Community-Acquired Bacterial Pneumonia: Developing Drugs for Treatment

Administrative guidance, not enacted legislation. This captured publisher edition preserves the listed document and attachments; later developments are not independently consolidated.

Community-Acquired
Bacterial Pneumonia:
Developing Drugs for
Treatment
Guidance for Industry
U.S. Department of Health and Human Services
Food and Drug Administration
Center for Drug Evaluation and Research (CDER)
June 2020
Clinical/Antimicrobial

Community-Acquired
Bacterial Pneumonia:
Developing Drugs for
Treatment
Guidance for Industry
Additional copies are available from:
Office of Communications, Division of Drug Information
Center for Drug Evaluation and Research
Food and Drug Administration
10001 New Hampshire Ave., Hillandale Bldg., 4th Floor
Silver Spring, MD 20993-0002
Phone: 855-543-3784 or 301-796-3400; Fax: 301-431-6353
Email: druginfo@fda.hhs.gov
https://www.fda.gov/drugs/guidance-compliance-regulatory-information/guidances-drugs
U.S. Department of Health and Human Services
Food and Drug Administration
Center for Drug Evaluation and Research (CDER)
June 2020
Clinical/Antimicrobial

TABLE OF CONTENTS
I. 	INTRODUCTION............................................................................................................. 1
II. 	BACKGROUND ............................................................................................................... 2
III. 	DEVELOPMENT PROGRAM ....................................................................................... 2
A. 	General Considerations ................................................................................................................. 2
1. Nonclinical Development Considerations ....................................................................................... 2
2. Drug Development Population ........................................................................................................ 2
3. Efficacy Considerations ................................................................................................................... 2
4. Safety Considerations ...................................................................................................................... 3
B. 	Specific Efficacy Trial Considerations ......................................................................................... 3
1. Trial Design ..................................................................................................................................... 3
2. Trial Population ............................................................................................................................... 3
3. Entry Criteria ................................................................................................................................... 3
a. 	Clinical, radiographic, and microbiologic entry criteria ........................................................... 3
b. 	Exclusion criteria ...................................................................................................................... 4
4. Randomization and Blinding............................................................................................................ 4
5. Specific Populations......................................................................................................................... 5
6. Dose Selection.................................................................................................................................. 5
7. Choice of Comparators, Prior Antibacterial Drug Use, and Concomitant Therapy ....................... 5
8. Efficacy Endpoints ........................................................................................................................... 6
a. 	Primary endpoint ....................................................................................................................... 6
b. 	Secondary endpoints ................................................................................................................. 7
c. 	Intravenous and oral formulations ............................................................................................ 7
9. Trial Procedures and Timing of Assessments .................................................................................. 8
a. 	Entry visit .................................................................................................................................. 8
b. 	On-therapy and end-of-therapy visits ....................................................................................... 8
c. 	After therapy visit ..................................................................................................................... 8
10. 	Statistical Considerations............................................................................................................ 8
a. 	Analysis populations ................................................................................................................. 8
b. 	Noninferiority margins.............................................................................................................. 9
c. 	Sample size considerations ....................................................................................................... 9
C. 	Other Considerations..................................................................................................................... 9
1. Pharmacokinetic/Pharmacodynamic Evaluation ............................................................................ 9
2. Labeling Considerations ................................................................................................................ 10
REFERENCES............................................................................................................................ 11
APPENDIX:................................................................................................................................. 13

Contains Nonbinding Recommendations
1
Community-Acquired Bacterial Pneumonia:
Developing Drugs for Treatment
Guidance for Industry1
This guidance represents the current thinking of the Food and Drug Administration (FDA or Agency) on
this topic. It does not establish any rights for any person and is not binding on FDA or the public. You
can use an alternative approach if it satisfies the requirements of the applicable statutes and regulations.
To discuss an alternative approach, contact the FDA office responsible for this guidance as listed on the
title page.
I. 	INTRODUCTION
The purpose of this guidance is to assist sponsors in the clinical development of drugs for the
treatment of community-acquired bacterial pneumonia (CABP). Specifically, this guidance
addresses the FDA’s current thinking about the overall development program and clinical trial
designs for drugs to support an indication for the treatment of CABP.2
This guidance does not discuss the general issues of statistical analysis or clinical trial design.
Those topics are addressed in the ICH guidances for industry E9 Statistical Principles for
Clinical Trials (September 1998) and E10 Choice of Control Group and Related Issues in
Clinical Trials (May 2001), respectively.3
In general, FDA’s guidance documents do not establish legally enforceable responsibilities.
Instead, guidances describe the Agency’s current thinking on a topic and should be viewed only
as recommendations, unless specific regulatory or statutory requirements are cited. The use of
the word should in Agency guidances means that something is suggested or recommended, but
not required.
1 This guidance has been prepared by the Division of Anti-Infectives in the Center for Drug Evaluation and
Research (CDER) at the Food and Drug Administration.
2 For the purposes of this guidance, all references to drugs include both human drugs and therapeutic biological
products regulated by CDER unless otherwise specified.
3 We update guidances periodically. To make sure you have the most recent version of guidance, check the FDA
guidance web page at https://www.fda.gov/regulatory-information/search-fda-guidance-documents.

