1. November 7, 2008 MICROBIOTIX A small molecule, anti-infective drug discovery company CONFIDENTIAL

2. November 7, 2008 The development of novel broad- spectrum anti-bacterials for intracellular BW threats DTRA01-06-BAA-01 Project Title

3. November 7, 2008 Introduction – Goals of Program DTRA Mission: Protect the warfighter from conventional or genetically engineered biological threats Program Mission: Discover and develop broad spectrum anti-bacterials for military use against category A&B biowarfare pathogens Microbiotix Contract Objective : “Develop a new class of therapeutic agents, the bis-(imidazolinylindole) series discovered in preliminary studies, for use against intracellular bacterial warfare threats”

4. November 7, 2008 Introduction – Project Strategy Microbiotix originally structured this extremely rapid anti-bacterial development program to provide the greatest chance of success within the two year time-frame. The program was initially designed using the best case scenario with no complicating issues anticipated, based upon the data available at contract initiation.

5. November 7, 2008 AIMS Aim 1. Demonstrate potent, selective inhibitory activity of one or more bis- (imidazolinylindole) compounds in animal models of infection (year 1). Milestone: Identify an inhibitor exhibiting in vivo efficacy (ED 50 2 category A or B pathogens and minimum toxicity (MTD>300 mg/kg). Aim 2. Establish the mechanism of action of the bis-(imidazolinylindole) class of compounds (year 1). Milestone: Defined mechanism of action and target which are common to multiple bacterial BW species but distinctly different in mammalian cells Aim 3. Demonstrate structure-activity relationships for the potency and selectivity of the bis-(imidazolinylindole) class of compounds (year 2). Milestone: Identify key structural features for potency and selectivity; provide back-up compounds with MIC in serum 100. Aim 4. Conduct IND-enabling pharmacokinetic, toxicology and safety pharmacology studies (year 2). Milestone: Complete two species GLP toxicology & safety pharmacology studies for the optimal bis-(imidazolinylindole) compound suitable for IND submission. Aim 5. Prepare and file an IND application for a broad spectrum anti-bacterial active against intracellular BW threats (end of year 2). Milestone: IND approval for clinical Phase I human safety evaluation.

6. November 7, 2008 Synthesis of bis-(imidazolinylindole) compounds

7. November 7, 2008 Synthesis of Lead Compounds for Anti-Infective Studies StructureNSC #MBX #Synthesis 317,881 1066 (2 TFA) 1336 (free base) 5 steps 317,8801090 (2 TFA)7 steps 330,6871113 (free base)8 steps 369,7181128 (free base)13 steps

8. November 7, 2008 Representative Synthesis: MBX 1066

9. November 7, 2008 SAR Example: MBX 1066/1162 Tether Modifications

10. November 7, 2008 Lead and Backup Compounds and Salt Forms

11. November 7, 2008 IND-Enabling Studies: Scale-up of Lead Compound Precursors StructurePrecursor to: Amount Synthesized MBX 1336 (free base of MBX 1066) >100 g (several batches) MBX 109015 g MBX 11135 g MBX 1128650 mg

12. November 7, 2008 IND-Enabling Studies: Scale-up of Lead Compounds

13. November 7, 2008 IND-Enabling Studies: Radiolabeled Drug

14. November 7, 2008 Chemistry Summary  Established synthetic route for original 4 compounds  Small scale synthesis of ~100 analogs in SAR program to improve potency, solubility, and minimize cytotoxicity  MBX 1066 analog MBX 1162 identified as a potential backup  Scaled-up synthesis of three compounds  Performed salt selection studies  Synthesized radiolabeled MBX 1162 free base (MBX 1143)

15. November 7, 2008 In vitro activity (MICs) against category A and B pathogens

16. November 7, 2008 Average MIC (  g/mL) Bacterial StrainTest SiteMBX 1066MBX 1090MBX 1113MBX 1128MBX 1162 Burkholderia pseudomallei 1026b Calgary0.653.2>8 0.375 Burkholderia mallei GB3Calgary120.7>80.125 Burkholderia mallei ATCC 23344 USAMRIID0.421.61.8>9.70.6 Burkholderia pseudomallei DD503 USAMRIID1.73.11.8>9.70.9 Francisella tularensis Schu4USAMRIID1.71.60.94.91.8 Yersinia pestis CO92USAMRIID3.4>12.5>7.4>9.73.5 Bacillus anthracis AmesUSAMRIID0.070.100.110.150.4 Bacillus anthracis Ames 105-6 (Cipro MIC > 100) USAMRIID0.200.370.224.80.07 MBX Compounds Have Potent in vitro Activities Against Category A & B Biowarfare Agents

