Early study results show a good deal of promise for GS-7340, a newer form of tenofovir. The GS-7340 dose is about 10 times less than Viread, it appears to control HIV better, and it may help reduce side effects currently seen with Viread. GS-7340 will also be studied in a single pill regimen (with cobisistat, Prezista and Emtriva) as well as a replacement for Viread in the upcoming Quad pill.

In a small study of 38 people over 10 days, three doses of GS-7340 were given: 8, 25 and 40mg, compared to the regular dose of Viread. CD4 counts averaged 450. Everyone had viral loads >2,000 copies with no signs of resistance.

The researchers looked at how much viral load had decreased on day 11: placebo (0.07 log), Viread (0.97 log), 8mg (1.08 log), 25mg (1.46 log) and 40mg (1.73 log). Also promising were the lower blood concentration of GS-7340 (79% on 25mg and 98% on 40mg) which could mean fewer side effects including less kidney damage, as well as the higher cellular concentration of GS-7340 (20 times higher on 40mg) which could mean longer and more suppressive control of HIV over time.

The company that makes GS-7340 is moving the 25mg dose forward in other study.