Researchers reported data from two studies of consensus interferon at the Digestive Disease Week 2006 conference, recently held in Los Angeles. Consensus interferon is a recombinant product that contains the most common amino acids from various types of naturally occurring interferon alfa.

Consensus Interferon in Relapsers

In the first study, reported by Stephan Kaiser, MD, from the University of Tuebingen, 81 chronic hepatitis C patients (83% with genotype 1) who relapsed after 48 weeks of prior treatment with pegylated interferon plus ribavirin were retreated with either standard 180 mcg once weekly pegylated interferon alfa-2a (Pegasys) or 9 mcg once daily consensus interferon, both with weight-based ribavirin, for 72 weeks.

Results

After 12 weeks, 83% of patients in the consensus interferon arm achieved undetectable HCV RNA, compared with 78 % in the pegylated interferon arm. At the end of treatment at week 72, 89% in the consensus interferon arm and 76% in the pegylated interferon group had undetectable HCV RNA. Sustained virological response (SVR) rates after the end of therapy were significantly higher in the consensus interferon arm compared with the pegylated interferon arm (69% vs 44%; P < 0.05).

The overall tolerability of consensus interferon was similar to that of pegylated interferon. Patients in the consensus interferon group had more injection site reactions and a slightly higher dropout rate (18% vs 12%). Serious (grade 3) hematological toxicity was more common in the pegylated interferon arm. No patients developed severe (grade 4) neutropenia or thrombocytopenia; no blood cell growth factors were used in this study.

Conclusion

The researchers concluded that extended 72-week treatment with once-daily consensus interferon plus ribavirin showed "promising response rates" compared with pegylated interferon in this population of prior relapsers, most of whom had genotype 1 HCV. Although a significant proportion of patients experienced a second relapse after completion of therapy, the SVR rate with consensus interferon was nearly 70%. They suggested that combination therapy with consensus interferon "may be an effective treatment modality for this difficult-to-treat patient group."

Consensus Interferon in Non-Responders

A second study by the same authors evaluated the efficacy of an induction regimen using consensus interferon in non-responders to prior therapy and a group that is even more difficult to treat than those who initially respond but then relapse. However, most subjects in this study had easier-to-treat non-1 genotypes.

This analysis included 95 patients (9% with genotype 1). Subjects received either 9 mcg once daily consensus interferon monotherapy for 16 weeks, or else 27 mcg once daily consensus interferon for four weeks, followed by 18 mcg once daily for 12 weeks. Thereafter, all patients continued treatment with 9 mcg once daily consensus interferon plus weight-based ribavirin for 32-56 weeks, depending on timing of initial response, so that all received treatment for 48 weeks after achieving undetectable HCV viral load.

Results

Looking at response rates by which type of pegylated interferon was previously used: After the initial 12 weeks of consensus interferon monotherapy, undetectable HCV RNA was observed in 35% of patients previously treated with pegylated interferon alfa-2b (Peg-Intron) and 51% of prior non-responders to pegylated interferon alfa-2a (Pegasys). At the end of treatment, the corresponding rates of undetectable HCV RNA were 37% and 51%. Following the conclusion of treatment, sustained virological response (SVR) rates were 21% and 38%, respectively. Looking at response rates by consensus interferon dosing schedule: SVR rates for Peg-Intron non-responders were 18% in the 9 mcg arm and 25% in the high-dose induction arm. The corresponding SVR rates for Pegasys non-responders were 34% and 41%.

The overall tolerability of the 9 mcg consensus interferon regimen was similar to that seen with pegylated interferon plus ribavirin therapy. Consensus interferon was less well tolerated in the high-dose arm during the induction period. However, dropout rates were similar in the two arms.

Conclusion

The researchers concluded that daily consensus interferon induction therapy followed by treatment with lower-dose consensus interferon plus ribavirin "shows promising response rates in previous pegylated interferon combination therapy non-responders." Patients who previously did not respond to Pegasys appeared to benefit more than those who did not respond to Peg-Intron.

6/09/06

References

S Kaiser, H Hass, B Lutze, M Gregor. Comparison of daily consensus interferon versus peginterferon alfa 2a extended therapy of 72 weeks for peginterferon/ribavirin relapse patients with chronic hepatitis C. Abstract S1060. Digestive Disease Week 2006 (DDW 2006). May 20-25, 2006. Los Angeles, CA.

S Kaiser, H Hass, B Lutze, M Gregor. Higher susceptibility of peginterferon alfa 2a versus peginterferon alfa 2b nonresponder patients with chronic hepatitis C to retreatment with consensus interferon daily dosing and ribavirin. Abstract S1061. DDW 2006. May 20-25, 2006. Los Angeles, CA.

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FDA-approved Monotherapies for HCV

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FDA-approved Combination Therapies for HCV

Pegasys + Copegus PEG-Intron + Rebetol Intron A + Rebetol Roferon A + Ribavirin