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Summary of Considerations: Assessing the Overall Risks and Benefits of Telithromycin (Ketek®). FDA Anti-Infective Drugs Advisory Committee December 14-15, 2006 Rosemary Johann-Liang, MD Deputy Director Division of Drug Risk Evaluation Office of Surveillance and Epidemiology.

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Summary of considerations assessing the overall risks and benefits of telithromycin ketek l.jpg

Summary of Considerations: Assessing the Overall Risks and Benefits of Telithromycin (Ketek®)

FDA Anti-Infective Drugs Advisory Committee

December 14-15, 2006

Rosemary Johann-Liang, MD

Deputy Director

Division of Drug Risk Evaluation

Office of Surveillance and Epidemiology


Re assessment of ketek evaluation of evidence l.jpg
Re-assessment of Ketek: Evaluation of Evidence

  • Based upon the evidence, does the benefit outweigh the risk (harm) in the year 2006 for each of the three currently approved indications

    • Acute Exacerbation of Chronic Bronchitis (AECB)

    • Acute Bacterial Sinusitis (ABS)

    • Mild to Moderate Community Acquired Pneumonia (Outpatient CAP)

  • Approvals of indications are based on diseases, not organisms


Evaluation of evidence l.jpg

Safety Assessment

Analysis of Harm from medical intervention

“totality of Evidence”

Efficacy Assessment

Analysis of Benefit from medical intervention

“Substantial Evidence”

Evaluation of Evidence


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Ketek Risk Summary: Totality of Evidence

Ketek Risk in Perspective

Antibiotic use data

Other antibiotics for similar indications

Outpatient (oral only) Use Antibiotics

Cumulative exposure/Approval dates: safety track record

Toxicity Profiles of Appropriate Antibiotic Comparators

Ketek Benefit in Perspective

Non-inferiority Trial design: Evidence of Benefit??

Ketek Efficacy Summary: Substantial Evidence??

AECB

ABS

Outpatient CAP

Ketek Risk to Benefit


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Ketek Risk Summary

  • Risks Highlighted in OSE presentations

    • Hepatotoxicity

    • Visual toxicity

    • Loss of consciousness

    • Exacerbation of myasthenia gravis (MG)

  • Currently labeled under Warnings/Precautions

  • Clinical Characteristics of Ketek Toxicity

    • Cannot Mitigate Risk

    • Must define population that would benefit from drug that justifies the risks


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Reporting Rates by million person-yrs: “Rapid” Hepatotoxicity(Graham D. NEJM 355; 21: 2260-61 with additional analyses by DG)


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Rapid Clinical Toxicity Manifestation Hepatotoxicity

  • Vision Disorders

    • Of those reporting, more than half of the cases: first day of therapy within an hour or two of the dose

  • Disturbances of Consciousness

    • Of those reporting, over 70% with onset within first day of therapy with majority within 2 hours

  • Exacerbation of MG

    • 70% of cases with onset occurring after the first dose with median time of 1.25 hours.


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Top 10 ICD-9 3-digit Diagnosis Codes Associated with U.S. Drug Uses for Oral Antimicrobials Year 2005

Source: Verispan, LLC Physician Drug and Diagnosis Audit (PDDA). Data extracted 8/23/2006. Review by Carol Pamer, RPh


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Total Dispensed US Retail Prescriptions for Oral Antimicrobials Year 2005

Source: Verispan, LLC Vector One: National (VONA). Data extracted 8/23/2006.Review by Carol Pamer, RPh


Ketek risk in perspective l.jpg
Ketek: Risk in Perspective Antimicrobials Year 2005


Selected highlights of risk labeling warning precautions l.jpg

Β Antimicrobials Year 2005-lactams

Anaphylaxis/Hypersensitivity

Pseudomembranous colitis

Hepatic toxicity (Augmentin®)

Macrolides

Pseudomembranous colitis

Hepatic dysfunction (increased liver enzymes, hepatocellular and/or cholestatic hepatitis)