17. November 7, 2008 MIC 90 Values for 20 Strains each of B. pseudomallei and B. mallei Strain (n)CompoundMIC 90 (µg/mL)MIC 50 (µg/mL)Range Burkholderia pseudomallei (20)Tetracycline10.50.25 - 2 MBX 1066210.5 - >8 MBX 1090>881 - >8 MBX 116210.50.25 - 1 Burkholderia mallei (20)Tetracycline0.1250.060.03 – 0.25 MBX 10660.125 0.06 – 0.25 MBX 10900.25 0.125 - 1 MBX 11620.1250.060.06 – 0.25

18. November 7, 2008 MIC 90 values Against Multiple Isolates of Gram-positive and Gram-negative Species

19. November 7, 2008 Gram-Positive (Staphylococci) Laboratory/Clinical Strains Gr+ Bacterial SpeciesType# of IsolatesCompoundMIC 90 (µg/mL)MIC 50 (µg/mL)Range (µg/mL) Staphylococcus aureusMSSA27MBX 10660.250.120.004-0.5 MBX 11620.50.120.008-0.5 Linezolid422-4 Vancomycin10.50.5-2 Daptomycin0.5 0.25-1 S. aureusMRSA12MBX 10660.120.060.06-0.12 MBX 11620.120.060.03-0.12 Linezolid422-4 Vancomycin10.50.25-1 Daptomycin0.25 0.12-0.5 Staphylococcus epidermidisMSSE27MBX 10660.030.0080.004-0.06 MBX 11620.060.030.008-0.06 Linezolid210.5-2 Vancomycin211-4 Daptomycin10.50.5-1 S. epidermidisMRSE12MBX 10660.030.0150.004-0.03 MBX 11620.060.0150.008-0.06 Linezolid211-2 Vancomycin221-2 Daptomycin10.50.5-1

20. November 7, 2008 Gram-Positive (Enterococci) Laboratory/Clinical Strains Gr+ Bacterial SpeciesType# of IsolatesCompoundMIC 90 (µg/mL)MIC 50 (µg/mL)Range (µg/mL) Enterococcus faecalisVSE27MBX 10660.06 0.004-0.12 MBX 11620.06 0.004-0.25 Linezolid220.5-2 Vancomycin210.5-2 Daptomycin210.03-4 E. faecalisVRE12MBX 10660.060.030.015-0.06 MBX 11620.030.0150.008-0.03 Linezolid110.5-2 Vancomycin>64 Daptomycin20.50.25-2 Enterococcus faeciumVSE27MBX 10660.0150.0040.002-0.03 MBX 11620.0150.0040.002-0.03 Linezolid422-4 Vancomycin10.50.5-4 Daptomycin441-8 E. faeciumVRE12MBX 10660.004 0.002-0.008 MBX 11620.004 0.004-0.008 Linezolid221-2 Vancomycin>64 64->64 Daptomycin421-4

21. November 7, 2008 Gram-Positive (Streptococci) Laboratory/Clinical Strains Gr+ Bacterial SpeciesType# of IsolatesCompoundMIC 90 (µg/mL)MIC 50 (µg/mL)Range (µg/mL) Streptococcus pneumoniae PSSP 27MBX 10660.030.0150.008-0.12 MBX 11620.03 0.015-0.03 Linezolid210.5-2 Vancomycin0.25 0.12-0.25 Daptomycin0.250.06<0.03-0.5 S. pneumoniae PRSP 12MBX 10660.060.030.03-0.06 MBX 11620.060.030.015-0.06 Linezolid110.5-1 Vancomycin0.25 0.25-0.5 Daptomycin0.120.06<0.03-0.12 Streptococcus agalactiae12MBX 10660.06 0.03-0.12 MBX 11620.06 0.06-0.12 Linezolid221-2 Vancomycin0.5 0.5-1 Daptomycin10.50.12-2 Streptococcus pyogenes12MBX 10660.03 MBX 11620.03 Linezolid211-2 Vancomycin110.5-1 Daptomycin20.50.03-2