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II. 	BACKGROUND
CABP is defined as an acute bacterial infection of the pulmonary parenchyma associated with
chest pain, cough, sputum production, difficulty breathing, chills, rigors, fever, or hypotension
and is accompanied by the presence of a new lobar or multilobar infiltrate on a chest radiograph.
Common typical bacterial pathogens that cause CABP include Streptococcus pneumoniae,
Haemophilus influenzae, Staphylococcus aureus, and Moraxella catarrhalis. Atypical bacterial
pathogens such as Chlamydophila pneumoniae, Mycoplasma pneumoniae, and Legionella
pneumophila also cause CABP.
III. 	DEVELOPMENT PROGRAM
A. 	General Considerations
1. 	Nonclinical Development Considerations
In addition to the expected nonclinical toxicology/pharmacology studies (see Section III. C. 1,
Pharmacokinetic/Pharmacodynamic Considerations), sponsors should provide nonclinical data
from in vitro studies and in vivo animal studies demonstrating activity against one or more of the
commonly implicated pathogens for CABP.
2. 	Drug Development Population
The trial population should include individuals who have CABP, as defined in section II,
Background.
3. 	Efficacy Considerations
Noninferiority trials are acceptable to support an indication for the treatment of CABP. A
showing of superiority to an effective control would also be acceptable. Historical data show
that antibacterial drugs demonstrate a considerable treatment effect compared with
nonantibacterial therapies on clinical response evaluated on day 4 of therapy.
The Agency generally expects sponsors to conduct two adequate and well-controlled trials in
CABP to establish substantial evidence of effectiveness. Alternatively, a single adequate and
well-controlled trial in CABP with confirmatory evidence (e.g., efficacy in another indication or
data from a phase 2 clinical trial in CABP) can provide substantial evidence of effectiveness.
Sponsors should discuss their proposed development program with the Agency, including the
confirmatory evidence that would be used to support the efficacy findings from a single trial.4
4 See the draft guidance for industry Demonstrating Substantial Evidence of Effectiveness for Human Drug and
Biological Products (December 2019). When final, this guidance will represent the FDA’s current thinking on this
topic. For the most recent version of a guidance, check the FDA guidance web page at
https://www.fda.gov/regulatory-information/search-fda-guidance-documents.

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4. 	Safety Considerations
If the same or greater dose and treatment duration have been evaluated in other indications,
safety data from these indications can be used to support safety for CABP. Sponsors should
discuss the appropriate size of the premarketing safety database with the Agency during
development.
B. 	Specific Efficacy Trial Considerations
1. 	Trial Design
CABP trials should be randomized, double-blind, and active-controlled using a noninferiority or
superiority design. See section III. B. 4, Randomization and Blinding, for additional discussion
about double-blind trials. Placebo-controlled trials are not appropriate for this indication except
when they are add-on superiority trials in which patients receive either a placebo or an
investigational drug added to standard-of-care antibacterial drug therapy.
2. 	Trial Population
The trial population for efficacy trials should include patients with CABP based on the entry
criteria described in section III. B. 3, Entry Criteria. The FDA recommends that all patients in
trials of an intravenously administered drug have a Pneumonia Patient Outcomes Research Team
(PORT) classification of III or higher (Fine et al. 1997) and at least 25 percent should have a
PORT classification of IV or V. The reasons to exclude patients with a PORT II classification
from trials for intravenously administered drugs include the milder severity of illness in general
and the fact that patients with a PORT II classification are more likely to be treated appropriately
with oral antibacterial drug therapy. For trials in which most patients would be treated as
outpatients, all patients should have PORT II or PORT III classifications, with at least 50 percent
PORT III. Sponsors should discuss the trial population with the Agency in advance of a phase 3
trial.
3. 	Entry Criteria
a. 	Clinical, radiographic, and microbiologic entry criteria
Sponsors should use radiographic evidence as well as the entry criteria outlined in Table 1 to
select patients for enrollment in a CABP trial.
Table 1. Entry Criteria for a CABP Trial
At Least Two
Symptoms
At Least Two Vital
Sign Abnormalities
At Least One Finding of Other Clinical
Signs/Laboratory Abnormalities
- Difficulty breathing
- Cough
- Production of purulent
sputum
- Chest pain
- Fever
- Hypothermia
- Hypotension
- Tachycardia
- Tachypnea
- Hypoxemia
- Clinical evidence of pulmonary
consolidation
- An elevated total white blood cell count or
leukopenia