Drug interactions resulting in QT prolongation, ventricular arrythmias, and torsades de pointes

erythromycin

Inadequate concentrations to fetus to prevent congenital syphilis

Rhabdomyolysis with or without renal impairment with lovastatin

myasthenia gravis aggravation

Infantile hypertrophic pyloric stenosis (IHPS)

azithromycin

Rare serious allergic reaction

clarithromycin

Do not use in pregnant woman - adverse effects in animal pregnancy

Fluoroquinolones

Peds safety and efficacy not established (except Cipro)

Convulsions and toxic psychoses

Hypersensitivity/anaphylactic reactions

Peripheral neuropathy

Pseudomembranous colitis

Tendonopathy

Moderate to severe phototoxicity

Dysglycemia

Torsades de pointes

--------------------------------------

Levofloxacin and Moxifloxacin are also approved for more “serious indications” and have IV dosage form

Gemifloxacin: precaution on ↑ rash

Selected Highlights of Risk: Labeling: Warning/Precautions


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Cumulative US Exposures 1/1995 – 6/2006: Antimicrobials Year 2005Oral Antimicrobial Molecules

Source: Verispan, LLC Vector One®: National (VONA). Data extracted 8/23/2006.


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Approved Indications/Dosage Forms Antimicrobials Year 2005 (Modified from Farinas E. Appendix Table: Factive® AERS Review 9/06)


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Most Appropriate Comparisons Antimicrobials Year 2005

  • Cefditoren

    • Safety Profile does not appear to stand out from class: cephalosporins

  • Gemifloxacin

    • Safety Profile like other FQ: ↑ cutaneous reactions

    • FDA Advisory Meeting 9/06 for ABS: Vote 11-2; no evidence of efficacy, risk not justified; sNDA withdrawn

  • Telithromycin

    • Safety Profile like other macrolides: special senses, liver, QT?

    • UNIQUE and Notable toxicities


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Hepatotoxicity Antimicrobials Year 2005

Drug-injury

Rapid Clinical deterioration

Exacerbation of MG

Drug-injury

Rapid clinical deterioration

Visual toxicity

Seen in clinical trials; Drug-induced

Sudden blurry vision

Loss of consciousness

Not just syncope; Mechanism unknown

Umbrella of issues: neurological? cardiac?

Sudden loss

Rapid/Sudden Clinical Toxicity Manifestations

Cannot mitigate risk

Must define population to benefit from drug that justifies the risks

Ketek Risk in Perspective


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Safety Assessment Antimicrobials Year 2005

Analysis of Harm from medical intervention

“totality of Evidence”

Efficacy Assessment

Analysis of Benefit from medical intervention

“Substantial Evidence”

Evaluation of Evidence


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Efficacy: Substantial Evidence Antimicrobials Year 2005

  • FDA published regulations on criteria that define “substantial evidence” in 1970

  • U.S. district court finds that Congress intended specific definition of substantial evidence and did not mean it to be opinion based

    • Pharmaceutical Manufacturers of America v. Richardson, 1970

  • For medical interventions “substantial evidence” means data from “adequate and well controlled trials”, not individual interpretations.

  • Substantial evidence requirement applies to both serious and life threatening diseases as well as less serious diseases.


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“Adequate and Well-Controlled” Antimicrobials Year 2005

  • Clear statement of objectives

  • Study design permits valid quantitative comparison with a control

  • Select patients with disease (treatment) or at risk of disease (prevention)

  • Baseline comparability (randomization)

  • Minimize bias (blinding, etc.)

  • Appropriate methods of assessment of outcomes

  • Appropriate methods of analysis

    • 21 CFR 314.126


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Quantitation of Control Antimicrobials Year 2005

  • Clinical trials compare outcomes with drug to what would have occurred without drug. Cannot know for sure outcomes without drug so concurrent controls used for comparison – usually placebo-control used.