22. November 7, 2008 Gram-Negative (Nonfermentors) Laboratory/Clinical Strains Gr- Bacterial SpeciesType# of IsolatesCompoundMIC 90 (µg/mL)MIC 50 (µg/mL)Range (µg/mL) A. baumannii 27 MBX 1066>1620.06->16 MBX 11620.50.250.12-4 Imipenem10.120.06-8 Tigecycline10.50.06-4 Ciprofloxacin20.50.015->8 A. baumanniiMDR 13 MBX 1066>16 1->16 MBX 1162420.12-4 Imipenem>3240.06->32 Tigecycline420.25->32 Ciprofloxacin>8 0.12->8 P. aeruginosa 27 MBX 1066>16 0.06->16 MBX 116210.250.03->16 Imipenem>810.5->8 Tigecycline>881->8 Ciprofloxacin>20.250.12->2 B. cepacia 11 MBX 10660.06<0.015<0.015-4 MBX 11620.120.060.03-0.25 Imipenem>844->8 Tigecycline421-4 Ciprofloxacin220.5-2

23. November 7, 2008 Gram-Negative (Enterobacteriaceae) Laboratory/Clinical Strains Gr- Bacterial SpeciesType# of IsolatesCompoundMIC 90 (µg/mL)MIC 50 (µg/mL)Range (µg/mL) Escherichia coli 27 MBX 10660.50.120.03-0.12 MBX 11620.250.120.06-0.25 Imipenem0.25 0.06-0.5 Tigecycline0.250.120.12-0.25 Ciprofloxacin>20.030.015->2 Klebsiella pneumoniae 27MBX 1066820.25->16 MBX 11620.50.250.12-1 Imipenem160.250.06-32 Tigecycline20.50.25-2 Ciprofloxacin>80.120.06->8 K. pneumoniaeESBL 12 MBX 1066>1610.5->16 MBX 11620.50.120.06-0.5 Imipenem10.250.12-2 Tigecycline20.50.25-8 Ciprofloxacin>8 0.06->8 Serratia marcescens 12MBX 1066210.06-2 MBX 11620.250.120.12-0.5 Imipenem>842->8 Tigecycline110.5-2 Ciprofloxacin10.250.06->2

24. November 7, 2008 Gram-Negative (Atypical) and Gram-positive (Anaerobe) Laboratory/Clinical Strains Gr- Bacterial SpeciesType# of IsolatesCompoundMIC 90 (µg/mL)MIC 50 (µg/mL)Range (µg/mL) H. influenzae 12 MBX 1066>1641->16 MBX 1162410.5-4 Levofloxacin0.060.0150.008-1 Azithromycin210.5-2 Cefotaxime>410.03->4 Amox/Clav8/41/0.50.5/0.25-16/8 Clostridium difficile 16 MBX 10660.120.060.03-0.25 MBX 11620.06 0.03-0.12 Clindamycin>840.25->8 Imipenem440.5->8 Metronidazole0.50.120.06->8

25. November 7, 2008 MBX compounds are rapidly bactericidal Time (hr) to cidal effect Species / CompoundMBX-1066MBX-1090MBX-1142MBX-1162 Y. pestis≤1 B. anthracis6≤14

26. November 7, 2008 Mammalian cytotoxicity values consistent with favorable selectivity indices Compounds HeLa Cell CC 50 (µg/mL) MIC S. aureus 25923 (µg/mL) Selectivity Index (in vitro) MBX 1066 32.50.12270 MBX 1090 100.6316 MBX 1113 30.319.6 MBX 1128 170.2860 MBX 1142 140.2751 MBX 1143 130.12111 MBX 1162 40.1626 MBX 1195 15450.33 MBX 1196 150.1696 HB-EMAU 3557 Method: Human HeLa cells were exposed for 72 hours to serial dilutions of compounds, then assessed for cell viability using an MTT assay

27. November 7, 2008 Microbiology Summary  Potent in vitro activity against category A or B bioterrorism pathogens  Potent in vitro activity against a broad-spectrum of Gram-pos. and Gram-neg. strains, including clinical isolates and multiple-drug resistant strains  Potency vs. >10 isolates/species (MIC 90 values)  Rapidly bactericidal mechanism of action  Low 3-day cytotoxicity (CC 50 ) of compounds