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4
An adequate sputum specimen should be processed by a laboratory according to recognized
methods for Gram stain, culture, and in vitro antibacterial susceptibility testing.5
Use of rapid diagnostic or nonculture tests may help identify a patient for enrollment in a CABP
trial (e.g., urinary antigen test for S. pneumoniae or L. pneumophila; polymerase chain reaction,
serology). If the tests being used are not FDA cleared, sponsors should provide sufficient
information about the performance characteristics of the tests determined from analytical
validation studies.
The clinical trial of an antibacterial drug also may provide an opportunity to develop and
evaluate a new diagnostic test. Sponsors interested in using a clinical trial in patients with CABP
as a means to also evaluate a diagnostic test are encouraged to discuss this with the Agency.
b. 	Exclusion criteria
Exclusion criteria should include the following:
• 	Aspiration pneumonia
• 	Hospital-acquired bacterial pneumonia or ventilator-associated bacterial pneumonia
• 	Patients with known bronchial obstruction or a history of postobstructive pneumonia (this
criterion does not exclude patients who have chronic obstructive pulmonary disease)
• 	Patients with primary or metastatic lung cancer
• 	Patients with cystic fibrosis, known or suspected Pneumocystis jiroveci pneumonia, or
known or suspected active tuberculosis
4. 	Randomization and Blinding
Patients should be randomized to treatment groups at enrollment. All trials should be double-
blind unless there is a compelling reason for not blinding treatment allocation. If trials are
single-blind or open-label, sponsors should discuss potential biases with the Agency and how
these biases will be addressed before initiating the trial.
5 Standard methods for in vitro susceptibility testing are developed by organizations such as the Clinical and
Laboratory Standards Institute; see also the American Society for Microbiology, 2011, Manual of Clinical
Microbiology, 10th edition.

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5. 	Specific Populations
The trials should include patients of both sexes, patients of all races, and geriatric patients.6
Patients with renal or hepatic impairment may be enrolled, provided pharmacokinetics of the
drug has been evaluated in these patients and appropriate dosing regimens have been defined.
Sponsors should discuss drug development in the pediatric populations as early as feasible. The
Pediatric Research Equity Act (PREA), as amended by the Food and Drug Administration Safety
and Innovation Act, states that initial plans for conducting pediatric studies (referred to as an
initial pediatric study plan) shall be submitted to the FDA before the date on which required
pediatric assessments are submitted under PREA and no later than (1) 60 days after the end-of-
phase 2 meeting or (2) such other time as may be agreed upon by the FDA and the applicant.7
6. 	Dose Selection
To choose the dose or doses to be evaluated in phase 3 clinical trials, sponsors should integrate
the findings from nonclinical toxicology studies; animal models of infection; pharmacokinetics,
safety, and tolerability information from phase 1 clinical trials; and safety and efficacy
information from phase 2 dose-ranging clinical trials. Trials assessing drug penetration at the
site of action (e.g., epithelial lining fluid) may be helpful in defining doses that achieve
concentrations sufficient to exert an antibacterial effect.
For products with both intravenous (IV) and oral formulations, sponsors should collect
pharmacokinetic (PK) data in earlier phase studies to select the appropriate oral dose for the IV-
to-oral switch.
7. 	Choice of Comparators, Prior Antibacterial Drug Use, and Concomitant Therapy
In general, the active comparator should be considered standard of care for this indication.
When evaluating the current standard of care, the FDA considers recommendations by
authoritative scientific bodies (e.g., American Thoracic Society, Infectious Diseases Society of
America) that reflect current clinical practice based on clinical evidence and other reliable
information.
Ideally, patients enrolled in a CABP clinical trial should not have received antibacterial drug
therapy for treatment of CABP before enrollment because such therapy could do the following:
6 See the ICH guidances for industry E7 Studies in Support of Special Populations: Geriatrics (August 1994) and
E7 Studies in Support of Special Populations: Geriatrics; Questions and Answers (February 2012).
7 See PREA (Public Law 108-155; section 505B of the Federal Food, Drug, and Cosmetic Act; 21 U.S.C. 355c) as
amended by the Food and Drug Administration Safety and Innovation Act (Public Law 112-144) and the draft
guidance for industry Pediatric Study Plans: Content of and Process for Submitting Initial Pediatric Study Plans
and Amended Pediatric Study Plans (March 2016). When final, this guidance will represent the FDA’s current
thinking on this topic.

