Determination of the pharmacokinetics of single (SAD) and multiple ascending doses (MAD) of SPR741 in healthy volunteersL Utley1*, T Lister1, S Coleman2, PB Eckburg1

1Spero Therapeutics, Cambridge MA, USA; 2Acceleron Pharma, Cambridge MA

L UtleyApril 24, 2018Poster number, P2233

Spero Therapeutics857.242.1525

lutley@sperotx.com

Study Design: This was a double-blind, placebo controlled, ascending dose, multi-cohort trial, performed ata single investigative site in Australia in healthy volunteers. The study was conducted in two parts (SAD andMAD). All subjects signed written informed consent, and were screened for eligibility within 28 days of studyentry. SAD cohorts were dosed at 5, 15, 50, 100, 200, 400, 600, and 800 mg; MAD cohorts were dosed at50, 150, 400, and 600 mg q8h for 14 days.SAD: Blood draws were taken pre-dose (within 10 minutes), 30 minutes following the start of infusion, end ofinfusion and at 75, 90, 105, 120, and 150 minutes, 3, 4, 5, 6, 8, 10, 12, and 24 hours following start ofinfusion. Urine samples were collected pre-dose and during the following intervals: 0-4, 4-8, 8-12 and 12-24hours after start of infusion.MAD: One blood draw was taken prior to the morning dose (within 10 minutes) on Days 2, 3, 5, 7, 9, 11 and13. On Days 1 and 14, blood draws for PK were taken pre-dose (within 10 minutes), 30 minutes followingthe start of infusion, end of infusion and at 90, 150 minutes, 3, 4, 5, 6 and 8 hours following start of infusion(Day 1 (first dose) and Day 14 (last dose)). Five additional blood draws will be obtained at 10, 12, 24, 36 and48 hours following the start of infusion of the last dose (morning of Day 14). Urine was collected pre-doseDay 1 sample, total collection over 0-4, 4-8 hours following start of infusion of first dose on Day 1; then totalcollection over 0-4, 4-8, 8-12, and 12-24 hours following start of infusion of the last dose (Day 14).Analysis: Concentrations of SPR741 in plasma and urine were determined using validated LC-MS-MSmethods. The limit of quantitation for SPR741 was 50 ng/mL in plasma and 1 μg/mL in urine Plasmapharmacokinetic parameters were determined using non-compartmental analysis. Clearance and Volume ofdistribution were calculated using both nominal and measured dose and differences were found to be withinthe limits of the assay; therefore nominal concentrations were used in the MAD calculations. One subject, inMAD cohort 12, was removed from the PK summary statistics due to an error in sample collection; a secondsubject, in MAD cohort 10, withdrew from the trial due to personal reasons.

The emergence and spread of multidrug-resistant (MDR) strains of E. coli, K.pneumoniae, and A. baumannii, has revealed shortcomings in the current antibioticarmamentarium for treating infections caused by these bacteria. Such infections result insignificant morbidity and mortality and incur substantial economic costs. There is a lackof new classes of antibiotics with potential activity against MDR Gram-negative pathogenscurrently in clinical development. Spero Therapeutics has identified a series of novelpolymyxin analogs of which SPR741 is a lead candidate. SPR741 lacks significant directantibacterial activity against Gram-negative organisms (MIC >16 µg/mL for most species),however, when combined with antibiotics that have limited or no antibacterial activityagainst Gram-negative pathogens, SPR741 can expand the spectrum of the partnerantibiotic to include MDR Gram-negative species.

Presented herein is the pharmacokinetics (PK) of SPR741 after single- and multiple-dose intravenous (IV) administrations to healthy adult subjects.

