ETX2514: Responding to the global threat of nosocomial multidrug and extremely drug resistant Gram-negative pathogens Ruben Tommasi, PhD Chief Scientific Officer ECCMID 2017 April 24, 2017 Vienna, Austria
Increasing drug resistance results in large unmet need U.S.: 2 MM drug-resistant infections/year 1 Resistance trends in Gram-negative bacteria 5 >23,000 direct deaths 1 High mortality and morbidity CRE (carbapenem resistant Enterobacteriaceae) 75% mortality 2,3 Acinetobacter baumannii mortality 43% 4 and 63% multi-drug resistant (MDR) 2,3 14% 5 of Pseudomonas aeruginosa are MDR, occasional reports of resistance to last resort antibiotics 4 Resistance trends increase the urgency of the medical need Entasis aims to effectively address medical need caused by each of these Gram-negative pathogens ETX2514 designed to address these needs as best in class BLI 60% 50% 40% 30% 20% 10% 0% 13% 9% 23% 17% 0% 0.3% 1% 44% 43% 20% 25% 4% 4% 50% 2000 2005 2010 2012 2014 Carbapenem-resistant Enterobacteriaceae Carbapenem-resistant A. baumannii Carbapenem-resistant P. aeruginosa 20% 1 Antibiotic Resistance Threats in the Unites States, 2013; Centers for Disease Control 2 Nat. Rev. Drug Discov. 12:963. 3 Clin. Microbiol. 48:2271. 4 Expert Rev. Anti Infect. Ther. 10(8), 917-934 (2012) 5 CDC Antibiotic Resistance Patient Safety ATLAS; Center for Disease Dynamics, Economics & Policy 2
Avibactam and other DABCOs have broader spectra of inhibition than older β-lactamase inhibitors but Class D activity is still a gap in coverage β-lactamases use serine- or zinc-mediated hydrolysis to inactivate β-lactams 2,819 enzymes identified: Class A (1,155); Class B (361); Class C (693); Class D (610) Clavulanic acid Sulbactam Tazobactam Serine Enzymes b-lactamases Metallo Enzymes Class A Class C Class D Class B Emerging threat KPC Carbapenemase OXA Avibactam Relebactam Vaborbactam Major new opportunity Acinetobacter & Pseudomonas ETX2514 http://www.bldb.eu/ (15 March 2017) 3
The ultimate medicinal chemistry challenge How to inhibit hundreds of bacterial enzymes but no human ones? How to find the right balance between reactivity and hydrolytic stability? How to prepare synthetically challenging, diverse analogs to verify structural hypotheses? Crystal structures provided insights to avibactam s unique interactions with b-lactamases While large hydrophobic space is available for Class-D enzymes, Classes A & C require smaller group loop Ser 81 Room for derivatization a2-a3 loop : polar residues : hydrophobic residues 4
DE (kcal/mol) Discovery of ETX2514, a novel broad-spectrum serine BLI Using a combination of innovative chemistry, structure-based design and quantum mechanics simulations - DE - Tetrahedral INT. -18-19 -20 Rate of hydrolysis (M -1.s -1 ) r 2 = 0.81 0 0.5 1 1.5 2 2.5 avibactam -21-22 -23 ETX2514 di-aza-bicyclo-octenone Active site overlays of avibactam- (in grey, PDB: 4WM9) and an ETX2514 analog- (in green) bound OXA-24 structures. The water molecules are depicted as spheres. The hydrogen bonding network around the ETX2514 analog is shown in dashed lines. 5-24 -25