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• 	Obscure true treatment differences between an investigational drug and the control drug,
introducing bias toward a finding of no difference between treatment groups (i.e., a bias
toward noninferiority) (Pertel et al. 2008)
• 	Particularly influence the efficacy findings based on an endpoint early in therapy (day 4)
However, excluding all patients who have received prior antibacterial therapy also may pose
problems, including the following:
• 	Excluding patients with greater disease severity, which may result in a patient population
with lesser severity of illness and greater potential for spontaneous recovery; this could
bias trial results toward a finding of no difference between treatment groups (i.e., a bias
toward noninferiority)
• 	Certain trial sites may not participate because of concerns that trial treatment would not
represent standard of care
A pragmatic approach to these concerns is to (1) encourage prompt enrollment procedures so that
patients can receive the clinical trial treatment as their initial therapy and (2) allow enrollment of
some patients who have received a single dose of a short-acting antibacterial drug within 24
hours of enrollment (ideally, there would be few such patients, but up to 25 percent of the patient
population may be acceptable). This approach would allow patients in the trial to receive prompt
antibacterial drug therapy as clinically necessary, consistent with the standard of care. A
prespecified analysis of the efficacy results in the subgroup of patients (i.e., the majority of
patients) who did not receive prior effective antibacterial drug therapy would be important to
evaluate.
In general, concomitant antibacterial therapy with an antimicrobial spectrum that overlaps with
the spectrum of the investigational drug should not be administered during the trial. Sponsors
should discuss the additional antibacterial coverage for atypical pathogens with the FDA before
initiating the trial.
8. 	Efficacy Endpoints
a. 	Primary endpoint
The primary efficacy endpoint of clinical success should be defined as improvement at day 4 in
at least two (with no worsening) of the following symptoms of CABP compared with baseline:
chest pain, cough, amount of productive sputum, and difficulty breathing (Talbot et al. 2016).
The protocol should specify symptom evaluations on a four-point scale (absent, mild, moderate,
severe), defining improvement as at least a one-point improvement from baseline to the
assessment at day 4 (e.g., from severe to moderate, from moderate to mild, or from mild to

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absent).8 The protocol should clearly describe the ascertainment of patients’ symptoms as
improvement, no change, or worsening based on the four-point scale.
Another efficacy endpoint can be all-cause mortality at 28 days after enrollment, but feasibility would be
an issue in clinical trials in certain patient populations with a greater severity of CABP. Sponsors
considering using all-cause mortality as the primary efficacy endpoint should discuss the trial design with
the Agency.
b. 	Secondary endpoints
Following are some examples of secondary endpoints that could be evaluated:
• 	Improvement at day 4 in at least two (with no worsening) of the following symptoms of
CABP compared with baseline: chest pain, cough, amount of productive sputum, and
difficulty breathing; and improvement in vital signs (i.e., body temperature, blood
pressure, heart rate, and respiratory rate)9
• 	Clinical outcome (i.e., improvement/resolution of symptoms of CABP) at the end of
therapy)
• 	Clinical outcome (i.e., resolution of symptoms of CABP) at a fixed time point after
randomization and completion of therapy)
c. 	Intravenous and oral formulations
For drugs available only as an IV formulation, sponsors should conduct trials with the IV
formulation alone for the entire duration of therapy, if feasible, or at least until the day 4
assessment is complete. This will allow for the assessment of both the efficacy and the safety of
the investigational drug before switching to an oral antibacterial drug. Ideally, the duration of
oral antibacterial drug therapy (i.e., days of IV therapy plus days of oral drug therapy) should be
as short as possible so sponsors can assess the contribution of the IV investigational drug to
overall efficacy after completion of treatment. The criteria for switching to oral antibacterial
drug therapy should be included in the protocol.
For drugs that have both an IV and an oral formulation, the protocol should specify the criteria that
allow for IV-to-oral switch.
8 The Appendix describes the historical treatment benefit of antibacterial therapy at 3 to 5 days following initiation
of antibacterial drug therapy. Day 4 was selected as the recommended timing of the primary efficacy endpoint to
allow for clinical protocols to provide a window period for assessing the primary efficacy endpoint (i.e., a 24-hour
window before and after day 4). Sponsors should discuss with the Agency if a day 3 or a day 5 time point is being
considered for the timing of the primary efficacy endpoint in the protocol. See also Toerner et al. 2012. For
information about the development of patient-reported outcome measures, see the guidance for industry Patient-
Reported Outcome Measures: Use in Medical Product Development to Support Labeling Claims (December 2009).
9 Improvement or stabilization of vital signs and other signs attributable to CABP should be defined in the protocol.
For example, see table 10 in Mandell et al. 2007.

