The future is here:long-acting products

Dr. Paul GiangrandeOxford Haemophilia and Thrombosis Centre

&Nuffield Department of Clinical Medicine

University of Oxford

paul.giangrande@ndm.ox.ac.uk

Novel products:• Clinical trials well under way and more planned to

start soon• Development wholly based on recombinant

technology• Products under development include:

– Biosimilars (copies of current products)– Long-acting factor VIII– Long-acting factor IX– Porcine (pig) factor VIII– Activated factor VII analogues– Anti-TFPI antibodies

Novel products:• I am confident that at least some of these

products will be available within 3-5 years • Potential to change clinical practice radically• Success not guaranteed: several

failures/problems encountered already– FVIII and pegylated liposomes (Bayer)– TFPI inhibitor (Baxter)– Recombinant FIX (Ipsen/Inspiration)– Long-acting factor VII & vatreptacog (NovoNordisk)

• Need for vigilance for unexpected problems

Current therapy:

• Factor VIII has half life of around 12 hours• Factor IX has half life of around 18 hours• Prophylaxis involves self-treatment two or

three times a week• Factor levels still far from normal for most

of the week• Trough level of just 1% currently regarded

as satisfactory• Cost of products is the limiting factor

An example of decline in factor VIII level over time:

Factor VIII level (%)

Time (hours)

Typical troughs and peaks seen with prophylaxis:

Collins PW et al. Haemophilia 17: 2-10 (2011)

Risk of break through bleeds on prophylaxis:

Collins PW et al. Thromb. & Haemost. 7: 413-420 (2009)

What is our goal?Skinner M. Haemophilia 18 (Suppl. 4): 1-12 (2012)

• FVIII level of 1% “wholly insufficient”• Trough level of 15% “ideal” but

“unattainable in short term due to cost”• “Improving patient quality of life should

drive treatment decisions, not economics”• “Moving forward incrementally to higher

baseline levels of 3 or 5% would be a step in the right direction”

When attached to a drug, polyethylene glycol (PEG) polymer chains can sustain bioavailability by protecting the drug molecules from immune responses and other clearance mechanisms. In an aqueous medium, the long, chain-like PEG molecule is heavily hydrated andin rapid motion. This motion causes the PEG to sweep out a large volume and prevent the interference of other molecules.

Pegylation:

N9-GP (GlycoPegylated rFIX)

• Based on rFIX• Half-life prolongation with the

aim to provide • treatment of acute bleeds

with a single dose• at least a once-weekly

prophylaxis regimen• Designed using innovative

specific glycoPEGylationtechnology

• PEG attached to specific N-glycan sites with FIX activation peptide

• No modification of the peptide sequence

• Activated to native FIXa in normal way

Activation at site of injury

FIXa

N9-GP

Source: Østergaard et al. Blood 2011

Summary of N9-GP study:Negrier C et al. Blood 118: 2695-2701 (2011)

• 16 subjects: ≥18 years; FIX ≤ 2; ≥150 ED• Dose rFIX (N9-GP): 25-100 IU/kg• T½ 93 hours (5 fold longer than current FIX)• Incremental recovery was 94% higher than

rFIX and 20% higher than plasma-derived FIX• No inhibitors• One severe allergic reaction

Summary profiles comparing N9-GP to previous FIX –normalised to 50 U/kg

FIX

(U/m

L)

0.00.10.20.30.40.50.60.70.8

Time (hours)0 10 20 30 40 50 60 70 80 90 100110120130140150160170

N9-GPrFIXpdFIX

Treatment

1 week

Summary plot for N9-GP – log scale until 4 weeks

Two weeks after dosing, four patients had received FIX treatment as on-demand or prophylaxis. Four weeks after dosing, nine patients had received FIX treatment. FIX activity values from these patients were excluded from the pharmacokinetic evaluation after two or four weeks depending on the time when they received their FIX treatment.

