I have been waiting a long time to see the non-responder data(huge pool of patients) I thought these results were an absolute home run!! Hopefully the sustained response holds up. This was far above any expectation I had in mind!
Peter, I am not sure if you and I are looking at the same data here:
Background and Aims: Boceprevir is a mechanism-based inhibitor of the HCV-NS3 protease. We studied the efficacy and safety of boceprevir and Peginterferon-alfa-2b (PEG-IFN-alfa-2b) in 357 genotype-1 ‘null’ responders to peginterferon/ribavirin (P/R). Methods: All patients had documented <2log10 decrease in HCV-RNA after 12wks of P/R therapy or failure to achieve an undetectable HCV-RNA if treated more than 12 weeks. All patients received PEG-IFN-alfa-2b (1.5µg/kg/wk) plus boceprevir 100/200/400 or 800 mg po TID, or B400/R; the control was P/R/B placebo with cross-over to active boceprevir (400/800) at TW17 for detectable HCV-RNA at TW12. Results: Safety analysis by independent Drug-Safety-Monitoring-Board (DSMB) determined that lower doses of boceprevir were less effective and resistance to boceprevir was increased in the absence of Ribavirin (R). Therefore DSMB recommended all patients who showed a viral response to boceprevir (HCV-RNA <10.000IU) switch to P/R/B800 for an additional 24wks (n=143). Sustained virologic response (SVR) ranged from 2% (control) to 14% but no patients were treated initially, or for >24wks, with P/R/B800. Early response to therapy (HCV-RNA Undetectable <5wks) and viral negativity for >36 wks were major factors determining SVR. End of therapy (EOT) response rates ranged from 6%-32%, being higher in the P/R/B400 and P/B800 groups and highest in control patients who had boceprevir added to their regimen [14/34 (32%)]. Response to the addition of boceprevir was evaluated in the control arm based on P/R response at TW12; all 4 patients with a >2 log10 decrease at TW12 had undetectable HCV-RNA on P/R/B, compared to 50% with a 1-2 log10 decrease, and 20% of those with <1 log10 decrease. Boceprevir resistant variants were detected in the majority of subjects not achieving SVR. The safety of P/R/B800 was similar to that seen with P/R, except for incremental anemia (1-2 gm/dL) and nausea. No increase in skin disorders. Conclusions: Some ‘null’ responders to P/R can achieve an SVR with P/R/B800 but response is dependent on residual interferon responsiveness. Treatment failures to P/R with >2 log10 viral drop at TW12 may be good candidates for P/R/B800 therapy. Initial therapy with P/R, prior to the addition of boceprevir, provides additional benefit.
Good work, Michael. The essence is contained in the paragraph:
In a 28-week treatment regimen in which patients received 4 weeks of PEGINTRON(TM) (peginterferon alfa-2b) and REBETOL(R) (ribavirin, USP) prior to the addition of boceprevir (800 mg TID), the rate of sustained virological response at 12 weeks after the end of treatment (SVR 12) was 57 percent (ITT).(1-3) Importantly, this treatment regimen provided an indication of early predictability of response, with patients who had undetectable virus (HCV-RNA) in plasma after 4 weeks of boceprevir treatment achieving an SVR 12 rate of 86 percent.
The 4wk + 24wk arm has an SVR(12wk)of 57%, and patient achieving an RVR have a chance of 86%. All inferior to PROVE 1 OR 2 results