  • For Active-Controlled Trials - Quantitativeassessment

    • reliable and reproducible (based on trials that are themselves adequate and well controlled) of benefit of control over placebo, and

    • suitably conservative margin based on examination of confidence intervals

  • Non-inferiority (NI) trials: Inferior to Control “no-worse-than” by a certain suitable margin. SELECTION OF CONTROL “must be clearly established and quantifiedin well-designed and well-documented superiority trials and which can be reliably expected to have similar efficacy in the contemplated active controlled trial.”

    ICH E-9, Statistical Principles for Clinical Trials


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Problems: Quantitation of Control Antimicrobials Year 2005

  • Active-controlled clinical trials with non-inferiority (“no –worse than control by a certain margin”) design does not assure benefit of test drug over placebo in diseases with high spontaneous cure rates.

  • Infectious diseases such as ABS and AECB are such types of diseases.

  • There is no concurrent negative control; thus, well-established and reliable data from previous placebo-controlled trials are needed to establish a quantifiable margin of benefit (a historical negative control).


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placebo Antimicrobials Year 2005

Non-Inferiority MarginsDetermining the Effect of a Test Drug

control

100

control

test

80

success rates

0

past trials

current trial

Powers J. AIDAC 9/06


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Ketek: AECB and ABS clinical trials data: all NI setting Antimicrobials Year 2005(DAIOP Briefing Package; December 2006)


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Placebo?? Antimicrobials Year 2005

Ketek®: Lack of Substantial EvidenceAECB and ABS Indications

test

control

100

control

80

success rates

0

past trials

current trial


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Analysis of Placebo Controlled Trials in Acute Exacerbations of Chronic Bronchitis

no significant difference in time to resolution of symptoms p = 0.20

oxytetracycline

Elmes et al. 1957 n=88

no significant difference in time to resolution of symptoms p = 0.30

oxytetracycline d12

Fear et al. 1962 n=62

no significant difference in investigator clinical assessment of matched pairs

ampicillin d7

Elmes et al. 1965 n= 56

no significant difference in mean change in Pa O2 between groups

tetracycline d7

Nicotra et al. 1982 n=40

chloramphenicol d 10

Petersen et al 1967 n=19

amoxicillin d8

Jorgensen et al. 1992 n=278

amoxicillin or TMP-SMX d14

Sachs et al. 1995 n=71

oxytetracycline d14

Berry et al 1960 n=53

cefaclor d8

Manresa et al. 1987 n=19 (not randomized)

TMP-SMX or doxycycline d21

Anthonisen et al. 1987a n = 116 (crossover)

(first exacerbation only)

ofloxacin d30

Nouira et al. 2001 n=93

penicillin +streptomycin d14

Pines et al. 1968 n=30

tetracycline or chloramphenicol d7

Pines et al.1972 n=259

amoxicillin-clavulanate d5

Allegra et al 1991 n=335

0

+50

+40

+30

+20

+10

-30

-40

-50

-10

-20

Favors study drug

Favors placebo

Powers J. ICAAC 2005


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AECB: NI Regulatory Timeline of Chronic Bronchitis

  • February 2002: AIDAC on non-inferiority margins for Antibiotics to treat infectious diseases ( e.g. AECB)

  • November 2002: IDSA/PhRma/FDA Working Group Meeting

  • January 2003: AIDAC on Ketek (telithromycin)

  • April 2003: Factive (gemifloxacin) NDA approval for AECB, Mild to moderate Community-acquired pneumonia (CAP)

  • April 2004: Ketek (telithromycin) NDA approval for AECB, ABS, Mild to moderate CAP

  • April 2004: FDA/IDSA/ISAIP Working Group (AECB)

  • July 2005: Regulatory Briefing on AECB


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July 2005 FDA Regulatory Briefing of Chronic Bronchitis(minutes)

  • Is there a scientific basis for continuing to base approvals for AECB/AECOPD on non-inferiority trials?