10.000

1.000

0.100

0.010

0.001

FIX

(U/m

L)

0 50 100 150 200 250 300 350 400 450 500 550 600 650 700

Time (hours)

0.01 U/mL

0.03 U/mL

Treatment25 U/kg50 U/kg100 U/kg

1 week 2 weeks

4 weeks

Comparison of derived PK parameters between N9-GP and previous FIX (normalised to 50 U/kg)

PK ParametersN9-GP Mean

(N=15)

rFIXMean(N=7)

pdFIXMean(N=8)

RatioN9-GP/FIX

t1/2 (hours) 92.7 19.3 17.8 5.00

Incremental Recovery (U/dL per U/kg)

1.33 0.69 1.121.53

(1.94 ; 1.20)

CL (mL/hour/kg) 0.70 6.99 5.48 0.11

Vz (mL/kg) 94.2 195 141 0.57

Time to 1% activity (days) 22.5 4.5 4.0

Time to 3% activity (days) 16.2 2.8 2.7

N9-GP study:

• ‘Paradigm’ is the name for the portfolio of clinical trials with this agent

• Phase III study already started• No further allergic reactions: around 50

subjects have received product so far• Surgical study has started: protocol

envisages just 3-4 injections to cover major surgery

• Paediatric studies also planned

• Designed to provide treatment with less frequent dosing

• Based on full-length rFVIII• Comparable one stage and

chromogenic assay results• Designed using innovative

specific glycoPEGylationtechnology with a 40K-PEG

• No modification of the peptide

• Preliminary results suggest extension of half-life by 1.6 compared to normal factor VIII

N8-GP (GlycoPegylated rFVIII)

Source: Stennicke et al. WFH 2010Source: Stennicke et al. WFH 2010

Activation at site of injury

N8-GP

FVIIIa

Endocytosis and FcRn:

• Antibodies and albumin survive for a long time in the blood stream: half-life of many days

• This is because of “recycling” which takes place in the cells lining blood vessels (“endothelial cells”)

• Antibodies taken up into endothelial cells can either be released back into the circulation, or if they are not bound they will be destroyed

• A special receptor called FcRn is involved in the process

Endocytosis and FcRn:• This ability of FcRn to bind and release

albumin and antibodies back into the bloodstream is a form of recycling and allows them to outlive other proteins circulating in the bloodstream

• Therapeutic molecules attached to antibody molecules may also have half-lives extended by endothelial recycling:– Examples include romiplostin and etanercept– Biogen Idec have developed linked FVIII and

FIX molecules linked to antibody molecules

FIX

CH3

CH2

H

CH3

CH2

H

FIXFc Monomer

Product consists of a Fc-fusion construct that links a single copy of the drug to the Fc region on an antibody.

Optimized to bind to Fc receptors (FcRn) in the endothelial cells that line the blood vessels, “recycling” the drug to increase its circulating half-life.

Summary of rFIXFc study:Shapiro AD et al. Blood 119: 666-672 (2012)

• 14 subjects: ≥18 years; FIX ≤ 2; ≥150 ED• Dose rFIXFc: 1-100 IU/kg• Samples taken out to 240 hours (10 days):

also at 12 and 14 days after 100 iu/kg• Mean activity terminal t½ 56.7 hours (≈ 3 fold

longer than current FIX products)• No inhibitors or allergic reactions• Six subjects reported bleeds between 9 and

28 days after infusion

Fc-fusion molecules:• Study in dogs and mice documented ≈2 fold

extension of FVIII half-life Dumont JA et al. Blood 119: 3024-3030 (2012)

• Results of A-LONG study suggest 1.7 fold extension of FVIII T½ in humans Powell JS et al. Blood 119: 3031-3037 (2012)

• Could these products help induce immune tolerance or even reduce risk of inhibitor development in the first place?

Lei TC Blood 105: 4865-4870 (2005)

• Do these molecules cross the placenta?

