Tobira Therapeutics Inc., a clinical stage biotechnology company committed to research and product discovery for the treatment of life-threatening and life-altering infectious diseases, today announced results from an in vitro study evaluating TBR-652 in combination with lopinavir (LPV), darunavir (DRV), atazanavir (ATV), tenofovir (TDF), etravirine (ETV), and raltegravir (RAL) using the infectious replicative assay deCIPhR. Cytotoxicity (cell number, morphology) was also assessed. The average 50% inhibitory concentration (IC50) for TBR-652 was 0.99+0.19 (range 0.72-1.43) nM. Weak synergy was seen in combinations of TBR-652 with LPV (IC50 26.90-40.27 nM), ATV (IC50 57.66-78.89 nM), DRV (IC50 2.12-2.78 nM) and ETV (IC50 71.77-83.35 nM). Additive effects were seen with TBR-652 plus TDF (IC50 10.66-11.13 nM) or RAL (IC50 29.66-103.72nM). Importantly, no antagonism and no cytoxicity were observed with any 2-drug combination at any concentration tested.
"These in vitro results provide evidence that combination regimens containing TBR-652 and one or more of these agents are possible and should be further evaluated in HIV-infected patients," said James Sapirstein, CEO.
These data were presented at the 49th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC), held September 12-15, 2009 in San Francisco, California. The poster presentation can be viewed at www.tobiratherapeutics.com.