CENTER FOR DRUG EVALUATION AND
`
`RESEARCH
`
`APPLICA TION NUMBER:
`2 1 -976
`
`MICROBIOLOGY REVIEW
`
`

`

`DIVISION OF ANTIVIRAL PRODUCTS
`OFFICE OF NEW DRUGS
`MICROBIOLOGY REVIEW
`NDA: 21—976 SN: 000 DATE REVIEW COMPLETE: 06/19/2006
`
`NDA#: 21—976
`
`Microbiology Reviewer: Lisa K. Naeger, Ph.D.
`Serial #: 000
`
`Reviewer's Name:
`
`Lisa K. Naeger, Ph.D.
`
`Sponsor’s Name and Address:
`
`Tibotec—Virco, USA
`
`2505 Meridian Parkway
`Suite 350
`
`Durham, NC 27713
`
`Initial Submission Dates:
`
`Correspondence Date:
`CDER Receipt Date:
`Assigned Date:
`Review Start Date:
`
`December 23, 2005
`December 23, 2005
`December 23, 2005
`October 15, 2005
`
`Review Complete Date:
`PDUFA Date:
`
`June 14, 2006
`June 23, 2005
`
`Amendments:
`
`Related/Supporting Documents: IND62477
`
`Product N ame(s)
`Proprietary: PREZISTA/rtv
`Non-Proprietary/USAN: Darunavir/rtv; darunavir, TMC114
`Code Name/Number:
`'
`
`Empirical formula: C27H37N3O7S C2H5OH
`Chemical Name: {3—[(4—amino-benzenesu1fony1)—isobuty1—amino]— 1 —benzyl—2-hydroxy—
`propyl} —carbamic acidhexahydro—furo-[2,3-b]furan—3—yl
`ester.ethanolate
`
`Molecular mass: Relative molecular mass: 547.656 (active moiety) + 46.068 (ethanol,
`EtOH) = 593.724 (TMC 11 4-ethano late)
`
`Structural Formula:
`
`'
`
`NH2
`
`on (AIR /u\
`(\uu...»
`I’I-O
`
`R O
`I.
`
`s
`
`0
`
`O
`
`\S/O/
`/ \\
`O
`
`N
`H S
`
`R
`
`N
`
`Darunavir
`
`

`

`DIVISION OF ANTIVIRAL PRODUCTS
`OFFICE OF NEW DRUGS
`MICROBIOLOGY REVIEW
`
`NDA: 21—976 SN: 000 DATE REVIEW COMPLETE: 06/19/2006
`
`Microbiology Reviewer: Lisa K. Naeger, Ph.D.
`
`Drug category: antiviral for HIV infection
`Dosage Form(s): Oral; co—administratz'on ofrz'tonavir as 100—mg soft gelatin capsules
`Route(s) of Administration: Oral
`Indication(s): Combination antiretroviral treatment of HIV—1 infected adult subjects with
`. evidence of viral replication who are heavily treatment—experienced or have HIV-1
`strains resistant to multiple protease inhibitors.
`
`Dispensedsz X
`
`OTC
`
`Abbreviations: ABC, abacavir, APV, amprenavir; ATV, atazanavir; AZT, zidovudine;
`Control, comparator Pl arm; ddl, didanosine; d4T, stavudine; DLV, delavirdine; EFV, efavirenz;
`FTC,
`emtricitabine; HAART,
`highly
`active
`antiretroviral
`therapy; HIV-1,
`human
`immunodeficiency virus-1; 1C, inhibitory concentration; IDV, indinavir; LAM, lamivudine; LPV,
`lopinavir; NFV, nelfinavir; NVP, nevirapine; NNRTI, non-nucleoside reverse transcriptase '
`inhibitor; NRTI, nucleoside reverse transcriptase inhibitor; OBT, optimized background therapy;
`PBMC, peripheral blood mononuclear cells; PCR, polymerase chain reaction; Pl, protease
`inhibitor; /rtv, ritonavir-boosted; RT, reverse transcriptase; SQV, saquinavir; ENF, enfuvirtide;
`TNF, tenofovir; TPV, tipranavir
`
`
`
`EXECUTIVE SUMMARY
`
`It selectively inhibits the cleavage of
`Darunavir is an inhibitor of the HIV—1 protease.
`HIV encoded Gag—Pol polyproteins in infected cells, thereby preventing the formation of
`mature Virus particles. Darunavir exhibits activity against laboratory strains and clinical
`isolates of HIV—1 and laboratory strains of HIV—2 in acutely infected T—cell lines, human
`peripheral blood mononuclear cells and human monocytes/macrophages with median
`EC50 values ranging from 1.2 to 8.5 nM (0.7 to 5.0 ng/ml). Darunavir demonstrates
`antiviral activity in cell culture against a broad panel of HIV—1 group M (A, B, C, D, E, F,
`G), and group O'primary isolates with EC50 values ranging from < 0.1 to 4.3 nM. The
`EC5'0 value of darunavir increases by a median factor of 5.4 in the presence of human
`serum. Darunavir did not show antagonism when studied in combination with the
`protease inhibitors amprenavir, atazanavir,
`indinavir,‘ lopinavir, 'nelfinavir, ritonavir,
`saquinavir,or tipranavir, the N(t)RTls abacavir, didanosine, emtricitabine,, lamivudine,
`stavudine, tenofovir, zalcitabine, or zidovudine, the NNRTIs delavirdine, efavirenz , or
`nevirapine, and the fusion inhibitor enfuvirtide.
`
`Resistance
`
`Cell Culture: HIV—1 isolates with a decreased susceptibility to darunavir have been
`selected in cell culture and obtained from subjects treated with darunavir/ritonavir.
`Darunavir—resistant Virus derived in cell culture from wild—type HIV had 6- to 21—fold
`decreased susceptibility to darunavir and harbored 3 to 6 of the following amino acid
`substitutions S37N/D, R41E/S/T, K55Q, K70E, A71T, T74S, V771, or I85V in the
`protease. Selection in cell culture of darunavir resistant HIV—1 from nine HIV—1 strains
`
`

