How GS-7977+RBV performed in difficult-to-treat group
The following quote is straight out of Clinical Care Options website. The trial was conducted in D.C.by NIH, not by GILEAD. The participants are 73-92% Black, 40-80% male, and 67-84% IL28B CT/TT. You see 7977 is not invincible. My thinking is that VX-135+RBV or VX-135+GSK085 in 12 weeks can do just as well than 24 week dosing done in this trial.
[[ Date posted: 11/15/2012
Interim analysis of NIH/NIAID SPARE trial: 2-part randomized, open-label phase II study in Washington, DC
Summary of Key Conclusions
Peginterferon-free regimen of sofosbuvir (GS-7977) plus ribavirin (RBV) for 24 weeks produced sustained virologic response rates at 4 weeks posttreatment (SVR4) in majority of difficult-to-treat patients chronically infected with genotype 1 HCV
SVR4 77% with full-dose RBV
SVR4 56% with low-dose RBV
Sofosbuvir plus RBV very well tolerated
No safety signals
No drug-related discontinuations
Only 2 grade 3 adverse events reported; no grade 4 adverse events
Sofosbuvir, nucleotide analogue that inhibits HCV polymerase
Potent antiviral activity
Broad genotypic coverage
High barrier to resistance
Acceptable safety and tolerability profile
Currently being studied in combination regimens in multiple clinical trials
Current study evaluated the efficacy, safety, and tolerability of sofosbuvir plus full-dose or low-dose RBV for 24 weeks in treatment-naive patients chronically infected with genotype 1 HCV]]
"Peginterferon-free regimen of sofosbuvir (GS-7977) plus ribavirin (RBV) for 24 weeks produced sustained virologic response rates at 4 weeks posttreatment (SVR4) in majority of difficult-to-treat patients chronically infected with genotype 1 HCV
SVR4 77% with full-dose RBV"
Third, As you commented last week , 7977 and Riba failed miserably as GILD quitely slipped in the results in their last news release based on their reported data quoted below:
So I suspect when the NIH releases their SVR 12 and SVR 24 the results for these harder to treat group will be even worse. I bet GILD wishes the NIH study could have never taken place because if the result for the easy to treat group was so bad, they hate to see what it is going to look like for these harder to treat patients.
Success(90s%) or failure(60s%) of this 7977+RBV regimen for GT2/3 is important for the short term longevity of Incivek sales (off-label use for GT1 patients is possible). It is almost certain that they are not seeing the 100% SVR rate for GT2/3 when the treatment time length is 12 or less weeks contrary to their earlier results. If they can show that this most advanced regimen is better in efficacy than 6 mo. Peg/Rbv (80% SVR rate), then the 7977 regimen could reach the market before 2015, and Incivek sales will plummet well before its launch. If the recently released results (in the 60s %) are valid, then the drug can be used only for those patients who cannot tolerate Interferon, and Incivek sales could survive for another year or two until their triple combo (+5885) could become approved in 2016.