28. November 7, 2008 In vivo Potency in Murine Infection Models

29. November 7, 2008 Survivors GroupnIV treatmentDose, mg/kg8 hr18 hr24 hr48 hr% survival 110DMA/D5W-222220 210Dapto10 100 310MBX 106610988880 410MBX 109010 99990 52MBX 1113102 mice died immediately after injection 5’8MBX 11131211112.5 61MBX 1128101 mouse died immediately after injection 6'9MBX 1128152000 710MBX 116210 100 810MBX 116219 6 6660 MBX compounds are efficacious in a murine S. aureus infection model (i.p./i.v.) Infection: S.aureus (4X10 8 cfu, Smith strain) injected i.p. Treatment: Compound (10 or 1 mg/kg in 10% DMA/D5W) given IV 15 min. post-infection

30. November 7, 2008 MBX compounds are efficacious in a Yersinia pestis infection model when administered single-dose i.p. Infection: Y. pestis (100 cfu, CO92 strain) given i.p Treatment: Compound (1.5 mg/kg /injection in 1.5 % DMSO in water) given i.p. qid starting at 6 hours post- infection and ending 5 days post- infection

31. November 7, 2008 MBX compounds are efficacious in a Yersinia pestis infection model when administered i.p. or i.m. Infection: Y. pestis (100 cfu, CO92 strain) given i.p Treatment: Compound (2 mg/kg /injection in 1.5 % DMSO in water) given i.p. or i.m. qid starting at 6 hours post-infection and ending 5 days post- infection

32. November 7, 2008 MBX compounds are efficacious in a murine Burkholderia pseudomallei infection model (i.p./i.p.) Infection: B. pseudomallei (1x 10 6 cfu, 1026b strain) given by the i.p. route (n = 5) Treatment: Compound (10 mg/kg/injection in 10% DMSO/PBS) given i.p. once at 1 hour post-infection

33. November 7, 2008 MBX 1090 and 1162 are somewhat efficacious in a Burkholderia mallei murine infection model (intranasal/i.v.) Infection: B. mallei (1x 10 6 cfu, GB5 strain) given by the intranasal route (n = 5) Treatment: Compound (10 mg/kg/injection in 10% DMSO/PBS) given IV once at 1 hour post-infection *MBX 1066 was not tested due to the deaths observed in the B. pseudomallei model.

34. November 7, 2008 MBX compounds were not effective in a multiple-dose F. tularensis infection model (i.p./i.p.) Infection: F. tularensis (Schu4 strain) given i.p Treatment: Compound (1.0, 1.5, 1.5, 0.5 mg/kg/injection for MBX 1090, 1142, 1162 and 1113, respectively) given i.p. qid starting at 6 hours post-infection and ending 5 days post-infection

35. November 7, 2008 Infection: B. anthracis Ames spores (500 cfu) given IP Treatment: MBX 1066 (10 mg/kg/inj. dissolved in aq. 4% DMSO) given IP qid starting at the indicated post-infection time and ending after 5 days Demonstrated efficacy with MBX-1066 in a single-dose Bacillus anthracis infection model (i.p./i.p.)

36. November 7, 2008 Efficacy in a single-dose Bacillus anthracis infection model (i.p./i.v.) Infection: B. anthracis (860 cfu, Ames strain) given by the i.p. route (n = 10) Treatment: Compound (10 mg/kg for MBX 1066 and 1162, 5 mg/kg for MBX 1090 in 10% DMA/D5W) given IV at 6 hours post-infection; only 1 treatment

37. November 7, 2008 Efficacy in a multiple-dose Bacillus anthracis murine infection model (i.p./i.v.) Infection: B. anthracis (860 cfu, Ames strain) given by the i.p. route (n = 10) Treatment: Compound (10 mg/kg for MBX 1066 and 1162; 5 mg/kg for MBX 1090 in 10% DMA/D5W) given IV at 6 hours post-infection; 5 mg/kg for MBX 1066 and 1162; 2 mg/kg for MBX 1090 given IV at 18 and 42 hours post-infection—a total of 3 treatments

38. November 7, 2008 Summary of MBX-1066 & 1162 Efficacy in Animal Models of Infection Both are active against S. aureus in 1-10 mg/kg range, single-dose i.p. or i.v., with no toxicity observed Both prolonged survival inY. pestis infection model at 6-8 mg/kg/day x5d, multiple-dose i.p. and i.m. MBX-1162 is active against B. pseudomallei at 10 mg/kg, single- dose i.p. Slight prolongation of survival in B. mallei intranasal infection model at 10 mg/kg, single-dose i.v. Not active against F. tularensis under conditions examined Both are active against B. anthracis in 10-40 mg/kg range i.v. or i.p.

