Safety and pharmacodynamics of an engineered E. coli Nissle for the treatment of phenylketonuria: a first-in-human phase 1/2a study.

Phenylketonuria (PKU) is a rare disease caused by biallelic mutations in the PAH gene that result in an inability to convert phenylalanine (Phe) to tyrosine, elevated blood Phe levels and severe neurological complications if untreated. Most patients are unable to adhere to the protein-restricted diet, and thus do not achieve target blood Phe levels. We engineered a strain of E. coli Nissle 1917, designated SYNB1618, through insertion of the genes encoding phenylalanine ammonia lyase and L-amino acid deaminase into the genome, which allow for bacterial consumption of Phe within the gastrointestinal tract. SYNB1618 was studied in a phase 1/2a randomized, placebo-controlled, double-blind, multi-centre, in-patient study ( NCT03516487 ) in adult healthy volunteers (n = 56) and patients with PKU and blood Phe level ≥600 mmol l-1 (n = 14). Participants were randomized to receive a single dose of SYNB1618 or placebo (part 1) or up to three times per day for up to 7 days (part 2). The primary outcome of this study was safety and tolerability, and the secondary outcome was microbial kinetics. A D5-Phe tracer (15 mg kg-1) was used to study exploratory pharmacodynamic effects. SYNB1618 was safe and well tolerated with a maximum tolerated dose of 2 × 1011 colony-forming units. Adverse events were mostly gastrointestinal and of mild to moderate severity. All participants cleared the bacteria within 4 days of the last dose. Dose-responsive increases in strain-specific Phe metabolites in plasma (trans-cinnamic acid) and urine (hippuric acid) were observed, providing a proof of mechanism for the potential to use engineered bacteria in the treatment of rare metabolic disorders.

Powder properties and their influence on dry powder inhaler delivery of an antitubercular drug.

The purpose of this study was to determine if aerosol delivery of drug loaded microparticles to lungs infected with Mycobacterium tuberculosis may be achieved by predicting dispersion of dry powders through knowledge of particle surface properties. Particle sizes of rifampicin-loaded poly(lactide-co-glycolide) microparticles (R-PLGA), rifampicin alone, and lactose and maltodextrin carrier particles (bulk and 75-125- microm sieved fractions) were determined by electron microscopy for the projected area diameter (D(p)) and laser diffraction for the volume diameter (D(v)). Surface energies (gamma) of R-PLGA, rifampicin alone, lactose, and maltodextrin were obtained by inverse phase gas chromatography, surface areas (S(a)) by N2 adsorption, and cohesive energy densities by calculation. Particle dispersion was evaluated (Andersen nonviable impactor) for 10% blends of R-PLGA and rifampicin alone with bulk and sieved fractions of the carriers. D(p) for R-PLGA and rifampicin alone was 3.02 and 2.83 microm, respectively. D(v) was 13 +/- 1 and 2 +/- 1 microm for R-PLGA and rifampicin alone, respectively, indicating that R-PLGA was more aggregated. This was evident in gamma of 35 +/- 1 and 19 +/- 6 mJ/m2 for R-PLGA and rifampicin alone. D(p) for lactose and maltodextrin (sieved and bulk) was approximately 40 mm. Bulk maltodextrin (D(v) = 119 +/- 6 microm) was more aggregated than bulk lactose (D(v) = 54 +/- 2 microm). This was a result of the higher S(a) for maltodextrin (0.54 m2/g) than for lactose (0.21 m2/g). The gamma of bulk lactose and maltodextrin was 40 +/- 4 and 60 +/- 6 mJ/m2 and of sieved lactose and maltodextrin was 39 +/- 1 and 50 +/- 1 mJ/m2. Impaction studies yielded higher fine particle fractions of R-PLGA from sieved lactose, 13% +/- 3%, than from sieved maltodextrin, 7% +/- 1%, at 90 L/min. An expression, based on these data, is proposed as a predictor of drug dispersion from carrier particles. Delivery of dry powder formulations can be achieved by characterizing particle surfaces and predicting impact on dispersion.