INTRODUCTION

RESULTS

CONCLUSIONSSPR741, administered up to 400 mg q8h, (1.2 g per day) for up to 14 days displayed linear andproportional pharmacokinetics and showed no evidence of accumulation or time dependent changes inplasma exposure as measured by AUC, Cmax or Ctrough. Renal clearance decreased slightly with doseafter fourteen days of repeat dosing. These data support further clinical development of SPR741 inhumans

SAD: The geometric mean of the plasma concentration vs. time for each SAD cohort is plotted in Figure 1.At the end of the 1-hour infusion, plasma concentrations of SPR741 displayed plasma concentration profilesconsistent with first order elimination. Mean pharmacokinetic parameters for each of the SAD cohorts arelisted in Table 1. Mean t1/2 was 2.9 hours and did not increase with dose. Cmax and AUC increased in adose linear and proportional manner; mean Vd and Cl values were 20.5 L and 5.00 L/hr, respectively. Doselevels of 100 to 800 mg had greater than 50% of the administered dose of SPR741 excreted in the urine inthe first four hours post-dose. Renal clearance ranged 0.474 – 1.37 L/hr and was constant with dose atdoses above 100 mg.

METHODSABSTRACTBackground: SPR741 is a novel polymyxin B derivative with minimal intrinsicantibacterial activity and reduced non-clinical nephrotoxicity. SPR741 interacts with theouter membrane of Gram-negative (G-) bacteria enhancing penetration of co-administered antimicrobial compounds. Presented herein is the pharmacokinetics (PK) ofSPR741 after single- and multiple-dose intravenous (IV) administrations to healthy adultsubjects.

Materials/methods: This was a double-blind, placebo-controlled, multi-cohort trialconduted in normal healthing volunteers. SPR741 or placebo was administered as asingel 1-hour infusion at doses of 5-800 mg (SAD, n=8/cohort) and 50-600 mg q8h forfourteen days (MAD, n=8/cohort). Concentrations of SPR741 in plasma and urine weredetermined using validated LC-MS-MS methods. Plasma pharmacokinetic parameterswere determined using non-compartmental analysis.

Results: SAD: Mean t1/2 was 2.9 hours and did not increase with dose. Cmax and AUC increasedin dose linear and proportional manner; Vd and Cl values were 20.5 L and 5.00 L/hr,respectively. Dose levels of 100 to 800 mg had greater than 50% of the administereddose of SPR741 excreted in the urine in the first four hours post-dose. Renal clearanceranged 0.474 – 1.37 L/hr and was constant with dose at doses above 100 mg.

MAD: Mean t1/2 for all groups on day 1 was similar to the single dose values (2.3 hours) and was 9.0 hours on day 14. Clearance and Vd values on day 1 and 14 (4.23-5.77 L/hr and 17.2-30.8 L, respectively) were similar to the SAD phase of the study. There was no evidence of accumulation after 14 days of repeat dosing up to 400 mg. At 600 mg, one subject showed accumulating plasma levels after repeat dosing. Renal clearance on day 14 was 2.96-6.31 L/hr and decreased slightly with increasing dose.

Conclusions: SPR741, administered up to 400 mg q8h for up to 14 days, displayedlinear and proportional pharmacokinetics and showed no evidence of accumulation ortime dependent changes in plasma exposure as measured by AUC, Cmax or Ctrough.Renal clearance decreased slightly with dose after fourteen days of repeat dosing. Thesedata support further clinical development of SPR741 in humans.

Figure 1: Mean plasma concentration of SPR741 vs time after a 1-hour infusion.

RESULTS (cont inued)

Median

(Range)

Arithmetic Mean

(CV%)

SPR741Dose (mg)

Tmax

(hr)Cmax

(ng/mL)AUC0–inf

(hr*ng/mL)t½

(hr)

Actual DoseCL

(L/hr)Vd(L)

5 mg(n=6)

1.0(1.0 – 1.0)

370(10.9%)

1010(10.9%)

2.02(11.3%)

7.10(35.5%)

20.1(28.4%)

15 mg(n=6)

1.0(1.0 – 1.0)

924(7.6%)

3092(22.0%)

2.81(20.7%)

6.45(36.1%)

24.9(23.3%)

50 mg (n=6)

1.0(1.0 – 1.0)

3252(15.8%)

9745(10.7%)

2.48(14.0%)

5.27(12.9%)

19.1(26.6%)

100 mg (n=6)