39. November 7, 2008 Mechanism of action studies of the bis- (imidazolinylindole) class of compounds

40. November 7, 2008 Macromolecular Synthesis Assays None of the MMS pathways affected at killing dose (5x MIC) Target not identified by MMS studies DNA synthesis is inhibited at >10X MIC (secondary effect) S. aureus MBX-1066 Controls

41. November 7, 2008 Membrane perturbation assays MBX-1066 does not perturb bacterial or mammalian cellular membranes at bactericidal concentrations Bacterial membrane perturbation DiOC(2)/FACS Mammalian membrane lysis LDH release assay

42. November 7, 2008 Map loci responsible for bis- (imidazolinylindole) resistance Resistant mutants- 16X MIC MBX-1066 resistance is not detectable Serial passage of S. aureus NCTC-8325 in subinhibitory compound concentrations to select resistance mutants MBX-1162 resistance is not detectable ABCDEFGH MBX-1066 MBX-1090 MBX-1162 Passage Number

43. November 7, 2008 MBX-1090 resistance maps to mepR, regulator of a drug-sodium antiporter No cross resistance vs. other bis- (imidazolinylindole) compounds Model confirmed by extensive genetic and transcription profiling analyses MBX-1090 is a MepA substrate Other bis-(imidazolinylindole) compounds are NOT MepA substrates

44. November 7, 2008 Average MIC (µg/mL) Bacterial StrainMBX 1066MBX 1090MBX 1113MBX 1128MBX 1162 E. coli 700 TolC+ (efflux proficient)1.30.630.31800.16 E. coli 701 TolC- (efflux deficient)0.16 210.14 Pseudomonas aeruginosa PAO1 (efflux proficient) 7.53.125>800.29 P. aeruginosa PAO1 ΔmexAB-oprM (efflux deficient) 1.153.11.3>800.25 Compound MBX-1162 is not susceptible to bacterial efflux

45. November 7, 2008 Half-maximal DNA interaction by MBX- 1066 occurs at about 0.4 μM (~0.3 μg/ml) Fluorescence Enhancement of MBX- 1066 in the Presence of DNA – Concentration Dependence Affinity of MBX 1066 for AT-rich B. anthracis DNA is ~2-fold stronger than for calf thymus DNA DNA Interaction with MBX-1066 in the Presence of Increasing Concentrations of Calf Thymus or B. anthracis Genomic DNA Analysis of DNA binding activity of bis- (imidazolinylindole) compounds

46. November 7, 2008 In situ fluorescence of MBX-1066 in S. aureus cells is consistent with DNA binding at 1X MIC None1 X MBX-10664 X MBX-10661 X MBX-10904 X MBX-1090 4 X MBX-1113 DIC DAPI DIC DAPI Intracellular fluorescence readily detected at 1X MIC Consistent with DNA-dependent fluorescence enhancement 1 X MBX-1066 Contrast enhanced 10X zoom cytoplasmic localization

47. November 7, 2008 5’-CGXXXXC 3’-GCXXXXG A A A A A Fluorescent displacement assay MBX-1162 Preference for A/T rich sequences Highest affinity for AATT 136 possible sequences Relative affinity for AATT Scatchard plot (K app ) Dr. Eric Long (IUPUI) DNA sequence preference for MBX-1162 binding and affinity constant Slope = K app

48. November 7, 2008 Absence of correlation between DNA binding and biological activity antibacterial cytotoxicity MIC and cytotoxicity correlate poorly with DNA binding

49. November 7, 2008 Profiling the changes in gene expression in response to MBX-1066 and -1090 for MOA (in progress) Grow S. aureus NCTC 8325 in presence of MBX-1066, MBX-1090 and a compendium of antibiotics that affect RNA/DNA synthesis at 1- 2X MIC for 1 doubling time (3 h in MHB) in triplicate Harvest cells and prepare RNA. Microarray analyses at NimbleGen Identify genes up- and down-regulated by MBX-1066 and -1090. Compare profile to other antibiotics using statistical methods. Samples prepared for profiling

50. November 7, 2008 Genes affected by MBX-1066 and -1090 MBX-1066 691 MBX-1090 131 74 Numbers of genes Up- and Down- regulated (4X, 90% confidence) Up=333 Down=358 conserved hypothetical protein = 325 Up=44 Down=87 conserved hypothetical protein = 65 MBX-1090 selected genes

51. November 7, 2008 Hierarchical clustering: Intersection MBX-1090 and 1066 genes 4X UP and DOWN (74) MBX-1066 and MBX-1090 clusters with Distamycin (DNA minor groove binder)

52. November 7, 2008 Biolog-MOA using Phenotypic Arrays 1. Measure magnitude of synergy/antagonism (SAVs) of experimental compound against a panel of 60 antibiotics with known MOA using PM technology 2. Generate matrix of SAVs that describes the chemical interaction between the chemicals in the PM plate and the added inhibitors being tested. 3. Use statistical clustering program to group antibiotics based on SAVs. Antibiotics with like MOAs cluster together.