ETX2514 exhibits excellent β-lactamase inhibition across Ambler Classes A, C and D k inact /K i (M -1 s -1 ) Class A Class C Class D Compound Structure TEM-1 CTX-M-15 KPC-2 SHV-5 E. cloacae P99 P. aer. AmpC OXA-10 OXA-23 OXA-24 OXA-48 Avibactam 4 x 10 5 8 x 10 5 6 x 10 3 1 x 10 5 8 x 10 3 3 x 10 3 7 x 10 1 1 x 10 2 8 x 10 1 5 x 10 3 ETX2514 1 x 10 7 7 x 10 6 9 x 10 5 6 x 10 6 2 x 10 6 9 x 10 5 9 x 10 3 5 x 10 3 9 x 10 3 8 x 10 5 Fold increase in potency 25X 9X 150X 60X 250X 300X 130X 50X 110X 160X 6
ETX2514 restores β-lactam activity in multiple Gram-negative pathogens Excellent activity vs E. coli & K. pneumoniae with all β-lactams tested Restores imipenem to MIC 90 of 2 mg/l vs P. aeruginosa Restores sulbactam to MIC 90 of 4 mg/l vs A. baumannii Compound (MIC 90, mg/l) Imipenem Meropenem Aztreonam Ceftazidime Sulbactam E. coli n = 202 K. pneumoniae n = 198 P. aeruginosa n = 202 A. baumannii n = 195 alone 0.25 1 16 >64 + ETX2514 0.06 0.12 2 16 alone 0.06 0.06 16 >64 + ETX2514 0.06 0.06 8 16 alone 32 32 64 >64 + ETX2514 0.06 0.06 32 >64 alone 16 >64 >64 >64 + ETX2514 0.06 0.06 8 32 alone 64* >64 >64 64 + ETX2514 0.06* 0.12 >64 4 ETX2514 alone 1 8 >64 >64 *n = 21 strains n = 20 strains MIC 90 across recent clinical isolates (± ETX2514 at 4 mg/l) 7
Multi-drug resistant Acinetobacter baumannii Gram-negative bacteria that causes infections in critically ill patients, with mortality rates as high as 43% 1 CDC Unmet Need Threat Level: Serious 2 A. baumannii tops the WHO s 2017 list of priority pathogens 3 63% of A. baumannii isolates are considered multi-drug resistant, meaning at least three different classes of antibiotics no longer cure A. baumannii infections including carbapenems, often considered antibiotics of last resort A. baumannii Resistance to carbapenems in A. baumannii is associated with increasing prevalence of Class D b-lactamases 4-5 1. Am. J. Respir. Crit. Care Med. 2011.1409; Int. J. Antimicrob. Agents 2009.575 2. CDC. 2013. Antibiotic Resistant Threats in the US. pg. 58-60 3. http://www.who.int/mediacentre/news/releases/2017/bacteria-antibiotics-needed/en/ 4. M.M. Ehlers, et. al. 2012. InTech, DOI: 10.5772/30379 5. Potron, et al. 2015. Int. J. Antimicrob. Agents 45:568 8
Complexity of β-lactamase content in A. baumannii Whole-genome sequencing of 84 recent MDR A. baumannii strains provides insight into what is required for a successful next generation BL/BLI therapy Class A 7 (8.3%) A & D 1 (1.2%) Class B & D Class N % Most prevalent variant(s) A 45 53.6 TEM-1 (41/45) Class D (100%) 38 (45.2%) A, C & D Class C (extended spectrum) 33 (39.3%) esc & D B 1 1.3 IMP-1 Extended spectrum C* 71 84.5 D 84 100 *all strains contain chromosomal adc gene ADC-30 (18/84) ADC-73 (18/84) Multiple (70/84 encode two or more, (46/70 were OXA-23+OXA-51-like) Inhibition of Classes A, C and D required for robust BLI activity in A. baumannii 9