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9. 	Trial Procedures and Timing of Assessments
a. 	Entry visit
Sponsors should collect baseline demographic and clinical information at the entry visit, in
addition to microbiologic specimens and laboratory tests, as appropriate.
b. 	On-therapy and end-of-therapy visits
The protocol should specify the evaluation of patients on therapy and at the end of therapy.
These visits should capture patient symptoms, physical examination findings, assessments and
resolution of adverse effects, if any, and appropriate laboratory tests.
c. 	After therapy visit
The protocol should specify the evaluation of patients 5 to 10 days after completion of treatment.
These visits, used to evaluated secondary endpoints, should capture patient symptoms, physical
examination findings, assessments and resolution of adverse effects, if any, and appropriate
laboratory tests. The trial should assess all-cause mortality at day 28.
10. 	Statistical Considerations
In general, sponsors should submit a detailed statistical analysis plan stating the trial hypotheses
and the analysis methods before trial initiation.
a. 	Analysis populations
The following definitions apply to various analysis populations in CABP clinical trials:
• 	Safety population — All patients who received at least one dose of drug during the trial.
• 	Intent-to-treat (ITT) population — All patients who were randomized.
• 	Microbiological-ITT (micro-ITT) population — All randomized patients who have a
baseline bacterial pathogen that is known to cause CABP and that is susceptible to the
investigational drug and the active control, from an appropriate sputum specimen or
blood.
• 	Clinically evaluable or per-protocol populations — Patients who meet the definition for
the ITT population and who complete the trial as specified in the protocol.
• 	Microbiologically evaluable populations — Patients who meet the definition for the
micro-ITT population and who complete the trial as specified in the protocol.
Sponsors should discuss with the Agency the prespecified primary analysis population before
initiating the trial. In general, it is acceptable to consider the ITT population as the primary

Contains Nonbinding Recommendations
9
analysis population. For antibacterial drugs with a narrow spectrum of activity (e.g., a drug
active against a single genus and species of bacteria), the micro-ITT population will be
considered the primary analysis population.
b. 	Noninferiority margins
Historical experience indicates that there is a relatively large treatment effect of antibacterial
drug therapy on clinical response at day 4 (see the Appendix). In general, the selection of a
noninferiority margin of 12.5 percent is reasonable for CABP clinical trials using a clinical
response endpoint at day 4. In certain circumstances, sponsors may consider a noninferiority
margin greater than 12.5 percent. Sponsors should discuss with the Agency a clinically
appropriate noninferiority margin before initiating the trial.
c. 	Sample size considerations
A general framework is provided for sponsors to begin to discuss sample size considerations
with the Agency during protocol development. In this illustrative sample size calculation,
approximately 225 patients per group is estimated based on the following assumptions: (1) a rate
of clinical success for the active control and test therapy of 80 percent, (2) two-sided type I error
(α) of 0.05, (3) type II error (β) of 0.10 (power 0.90), (4) a noninferiority margin of 12.5 percent
(see the Appendix), and (5) an ITT analysis population.
C. 	Other Considerations
1. 	Pharmacokinetic/Pharmacodynamic Evaluation
Sponsors should evaluate the PK/pharmacodynamic (PD) characteristics of the drug using in
vitro methods and animal models of infection. Sponsors should also consider the limitations of
such models before evaluating the antibacterial drug (Tessier et al. 2002; Gavaldà et al. 1997;
Legget 1999; Miyazaki et al. 1997; Silverman et al. 2005).
Integration of these PK/PD characteristics of the drug with the findings from phase 1 clinical
trials can assist identification of appropriate dosing regimens for evaluation in phase 2 and phase
3 clinical trials.10
Sponsors should obtain blood samples from patients in phase 2 and phase 3 clinical trials (sparse
sampling) to estimate drug exposure in each patient. Sponsors should perform an exposure-
response analysis for clinical outcomes, microbiologic outcomes, and clinically relevant adverse
events. If phase 3 trials include a previously unstudied specific population, such as patients with
renal or hepatic impairment, collecting plasma drug concentrations from those specific
populations can aid in determining necessary dose adjustments.
10 See the guidance for industry Exposure-Response Relationships — Study Design, Data Analysis, and Regulatory
Applications (April 2003) and the ICH guidance for industry E4 Dose-Response Information to Support Drug
Registration (November 1994).

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2. 	Labeling Considerations
Generally, the labeled indication should be the treatment of CABP caused by the specific
bacteria identified in the clinical trials.