53. November 7, 2008 Phenotypic Microarray-Clustering results MBX-1066 and MBX-1090 cluster with toxic cations—suggests non- specific MOA

54. November 7, 2008 MOA Summary Activity against DNA-dependent macromolecular synthesis Inhibition of DNA and RNA synthesis at >10x MIC in cell-based MMS assay Inhibition of replicative helicase (IC 50 ~1 μM; 4X MIC) Inhibition of Replix TM (IC 50 ~2 μM; 8X MIC) Above activities are not potent enough to correlate with antibacterial activity Minimal effects on bacterial and mammalian cell membranes Extremely low frequency of resistant mutants The bis-(imidazolinylindole) compounds interact with DNA Fluorescence enhancement in the presence of DNA (Max 1/2 ~0.4 μM) Intracellular fluorescence observed at 1X MIC AATT is optimal binding site DNA binding affinity correlates poorly with antibacterial activity & cytotoxicity Profiling studies suggest non-specific or multiple MOAs

55. November 7, 2008 Selection of Lead and Backup Compounds MBX 1066 was selected as a preclinical candidate Potent vs. category A and B biothreat agents Broad-spectrum antibacterial activity Undetectable frequency of mutation to resistance Maximal in vitro selectivity index Rapid bactericidal activity Low cost of goods; ease of synthesis scale-up; short synthetic route Prolongs survival in multiple animal models of infection MBX 1162 (analog of MBX 1066) was selected as a backup candidate by SAR Similar benefits as MBX 1066 Greater potency vs. Gram-neg. while retaining Gram-pos. potency Broader spectrum of activity than MBX 1066 Increased solubility

56. November 7, 2008 IND Enabling Studies

57. November 7, 2008 Nomenclature MBX-1066 (TFA salt of MBX-1336) MBX-1162 (TFA salt of MBX-1143) MBX-1336 (free base of MBX-1066) MBX-1143 (free base of MBX-1162)

58. November 7, 2008 Target Product Profile Indication: Treatment and prevention of infections from biowarfare agents Mechanism of Action: Broad-spectrum antibacterial activity against intracellular biowarfare agents. Safety Profile: The benefits of treatment outweigh the risks. MIC: <1 µg/ml Clinical Efficacy: Must be effective in primate efficacy model. Resistance: Compounds with new mechanisms of resistance or no resistance will be favored. Route of Administration: Intramuscular may be more field-deployable; intravenous will be used initially (bolus ideal; up to 1 hour infusion acceptable). Dosing Regimen: Ideally one time dose; for multiple dosing 1 -2 times daily, no more than 3-4 times daily. Dosage Form: Low volume parenteral compatible with standard intravenous solutions Monitoring Requirements: Monitoring of serum/plasma drug concentrations should not be required. No clinically significant adverse reactions observed in the efficacious dose range. Product Stability: Drug product should be stable for at least 2 years. Product Storage Conditions: The drug product ideally should be stored at room temperature. Refrigerated or frozen drug product may be acceptable.

59. November 7, 2008 Preclinical Studies Pilot Rat Toxicology Genetic Toxicology AMES CHO Rat Micronucleus Rat Single Dose PK Rat Single Dose Acute Toxicity (Bolus) Rat Single Dose Acute Toxicity (Infusion) Rat ADME - ongoing Dog Dose Escalation (Infusion) – ongoing

60. November 7, 2008 Pilot Rat Toxicology Study Single Dose Toxicity (MBX-1066, MBX-1162) Bolus administration (5, 10, 15 mg/kg) to male rats Doses limited by solubility of MBX-1066 Toxicity seen with higher vehicle concentrations (20 % DMA in D 5 W); modified to 10% DMA in D 5 W MBX-1066 MTD: 5 mg/kg MBX-1162 MTD: 15 mg/kg Conclusions: Solubility limited; unclear if formulation is contributing to toxicity

61. November 7, 2008 Resolution of Formulation Issues Six month extension requested due to compound formulation issues which included low solubility, use of organic solvent, and potential vehicle toxicity Hired contractor to develop a new suitable clinical formulation Formulation issue resolution included a change to the free base form and new formulation of the lead compound Microbiotix set-up pilot GMP manufacturing and preliminary stability studies with the lead compound, MBX-1336 (free base form of MBX-1066). A pilot batch of MBX-1336 was made in April 2008. A non-GMP batch of MBX-1143 (back-up compound) was made.

