Shares in Sangamo BioSciences plummeted over 30% yesterday on the news that the firm was shelving further development of its lead candidate, SB-509 for diabetic neuropathy, due to poor Phase IIb study results. SB-509 comprises a plasmid encoding zing finger DNA-binding protein (ZFP) transcription factor (TF), designed to upregulate endogenous VEGF-A expression.
Sangamo's stock price dropped as low as $3.25 in early morning trading yesterday after closing Friday at $4.35. It finally closed Monday at $3.02, a 30.57% drop in value.
The placebo-controlled trial in 170 subjects evaluated the effects of SB-509 on nerve conduction velocity in the sural nerve as the primary endpoint along with neurological impairment score in the lower limb (secondary endpoint) and other exploratory endpoints including lower extremity neurological sensory examination (LENSE), quality of life assessments, and intraepidermal nerve fiber density (IENFD).
The trial failed to meet its primary endpoint at 180 days and also missed its secondary endpoint and IENFD endpoints, although, the drug did provide clinically relevant improvements in the mean total LENSE score.
“Based on these results, we will discontinue further development of SB-509 and will focus our attention and resources on our pipeline of ZFP therapeutics for HIV and monogenic diseases,” notes Edward Lanphier, Sangamo president and CEO.
The firm’s SB-728 program is a ZFP-nuclease-based approach to modifying the gene encoding CCR5, the major HIV co-receptor. Lead candidate, an autologous ZFN-CCR5-modified T-cell product (SB-728-T), is being evaluated in a Phase I/II and two Phase I trials in subjects with HIV and AIDS. Positive data from Phase I studies evaluating the therapeutic candidate in HIV patients receiving HAART therapy were presented in September. Additionally, an SB-728 hematopoietic stem cell (HSC) product is in preclinical development.