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REFERENCES	1
2
Austrian, R and J Gold, 1964, Pneumococcal Bacteremia With Especial Reference to Bacteremic	3
Pneumococcal Pneumonia, Ann Intern Med, 60:759–776.	4
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Bullowa, JGW, 1937, The Course, Symptoms and Physical Findings, In: Bullowa JGW, editor,	6
The Management of Pneumonias, Oxford University Press; New York.	7
8
Dowling, HG and MH Lepper, 1951, The Effect of Antibiotics (Penicillin, Aureomycin, and	9
Terramycin) on the Fatality Rate and Incidence of Complications in Pneumococcic Pneumonia:	10
A Comparison With Other Methods of Therapy, AM J Med Sci, 222(4):396–403.	11
12
Fine, MJ, TE Auble, DM Yealy, BH Hanusa, LA Weissfeld, DE Singer, CM Coley, TJ Marrie,	13
and WN Kapoor, 1997, A Prediction Rule to Identify Low-Risk Patients With Community-	14
Acquired Pneumonia, N Engl J Med, 336:243–250.	15
16
Finland, M, 1943, Chemotherapy in the Bacteremia, Conn State Med J, 7:92–100.	17
18
Finland, M, WC Spring Jr., and FC Lowell, 1940, Specific Treatment of the Pneumococcic	19
Pneumonias; An Analysis of the Results of Serum Therapy and Chemotherapy at the Boston City	20
Hospital From July 1938 Through June 1939, Annals of Internal Medicine, 13:1567–1593.	21
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Flippin, HF, JS Lockwood, DS Pepper, and L Schwartz, 1939, The Treatment of Pneumococcic	23
Pneumonia With Sulfapyridine: A Progress Report on Observations in 100 Cases, JAMA,	24
112(6):529–534.	25
26
Gavaldà, J, JA Capdevila, B Almirante, J Otero, I Ruiz, M Laguarda, H Allende, E Crespo, C	27
Pigrau, and A Pahissa, 1997, Treatment of Experimental Pneumonia due to Penicillin-Resistant	28
Streptococcus Pneumoniae in Immunocompetent Rats, Antimicrob Agents Chemother,	29
41(4):795–801.	30
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Higgins, K, M Singer, T Valappil, S Nambiar, D Lin, and E Cox, 2008, Overview of Recent	32
Studies of Community-Acquired Pneumonia, Clin Infect Dis, 47 (Suppl 3) S150–S156.	33
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Kingston, JR, RM Chanock, MA Mufson, LP Hellman, WD James, HH Fox, MA Manko, and J	35
Boyers, 1961, Eaton Agent Pneumonia, JAMA, 176(2):118–123.	36
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Legget, J, 1999, Murine Models of Pneumonia Using Aerosol Infection, In: Zak O, Sande MA,	38
eds., Handbook of Animal Models of Infections: San Diego, Academic Press, 533–538.	39
40
Mandell, LA, RG Wunderink, A Anzueto, JG Bartlett, GD Campbell, NC Dean, SF Dowell, TM	41
File, Jr., DM Musher, MS Niederman, A Torres, and CG Whitney, 2007, Infectious Diseases	42
Society of America/American Thoracic Society Consensus Guidelines on the Management of	43
Community-Acquired Pneumonia in Adults, Clin Infect Dis, 44:S27–S72.	44
45

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Meakins, JC and FR Hanson, 1939, The Treatment of Pneumoccic Pneumonia With	46
Sulfapyridine, The Canadian Medical Association Journal, April, 333–336.	47
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Miyazaki, S, T Nunoya, T Matsumoto, K Tateda, and K Yamaguchi, 1997, New Murine Model	49
of Bronchopneumonia Due to Cell-Bound Haemophilus Influenzae, J Infect Dis, 175(1):205–	50
209.	51
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Pertel, PE, P Bernardo, C Fogarty, P Matthews, R Northland, M Benvenuto, GM Thorne, SA	53
Luperchio, RD Arbeit, and J Alder, 2008, Effects of Prior Effective Therapy on the Efficacy of	54
Daptomycin and Ceftriaxone for the Treatment of Community-Acquired Pneumonia, Clin Infect	55
Dis, 46(8):1142–1151.	56
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Silverman, JA, LI Mortin, AD VanPraagh, T Li, and J Alder, 2005, Inhibition of Daptomycin by	58
Pulmonary Surfactant: In Vitro Modeling and Clinical Impact, J Infect Dis, 191(12):2149–2152.	59
60
Talbot, GH, JH Powers, and SC Hoffmann, 2016, Developing Outcomes Assessments as	61
Endpoints for Registrational Clinical Trials of Antibacterial Drugs: 2015 Update From the	62
Biomarkers Consortium of the Foundation for the National Institutes of Health; Clin Infect Dis.	63
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Pharmacodynamic Assessment of Clarithromycin in a Murine Model of Pneumococcal	67
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1439.	76