`

`DIVISION OF ANTIVIRAL PRODUCTS
`OFFICE OF NEW DRUGS
`MICROBIOLOGY REVIEW
`
`NDA: 21—976 SN: 000 DATE REVIEW COMPLETE: 06/19/2006
`
`Microbiology Reviewer: Lisa K. Naeger, Ph.D.
`
`harboring multiple protease inhibitor resistance-associated mutations resulted in the
`overall emergence of 22 mutations in the protease gene, including LIOF, V111, 113V,
`115V, G16E, L231, V321, L33F, S37N, M461, 147V, 150V, F53L, L63P, A71V, G73S,
`L76V, V821, 184V, T9lA/S, and Q92R, of which LIOF, V321, L33F, S37N, M461, 147V,
`150V, L63P, A71V, and I84V were the most prevalent. These darunavir—resistant viruses
`had at least eight protease mutations and exhibited 50— to 64] -fold decreases in darunavir
`susceptibility with final EC50 values ranging from 125 nM to 3461 nM
`
`
`In the Phase 2
`Clinical studies of darunavir/ritonavir in treatment-emnced subiects:
`trials Studies C202, C213 and C215, multiple protease inhibitor—resistant HIV-l isolates
`from highly treatment—experienced subjects who received 600/100 mg darunavir/rtv b.i.d.
`and experienced virologic failure, either by rebound, or by never being suppressed,
`developed amino acid substitutions that were associated with a decrease in susceptibility
`to darunavir. The amino acid substitution V321 developed on darunavir/rtv 600/ 100 mg
`b.i.d. in greater than 30% of virologic failure isolates and substitutions at amino acid 154
`developed in greater than 20% of virologic failure isolates. Other substitutions that
`developed in 10% to 20% of darunavir/rtv virologic failure isolates occurred at amino
`acid positions 115, L33, 147, G73 and L89. The median darunavir phenotype (fold
`change from reference) of the virologic failure isolates was 21—fold at baseline and 94-
`fold at failure.
`
`Cross-resistance
`
`Darunavir has a <10—fold decreased susceptibility in cell culture against 90% of 3309
`clinical
`isolates resistant
`to amprenavir, atazanavir,
`indinavir,
`lopinavir, nelfinavir,
`ritonavir, saquinavir and/or tipranavir showing that viruses resistant to most protease
`inhibitors remain susceptible to darunavir.
`In Studies C202 and C213, 60% (24/40) of
`subjects with decreased susceptibility to tipranavir
`(fold change >3) at baseline
`demonstrated a 1
`logo decrease from baseline at week 24 on darunavir/rtv and 45%
`(18/40) achieved <50 copies/mL serum HIV RNA levels. In Study C215, 60% (64/107)
`of subjects with resistance to tipranavir (>3—fold change) at baseline achieved a 1
`loglo
`decrease from baseline at week 24 on darunavir/rtv and 33% (35/107) achieved <50
`copies/mL serum HIV RNA levels.
`
`indinavir,
`Darunavir—resistant Viruses were not susceptible to amprenavir, atazanavir,
`lopinavir, nelfinavir, ritonavir or saquinavir in cell culture. However, six of nine
`darunavir-resistant viruses selected in cell culture from protease inhibitor—resistant
`viruses showed a fold change in EC50 values <3 for tipranavir, indicative of limited cross—
`resistance between darunavir and tipranavir. Of the viruses isolated from subjects
`experiencing virologic failure on darunavir/ritonavir 600/ 100 mg b.i.d., greater than 50%
`were still susceptible to tipranavir while less than 5% were susceptible to other protease
`inhibitors
`(amprenavir,
`atazanavir,
`indinavir,
`lopinavir, nelfinavir,
`ritonavir,
`or
`saquinavir).
`
`

