Publications by authors named "S Cyrus Khojasteh"

76 Publications

Biosynthetic Strategies for Macrocyclic Peptides.

Molecules 2021 Jun 1;26(11). Epub 2021 Jun 1.

Drug Metabolism and Disposition, Genentech, 1 DNA Way, South San Francisco, CA 94080, USA.

Macrocyclic peptides are predominantly peptide structures bearing one or more rings and spanning multiple amino acid residues. Macrocyclization has become a common approach for improving the pharmacological properties and bioactivity of peptides. A variety of ribosomal-derived and non-ribosomal synthesized cyclization approaches have been established. The biosynthesis of backbone macrocyclic peptides using seven new emerging methodologies will be discussed with regard to the features and strengths of each platform rather than medicinal chemistry tools. The mRNA display variant, known as the random nonstandard peptide integrated discovery (RaPID) platform, utilizes flexible in vitro translation (FIT) to access macrocyclic peptides containing nonproteinogenic amino acids (NAAs). As a new discovery approach, the ribosomally synthesized and post-translationally modified peptides (RiPPs) method involves the combination of ribosomal synthesis and the phage screening platform together with macrocyclization chemistries to generate libraries of macrocyclic peptides. Meanwhile, the split-intein circular ligation of peptides and proteins (SICLOPPS) approach relies on the in vivo production of macrocyclic peptides. In vitro and in vivo peptide library screening is discussed as an advanced strategy for cyclic peptide selection. Specifically, biosynthetic bicyclic peptides are highlighted as versatile and attractive modalities. Bicyclic peptides represent another type of promising therapeutics that allow for building blocks with a heterotrimeric conjugate to address intractable challenges and enable multimer complexes via linkers. Additionally, we discuss the cell-free chemoenzymatic synthesis of macrocyclic peptides with a non-ribosomal catalase known as the non-ribosomal synthetase (NRPS) and chemo-enzymatic approach, with recombinant thioesterase (TE) domains. Novel insights into the use of peptide library tools, activity-based two-hybrid screening, structure diversification, inclusion of NAAs, combinatorial libraries, expanding the toolbox for macrocyclic peptides, bicyclic peptides, chemoenzymatic strategies, and future perspectives are presented. This review highlights the broad spectrum of strategy classes, novel platforms, structure diversity, chemical space, and functionalities of macrocyclic peptides enabled by emerging biosynthetic platforms to achieve bioactivity and for therapeutic purposes.
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http://dx.doi.org/10.3390/molecules26113338DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8199541PMC
June 2021

Intestinal Excretion, Intestinal Recirculation, and Renal Tubule Reabsorption Are Underappreciated Mechanisms That Drive the Distribution and Pharmacokinetic Behavior of Small Molecule Drugs.

J Med Chem 2021 06 19;64(11):7045-7059. Epub 2021 May 19.

Aranmore Pharma Consulting, 11 Andrew Drive, Lawrenceville, New Jersey 08648, United States.

Drug reabsorption following biliary excretion is well-known as enterohepatic recirculation (EHR). Renal tubular reabsorption (RTR) following renal excretion is also common but not easily assessed. Intestinal excretion (IE) and enteroenteric recirculation (EER) have not been recognized as common disposition mechanisms for metabolically stable and permeable drugs. IE and intestinal reabsorption (IR:EHR/EER), as well as RTR, are governed by dug concentration gradients, passive diffusion, active transport, and metabolism, and together they markedly impact disposition and pharmacokinetics (PK) of small molecule drugs. Disruption of IE, IR, or RTR through applications of active charcoal (AC), transporter knockout (KO), and transporter inhibitors can lead to changes in PK parameters. The impacts of intestinal and renal reabsorption on PK are under-appreciated. Although IE and EER/RTR can be an intrinsic drug property, there is no apparent strategy to optimize compounds based on this property. This review seeks to improve understanding and applications of IE, IR, and RTR mechanisms.
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http://dx.doi.org/10.1021/acs.jmedchem.0c01720DOI Listing
June 2021

Absorption, metabolism and excretion of pictilisib, a potent pan-class I phosphatidylinositol-3-Kinase (PI3K) inhibitor, in rats, dogs, and humans.

Xenobiotica 2021 Jul 24;51(7):796-810. Epub 2021 May 24.

Clinical Pharmacology, Genentech Inc, South San Francisco, CA, USA.

