC tumor marker called alpha fetoprotein (AFP).
Investors appear disappointed with the results, possibly by the low number of data points thus far.
Results from a pivotal Phase 3 study supporting Bayer's marketing application showed HCC patients treated with NEXAVAR experienced median overall survival (OS) of 10.7 months (n=143) and median progression-free survival (PFS) of 5.5 months (n=107), the co-primary endpoints. There was a 2.3% partial response rate (n=7/299) while 70.6% had stable disease (n=211/299), implying a disease control rate of 72.9% (n=218/299). The addition of TRC105, at least preliminarily, produced a ten-fold increase in response rate.
Enrollment of ~33 subjects should be completed by year-end.
TRC105 is an antibody that binds to a protein called endoglin which is overexpressed on proliferating endothelial cells that play an essential role in angiogenesis (formation of new blood vessels).
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