As expected, the FDA approved the next treatment option for HCV on Friday -- "Viekira Pak", a (sometimes complete) regimen consisting of ritonavir-booted parataprevir and ombitasvir given as a two pills once a day, plus one pill of of dasabuvir given twice daily. It is indicated for treatment of HCV genotype 1.
For those of you mechanistically inclined, parataprevir is a protease inhibitor, ombitasvir an NS5A inhibitor, and dasabuvir the first approved non-nucleoside polymerase inhibitor. Ritonavir is there for PK boosting.
Cure rates have been outstanding -- 90% and higher -- and severe adverse events rare. All good news so far.
So what's the issue? The full prescribing information is here, but this is the key table:
Obviously, many patients will require concomitant administration of ribavirin, which makes this a considerably more complex regimen than the sofosbuvir/ledipasvir combination pill that has been available since October. Two other disadvantages include more drug-drug interactions (ID/HIV doctors are certainly familiar with ritonavir), and the potential for broader antiviral resistance if the treatment fails.
Whether these make a difference or not in clinical practice is a key unknown. But you can bet good Hanukkah gelt that payors are highly motivated to find out. Here's some proof.