  • Regulatory Briefing Panel:

    “Based on current data, the panel believed there is NOT a scientific basis for non-inferiority trials in Acute Exacerbations of Chronic Bronchitisgiven both the lack of historical evidence of sensitivity to drug effects and issues with defining both the disease and lack of appropriate clinical outcome measures. Trials should be done as superiority trial designs. The panel asked about other disease indication where these issues with non-inferiority trials have arisen, and the discussion included trials in acute otitis media and acute bacterial sinusitis, where these same issues apply”.


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July 2005 FDA Regulatory Briefing of Chronic Bronchitis(minutes)

  • Are there precedents where superiority trials were successfully performed when there is reported resistance by sponsors of clinicians to performing these trials? How were these trials moved forward?

  • Regulatory Briefing Panel:

    “During the late 1990s, … the Director of Anesthetics, Critical Care and Addiction Drug Products, encountered years of significant resistance from industry before sponsors finally agreed to switch from conducting non-inferiority clinical trials to placebo- and active controlled studies in situations where sponsors submitted formulation changes of existing opiate products. It is important to note that when such trials were undertaken, it was discovered that some of the products did not prove to be more effective than placebo, substantiating the concerns regarding non-inferiority trials. The Panel emphasized that as science changes the standards for regulatory approval also must change to reflect what we have learned. In this case (AECB), the data point to the lack of information upon which to base non-inferiority trials.”


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Analysis of Efficacy in Placebo Controlled Trials in Acute Bacterial Sinusitis

cefuroxime d14

Kristo et al. 2005 n=82

pivampicillin d8

Norrelund et al. 1978 1978 n=135

doxycycline d10

Stalman et al. 1997 n=186

amox or amoxicillin-clav d14

Garbutt et al. 2001 n=161

Lindbaek et al. 1998 n=70

amoxicillin or penicillin d10

amoxicillin-clavulanate d14

Bucher et al. 2003 n=251

amoxicillin d14

Merenstein et al. 2005 n=135

amoxicillin d14

van Buchem et al. 1997 n=206

amoxicillin d10

deSutter et al. 2003 n=135

pencillin or lincomycin d10

Axelsson et al. 1970 n=142

amox or doxy or penicillin d 14

Varonen et al.2003 n=146

amoxicillin or amox-clav d10

Wald et al. 1986 n=93

azithromycin d8

b

Kaiser et al. 2001 n=265a (77)b

a

penicillin d7

Hansen et al. 2000 n=127

azithromycin d14

Haye et al. 1998 n=168

amoxicillin or penicillin d10

Lindbaek et al. 1996 n=127

cyclacillin (not specified)

Ganaca et al. 1973 n=50

0

50

40

30

20

10

30

40

50

10

20

Favors study drug

Favors placebo

Powers J. AIDAC 9/2006


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ABS: NI Regulatory Timeline Bacterial Sinusitis

  • November 2002: IDSA/PhRma/FDA Working Group Meeting

  • January 2003: AIDAC on Ketek (telithromycin)

  • October 2003: AIDAC on ABS

  • January 2004: sNDA approval for azithromycin for 3 days

  • April 2004: telithromycin NDA approval for AECB, ABS, Mild/moderate CAP

  • July 2005: Regulatory Briefing on AECB

  • August 2005: Levaquin (levofloxacin) for 5 days for ABS

  • September 2006: AIDAC on Factive and ABS

    Do the safety and effectiveness data presented demonstrate an acceptable risk/benefit profile of Factive® (gemifloxacin mesylate) for the 5-day treatment of patients with acute bacterial sinusitis? No:11, Yes: 2


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Efficacy of Ketek Bacterial Sinusitis

  • All clinical trials leading up to approval of Ketek for ABS, AECB and CAP were non-inferiority trials with >10% non-inferiority margins. Response rates in the 80% range with spread, similar for both Ketek and controls.

  • So the questions are for AECB and ABS

    • Has substantial evidence of drug efficacy via “adequate and well-controlled studies” standard been shown when the drug has been assessed exclusively in non-inferiority setting?

