L9 Cystic Fibrosis III

what did the Phase III clinical trial have no effect on

ppFEV_1.0

give an example of a pharma currently developing a readthrough agent that isnt in clinical use yet

ELX-02 (Elaxuren) from Eloxx pharmaceutical is a synthetic aminoglycoside

• phase II clinical Trials is on-going (some +ve results)

give examples of amplifiers

Class V (PTI therapeutics- PTI-148 (Nesolicaftor) - in Phase I trial)

give examples of stabilisers

Class VI mutants as well as class II

what is the general hypothesis for new therapies of CF

genetic therapies and/or regulation of non-CFTR channels

what is the definition of genetic therapy

therapeutic approaches that:

• deliver copies of the healthy gene using gene addition (DNA or mRNA)

• fix chromosomal DNA using genome editing

give an examples of fixing chromosomal DNA using genome editing

CRISPR/Cas9-based approaches, such as prime and base editing

what are the two vectors used for gene therapy for CF

• viral vector

• liposome vector

what are the main problems of gene therapy

physical and/or immune barriers

describe the CF Trust UK and Gene Therapy Consortium (GTC) Trial

• July 2015-phase 2b clinical trial results using a nebulised liposome vector and CFTR cDNA

• Showed a ~3% improvement in ppFEV_1.0

• First proof of concept trial and largest gene therapy trial for CF to date

what is used to improve efficacy of gene therapy

gene transfer agent (GTA)

what why is Lentivirus, AAV used as a gene transfer agent (GTA)

• long term

• stable correction from a single dose because the gene is integrated into DNA

why do gene transfer agents modify the virus

to make them less immunogenic

what are other non-viral approaches to improve the efficacy of gene therapy

nanoparticles

what are the problems of improving the efficacy of gene therapy through gene transfer agents

• need to target the ‘right’ cells in lungs

• mucus is a barrier

• potential disruption of other genes

what are the right cells to target in the lungs for gene therapy

basal (stem) cells

give examples of direct in vitro delivery of approaches to gene therapy

nucleic acids combined with a delivery vehicle (viral/non-viral)

• DNA addition gene editing

• tRNA/mRNA

• Antisense oligonucleotides (no need for delivery vehicle)

describe the steps of cell therapy

• isolate cells from tissue

• generation of induced pluripotent stem cells

• correct the CFTR mutation to the wildtype condition

• differentiate the cells to basal airway stem cells

• engraftment onto the basal membrane

describe Inhaled mRNA-mediated therapy

• translate Bio-(2018) clinical trial of MRT5005 to introduce normal CFTR mRNA into lung cells (mutation-independent)

• March 2021- interim report showed no improvement in ppFEV_1.0

• Other companies (Recode and Arcturus) have got positive preclinical results and are recruiting for Phase II clinical trials

what is antisense oligonucleotide (ASO)-mediated therapy

potentially suitable for Class I mutations (nonsense (stop), splicing and frameshift)

how can alternate channel therapy benefit everyone with CF

its independent of CF mutation

what does alternate channel therapy use

• alternative chloride channels (ACCs) that are present in CF cells to bypass defective CFTR and restore Cl-/HCO3- and fluid transport

• inhibitors of ENaC to help reduce salt and fluid absorption

what are Enterprise Therapeutics (UK based) developing drugs that target

both alternative chloride channels and ENaC

what is the main target of alternative chloride channels

TMEM16A

how is TMEM16A the main target of alternative chloride channels

activation increases Cl- and fluid secretion in CF airway cells by physiological agonists such as ATP and UTP

ATP/UTP are released from the epithelial cells into ASL during…

normal breathing cycles

how is TMEM16A activated by increased cytosolic Ca2+

ATP/UTP bind to purinergic receptors

the effect of UTP on fluid secretion is relatively…

short-lived

describe the drug needed for alternative chloride channels

• directly activates the channel without involving Ca2+ (channel opener)

• potentiates channel activity to boost fluid secretion above normal and by-pass defective CFTR

what are Roche conducting a Phase I clinical trial with

a TMEM16A potentiator (GDC-6988)

how do we decrease ENaC activity

• use amiloride-like drugs

• Target ENaC regulation

describe the process using amiloride-like drugs

not successful so far

• Enterprise Therapeutics (UK) have developed an ENaC inhibitor which is being tested in a Phase I clinical trial

describe the process using target ENaC regulation

• inhibiting proteases that activate ENaC

• target ENaC regulatory proteins (SPLUNC1)

Spyryx developed an acid-resistant version of SPLUNC1 (SPX-101) which passed Phase I trials in 2017, but did not meet end-targets for the Phase II trial (based on ppFEV_1.0) in…

2019 for some unknown reason

what are synthetic anion channels and transporters

anionophores

give an example of synthetic anion channels and transporters

Amphotericin (Nature, 2019)

Target SLC26A anion exchangers that modulate…

pH

• Delpiano et al., PNAS 2023)

Target the H+ ATPase in airway cells that…

acidifies the airway surface liquid