62. November 7, 2008 Plan as of May 2008 Results of June-initiated toxicology and pharmacokinetic studies will:  Confirm lead compound  Trigger cGMP manufacturing  Trigger remaining IND-enabling preclinical toxicology studies  Trigger request for pre-IND meeting with FDA

63. November 7, 2008 Genetic Toxicology Ames Testing (MBX-1066, MBX-1162) Completed in March 2008 Neither compound induced mutations CHO Study (MBX-1143) Completed in August 2008 Did not induce chromosomal aberrations Rat Micronucleus Study (MBX-1143) Completed in August 2008 Did not increase incidence of micronucleated polychromatic erythrocytes Conclusion: There were no issues in the genetic toxicology studies. Results support proceeding with additional studies.

64. November 7, 2008 Single Dose Rat Pharmacokinetic Study Bolus injection (MBX-1336, MBX-1143) IV, IM, IP administration at 1 and 10 mg/kg 11/12 rats in MBX-1336 IV 10 mg/kg group died within 1 minute of administration (6M, 5F) No toxic effects observed for MBX-1143 PK parameters  MBX-1336 IM and IP had BLQ plasma levels  See other data next slide

65. November 7, 2008 PK Parameters CompoundRouteDose (mg/kg) SexT max (hr) t 1/2 (hr)Cmax (ng/mL) AUC last (hr*ng/mL) AUC 0-∞ (hr*ng/mL) MBX-1336IV1M041.0365818691165 MBX-1336IV1F0NR9565892918 MBX-1336IV10MNR MBX-1336IV10F02.46351611041122 MBX-1143IV1M01.581359416741696 MBX-1143IV1F02.351424016921698 MBX-1143IV10M02.651627951693016976 MBX-1143IV10F05.651462001634916418 MBX-1143IP1M15.452.3435461 MBX-1143IP1F1.52.7946.3278296 MBX-1143IP10M610.4732143645789 MBX-1143IP10F68.8538045605663 MBX-1143IM1M422.4514.5258490 MBX-1143IM1F61617.4346540 MBX-1143IM10M12NR33.2631NR MBX-1143IM10F12NR37.0740NR

66. November 7, 2008 Single Dose Rat Pharmacokinetic Study Results / Conclusions MBX-1336 caused toxicity at the high end of the pharmacologic range (10 mg/kg) Plasma levels provided insight into pharmacology data MBX-1336 does not reach the plasma when given i.p. or i.m. MBX-1143 does reach the plasma when administered i.p., i.m., or i.v. MBX-1143 PK data was dose-proportional (with exception of i.m.) MBX-1143 was selected as the new lead candidate

67. November 7, 2008 Single Dose Rat Acute Toxicity MBX-1143 (free base of MBX-1162) Bolus Study Design 6 groups of 6M, 6F 10, 30, 20, 15 and 5 mg/kg and vehicle control Dose followed by 14 day observation period

68. November 7, 2008 Findings Dose (mg/kg; n=6/sex/group) 0510152030 MFMFMFMFMFMF Unscheduled Deaths*0 (1) 0000 (2)31 (3)61 (2)66 Clinical Signs++++++++ +++ Body Weight (thru Day 11) ↑↑ ↑ ↑ ↓↑↓↓↓↓ Food Consumption (Days -1 to4 compared to control) --N/A ↓↓↓↓↓↓↓ ↓ Clinical Pathology--++++++N/A+ Gross Pathology--==++++++++ Organ Weights--++++++++N/A *Number of deaths is expressed as non-procedure related deaths (total deaths). Single Dose Rat MBX-1143 (free base of MBX-1162) Acute Toxicity – Bolus

69. November 7, 2008 Single Dose Rat MBX-1143 (free base of MBX-1162) Acute Toxicity – Bolus Summary of Results 5 mg/kg: minor clinical signs – minor changes in clinical pathology 10 mg/kg: some clinical signs – changes in clinical pathology; decreased body weight & food consumption 15 mg/kg: 3M and 1F died/sac’d 20 mg/kg: 6M and 1F died/sac’d 30 mg/kg: 6M and 6F died/sac’d

70. November 7, 2008 Single Dose Rat MBX-1143 (free base of MBX-1162) Acute Toxicity – Bolus Results / Conclusions NOAEL <5 mg/kg MBX-1143 was toxic to animals that received >15 mg/kg Number of deaths per group increased with dose Males appeared to be more sensitive Two phases of toxicity resulting in death Acute within 1 hr of dosing Sub-acute within 9-13 days of dosing Unclear if the toxicity was related to C max or AUC.