`

`DIVISION OF ANTIVIRAL PRODUCTS
`OFFICE OF NEW DRUGS
`MICROBIOLOGY REVIEW
`
`NDA: 21— 976 SN: 000 DATE REVIEW COMPLETE. 06/19/2006
`Microbiology Reviewer: Lisa K. Naeger, Ph.D.
`
`Cross-resistance between darunavir and the nucleoside/nucleotide reverse transcriptase
`inhibitors, the non-nucleoside reverse transcriptase inhibitors or the fusion inhibitor is
`unlikely because the Viral targets are different.
`
`Baseline Genotype/Phenotype and Virologic Outcome Analyses
`Genotypic and/or phenotypic analysis of baseline Virus may aid in determining darunavir
`susceptibility before initiation of 600/100 mg b i. d darunavir/rtv therapy.
`As—treated
`analyses were conducted to evaluate the impact of specific baseline protease inhibitor
`resistance—associated mutations and the number of protease inhibitor
`resistance—
`associated mutations at baseline on virologic response. Both specific mutations and the
`number of baseline mutations as well as susceptible drugs in the optimized background
`regimen and enfuvirtide use affected darunavir/11v response rates in Phase 2 Studies C202
`and C213.
`
`The presence at baseline of the mutations V321, l47V, or 154L or M, was associated with
`a decreased virologic response to darunavir and decreased susceptibility to darunavir. In
`addition, a diminished virologic response was observed in subjects with 27 protease
`inhibitor resistance—associated mutations (any change at amino acid positions 30, 32, 36,
`46, 47, 48, 50, 53, 54, 73, 82, 84, 88, or 90) at baseline. The response rate in all
`subgroups (by type and number of mutations at baseline) was generally higher in the
`darunavir/1W group compared to the control group.
`
`Baseline darunavir phenotype (shift in susceptibility relative to reference) was shown to
`be a predictive factor of virologic outcome. Analyses showed that response rates at
`Week 24 decreased when the baseline darunavir phenotype was >7—fold. Phenotypic
`subgroups of 0—2, >2—7, >7-30 and >30 described responses rates in four tiers of 88%,
`73%, 52% and 43% with a 1 logo decrease from baseline, respectively, and 60%, 47%,
`24% and 19% with <50 copies/mL, respectively.
`
`The number of susceptible drugs in the optimized backgrOund regimen and enfiJViItide
`use affected darunavir/rtv response rates. In Studies C202 and C213, subjects with no
`susceptible NRTIs at baseline had lower response rates (38% with 1 logo decrease and
`13% with <50 copies/mL) than those with at least one susceptible NRTI. In addition, for
`subjects with baseline darunavir phenotypes of >10 in studies C202, C213 and C215,
`response rates were 81% (13/ 16) when ENF was used for the first time concomitantly
`with darunavir while response rates were 36% (27/74) for those who did not use ENF
`concomitantly.
`
`
`

`

`DIVISION OF ANTIVIRAL PRODUCTS
`OFFICE OF NEW DRUGS
`MICROBIOLOGY REVIEW
`
`NDA: 21-—976 SN: 000 DATE REVIEW COMPLETE: 06/19/2006
`Microbiology Reviewer: Lisa K. Naeger, Ph.D.
`
`Table of Contents
`
`ExecutiVe Summary
`Recommendations
`
`1.1.Rec0mmendati0ns 0n Approvability
`1.2 Recommendation on Phase 4 Commitments
`
`Summary ofMicrobiology Assessments
`2.1 Non—clinical
`2.2 Clinical
`
`Administrative signatures
`Microbiology Review
`4.1 Important Milestones in Development
`4.2 Methodology
`4.3 State ofantimicrobials usedfor the indication sought
`4.4 Non—clinical Microbiology
`4.5 Clinical Studies
`
`4.6 Clinical Microbiology
`Conclusion
`
`Package Insert
`Appendices
`Appendix A
`Appendix B
`Appendix C
`Appendix D
`Appendix E
`Appendix F
`Appendix G
`
`Page 2
`
`Page 6
`Page 6
`
`Page 7
`Page 8
`Page 10
`
`Pagell
`Pagell
`Pagel3
`Page14
`Page28
`Page30
`Page42
`Page44
`
`Page 48
`Page 50
`. Page 52
`Page 53
`Page 54
`Page 60
`Page 62
`
`AL»
`
`\IG\UI
`
`