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APPENDIX:	77
NONINFERIORITY MARGIN JUSTIFICATION FOR CABP	78
79
Background	80
81
Selecting a noninferiority margin depends on a reliable estimate of the treatment effect of the	82
active comparator (i.e., effect of the active comparator over placebo, referred to as M1 ), usually	83
based upon placebo-controlled trials, that can be assumed to hold for the noninferiority trial.	84
After M 1 is established, clinical judgment determines how much of the estimated treatment effect	85
(M 1 ) should be preserved in determining a clinically acceptable noninferiority margin, referred to	86
as M 2 .	87
88
Historical studies and clinical trials of antibacterial drug therapy for bacterial pneumonia provide	89
evidence that antibacterial drugs have the following treatment effects:	90
91
• 	Achieving a greater proportion of patients with favorable clinical responses at time points	92
earlier in the course of antibacterial drug therapy (i.e., at day 3 to day 5)	93
94
• 	Reducing mortality in patients with pneumococcal or lobar pneumonia	95
96
An area of uncertainty in evaluating historical data is the spectrum of bacterial pathogens that	97
cause community-acquired bacterial pneumonia (CABP) today. In most of the historical studies	98
and historical controlled clinical trials, CABP was considered synonymous with pneumococcal	99
pneumonia because Streptococcus pneumoniae was regularly identified. A review of recently	100
conducted trials showed that less than 20 percent of the total patient populations had documented	101
S. pneumoniae (Higgins et al. 2008). CABP is also caused by other pathogens such as	102
Haemophilus influenzae, Haemophilus parainfluenzae, Staphylococcus aureus, and Moraxella	103
catarrhalis, as well as atypical bacteria such as Mycoplasma pneumoniae, Chlamydophila	104
pneumoniae, and Legionella species. Limited information is available on a treatment effect of	105
antibacterial drugs in CABP caused by M. pneumoniae (Kingston et al. 1961). A fundamental	106
assumption is that historical response rates in infections such as S. pneumoniae CABP are	107
relevant to response rates in modern infections with sensitive organisms.	108
109
The steps taken to determine a noninferiority margin for the primary outcome measure based on	110
the outcome assessments of chest pain, frequency or severity of cough, amount of productive	111
sputum, and difficulty breathing at day 4 after enrollment is as follows:	112
113
Primary Endpoint Based on Clinical Outcome Assessments at Day 4 after Enrollment	114
115
Studies conducted around the time of the introduction of antibacterial drug therapy described	116
clinical responses among untreated patients and patients treated with antibacterial drugs. These	117
observational studies provide an estimate of the effect of antibacterial drugs on clinical response	118
endpoints other than mortality.	119
120
Several papers described the clinical course of patients with pneumococcal pneumonia in a	121
similar way; patients were recorded as having a successful clinical result by demonstrating fever	122

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resolution and accompanying improvement and resolution of other signs and symptoms of	123
pneumonia. For example, a description in one of the papers stated, “This fall in temperature was	124
in all cases accompanied by a conspicuous reduction in the pulse and respiratory rates, and the	125
patients were improved subjectively” (Meakins and Hanson 1939). One study described the	126
clinical course of 663 patients who did not receive antibacterial drug therapy (Bullowa 1937),	127
whereas two other studies included patients who received antibacterial drug therapy. One study	128
described the clinical course over the first 4 days after therapy in 100 patients with	129
pneumococcal pneumonia (Flippin et al. 1939) and another study described the clinical course	130
over 7 days in 30 patients with pneumococcal pneumonia (Meakins and Hanson 1939). Figure 1	131
compares the three studies in the rates of clinical recovery, defined generally as the improvement	132
in both clinical signs and symptoms.	133
134
Figure 1. Rates of Clinical Recovery Recorded at Each Day (Meakins and Hanson 1939;	135
Bullowa 1937; Flippin et al. 1939)	136
137 The difference in clinical recovery rates at day 4 between patients in the two treatment studies	138
and patients in the study without treatment were 72 percent and 77 percent.	139
140
Figure 2 shows the rates of clinical recovery in an observational study of patients with	141
pneumococcal pneumonia who received antibacterial drug therapy (sulfapyridine) and a group of	142
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
1 	2 	3 	4 	5 	6 	7
Days
Recovery (%)
Untreated (Bullowa)
Sulfapyridine (Flippin)
Sulfapyridine (Meakins)
Sample sizes: Bullowa: N = 663; Flippin: N = 100; Meakins: N = 30

