AZD5847 Oxazolidinone for the treatment of Tuberculosis CPTR Workshop, 2012 Arlington, VA Scott Butler Infection Innovative Medicines Group AstraZeneca R&D, Boston AZD5847: An oxazolidinone to treat tuberculosis MIC – 163 TB isolates MICdistribution Distribution - 163 Mtu Isolates Product Concept: Antimicrobial to be incorporated into (84 sensitive, 18 SDR, 36 MDR & 25 XDR) novel combination therapies to treat DS and/or MDR/XDR tuberculosis (including HIV co-infected) HO Number of isolates O F O O N N O 60 N Sensitive SDR MDR XDR 40 20 O F HO AZD5847 0 0.25 0.5 1 2 4 8 16 MIC (M) • Originally targeted as once daily IV/oral treatment for staphylococcal infections • Development was discontinued in 2002 when pharmacokinetics in healthy volunteers did not support QD IV dosing* • Now re-positioned for the treatment of tuberculosis by oral administration • Ready to start Phase 2 *Gravestock MB et al.. Bioorg. Med. Chem. Lett. 2003. 13:4179-86 2 AZD5847 is bactericidal against intracellular TB • Bone marrow derived macrophage model: AZD5847and rifampicin are effective against intracellular TB, whereas isoniazid and linezolid are weakly active Rifampicin 6 AZD5847 5 Untreated R16 R4 R1 R0.25 4 p < 0.001 Log10CFU/ml Log10CFU/ml 5 6 Isoniazid 6 3 p < 0.05 Untreated H16 H4 H1 H0.25 4 3 0 2 4 6 8 10 0 4 0 2 4 6 Days 8 10 6 6 5 5 Untreated 4 p < 0.001 P16ug/ml Untreated L16ug/ml 4 L8ug/ml L4ug/ml P4ug/ml L2ug/ml P2ug/ml 3 P1ug/ml L1ug/ml L0.5ug/ml P0.5ug/ml 0 2 10 p > 0.05 P8ug/ml 3 8 Linezolid PNU100480 p < 0.001 Untreated A16ug/ml A8ug/ml A4ug/ml A2ug/ml A1ug/ml A0.5ug/ml 6 Days Log10CFU/ml 4 3 4 6 Days 3 2 Days Log10CFU/ml Log10CFU/ml 5 8 10 0 2 4 6 Days 8 10 AZD5847 retains PKPD index vs. slowly dividing TB in mouse model • AZD5847 and Linezolid are equally effective versus rapidly dividing TB in mouse lung TB model • AZD5847 has higher efficacy versus slowly dividing TB, that is key to achieving sputum sterilization. Once daily oral dosing for 4 weeks 4 Lower risk of toxicities related to inhibition of Mitochondrial Protein Synthesis • Inhibition of mammalian MPS (by oxazolidinones) has been associated with myelotoxicity, lactic acidosis, and neuropathies1,2,3 • AZD5847 maintains lower exposures relative to in vitro IC50 for MPS at therapeutic doses doses AZD5847 5 400 B ID f asted/f ed 400 B ID f ed/f ed 800 B ID f ed/f ed 1600 Q D f ed 1200 B ID f ed/f ed F o ld MPS IC 50 4 3 2 1 0 0 Rx Dose 1. 2. 3. 4. 5 6 12 18 T im e (h) Garrabou, G., Soriano, A., et al.. (2007). Antimicrob. Agents Chemother. 51, 962-967. Nagiec, E. E.; Swaney, S. M.; et al.. (2005) Antimicrob. Agents Chemother. 49, 3896-3902. McKee, E. E.; Ferguson, M.; et al.. (2006) Antimicrob. Agents Chemother. 50, 2042-2049. Wallis R. S. et al.. (2011) Antimicrob Agents Chemother. 55(2):567-74. 24 Modelling of Ph1 data for likely attainment of preclinical PD target • Accounted for: Inter-subject PK variability and the MIC distribution against M. tuberculosis • Monte-Carlo simulation - target attainment in 85% patients • Modeling predicts efficacy @ 800 mg QD / 400 mg BID 15 10 %patients to achieve PD target Concentration (G.Mean + SD) uM SAD 600 mg Crossover Fed Fasted 5 0 0 10 20 30 40 q24 q12 q8 50 Time (h) Human Dose (mg) 6 AZD5847 Ph1 Clinical safety summary AZD5847 was generally well tolerated over 14 days in healthy volunteers at doses predicted to drive efficacy in humans • n=42 single-dose (SAD) subjects; n=45 multiple-dose (MAD) subjects • Maximum administered dose 2400mg per day x 14 days • Predicted therapeutic dose 400mg BID / 800mg QD • No SAEs; 3 DAEs: pustular rash, self limited rectal bleed, migraine/scotoma • Most common AE: Dose-related nausea, reduced by dosing with food • Decreased WBC counts (5/9 volunteers 2400mg/day) and increased reticulocyte counts (1600-2400mg/day) were observed • Transient myalgias noted for 3/9 volunteers @ 2400mg/day (no CPK elevation) • No clinically significant ECG findings. 7 AZD5847: Carboxylic acid metabolite • Exposure o Metabolite was identified during analysis of pooled plasma samples from healthy subjects in the MAD study o Total AUC approximately 50% of the parent compound (free is <10%) o Exposure of metabolite in rat and dog did not provide in vivo toxicology qualification • Activity o Metabolite is equipotent to AZD5847 against TB in vitro and has nearly identical PK profile • Safety o No structural alerts for genetic toxicity and negative in Ames assay o Active against mitochondrial protein synthesis, however less potent than the parent molecule (30 µM IC50 versus 13 µM IC50) o Secondary pharmacology panel (including hERG and cardiac channels) o Some differences from parent, but no risks identified o No change to risk - benefit ratio. 8 Phase 2a: EBA Study (Sponsored by NIAID) Short duration (14 days) monotherapy with AZD5847 in patients with drug sensitive TB • To be conducted in South Africa (TASK, Andreas Diacon) • Scheduled start in late October Inclusions/exclusions; HAINE test to for sensitivity to rifampin and isoniazid; Baseline safety labs Active pulmonary tuberculosis documented by positive sputum smear x 2 Treatment: 14 days Daily quantitative sputum culture for M.tb Days 0-2 = early bactericidal activity Days 3-14 = sterilizing activity 1 2 Randomization Initiate SOC for DS-pulmonary TB 3 4 5 PK sampling days 1 and 14, trough levels days 5 and 10 Safety labs on days 7 and 14 Treatment groups (total enrollment ~75: 15 per arm) 1. AZD5847 500mg qd 2. AZD5847 500mg bid 3. AZD5847 1200mg qd 4. AZD5847 800mg bid 5. Rifafour 1 tab PO qd (weight based) 9 Endpoint: Rate of change in sputum colony forming unit (CFU) counts (bactericidal activity) during the entire 14 days of study drug administration (EBA0-14) Next steps • Preparation for potential Ph2b • 90 day chronic toxicology studies in mouse and dog (currently setting up) • DDI studies as appropriate for specific design and population • Pharmaceutical development Summary • Oxazolidinones offer a promising (clinically validated) addition to future novel combination regimens (MDR/XDR treatment or simplification/reduced duration) • AZD5847 has potential to differentiate in the clinic: • Active against slowly dividing TB • Active against intracellular TB • Has reduced potency against human mitochondrial protein synthesis • AZD5847 is safe and well tolerated at predicted efficacious doses • Phase 2a trial to start October/November 2012 10