`

`DIVISION OF ANTIVIRAL PRODUCTS
`OFFICE OF NEW DRUGS
`MICROBIOLOGY REVIEW
`
`‘
`
`NDA: 21-976 SN: 000 DATE REVIEW COMPLETE: 06/19/2006
`
`Microbiology Reviewer: Lisa K. Naeger, PhD.
`
`1.
`
`Recommendations
`
`1.1. Recommendation and Conclusion on Approvability
`
`This NDA for is approvable with respect to microbiology for combination
`antiretroviral treatment of HIV—1 infected treatment—experienced adult subjects.
`
`1.2. Recommendation on Phase 4 (Post-Marketing) Commitments, Agreements,
`and/or Risk Management Steps, if Approvable.
`
`We request the following to be submitted with traditional approval (included in the
`approval letter of this NDA):
`.
`1) Determine response rates based upon presence of specific cleavage site mutations
`at baseline and submit this analysis with the PREZISTA traditional approval
`application.
`2) Determine the protease cleavage site mutations that occur most frequently (>10%)
`in virologic failure isolates and submit this analysis with the PREZISTA
`traditional approval application.
`3) Determine if the most frequently occurring protease cleavage site mutations
`contributed to decreases in darunavir susceptibility through site-directed
`mutagenesis and submit this analysis with the PREZISTA traditional approval
`application.
`
`

`

`DIVISION OF ANTIVIRAL PRODUCTS
`OFFICE OF NEW DRUGS
`MICROBIOLOGY REVIEW
`
`NDA: 21-976 SN: 000 DATE REVIEW COMPLETE: 06/19/2006
`
`Microbiology Reviewer: Lisa K. Naeger, Ph.D.
`
`2. Summary of Microbiology Assessments
`
`2.1 Non-clinical Microbiology
`
`Complete study reports describing the mechanism of action, antiviral activity, in vitro
`combination activity, in vitro resistance selection and cross—resistance of darunavir were
`submitted and reviewed in this NDA. Enzymatic assays and time of addition studies
`confirmed that darunavir acts as a protease inhibitor. Darunavir had a K; value of <0.09
`nM when tested in enzymatic assays showing that it has comparable inhibition against
`HIV-1 protease as the currently approved PIs. Crystal structures for darunavir bound to
`WT or mutant HIV-l protease showed that darunavir formed van der Waals interactions
`with protease residues L23, G49, 150, P81, V82 and 184 and interacted with residues
`A28, D29, D30, V32, I47 and I50.
`
`The median ECso values of darunavir against laboratory strains HIV-1“113 and HIV—1ND“3
`ranged from 2.3 to 6.3 nM in MTT and cell-based assays. The median EC50 values were
`1.2 nM, 1.7 nM, and 5 nM against HIV—1"“3, HIV-ls”, and HIVBAL, respectively, in
`PBMCs and macrophages/monocytes using a p24 assay. Darunavir demonstrated
`antiviral activity against HIV—2 and SIV with EC50 values less than 10 nM and
`demonstrated activity against all of the HIV—1 subtype isolates evaluated with ECso
`values ranging from <0.1 nM to 4.28 nM. These results indicate that darunavir had
`antiviral activity against a broad range of virus subtypes. The CC50 value in MT4 cells in
`a 5—day MTT assay was >100 uM giving a therapeutic index of >26,000. The 50% toxic
`concentration of darunavir on cell viability was greater than 200 uM for the cell types
`tested.
`
`'
`
`The antiviral activity of darunavir was decreased by a median 52—fold and 5.4—fold by the
`presence of 1 mg/mL AAG and 50% human serum, respectively. No loss of activity was
`observed for darunaVir in the presence of 45 mg/mL human serum albumin with a 1.6—
`fold median change in antiviral activity. The data from in vitro antiviral activity drug
`combination assays showed that darunavir was not antagonistic with any of the currently
`approved antiretroviral drugs and that synergy was observed in vitro with three PIS:
`amprenavir, nelfinavir and ritonavir
`
`In vitro selection experiments were performed starting from wild-type. Replicating
`viruses could not be selected in the presence of darunavir at concentrations above 220 nM
`out to 738 days. Selection of viruses was slower with darunavir in comparison with other
`PIs tested at micromolar concentrations. Darunavir—resistant virus derived in cell culture
`from wild-type HIV had 6— to 21—fold decreased susceptibility to darunavir and harbored
`3 to 6 of the following amino acid substitutions S37N/D, R41E/S/T, K55Q, K70E, A71T,
`T74S, V771, or I85V in the protease. Selection in cell culture of darunavir resistant HIV—
`1
`from nine HIV-1 strains harboring multiple protease inhibitor resistance—associated
`mutations resulted in the overall emergence of 22 mutations in the protease gene,
`including LIOF, V111, 113V, 115V, G16E, L23I, V321, L33F, S37N, M461, I47V, I50V,
`
`