The absorption, metabolism and excretion of pictilisib, a selective small molecule inhibitor of class 1 A phosphoinositide 3-kinase (PI3K), was characterized following a single oral administration of [C]pictilisib in rats, dogs and humans at the target doses of 30 mg/kg, 5 mg/kg and 60 mg, respectively.Pictilisib was rapidly absorbed with T less than 2 h across species. In systemic circulation, pictilisib represented the predominant total radioactivity greater than 86.6% in all species.Total pictilisib and related radioactivity was recovered from urine and faeces in rats, dogs, and human at 98%, 80% and 95%, respectively, with less than 2% excreted in urine and the rest excreted into faeces.In rat and dog, more than 40% of drug-related radioactivity was excreted into the bile suggesting biliary excretion was the major route of excretion. Unchanged pictilisib was a minor component in rat and dog bile. The major metabolite in bile was -glucuronide of oxidation on indazole moiety (M20, 21% of the dose) in rats and an oxidative piperazinyl ring-opened metabolite M7 (10.8% of the dose) in dogs.Oxidative glutathione (GSH) conjugates (M18, M19) were novel metabolites detected in rat bile, suggesting the potential generation of reactive intermediates from pictilisib. The structure of M18 was further confirmed by NMR to be a -hydroxylated and GSH conjugated metabolite on the moiety of the indazole ring.
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http://dx.doi.org/10.1080/00498254.2021.1923859DOI Listing
July 2021

Novel advances in biotransformation and bioactivation research - 2020 year in review.

Drug Metab Rev 2021 Jun 24:1-50. Epub 2021 Jun 24.

Drug Metabolism & Pharmacokinetics, Biogen Inc., Cambridge, MA, USA.

This annual review is the sixth of its kind since 2016 (see references). Our objective is to explore and share articles which we deem influential and significant in the field of biotransformation and bioactivation. These fields are constantly evolving with new molecular structures and discoveries of corresponding pathways for metabolism that impact relevant drug development with respect to efficacy and safety. Based on the selected articles, we created three sections: (1) drug design, (2) metabolites and drug metabolizing enzymes, and (3) bioactivation and safety (Table 1). Unlike in years past, more biotransformation experts have joined and contributed to this effort while striving to maintain a balance of authors from academic and industry settings.[Table: see text].
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http://dx.doi.org/10.1080/03602532.2021.1916028DOI Listing
June 2021

Preclinical Characterization of the Distribution, Catabolism, and Elimination of a Polatuzumab Vedotin-Piiq (POLIVY) Antibody-Drug Conjugate in Sprague Dawley Rats.

J Clin Med 2021 Mar 23;10(6). Epub 2021 Mar 23.

Preclinical and Translational Pharmacokinetics and Pharmacodynamics, Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA.

Polatuzumab vedotin (or POLIVY), an antibody-drug conjugate (ADC) composed of a polatuzumab monoclonal antibody conjugated to monomethyl auristatin E (MMAE) via a cleavable dipeptide linker, has been approved by the United States Food and Drug Administration (FDA) for the treatment of diffuse large B-cell lymphoma (DLBCL). To support the clinical development of polatuzumab vedotin, we characterized the distribution, catabolism/metabolism, and elimination properties of polatuzumab vedotin and its unconjugated MMAE payload in Sprague Dawley rats. Several radiolabeled probes were developed to track the fate of different components of the ADC, with I and In used to label the antibody component and H to label the MMAE payload of the ADC. Following a single intravenous administration of the radiolabeled probes into normal or bile-duct cannulated rats, blood, various tissues, and excreta samples were collected over 7-14 days post-dose and analyzed for radioactivity and to characterize the metabolites/catabolites. The plasma radioactivity of polatuzumab vedotin showed a biphasic elimination profile similar to that of unconjugated polatuzumab but different from unconjugated radiolabeled MMAE, which had a fast clearance. The vast majority of the radiolabeled MMAE in plasma remained associated with antibodies, with a minor fraction as free MMAE and MMAE-containing catabolites. Similar to unconjugated mAb, polatuzumab vedotin showed a nonspecific distribution to multiple highly perfused organs, including the lungs, heart, liver, spleen, and kidneys, where the ADC underwent catabolism to release MMAE and other MMAE-containing catabolites. Both polatuzumab vedotin and unconjugated MMAE were mainly eliminated through the biliary fecal route (>90%) and a small fraction (<10%) was eliminated through renal excretion in the form of catabolites/metabolites, among which, MMAE was identified as the major species, along with several other minor species. These studies provided significant insight into ADC's absorption, distribution, metabolism, and elimination (ADME) properties, which supports the clinical development of POLIVY.
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http://dx.doi.org/10.3390/jcm10061323DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8004598PMC
March 2021
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