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New Dosing Regimen for REYATAZ/ritonavir in Treatment-Experienced Patients

Food and Drug Administration - July 7, 2004
Richard Klein, Kimberly Struble


On July 6, 2004, the Division of Antiviral Drug Products approved a new dosing regimen for REYATAZ. In antiretroviral-experienced patients the new recommended dose is:

REYATAZ 300 mg (two 150 mg capsules) once daily plus ritonavir 100 mg once daily taken taken with food.

For antiretroviral-na ve patients the recommended dose remains as REYATAZ 400 mg (two 200 mg capsules) once daily with food.

The data to support the new dosing regimen came from study AI424-045, a study of patients who had failed at least two regimens containing medications from the three ARV drug classes available at the time of enrollment. This 48-week trial evaluated the efficacy and safety of REYATAZ 300 mg + ritonavir 100 mg once daily or REYATAZ 400 mg + saquinavir 1200 mg once daily compared to lopinavir/ritonavir 400/100 mg twice daily each with tenofovir and an nucleocide reverse transcriptase inhibitor (NRTI).

REYATAZ/ritonavir and lopinavir/ritonavir were similar for the primary efficacy outcome measure of time-averaged difference in change from baseline in HIV RNA level. The HIV RNA change from baseline was -1.58 log10 copies/mL for REYATAZ/ritonavir and -1.70 log10 copies/mL for lopinavir/ritonavir.

Study AI424-045 was not large enough to reach a definitive conclusion that REYATAZ/ritonavir and lopinavir/ritonavir are equivalent on the secondary efficacy outcome measures of proportion below the HIV RNA lower limit of detection. The proportion of patients with HIV RNA < 400 copies/mL and < 50 copies/mL at week 48 was 55% and 38% for REYATAZ/ritonavir and 57% and 45% for lopinavir/ritonavir, respectively.

The major revisions to the package insert are summarized below.

INDICATIONS AND USAGE:

Information that should be considered when initiating therapy with REYATAZ was added as follows. This data pertains to REYATAZ/ritonavir.

The following points should be considered when initiating therapy with REYATAZ:

CLINICAL PHARMACOLOGY

Microbiology

A table was included to provide information regarding HIV RNA response at week 48 by number and type of baseline protease inhibitor mutations and baseline phenotype in treatment-experienced subjects (study AI424-045). In summary, HIV RNA the response rate (< 400 copies/mL) was 75% for both REYATAZ/ritonavir (50/67) and lopinavir/ritonavir (50/67) in patients with 0-2 baseline primary protease inhibitor mutations. In patients with 3-4 baseline primary protease inhibitor mutations the response rates were 41% (14/34) and 43% (12/28) for REYATAZ/ritonavir and lopinavir/ritonavir, respectively. In patients with 5 or more baseline primary protease inhibitor mutations the response rates were 0% (0/9) and 23% (5/18) for REYATAZ/ritonavir and lopinavir/ritonavir, respectively.

 

Table 1: HIV RNA Response by Number and Type of Baseline PI Mutation, Antiretroviral-Experienced Patients in Study AI424-045, As-Treated Analysis

 

Virologic Response = HIV RNA <400 copies/mLb

Number and Type of Baseline PI Mutationsa

ATV/RTV

(n=110)

LPV/RTV

(n=113)

3 or more primary PI mutations including:c

   

D30N

75% (6/8)

50% (3/6)

M36I

20% (3/15)

33% (6/18)

M46I/L/V

24% (4/17)

23% (5/22)

I54V/L/T/M/A

31% (5/16)

31% (5/16)

A71V/T/I

34% (10/29)

39% (12/31)

G73S/A/C

14% (1/7)

43% (3/7)

V77I

47% (7/15)

44% (7/16)

V82A/F/T/S/I

29% (6/21)

27% (7/26)

I84V

13% (1/8)

33% (2/6)

N88D

63% (5/8)

67% (4/6)

L90M

10% (2/21)

44% (11/25)

Number of baseline primary PI mutationsa

All patients, as-treated

58% (64/110)

59% (67/113)

0-2 PI mutations

75% (50/67)

75% (50/67)

3-4 PI mutations

41% (14/34)

43% (12/28)

5 or more PI mutations

0% (0/9)

28% (5/18)

a Primary mutations include any change at D30, V32, M36, M46, I47, G48, I50, I54, A71, G73, V77, V82, I84, N88, and L90.

b Results should be interpreted with caution because the subgroups were small.

c There were insufficient data (n<3) for PI mutations V32I, I47V, G48V, I50V, and F53L.

 

Table 2: Baseline Phenotype by Outcome, Antiretroviral-Experienced Patients in Study AI424-045, As-Treated Analysis

 

Virologic Response = HIV RNA <400 copies/mLb

Baseline Phenotypea

ATV/RTV

(n=111)

LPV/RTV

(n=111)

0-2

71% (55/78)

70% (56/80)

>2-5

53% (8/15)

44% (4/9)

>5-10

13% (1/8)

33% (3/9)

>10

10% (1/10)

23% (3/13)

a Fold change in in vitro susceptibility relative to the wild-type reference.

b Results should be interpreted with caution because the subgroups were small.

WARNINGS

PR Interval Prolongation

The following statement was added - There have been rare reports of second-degree AV block and other conduction abnormalities and no reports of third-degree AV block.

Information regarding reports of first-degree AV block from Study 045 was added.

PRECAUTIONS

A subsection regarding rash was included to state that the incidence of rash in controlled clinical trials (n=1597) was 21%. The median time to onset of rash was 8 weeks after initiation of REYATAZ and the median duration of rash was 1.3 weeks. Rashes were generally mild-to-moderate maculopapular skin eruptions. Dosing with REYATAZ was often continued without interruption in patients who developed rash. The discontinuation rate for rash in clinical studies was 0.4%. REYATAZ should be discontinued if severe rash develops. Cases of Stevens-Johnson syndrome and erythema multiforme have been reported in patients receiving REYATAZ.

Drug Interactions

A change to the clinical comment for the interaction between efavirenz and REYATAZ was made to distinguish the dose adjustment of REYATAZ/ritonavir/efavirenz 300/100/600 mg once daily applies to treatment-na ve subjects. Appropriate dosing recommendations for efavirenz and REYATAZ in treatment-experienced subjects have not been established.


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SOURCE: Food and Drug Administration (FDA).

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