`

`DIVISION OF ANTIVIRAL PRODUCTS
`OFFICE OF NEW DRUGS
`MICROBIOLOGY REVIEW
`
`NDA: 21-976 SN: 000 DATE REVIEW COMPLETE: 06/19/2006
`Microbiology Reviewer: Lisa K. Naeger, Ph.D.
`
`F53L, L63P, A71V, G738, L76V, V821, 184V, T91A/S, and Q92R, of which L10F, V321,
`L33F, S37N, M461, 147V, 150V, L63P, A71V, and 184V were the most prevalent. These
`darunavir—resistant viruses had at least eight protease mutations and exhibited 50- to 641—
`fold decreases in darunavir susceptibility with final EC50 values ranging from 125 nM to
`346] nM.
`
`2.2 Clinical Microbiology
`
`For the clinical microbiology assessment, genotypes and phenotypes from 319 subjects
`(1584 total isolates) from study C202 (POWER 2) and 318 subjects (1767 total isolates)
`from study C213 (POWER 1) were submitted and reViewed for this NDA.
`In addition,
`genotypes and phenotypes from 460 subjects (1935 total isolates from study C215
`(POWER 3) were submitted and reviewed. Subjects in studies C202, C213, and C215
`who rebounded or were never suppressed were analyzed for mutations developing on
`treatment in the FDA analysis.
`‘
`
`The FDA analysis of resistance focused on the comparator PI control group and 600 mg
`darunavir/rtv bid group from studies C202 and C213 since 600 mg darunavir/rtv bid is
`the registrational dosage. Baseline genotypic response analyses were performed only on
`the controlled phase 2 studies C202 and C213 using Week 24 data. Baseline phenotypic
`response analyses were performed on the phenotypic data from studies C202, C213 and
`C215 in order to have a largerpool of data to describe baseline darunavir phenotypic
`subgroups. These baseline response analyses were performed on a censored as-treated
`dataset. Subjects who discontinued while suppressed or discontinued at week 2 were
`censored from the analyses. In addition, the virologic failures from studies C202, C213
`and C215 were analyzed for mutations developing on darunavir/11v treatment.
`
`Resistance
`
`1n the Phase 2 trials Studies C202, C213 and C215, multiple protease inhibitor—resistant
`HIV—1 isolates from highly treatment-experienced subjects who received 600/100 mg
`darunavir/rtv b.i.d. and experienced virologic failure (n=164), either by rebound, or by
`never being suppressed, developed amino acid substitutions that were associated with a
`decrease in susceptibility to darunavir. The amino acid substitution V321 developed on
`darunavir/rtv 600/100 mg b.i.d. in 35% of virologic failure isolates and substitutions at
`amino acid 154 developed in 24% of virologic failure isolates. Other substitutions that
`developed in 10% to 20% of darunavir/rtv virologic failure isolates occurred at amino
`acid positions 115, L33, 147, G73 and L89. The median darunavir phenotype (fold
`change from reference) of the virologic failure isolates was 21-fold at baseline and 94-
`fold at failure.
`'
`
`Cross-resistance
`
`Darunavir has a <10-fold decreased susceptibility in cell culture against 90% of 3309
`clinical
`isolates resistant
`to amprenavir, atazanavir,
`indinavir,
`lopinavir, nelfinavir,
`ritonavir, saquinavir and/or tipranavir showing that viruses resistant to most protease
`
`

