Adefovir clinical studies

Adefovir
HEPSERA® FDA Package Insert
Description
Clinical Pharmacology
Microbiology
Indications and Usage
Contraindications
Warnings and Precautions
Adverse Reactions
Overdosage
Clinical Studies
Dosage and Administration
How Supplied
Labels and Packages

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Clinical Studies

Studies 437 and 438 (Pivotal Studies)

HBeAg-Positive Chronic hepatitis B

Study 437 was a randomized, double-blind, placebo-controlled, three-arm study in patients with HBeAg-positive chronic hepatitis B that allowed for a comparison between placebo and HEPSERA. The median age of patients was 33 years. Seventy-four percent were male, 59% were Asian, 36% were Caucasian, and 24% had prior interferon-α treatment. At baseline, patients had a median total Knodell Histology Activity Index (HAI) score of 10, a median serum HBV DNA level as measured by the Roche Amplicor Monitor polymerase chain reaction (PCR) assay (LLOQ = 1000 copies/mL) of 8.36 log10 copies/mL and a median ALT level of 2.3 times the upper limit of normal.

HBeAg-Negative (Anti-HBe Positive/HBV DNA Positive) Chronic hepatitis B

Study 438 was a randomized, double-blind, placebo-controlled study in patients who were HBeAg-negative at screening, and anti-HBe positive. The median age of patients was 46 years. Eighty-three percent were male, 66% were Caucasian, 30% were Asian and 41% had prior interferon-α treatment. At baseline, the median total Knodell HAI score was 10, the median serum HBV DNA level as measured by the Roche Amplicor Monitor PCR assay (LLOQ = 1000 copies/mL) was 7.08 log10 copies/mL, and the median ALT was 2.3 times the upper limit of normal.

The primary efficacy endpoint in both studies was histological improvement at Week 48; results of which are shown in Table 4.

Table 5 illustrates the changes in Ishak Fibrosis Score by treatment group.

At Week 48, improvement was seen with respect to mean change in serum HBV DNA (log10 copies/mL), normalization of ALT, and HBeAg seroconversion as compared to placebo in patients receiving HEPSERA (Table 6).

Treatment Beyond 48 Weeks

In Study 437, continued treatment with HEPSERA to 72 weeks resulted in continued maintenance of mean reductions in serum HBV DNA observed at Week 48. An increase in the proportion of patients with ALT normalization was also observed in Study 437. The effect of continued treatment with HEPSERA on seroconversion is unknown.

In Study 438, patients who received HEPSERA during the first 48 weeks were re-randomized in a blinded manner to continue on HEPSERA or receive placebo for an additional 48 weeks. At Week 96, 50 of 70 (71%) of patients who continued treatment with HEPSERA had undetectable HBV DNA levels (less than 1000 copies/mL), and 47 of 64 (73%) of patients had ALT normalization. HBV DNA and ALT levels returned towards baseline in most patients who stopped treatment with HEPSERA.

From 141 eligible patients, there were 125 (89%) patients in Study 438 who chose to continue HEPSERA for up to 192 weeks or 240 weeks (4 years or 5 years). As these patients had already received HEPSERA for at least 48 weeks and appeared to be experiencing a benefit, they are not necessarily representative of patients initiating HEPSERA. Of these patients, 89/125 (71%) and 47/70 (67%) had an undetectable HBV DNA level (less than 1000 copies/mL) at Week 192 and Week 240, respectively. Of the patients who had an elevated ALT at baseline, 77/104 (74%) and 42/64 (66%) had a normal ALT at Week 192 and Week 240, respectively. Six (5%) patients experienced HBsAg loss.

Study 435 (Pre- and Post- Liver Transplantation Patients)

HEPSERA was also evaluated in an open-label, uncontrolled study of 467 chronic hepatitis B patients pre- (N=226) and post- (N=241) liver transplantation with clinical evidence of lamivudine- resistant hepatitis B virus (Study 435). At baseline, 60% of pre-liver transplantation patients were classified as Child-Pugh-Turcotte score of Class B or C. The median baseline HBV DNA as measured by the Roche Amplicor Monitor PCR assay (LLOQ = 1000 copies/mL) was 7.4 and 8.2 log10 copies/mL, and the median baseline ALT was 1.8 and 2.0 times the upper limit of normal in pre- and post-liver transplantation patients, respectively. Results of this study are displayed in Table 5. Treatment with HEPSERA resulted in a similar reduction in serum HBV DNA regardless of the patterns of lamivudine-resistant HBV DNA polymerase mutations at baseline. The significance of the efficacy results listed in Table 7 as they relate to clinical outcomes is not known.

Study 461 (Clinical Evidence of lamivudine Resistance)

In Study 461, a double-blind, active controlled study in 59 chronic hepatitis B patients with clinical evidence of lamivudine-resistant hepatitis B virus, patients were randomized to receive either HEPSERA monotherapy or HEPSERA in combination with lamivudine 100 mg or lamivudine 100 mg alone. At Week 48, the mean ± SD decrease in serum HBV DNA as measured by the Roche Amplicor Monitor PCR assay (LLOQ = 1000 copies/mL) was 4.00 ± 1.41 log10 copies/mL for patients treated with HEPSERA and 3.46 ± 1.10 log10 copies/mL for patients treated with HEPSERA in combination with lamivudine. There was a mean decrease in serum HBV DNA of 0.31 ± 0.93 log10 copies/mL in patients receiving lamivudine alone. ALT normalized in 47% of patients treated with HEPSERA, in 53% of patients treated with HEPSERA in combination with lamivudine, and 5% of patients treated with lamivudine alone. The significance of these findings as they relate to clinical outcomes is not known.

Study 518 (Pediatric Study)

Study 518 was a double-blind, placebo-controlled, study in which 173 pediatric patients (ages 2 to less than 18 years) with chronic hepatitis B (CHB) infection and elevated ALT were randomized 2:1 (115 receiving adefovir dipivoxil and 58 receiving placebo). Randomization was stratified by prior treatment and age 2 to less than 7 years old (cohort 1), 7 to less than 12 years old (cohort 2), and 12 to less than 18 years old (cohort 3). All patients in cohort 3 received 10 mg tablet formulation; all patients in cohorts 1 and 2 received an investigational suspension formulation (0.3 mg/kg/day cohort 1, 0.25 mg/kg/day cohort 2) once daily. The primary efficacy endpoint was HBV DNA less than 1000 copies/mL plus normalization of ALT at the end of Week 48.

In cohort 3 (N=83), significantly more patients treated with HEPSERA achieved the primary efficacy endpoint at the end of 48 weeks of blinded treatment (23%) when compared to placebo-treated patients (0%). The proportion of patients from cohorts 1 and 2 who responded to treatment with adefovir dipivoxil was not statistically significant when compared to the placebo arm, although the adefovir plasma concentrations in these patients were comparable to those observed in older patients. Overall, 22 of 115 (19%) of pediatric patients who received adefovir dipivoxil versus 1 of 58 (2%) of placebo treated patients responded to treatment by Week 48 [See Adverse Reactions (6.3), Use In Specific Populations (8.4) and Clinical Pharmacology (12.3, 12.4)].

References

Adapted from the FDA Package Insert.