L5 - CF and Small Molecules (Part 2) Flashcards
VX-809
Lumacaftor
VX770
Ivacaftor
Describe what was seen when western blotting for CFTR in rat thyrouid cells that had the f508 mutation
Decreased ammout of CFTR (band C) shows that degradation of CFTR was occuring the F508 mutant
How many bands for CFTR on a blot, why?
Two
Mature and heavy
Heavy band - mature - fully glycosylated
What is the impact of the F508 mutation
In a blot the lower band prodominates - not glycosylated
This immature protein is sent for degradtion
Describe what was seen when applying Lumacaftor (809) to rat thryoid cells (f508) on the western blot
Total ammount of mature (band C) had increased and the degradation that normally happens here has been bypassed
When looking at Cl secretion why is it nescesary to add amiloride
Prevent any contaimination
Describe the results when looking at lumacaftor on SSC
As lumacafotr concentration increases in presence of cAMP then short circuit curretns are bigger and bigger
Lumacaftor clinical trials were
Randomised
Double blind
Placebo controlled
Lumcafotr (809) stats
18-19 CF patients
Homo F508
28 days
Once placebo group
Lumacaftor clinical trials - effect on lung function
NO EFFECT
Results all over the place
Lumacaftor clinical trials - effect on sweat chloride
Only a 8mM drop
But this is just a diagnostic marker - unlikely to have any effects on the patients
Compare the sweat chloride drop in the 770 and 809 trial
In 809 (luma) onl a 5mM drop compared to 55mM in the (iva)
Were the results from the lumacaftor trials positive or negative - what were the next steps
Negative - nothing really changed
Next step was a combination therapy
What was the combination therapy proposed
What made up the therapy and what was the role of each of the components?
ORKAMBI
Ivacaftor and lumacaftor
Ivacaftor the potentiator
Lumacaftor the corrector
Evidence for Ivacaftor acting as a potentiator
Single channel recordings - in the presence of 770 increased frequency of channel openings
Evidence for Lumacaftor acting as a corrector
In the western blot of F508 cells
Increased band c in presence of 809
N number of orkambi trials
1108
Orkambi clinical trials stats
1108
Homo F508
12 years
Placebo control
Orkambi clinical trials - lung function
After 15 days there is an improvement
Peak improvment around 3%
What can be said about the variance of the lung function data
Was the 10% improvement (seen in G551D treated with ivacaftor) seen
Data had high variance
Mixed spread of dosing protocols and improvements
Some had 10% improvement - others not
What does a forrest plot allow
Us to compare a huge number of parameters
What was the main conclusion that could be made from the forrest plot
Combination therapy DOES have a positive effect
Orkambi clinical trials - time to first pulmonary exacerbation
generally took longer for the treatment groups to have an event compared to the placebo
Orkambi clinical trials - events leading to hospitalisation or requiring IV antibiotics
Reduced number of events in both treatment groups relative to the placebo
What is the effect of 809 on F508
Can traffic it to the membrane and here it is fucntional
In F508 is 809 alone enough to improve symptoms
No
Describe how the 770, 809 combination can relieve symptoms
809 traffics the f508 CFTR to the membrane and then the 770 can enhance the function and relieve symptoms
Give some more examples of combinations and the mutations that they have been designed to target
Tezacaftor and ivacaftor for F508
Triple Elexa, Teza and Iva for F508
Studies into the various combinations - Key points from the western blotting
Normalisied to Calnexin (intensity)
Teza and elexa the most effective combination giving the greatest realtvie band C intensity
Studies into the various combinations - effect on chloride transport
Triple combination leads to a massive increase in the ammount of Cl transport (most effective)
Teza and Iva (f508 clinical trials) - lung function
Increase by around 3%
Same as seen in luma/iva (orkambi)
Teza and Iva (f508 clinical trials) - Sweat cl
10 mM drop
Elexa, teza and iva (F508) triple therapy clinical trials - lung function
MAssive improvement (13/14%)
Elexa, teza and iva (F508) triple therapy clinical trials - sweat NaCl
Drop by 45mM (HUGE)