`

`DIVISION OF ANTIVIRAL PRODUCTS
`'
`OFFICE OF NEW DRUGS
`MICROBIOLOGY REVIEW
`
`NDA: 21—976 SN: 000 DATE REVIEW COMPLETE: 06/19/2006
`
`Microbiology Reviewer: Lisa K. Naeger, Ph.D.
`
`In studies C202, C213 and C215, 60%
`inhibitors remain susceptible to darunavir.
`(88/147) of subjects with decreased susceptibility to tipranavir (fold change >3) at
`baseline demonstrated a 1 logo decrease from baseline at week 24 on darunavir/rtv and
`36% (53/147) achieved <50 copies/mL serum HIV RNA levels.
`
`indinavir,
`Darunavir—resistant viruses were not susceptible to amprenavir,' atazanavir,
`lopinavir, nelfinavir, ritonavir or saquinavir in cell culture. However, six of nine
`darunavir—resistant viruses selected in cell culture from protease inhibitor—resistant
`Viruses showed a fold change in ECSO values <3 for tipranavir, indicative of limited cross—
`resistance between darunavir and tipranavir. Of the viruses isolated from subjects
`experiencing Virologic failure on darunavir/ritonavir 600/100 mg b.i.d., greater than 50%
`were still susceptible to tipranavir while less than 5% were susceptible to other protease
`inhibitors
`(amprenavir,
`atazanavir,
`indinavir,
`lopinavir, nelfinavir,
`ritonavir,
`or
`saquinavir).
`'
`
`Cross—resistance between darunavir and the nucleoside/nucleotide reverse transcriptase
`inhibitors, the non-nucleoside reverse transcriptase inhibitors or the fusion inhibitor is
`unlikely because the Viral targets are different.
`
`Baseline Genotype/Phenotype and Virologic Outcome Analyses
`Genotypic and/or phenotypic analysis of baseline virus may aid in determining darunavir
`susceptibility before initiation of 600/ 100 mg b.i.d darunavir/rtv therapy. Analyses were
`conducted to evaluate the impact of specific baseline protease inhibitor resistance—
`associated mutations and the number of protease inhibitor resistance—associated mutations
`at baseline on Virologic response. Both specific mutations and the number of baseline
`mutations as well as susceptible drugs in the optimized background regimen and
`enfuviitide use affected darunavir/rtv response rates in Phase 2 Studies C202 and C213.
`
`The presence at baseline of the mutations V321, 147V, or 154L or M, was associated with
`a decreased Virologic response to darunavir and decreased susceptibility to darunavir. In
`addition, a diminished Virologic response was observed in subjects with 27 protease
`inhibitor resistance-associated mutations (any change at amino acid positions 30, 32, 36,
`46,- 47, 48, 50, 53, 54, 73, 82, 84, 88, or 90) at baseline. However, the response rate in all
`subgroups (by type and number of mutations at baseline) was generally higher in the
`darunavir/rtv group compared to the control group.
`
`Baseline darunavir phenotype (shift in susceptibility relative to reference) was shown to
`be a predictive factor of Virologic outcome. Response rates of 340 subjects in studies
`C202, C213, and C215 who received 600/ 100 mg b.i.d darunavir/rtv therapy assessed by
`the baseline darunavir phenotype showed that a baseline darunavir phenotype of greater
`than 7—fold change from reference resulted in decreased response rates at Week 24. The
`subgroup of subjects with baseline darunavir phenotypes of 0-2 had response rates of
`88% (1 logo decrease from baseline) and 60% (<50 copies/mL). The subgroup of
`subjects with baseline darunavir phenotypes of >2—7 had response rates of 73% (1 logo
`
`

`

`DIVISION OF ANTIVIRAL PRODUCTS
`OFFICE OF NEW DRUGS
`MICROBIOLOGY REVIEW ,
`
`NDA: 21—976 SN: 000 DATE REVIEW COMPLETE: 06/19/2006
`
`Microbiology Reviewer: Lisa K. Naeger, Ph.D.
`
`decrease from baseline) and 47% (<50 copies/mL). The subgroup of subjects with
`baseline darunavir phenotypes >7—30 had response rates of 52% (1 log“) decrease from
`baseline) and 24% (<50 copies/mL). The subgroup of subjects with baseline darunavir
`phenotypes >30 had response rates of 43% (1 logo decrease from baseline) and 18% .
`(<50 copies/mL).
`
`The number of susceptible drugs in the optimized background regimen and enfuvirtide
`use affected darunavir/rtv response rates.
`In Studies C202 and C213, subjects with no
`susceptible NRTIs at baseline had lower response rates (38% with 1 log”) decrease and
`13% with <50 copies/mL) than those with at least one susceptible NRTI. In addition, for
`subjects with baseline darunavir phenotypes of >10 in studies C202, C213 and C215,
`response rates were 81% (13/16) when ENF was used for the first time concomitantly
`with darunavir while response rates were 36% (27/74) for those who did not use ENF
`concomitantly.
`
`3. Administrative
`
`3.]. Reviewer’s Signature(s)
`
`
`
`Lisa K. Naeger, Ph.D.
`Sr. Microbiologist, HFD-530
`
`_
`
`3.2. Concurrence
`
`HFD—5 30/Si gnatory Authority
`
`Signature
`
`8
`
`Date
`
`
`HFD—530/Micro TL .
`'
`
`Signature
`
`Date
`
`10
`
`