1.0(1.0 – 1.0)

6008(11.8%)

18151(9.3%)

2.57(15.6%)

5.82(18.1%)

21.7(24.8%)

200 mg(n=6)

1.0(1.0 – 1.0)

13367(10.9%)

37304(14.3%)

2.62(23.0%)

6.51(29.2%)

24.0(26.3%)

400 mg(n=6)

1.0(1.0 – 1.0)

26017(11.8%)

82232(7.6%)

3.47(6.0%)

4.76(15.8%)

23.8(18.7%)

600 mg(n=6)

1.0(1.0 – 1.0)

38050(9.2%)

133110(17.2%)

3.76(16.2%)

5.09(23.5%)

27.3(22.0%)

800 mg(n=6)

1.0(1.0 – 1.0)

52617(9.9%)

189706(9.8%)

3.46(3.5%)

4.53(19.7%)

22.5(16.8%)

Table 1: Mean PK Parameters by Cohort in SAD.

MAD: The day 1 and day 14 geometric mean of the plasma concentration vs. time for each MADcohort is plotted in Figure 2. Trough values on days 2-13 for all cohorts are displayed in Figure 3.At the end of the 1-hour infusion, plasma concentrations of SPR741 displayed plasmaconcentration profiles consistent with first order elimination. Mean pharmacokinetic parametersfor each of the MAD cohorts are listed in Table 2. Mean t1/2 for all groups on day 1 was similar tothe single dose values (2.3 hours) and was 9.0 hours on day 14. Clearance and Vd values onday 1 and 14 (4.23-5.77 L/hr and 17.2-30.8 L, respectively) were similar to the SAD phase of thestudy. There was no evidence of accumulation after 14 days of repeat dosing up to 400 mg. At600 mg, one subject showed accumulating plasma levels after repeat dosing. Renal clearanceon day 14 was 2.96-6.31 L/hr and decreased slightly with increasing dose.

Figure 2: Mean plasma concentration of SPR741 vs time after a 1-hour infusion, days 1 and 14. Time is measured from the start of the infusion.

Figure 3: Mean trough concentrations, days 2-13.

Median

(Range)

Arithmetic Mean

(CV%)

DaySPR741

Dose (mg)Tmax

(hr)Cmax

(ng/mL)AUC*

(hr*ng/mL)t½

(hr)

Nominal DoseCL

(L/hr)Vd(L)

Day 1

50 mg(n=6)

1.00(1.0 – 1.0)

3130(10.8%)

9264(15.5%)

2.21(14.5%)

5.51(16.0%)

17.2(8.9%)

150 mg(n=5)

1.0(1.0 – 1.0)

10164(14.2%)

29232(17.7%)

2.21(14.8%)

5.27(18.7%)

16.6(17.1%)

400 mg (n=6)

1.0(1.0 – 1.0)

25183(20.8%)

68459(11.3%)

2.07(7.6%)

5.91(11.5%)

17.5(4.0%)

600 mg (n=5)

1.0(1.0 – 1.0)

35620(16.6%)

105800(17.0%)

2.26(15.8%)

5.82(18.8%)

18.8(17.7%)

Day 14

50 mg(n=6)

1.0(1.0 – 1.0)

3275(14.9%)

9623(10.2%)

3.16(48.8%)

5.24(10.1%)

23.2(38.8%)

150 mg(n=5)

1.0(1.0 – 1.0)

10664(16.9%)

29747(19.3%)

9.88(61.9%)

5.19(18.4%)

69.3(44.8%)

400 mg (n=6)

1.0(1.0 – 1.0)

27033(19.9%)

77305(20.8%)

14.04(52.6%)

5.34(18.7%)

112.4(31.0%)

600 mg (n=5)

1.0(1.0 – 1.0)

39720(13.6%)

126433(10.6%)

8.71(17.4%)

4.80(12.2%)

59.8(15.1%)

Table 2: Mean PK Parameters by Cohort in MAD.

Key = * AUCinf for Day 1 and AUC0-8h for Day 14 (Steady State)