Cloudbreak: Antibody-Drug Conjugates for Treatment of MDR Gram-Negative Bacterial Infections

Transcription

1 Cloudbreak: Antibody-Drug Conjugates for Treatment of MDR Gram-Negative Bacterial Infections James C. Levin, Ph.D. Director of Preclinical Development Discovery on Target Conference September 26, 2018

2 Advantages of antibody Fc-drug conjugates (ADCs) Gram-negative pathogen 4 TM TM 3 Fc TM 5 Outer membrane Direct kill: Novel targeting moieties (TMs) tightly bind LPS and kill bacteria KAPE spectrum Immunomodulatory: Fc recruits and initiates an innate immune system response Potentiation: Enhances permeability of standard of care therapeutics to provide additional efficacy Superior PK/ADME: Antibody-like PK, receptor mediated transport to lung, limited kidney exposures Protection from septic shock: Attenuation of sepsis response through LPS scavenging

3 Additional considerations of Cloudbreak ADCs v Non-cleavable linker between TM and Fc: No dissociation = Prolonged half-life v Optimization of drug to antibody Fc ratio (DAR): Recycling TM TM Fc TM to Fc Ratio TM activity PK properties (DAR optimization ongoing) Transport Cavaco et al. (2017). Biopolymers:110

4 Additional considerations of Cloudbreak ADCs v Criteria to select Fc type? v Human Fc conjugates in mouse efficacy models? Medical Immunology: Immunoglobulin Structure Overdijk et al., 2012 (Human IgG1 is well recognized by mouse effector cells)

5 ADCs bind, permeabilize, and synergize with SOC agents Binding FITC ADC 08b Permeabilization SYTOX green + ADC 08b A. b a u m a n n ii A B L u n g in fe c tio n A. baumannii L u n g b u r d e n (C F U / g ) A D C 1 0 b A Z M 2 5 A Z M + A D C 1 0 b v ADCs are designed as mono-therapeutics Synergy with existing therapeutics is an additional benefit (e.g. azithromycin; AZM)

6 MIC comparison of two distinct ADC classes (Generation 1) (Generation 2) 08b Resistance (2x MIC shift) 2 x 10-8 <3 x 10-8 <8 x 10-9 <7 x 10-9 ü Potency increase evident with 2 nd generation ADC ü Favorable resistance frequencies across KAPE spectrum

7 Engagement of the innate immune system by ADCs E. coli (25922) ADC 08b MIC (RPMI+5% LB) ADC 08b MIC (40% Blood) A. baumannii (AB5075) (5075) P. aeruginosa (PAO1) MIC (µm) ü Significant MIC activity under physiologically relevant conditions Decreased MIC in blood suggests immune engagement Inactivation of complement reduces ADC potency in blood (data not shown)

8 Engagement of the innate immune system by ADCs N e u tro p h il k illin g o f E. c o li A T C C N e u t r o p h ils o n ly % o f in o c u lu m N o a d d it io n s A D C 0 8 b Cloudbreak effect A D C 0 8 b + n e u t r o p h ils M in u t e s v Activation of neutrophils by ADCs = Enhanced potency ü Multiple studies confirming immune involvement Phagocytic killing assays C3b deposition by flow cytometry Aglycosylated Fc controls

9 MICs and immune activation translate to in vivo efficacy In vitro Ec Bacteremia Ab Pneumonia Pa Pneumonia Intra-abdominal (IAI) Single dose of T+1 hours Endotoxemia E. coli Colistin (0.3) ADC 08b (50) (25) (12.5) (6.25) PBS ADC 08b Dose Response (day 3 survival) (mg/kg) 08b/COL MW = ~ % Survival ü In vivo efficacy with therapeutic dosing, and expected dose response

10 MICs and immune activation translate to in vivo efficacy v Screening of bacteremia active compounds for lung efficacy A. b a u m a n n ii A B P n e u m o n ia m o d e l ADC/hIgG1 Fc Dosed T-12 hours Colistin Dosed T+1, bid x 3 days higg1 Fc (No TM); (mg/kg) % S u r v iv a l V e h ic le h Ig G 1 F c (5 0 ) C o lis t in (1 0 ) A D C 0 8 b (5 0 ) ü Full protection with a single ADC dose ü Also efficacious in a P. aeruginosa lung model T im e (d a y )

11 ADCs potently bind and neutralize LPS Lipopolysaccharide (LPS) Initiation of a dysregulated host response to infection Sepsis, characterized by life-threatening organ dysfunction In h ib itio n o f L P S s ig n a lin g (n it r ic o x id e ) % In h ib it io n A D C 0 8 b ü ADCs are more potent than colistin at immune silencing LPS [ µ M ] C o listin h Ig G 1 F c

12 ADCs are active in endotoxemia models v D-galactosamine sensitized model of endotoxemia LPS sensitivity: Species mg/kg* Humans Rabbits 0.02 Dogs 3 Rats 7 Mice (D-GalN) 0.01 Rhesus 12.5 *LD 50/100 or shock ü Full protection with a single ADC dose % s u r v iv a l Colistin: CTC-07a: (mg/kg) E n d o t o x e m ia (D -G a ln ; P u r ifie d E c L P S ) IP, T-1 & T+3 hours IV, T-1 hour P B S h Ig G 1 F c ( 2 5 ) C o lis t in (1 0 ) A D C 0 7 a (2 5 ) T im e (d a y s )

13 ADCs are active in endotoxemia models v Dose response in a sensitized mouse model of endotoxemia A D C 0 7 a D o s e T it r a t io n (E n d o t o x e m ia, D -G a ln ) IV dosing of T-1 hour 18 ng E. coli 0111:B4 LPS (IP) (mg/kg) P B S C O L (5 ) h Ig G 1 F c (3 0 ) (3 0 ) ü Identical results in neutropenic mice ü 3 rd generation ADCs efficacious at 1 mg/kg ü Protective against multiple LPS types: ( A D C 0 7 a ) (1 0 ) (3 ) (1 ) % S u r v iv a l (Screened to date) K. pneumoniae A. baumannii P. aeruginosa E. coli (3 LPS types) S. marcescens P. mirabilis N. gonorrhoeae

14 Summary and Future directions v Properties of Cidara s 1 st and 2 nd generation ADCs Coverage of KAPE pathogens, including colistin-resistant strains Efficacy in multiple infection models Demonstrated engagement of the innate immune system Protection against sepsis by neutralizing LPS v 3 rd generation ADCs being evaluated, so far demonstrating: Increased potency Improved half-life v Models of infection with significant LPS involvement being developed: Cecal Ligation and Puncture (CLP) A. baumannii lung model (sepsis-dominant mortality)

15 Acknowledgements ü a supportive management team ü an innovative and dedicated R&D team Chemistry department Immunology department In vivo team Microbiology department Protein Chemistry department