`

`DIVISION OF ANTIVIRAL PRODUCTS
`OFFICE OF NEW DRUGS
`MICROBIOLOGY REVIEW
`
`.
`
`NDA: 21—976 SN: 000 DATE REVIEW COMPLETE: 06/19/2006
`
`Microbiology Reviewer: Lisa K. Naeger, Ph.D.
`
`Microbiology Review
`
`4.]
`
`Important Milestones in Product Development
`
`January 2005: Submission of Phase II resistance data in the HIV resistance template
`format (SAS datasets) was discussed with the sponsor and agreed upon.
`
`The NDA was proposed for rolling review submission (IND62477 Serial No. 223)
`and accepted by the Division (FDA facsimile correspondence dated April 5, 2005 and
`email correspondence dated April 7, 2005).
`
`June 2005: Discussions were held regarding NDA submission of'virology reports.
`The sponsor stated that the initial Virology Summary would be provided in the
`September 2005 submission and include the currently available in vitro virology data
`and clinical virology data from trials TMCl l4—C201 and TMC114—C207. The in Vitro
`virology part contains Mechanism of Action, In Vitro Drug Resistance, and
`Combinations with current HIV—1 inhibitors. The clinical virology part contains
`exploratory clinical virology data supporting the efficacy in the controlled clinical
`studies. The updated Virology Summary would be provided in the December 2005
`submission to include the available exploratory clinical virology data from trials
`TMCI l4—C202 and TMCl 14—C2l3 to constitute a comprehensive overview of the
`virology of darunavir.
`’
`
`June 2005: In an effort to get as much resistance data as possible, the Division
`requested that the sponsor provide genotypes and phenotypes from study C215. hi
`addition, we requested that sponsor to provide the Cmin and IQ data in the template
`datasets.
`'
`
`4.2 Methodology
`
`Genotypes and phenotypes were determined by default on plasma samples taken at
`’ predefined timepoints (i.e. screening, Week —2, baseline, Week 2, Week 24, Week 48,
`Week 96 and final/withdrawal visit) when the viral load was > 1000 copies/mL.
`Furthermore, samples at other timepoints, such as confirmed virologic failure, were
`also analyzed upon request of the Protocol Virologist. Isolates from subjects from
`Studies C202, C213, and C215 who started from Day 1 on the recommended dose
`(darunavir/rtv 600 mg b.i.d.), and who were rebounders (i.e.: experienced virologic
`failure by rebound) were analyzed for genotypic and phenotypic changes at virologic
`failure compared to baseline.
`
`Note: In the exploratory resistance analysis, virologic failure by rebound was defined
`as viral load > 0.5 logioHlV-l RNA copies/mL above nadir at 2 consecutive visits,
`following a confirmed virologic response of 2 consecutive viral load measurements >
`1 logro HIV-1 RNA copies/mL below baseline.
`
`11
`
`

`

`DIVISION OF ANTIVIRAL PRODUCTS
`OFFICE OF NEW DRUGS
`MICROBIOLOGY REVIEW
`
`NDA: 21—976 SN : 000 DATE REVIEW COMPLETE: 06/19/2006
`
`Microbiology Reviewer: Lisa K. Naeger, Ph.D.
`
`Genotypes and phenotypes from 319 subjects (1584 total isolates) from study C202
`(POWER 2) were submitted for review [63 subjects in 400 mg bid group, 65 subjects
`in 400 mg qd group, 64 subjects from 800 mg qd group 66 subjects from 600 mg bid
`darunavir dosage group and 61 subjects from the control group]. Note: subjects 6603
`and 6604 were mixed up in the treatment arm column, so I assigned 6603 to 4Q and
`6604 to 8Q. Genotypesand phenotypes from 318 subjects (1767 total isolates) from ‘
`study C213 (POWER 1) were submitted for review [63 subjects in 400 mg bid group,
`64 subjects in 400 mg qd group, 63 subjects from 800 mg qd group, 65 subjects from
`600 mg bid darunavir dosage group and 63 subjects from the control group]. In
`addition, genotypes and phenotypes from 460 subjects (1935 total isolates from study
`C215 (POWER 3) were submitted for review. Subjects in study C215 who
`rebounded (n=46) or were never suppressed (n=78) were analyzed in the FDA
`analysis.
`
`The FDA analysis of resistance focused on the control group and 600 mg darunavir
`bid group from studies C202 and C213 since 600 mg darunavir bid is the registration
`dosage. Baseline genotypic response analyses were only done on the controlled
`phase 2 studies C202 and C213, but baseline phenotypic response analyses were done
`on studies C202, C213 and C215. A censored as—treated dataset was used for the
`baseline response analyses. Subjects who discontinued while suppressed or
`discontinued at week 2 were censored. In addition, the virologic failures from studies
`C202, C213 and C215 were analyzed for mutations developing on darunavir
`treatment.
`
`Genotypic Methods
`' Genotypic analyses were performed at Virco by automated population sequencing.
`Individual data were reported as amino acid changes along the PR as compared to the
`HIV—1/HXB2 wild—type reference. Genotypic mixtures (a combination of different
`amino acids at 1 position) were reported. In addition, single genome sequencing
`(SGS) was used to detect mutations that could be missed by population sequencing.
`SGS was performed at Virco on the baseline samples and used to determine whether
`the emerging mutations were selected during the treatment period or were already
`present, at low prevalence, in the baseline species.
`
`Briefly, the HIV-1 complementary DNA (cDNA) region encompassing the PR and
`the first 400 codons of the RT was derived from plasma RNA by reverse transcription
`and amplified by polymerase chain reaction (PCR). The corresponding 2.2 kilobases
`PR—RT fragments were run and extracted from a 1% agarose gel. Ligations and
`
`transformations of these fragments were performed using the
`.
`——-—A—-————————~.
`Sixty—four single colonies were picked
`and resuspended individually in the PCR reaction mix. The cloned HIV—l PR-RT
`segments were then reamplified by PCR and sequenced. For analysis all clones
`mutation profiles were recorded per unique sequences, and a composite profile of the
`overall detected mutations was generated.
`
`12
`
`