71. November 7, 2008 Single Dose Rat Acute Toxicity MBX-1143 (free base of MBX-1162) Infusion Study Design 1 hour infusion 3 dose groups (10, 30 and 50 mg/kg) 2 TK groups (low and high dose) 1 vehicle control group

72. November 7, 2008 Findings Dose (mg/kg; n=6/sex/group, except control n=2/sex) 0103050 MFMFMFMF Unscheduled Deaths*00006/6 Clinical Signs-- ↓ feces ++++ Body Weight (thru Day 11)↑↑ ↑↑↓↓ Food Consumption (Days -1 to 3 compared to control) --==↓=↓↓ Clinical Pathology--++N/A Gross Pathology--++++++ Organ Weights--++N/A Single Dose Rat MBX-1143 (free base of MBX-1162) Acute Toxicity - Infusion

73. November 7, 2008 Single Dose Rat MBX-1143 (free base of MBX-1162) Acute Toxicity – Infusion Summary of Results 10 mg/kg: some clinical signs – decreased feces (2/6 animals) 30 mg/kg: 6M and 6F died/sac’d; all died on day 10-11 50 mg/kg: 6M and 6F died/sac’d; males, day 1-8; females, day 9-10

74. November 7, 2008 Single Dose Rat Acute Toxicity MBX-1143 (free base of MBX-1162) Infusion Results / Conclusions NOAEL <10 mg/kg MBX-1143 was lethal to animals that received >30 mg/kg at 30 mg/kg sub-acute tox in both sexes at 50 mg/kg males suffered acute to sub-acute tox and females suffered sub-acute tox MBX-1143 was toxic by infusion at doses of 30 mg/kg. We were unsure if this was species-specific toxicity, so we decided to evaluate the compound in dogs.

75. November 7, 2008 Dose Escalation MBX-1143 (free base of MBX-1162) Dog Study Study Design Group 1 (1M, 1F): 0.3 mg/kg; 3 mg/kg Group 2 (1M, 1F): 1 mg/kg; 10 mg/kg 4 days between each dose level (groups alternate) Confirmation group

76. November 7, 2008 Results 0.3 mg/kg: No issues during 1 week follow-up 1 mg/kg: No issues during 1 week follow-up 3 mg/kg: No issues in 4 days following dosing so 10 mg/kg group dosed; Male found dead 9 days after 3 mg/kg dose; Female sac’d 10 days after last dose 10 mg/kg: Male sac’d moribund 2 days after dosing; Female found dead 5 days after dosing Dose Escalation MBX-1143 (free base of MBX-1162) Dog Study

77. November 7, 2008 Results Male received 0.3 and 3.0 mg/kg; found dead 9 d after the 3 mg/kg dose Female received 0.3 and 3.0 mg/kg; sac’d 10 d after 3 mg/kg dose Male received 1 and 10 mg/kg; sac’d 2 d after 10 mg/kg dose Female received 1 and 10 mg/kg; found dead 10 d after 10 mg/kg dose Dose Escalation MBX-1143 (free base of MBX-1162) Dog Study

78. November 7, 2008 Conclusions: Severe toxicity observed in both groups Two phases of toxicity resulting in death Acute within 2 days of dosing Sub-acute within 5-10 days of dosing Dose Escalation MBX-1143 (free base of MBX-1162) Dog Study

79. November 7, 2008 There is a toxicity issue preventing further development Lethal at 10-15 mg/kg in rat Lethal at 0.3-3.3 mg/kg in dog The efficacious dose is 1-10 mg/kg There is not an acceptable margin of safety for continued development As a result, we will not continue additional animal studies and we will not meet the IND milestone Summary of MBX-1143 Toxicity Studies

80. November 7, 2008 Further development of backups – e.g., MBX-1090 Topical treatment for wounds – e.g., MDR A. baumannii Alternative indications – device-related infections Future Alternatives

81. November 7, 2008 Future SAR Plans: Analogs of MBX 1090