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15
patients who received no specific therapy. Clinical recovery was defined as a “permanent drop	143
in oral temperature below 100°F, with subsidence of other symptoms of acute infection”	144
(Finland et al. 1940). Time points at 36 to 48 hours and 48 to 72 hours after therapy initiation	145
show the greatest treatment effect on clinical recovery. The treatment difference is	146
approximately 30 percent (95 percent confidence interval: 22 percent, 37 percent) at the 48- to	147
72-hour time point. Clinical observations that were reported at any time after the 48- to 72-hour	148
assessment are displayed as 72+ in Figure 2. The time points after 72 hours (i.e., 72+) included	149
recovery time points out to several weeks following therapy completion.	150
151
Figure 2. Rates of Clinical Recovery of Acute Bacterial Pneumonia (Finland et al. 1940)	152
153 Another paper described the outcomes among pediatric patients with pneumococcal pneumonia	154
and provides additional support for a treatment effect of antibacterial drugs relatively early in	155
therapy. The mean time to clinical recovery was 4.7 days among patients who received	156
antibacterial drug therapy whereas patients who did not receive antibacterial drug therapy had a	157
mean time to clinical recovery of 8.9 days (Wilson et al. 1939).	158
159
The clinical response endpoints that were evaluated in each of these studies were not well	160
defined. The studies evaluated both signs and symptoms together. A large treatment effect was	161
observed at the early time point in the course of therapy (i.e., day 3 to day 5 after therapy	162
69%
16%
33%
55%
63%
71%
79%
41%
31%
28%
21%
12%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
≤12 	12--24 	24--36 	36--48 	48--72 	72+
Hours
Recovery (%)
Sulfapyridine (N=225)
No Therapy (N=472)

Contains Nonbinding Recommendations
16
initiation) for an endpoint that included improvement in both signs and symptoms. The studies	163
show that the treatment differences become smaller at times beyond day 3 to day 5 of therapy.	164
Features of these studies that support their use as an estimate of M 1 at day 4 include the	165
following:	166
167
• 	The studies documented bacterial pneumonia, all as S. pneumoniae.	168
169
• 	The estimate of the treatment difference appears to be large and is consistent across	170
studies.	171
172
• 	Some patients included in the no therapy group in Figure 2 were patients who had signs	173
and symptoms of milder pneumonia. Even after the availability of antibacterial drugs,	174
the clinician chose not to treat such patients with antibacterial drug therapy because of the	175
likelihood of spontaneous recovery. Including patients more likely to experience	176
spontaneous recovery of pneumonia in the no-therapy group led to an underestimate of	177
the true treatment difference among patients with more serious disease.	178
179
• 	The clinical response measurements are plausible consequences of treating an infection.	180
181
The limitations of these studies include the following:	182
183
• 	The studies were not randomized	184
185
• 	Historically controlled studies created a greater level of uncertainty in estimating	186
treatment differences	187
188
• 	The clinical response evaluations were not defined	189
190
• 	The clinical response evaluations included improvement in both signs and symptoms	191
together and did not separately evaluate improvement in chest pain, frequency or severity	192
of cough, amount of productive sputum, and difficulty breathing	193
194
The treatment difference appears to be large for an endpoint based on clinical outcome	195
assessments earlier in the course of therapy for CABP. However, the results are variable,	196
ranging from the point estimate of 30 percent treatment difference at a 48- to 72-hour time point	197
noted in Figure 2 to a point estimate of 77 percent treatment difference at day 3 noted in Figure	198
1.	199
200
It is difficult to provide a precise numerical value for the treatment effect of a proposed primary	201
endpoint of symptom improvement at day 3 to day 5. However, an M 1 of at least 20 percent	202
appears to be a reasonably appropriate and conservative estimate, accounting for the	203
uncertainties with clinical recovery in the historical literature. A conservative estimate of M 1 at	204
20 percent is still large enough to support selecting a noninferiority margin (M 2 ) of 12.5 percent	205
for the endpoint of symptom improvement at day 4. Selecting the noninferiority margin (M 2) is	206
a matter of clinical judgment and should be justified by the sponsor.	207
208

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The Agency also evaluated the literature from just before and just after the introduction of	209
antibacterial drug therapy in the mid-twentieth century (Finland 1943; Dowling and Lepper	210
1951; Austrian and Gold 1964). The Agency found support for a treatment effect of antibacterial	211
drug therapy on the endpoint of all-cause mortality.	212
213
Summary	214
215
The available data provide a basis for a noninferiority margin specification for primary efficacy	216
outcome assessments based on symptom improvement at day 4 compared with baseline.	217