`

`DIVISION OF ANTIVIRAL PRODUCTS
`'
`OFFICE OF NEW DRUGS
`MICROBIOLOGY REVIEW
`NDA: 21-976 SN: 000 DATE REVIEW COMPLETE: 06/19/2006
`
`Microbiology Reviewer: Lisa K. Naeger, Ph.D.
`
`Phenotygic Methods ‘
`Phenotypic analyses were performed at Vireo. Recombinant clinical isolates were
`constructed according to the Antivirogram® method. Briefly, protease (PR) and
`reverse transcriptase (RT) coding sequences were amplified from patient—derived
`Viral RNA with HIV—1 specific primers. After homologous recombination of
`amplicons into a PR—RT deleted proviral clone, the resulting recombinant viruses
`were harvested and used for in vitro susceptibility testing. Cut—offs used based on the
`Antivirogram assay to- determine resistance are shown in Table].
`
`Table 1. Resistance Call Determination Using Biological or Clinical Cut-off (FC)
`based on the Antivirogram
`
`- Biolo ital Cut-off (FC)
`
`Clinical Cut-ofi’fFC)
`
`NNRTI
`
`
`
`
`
`4.3 State of antimicrobials used for the indication (s) sought:
`
`An estimated 40 million people worldwide were infected with HIV in 2001 and 3
`million died from AIDS. Since HAART regimens have been introduced, the number of
`AIDS cases has decreased dramatically. HAART does not eradicate HIV from subjects
`completely and even though the number of HIV RNA copies is reduced to undetectable
`levels, HIV re—emerges quickly after discontinuation of HAART. Therefore, with the
`currently available regimens, it is likely that most HIV—infected subjects will require
`antiretroviral therapy throughout their lives.
`
`There are currently over 20 FDA—approved anti—HIV drugs including seven Pls
`(amprenavir/fosamprenavir, atazanavir, indinavir, lopinavir, nelfinavir, ritonavir,
`saquinavir, tipranavir), eight NRTIs (abacavir, didanosine, emtn'citabine, lamivudine,
`
`l3
`
`

`

`DIVISION OF ANTIVIRAL PRODUCTS
`OFFICE OF NEW DRUGS
`MICROBIOLOGY REVIEW
`
`NDA: 21-976 SN : 000 DATE REVIEW COMPLETE: 06/19/2006
`
`Microbiology Reviewer: Lisa K. Naeger, Ph.D.
`
`stavudine, tenofovir, zalcitabine, zidovudine), three NNRTIs (delavirdine, efavirenz,
`nevirapine) and the fusion inhibitor enfuvirtide.‘ PIS work at the late stage of viral
`replication to prevent virus production from infected cells. They block the HIV
`protease enzyme, which is necessary for the production of mature virions, resulting in
`defective particles that are unable to infect new cells. NRTls mimic nucleosides and
`target HIV-1 RT by competing with natural deoxynucleoside triphosphates for binding
`to RT and by incorporating into newly synthesized Viral DNA resulting in chain—
`terrnination. NNRTls inhibit HIV—l RT by binding near the catalytic site of RT and
`. acting as noncompetitive inhibitors. Enfuvirtide (T—20) is a gp4l fusion inhibitor
`preventing the joining of the viral and cellular membranes necessary for virus entry.
`
`Unfortunately, HIV develops resistance to antiretroviral drugs over time usually from
`the accumulation of multiple mutations. HAART regimens are also associated with
`. acute toxicities such as diarrhea, kidney stones, rash, CNS toxicities and hepatotoxicity.
`Long—term toxicities from antiretroviral therapies include mitochondrial toxicities
`associated with NRTls (lactic acidosis, myopathy, neuropathy, pancreatitis), and
`disorders of lipid metabolism (dyslipidemia) and glucose metabolism (lipodystophy,
`hypercholesterolemia, hypertriglyceridemia)