Albumin fusion productsSchulte S. Thrombosis Research 128 (Suppl. 1) S9-S12 (2011):

• Marketed as “natural alternative” to PEG, which is not entirely biodegradable

• DNA construct encoding both target protein and albumin in a single recombinant molecule

• Short linker in between to avoid problems due to steric hindrance and ensure retention of maximum potency

Albumin fusion products:• Phase 1 study completed in 19 subjects

with FIX-FP using 25, 50 and 75 iu/kg• T½ 91.5 hrs (5.3 fold extension)• 7 fold increase in AUC• Trough levels of 7.4% and 2.5% at days 7

and 14 after 25 iu/kg• Problem of steric hindrance with FVIIa-FP:

starting dose needs to be 1000 µg/kg• Phase 1 study has begun: 6 fold increase

in T½ anticipated

The factor VIII gene:

Single-chain factor VIII (CSL627):• Most of B-domain and 4 amino acids of

adjacent A3 domain deleted (amino acids 765-1652 of full length molecule)

• Covalent link between heavy and light chains prevents dissociation

• Binding site for VWF also modified to increase affinity twofold

• Very preliminary data suggest T½ extension of 1.6 fold

• Clinical trials now underway

Why is it more difficult to prolong half-life of factor VIII?

• Clear difference noted with various methods used (pegylation, Fc fusion, albumin)

• 2 vs. 5 fold difference in extension• Difference attributed to role of VWF• In FVIII and VWF knockout mice, it is

possible to extend T½ of rVIII-Fc fivefold compared to normal factor VIII

• Similar observation with pegylated FVIII

Porcine factor VIII for patients with inhibitors:

• Previous product derived from porcine plasma (Hyate:C) withdrawn in 1996

• Pig factor VIII similar to human factor VIII in structure so works almost as well in humans

• Differences in structure protect it against rapid inactivation by antibodies against human factor VIII

• Recombinant porcine factor VIII (Baxter) now undergoing phase 3 clinical trials in acquired and congenital haemophilia with inhibitors

• Potential problem is antibody formation after repeated administration (e.g. surgery)

The role of TFPI:Tissue Factor Pathway Inhibitor

Tissue Factor Pathway Inhibitor (TFPI):

• Serine protease inhibitor protein• Encoded on chromosome 2q• Associated with lipoproteins in plasma• ≈10% located in platelets • Heparin enhances activity• TFPI inhibits TF-FVIIa complex• Do inhibitors of TFPI have a possible role as

adjunctive therapy in haemophilia?

Inhibition of TFPI and haemophilia:

• Fucoidan is a non-anticoagulant sulphated polysaccharide

• Inhibits TFPI• Accelerates clotting time of human

haemophilic plasma in test tube• Clinical trial of similar agents being

explored as oral therapy to help prevent bleeding in patients with haemophilia

Inhibition of TFPI and haemophilia:

TFPI inhibitors:• Blocking of Tissue Factor Pathway

Inhibitor (TFPI) may facilitate haemostasis initiated by FVIIa/TF • Thereby compensating for impaired

FIX/FVIII-dependent coagulation

• mAb2021 is antibody developed by NovoNordisk against Kunitz 2 domain of TFPI

• Grown in serum free CHO cells• Liquid formulation designed for

injection with injector pen• Anti-TFPI monoclonal antibody may

become a potential subcutaneous prophylaxis treatment option for all haemophilia patients without the risk of development of inhibitors to FVIII and FIX

• Phase 1 trial of NovoNordisk product already completed

• BAX499 (Baxter) is an aptamer with similar effect, also undergoing clinical trials

Principal conclusions:• Gene therapy will ultimately offer a

permanent cure for haemophilia• Longer-acting factor concentrates are a

much more realistic early goal• Activity of coagulation factors can be

extended by various technologies: e.g.– Pegylation– Binding to immunoglobulin molecules– Genetic fusion with albumin

• Much easier to extend duration of action of factor IX compared to factor VIII