Emerging therapies in respiratory diseases

Question 1

DRIVEs

Answer 1

Unmet clinical need
Scientific progress
Commercial factors

Question 2

DRAGs (negative factors)

Answer 2

Healthcare providers
Generics
Rationing
Pricing policy

Question 3

Asthma Impacts:

Answer 3

400M sufferers worldwide by 2025

High incidence in USA, UK, Australia, NZ

Growing incidence in BRICs

Pharmaceutical market US$22bn in
2019

Question 4

Traditional hurdles to new medicine:

Answer 4

safety, quality, efficacy, clinical cost effectiveness, affordability + impact on services, appropriateness

Question 5

Do we really need new therapies?

Answer 5

DRAGs and DRIVEs

Question 6

Asthma:

Answer 6

Not a trivial disease that is well managed by inexpensive, generic medicines- much is poorly controlled

Efficacious + safe treatments

Inhaled corticosteroids (ICS)

Short-acting inhaled B2 agonists

ICS/LABA combinations

Leukotriene antagonists

Anti-IgE hMab

Anti-cytokine hMab

Question 7

Current medicines for asthma+COPD

Answer 7

BTS + international guidelines

Mainstays:
B2 agonists (asthma + COPD)
Corticosteroids (ICS (asthma + COPD, but a significant proportion of COPD patients do not respond well to ICS)
Muscarinic antagonists (COPD > asthma)

Modern preference is to use these medicines in combination products: ‘closed doubles’ + ‘closed triples’

Question 8

Therapies

Answer 8

Leukotriene antagonists- effective in some patients

Anti-IgE mAb- works by depleting circulating
IgE, no effect on innate immune pathways:
Expensive treatment, works only in a proportion of those who receive it
Restricted use, long-term benefits still emerging

Phosphodiesterase inhibitors- emesis is a dose-limiting side effect in many people

B2 agonists

Question 9

Strengths and weaknesses of B2 agonists

Answer 9

Strengths- cheap, generic versions exist, once daily dosing possible, life saving in an emergency, action is mediatory-independent
Weaknesses-
Does not treat underlying disease
Mask progression of condition
Some drugs associated w cardiotoxicity
Need inhaled delivery to limit on-target side effects

Question 10

Strengths and Weaknesses of corticosteroids

Answer 10

Strengths- generic options exist, cheap, wide-ranging action spans many cells + mediators

Weaknesses-
Metabolic effects are undesirable on-target actions
Immunosuppressant action (desirable) but is non-specific (undesirable)
Not all cells/mediators affected
Effectiveness is diminished in exacerbations (Th17/neutrophil events)
‘steroid phobia’ inhibits aggressive use
Not all patients respond (esp. in COPD, also some severe asthma)
Need inhaled delivery to limit on-target side effects

Question 11

Strengths and weaknesses of muscarinic antagonists

Answer 11

Strengths- generic options available, cheap, once daily dosing feasible w some drugs
Weaknesses
Undesirable on-target actions require inhaled delivery
Moderate efficacy in asthma, better in COPD

Question 12

New therapy criteria:

Answer 12

Must provide advantages over existing therapies
Must address gaps in existing treatment
Stratification? Which patients will benefit?
Requires validated high value target
Combination therapy may increase treatment potential

Question 13

Strategies:

Answer 13

Problem for both asthma + COPD is that they are heterogenous disorders + this makes them difficult problems for new drug design if the answer has to be a molecule which works in most people

Biologicals- expensive, poor oral bioavailability, regulatory hurdles are greater

Small molecules- need tractable target, potentially cheap, constrained by ‘medicine space’

Question 14

New or near-market approaches: Asthma

Answer 14

Various mAb therapies (e.g., anti-IL5, anti-IL receptor subunits) targeting severe allergic asthma
Immunotherapy (allergen desensitisation, Th2/Th1 deviation)
New small-molecule medicines for precendented mechanisms (once a day dosing, closed triples) or novel targets (CRTH2 antagonist, dexpramipexole)

Question 15

New or near-approaches: COPD

Answer 15

LAMA/LABA and LAMA/LABA/ICS combinations
MABAs (muscarinic antagonist/beta agonist activity in the same molecule)
Oral + inhaled theophylline (to restore ICS responsiveness)
Anti-IL5 mAb for eosinophilic COPD

Question 16

Asthma emerging therapy

Answer 16

Latest medicines are monoclonal antibodies

Question 17

Asthma future therapies

Answer 17

Fevipiprant- Novartis CRTH2 antagonist
Now abandoned after recent failures in 2x Phase 2 trials
Dexpramipexole- decreases blood eosinophils by an unknown mechanism, orally active
Resurrected for possible use in asthma + other allergic conditions after Phase 3 failure in amyotrophic lateral sclerosis
Positive data obtained in Phase 2 for asthma, but much still to be proven about clinical improvement for patients

Question 18

What is being treated+where?

Answer 18

Affects preferred route of delivery

Inhaled drug delivery

Expensive to develop

Device adds to prescription cost

Multiple inhalers not popular w patients
Cannot be used w coloured drugs or those w unpleasant taste or effects on taste perception

Oral drug delivery: Constrained by Lipinski rules
Greater off-target vulnerabilities
Compounds need clean safety profiles

Biologics- route of delivery is usually constrained by poor bioavailability

Question 19

Inhaled therapy:

Answer 19

Inhalation requires the drug to be suspended in a respirable form in air
Several device options can do this: nebuliser, pressurised metered dose inhaler (pMDI), dry powder inhaler (DPI)

To non-experts, an easy, fast, cheap option

Question 20

Nebuliser strengths and weaknesses:

Answer 20

Least portable; usually restricted to hospital/clinic use
Requires drug to have good aqueous solubility
Requires least pharmaceutical development
Good for prolonged delivery and do not require co-ordination skills

Question 21

pMDI+DPI: strengths and weaknesses

Answer 21

Requires specialised devices and extensive pharmaceutical development
Convenient for patients – usable anywhere
The mainstay of asthma drug delivery

Question 22

In reality, inhaled therapy is difficult, why?

Answer 22

Oral DMPK hurdles become other challenges- e.g., to avoid irritancy, have an acceptable physical form, potency + solubility

However, greater chemical design opportunities can exist because the Lipinski rules can sometimes be ignored- so high plasma protein binding, first pass metabolism + poor bioavailability may be virtuous

Potency must be high bc the device needs to contain many doses

For once daily dosing drugs and/or their effects must persist- this may be challenging for stability + selectivity reasons

Question 23

Pharmaceutical profiling

Answer 23

Inhaled drug development has uncommon requirements
Pharmaceutical profile of compounds is an important decision tool in discovery, especially for drugs intended for dry powder inhalers
Profiling at an early stage mitigates later risks
Insures against unpredictable slower developability
Profiling puts early emphasis on physical properties:
- Crystallinity,
- solubility,
- low hygroscopicity
- Thermal behaviour
- Particle behaviour
- Stability w likely excipients

Question 24

Late stage clinical development challengend in asthma+COPD

Answer 24

Clinical trials
How can disease-modifying agents be identified?
How can prophylactic agents be identified?
Which patients should be selected (patient stratification)?
What is a meaningful disease readout which can indicate success?
Lung function
Biomarkers e.g., inflammatory mediator levels + cell counts
Exacerbation rates
Equality of life questionnaire results
** plus huge issues w cost