Sulbactam/ETX2514: A novel combination against multi-drug resistant A. baumannii Sulbactam/ETX2514 maintains excellent activity over time MIC (mg/l) 0.06 0.12 0.25 0.5 1 2 4 8 16 32 >64 2011 N=195 2012 N=209 2013 N=207 2014 N=1131 2015* N=202 Cumul % 1 3.1 13.8 41.5 65.6 89.7 96.9 97.9 99.5 100 100 Cumul % 0 0.5 2.9 20.1 46.9 79 98.6 100 100 100 100 Cumul % 0 0 4.3 15.9 43.4 73.8 96.5 97.5 99 99 100 Cumul % 1 1.6 7.8 27.9 63.7 88.9 99.6 99.6 99.7 100 100 Cumul % 0 1.0 7.4 43.1 78.7 97.0 99.5 99.5 100 100 100 MIC distributions for globally diverse A. baumannii clinical strains *2015 study performed at JMI 10
Sulbactam/ETX2514 activity remains unchanged in carbapenem-resistant, colistin-resistant and MDR strains 50 % susceptible strains 40 30 20 10 0 0.25 0.5 1 2 sulbactam alone vs. all (N = 1131) sulbactam:etx2514 vs. all (N = 1131) 4 8 MIC (mg/l) 16 32 64 128 sulbactam:etx2514 vs. MEM-R (N = 731) sulbactam:etx2514 vs. COL-R (N = 56) sulbactam:etx2514 vs. MDR (N = 778) 11
Log(CFU/g) Log(CFU/g) Sulbactam:ETX2514 exhibits excellent in vivo activity Greater than 2-log kill achieved in both neutropenic mouse thigh and lung models of A. baumannii infections using an XDR * clinical isolate Sulbactam/ETX2514 dose response (IV, 4/1 ratio, 24 hrs) 10 Thigh 10 Lung 9 9 9.40 8 7 8.03 8.02 8 7 7.40 8.40 8.03 Stasis 8.55 6 6.36 6.72 Stasis 6 6.63 6.19 5 4 3 4.39 4.24 3.97 4.01 4.07 4.77 5 4 3 4.85 4.61 4.19 2 Pretreatment Pretreatment Vehicle 2.5 / 0.625 5 / 1.25 10 / 2.5 20 / 5 30 / 7.5 40 / 10 80 / 20 Colistin 40 mg/kg SC sulbactam/etx2514 (mg/kg) q3h UID 2 Vehicle 2.5 / 0.625 5 / 1.25 10 / 2.5 20 / 5 30 / 7.5 40 / 10 80 / 20 Colistin 40 mg/kg SC sulbactam/etx2514 (mg/kg) q3h UID * XDR A. baumannii ARC3486 (OXA-72, OXA-66, TEM-1, AmpC) - MIC(sulbactam) 32 mg/l, MIC(sulbactam/ETX2514) = 0.5 mg/l Similar results obtained for 9 additional clinical isolates 12
log CFU/ml Imipenem provides potency boost to SUL/ETX2514 activity in vitro In vitro hollow-fiber model was used to evaluate clinical regimens of 1 gm sulbactam, 1 gm ETX2514 and 500 mg imipenem q6h MICs Resistance or β-lactamase content Sulbactam (alone) Imipenem (alone) Sulbactam + ETX2514 @ 4 mg/l Imipenem + ETX2514 @ 4 mg/l Imipenem + ETX2514 @ 4 mg/l + Sulbactam @ 4 mg/l ARC5950 OXA-10/OXA-69; OXA-23; ADC-11 64 32 8 8 2 12 10 8 6 4 2 0 0 5 10 15 20 25 Time (hr) Sterilization of cartridge was achieved with the triple combination LLOQ =1.2 log CFU/mL Sulbactam + ETX2514 + Imipenem Sulbactam + EXT2514 Growth Control 13
Summary and conclusions ETX2514 is a potent inhibitor of a broad-spectrum of Class D β-lactamases while maintaining exquisite potency on Class A and C enzymes. ETX2514 potently restores the activity of multiple β-lactams in Gram-negative MDR pathogens. Sulbactam:ETX2514 is a novel BL:BLI combination to treat MDR A. baumannii infections, with an MIC 90 = 4 mg/l (N = 1742 clinical isolates) and excellent in vivo activity. ETX2514 is currently in Phase I clinical trials 14
Acknowledgements The team at Entasis AstraZeneca Infection Discovery AstraZeneca Pharmaceutical Development Novexel Pharmaron, Syngene IHMA Inc., JMI Laboratories Linneas Bioscience 15