    • Did these non-inferiority trials provide substantial evidence that the use of Ketek added any benefit over and above the natural history of the disease?

  • Superiority trial designs have been recommended by members of this committee three months ago (at the Factive® FDA Advisory on ABS) in order to PROVE with substantial evidence that taking the drug benefits the patient and therefore is worth the risk of adverse reactions.


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Ketek CAP considerations Bacterial Sinusitis

  • Original benefit shown for pneumonia with “severe” disease with endpoint of mortality. Ketek is indicated for mild-moderate (Outpatient – treatment) pneumonia only, so the margin of benefit is less clear. However, this disease is less spontaneously resolving, so there is still probably a preservation of efficacy margin for study in non-inferiority setting.

  • Issue of Resistance: Ketek’s claim is for treating “resistant pathogens” , particularly “macrolide resistance”. This implies that Ketek is superior to older drugs which are ineffective against “resistant pathogens”. YET, all trials were performed as non-inferiority trials (no-worse-than-to-older drug).

  • Medical Need: Demonstration of evidence that Ketek is superior to older drug if Ketek is better for resistant pathogens.

    Active-controlled Trials demonstrating SUPERIORITY to older drugs

    Example: Demonstrate that CAP patients with macrolide- resistant organisms have BETTER clinical outcome than patients treated with other macrolides.


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“Activity” not same as “Efficacy” Bacterial Sinusitis

  • Pre-clinical in vitro and animal data provide hypotheses upon which clinical trials of antimicrobials based

  • In vitro activity and animal models alone do not define substantial evidence

  • “Recent studies that have assessed the impact of β-lactam and macrolide resistance on clinical outcomes in CAP fail to provide incontrovertible evidence for a direct link between in vitro resistance and treatment failure” Rothermel C. CID 2004:38 S346-49

    “….. A couple people on the panel have made the comment …that ..so regardless of what the clinical trials have shown, that in vitro data are convincing enough that they feel comfortable that this drug would be efficacious for the treatment of acute bacterial sinusitis. I just want to say I m pretty uncomfortable with that approach. If all we need are in vitro data, there’s really not much point in doing clinical trials, at least for efficacy. ….Gregory Townsend, MD, AIDAC 9/06


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Risk to Benefit Ratio: CAP Bacterial Sinusitis

  • Hard to quantify with exact numbers for outpatient CAP treatment with Ketek

  • Superiority trials, using an active control (an older antibiotic) are needed to clinically demonstrate that patients ill with resistant pathogens and being treated with Ketek have better outcome those treated with comparator drug.

  • Can Risk be managed? “Sudden” and “Rapid” nature of clinical toxicity manifestation makes risk mitigation difficult.

  • Clear Risk communication to the patient

  • Clear Risk communication to the prescriber


Risk to benefit ratio l.jpg

Risk: “Totality of Evidence” Bacterial Sinusitis

Hepatotoxicity

Exacerbation of MG

Visual toxicity

Loss of consciousness

Rapid/Sudden Clinical Toxicity Manifestations

Cannot mitigate risk

Must define population to benefit from drug that justifies the risks

Benefit: “Substantial Evidence”

Based on non-inferiority trials without quantification of control for the indications of AECB and ABS. Uncertain as to drug effect over and above the natural history of disease resolution

For CAP:

Drug effect over and above the natural history of disease resolution

Still need demonstration of clinical outcome superiority over older drugs for disease caused by “resistant” organisms

Risk to Benefit Ratio


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Acknowledgements Bacterial Sinusitis

Does Ketek’s Benefit Outweigh the Risks for each of the indications??

  • Carol Pamer, R Ph

  • Jenna Lyndly, RN

  • Melissa Truffa, R Ph

  • David Graham, MD MPH

  • Evelyn Farinas, R Ph MS

  • John H. Powers, MD

  • Gerald DalPan, MD, MHS


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Return Bacterial Sinusitis

Return to agenda


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