Dose-response Relationship Study of S42909 on Leg Ulcer Healing

S42909 is an inhibitor of β-Nicotinamide Adenine Dinucleotide Phosphate (NADPH) oxidase which
also inhibits vascular leukocyte adhesion to endothelial cells, Matrix Metalloproteinase-2
(MMP-2) and Plasminogen Activator Inhibitor-1 (PAI-1) activity. It is proposed for
development in the treatment of venous and mixed leg ulcers.

This proof of concept study is a randomized, double-blind, placebo-controlled, multicenter,
Phase IIa trial to evaluate the dose response of S42909 for the treatment of venous leg
ulcers.

Patients suffering from chronic venous disease and having at least one active venous leg
ulcer will be selected at the selection visit (ASSE). One Reference Ulcer (RU) defined as the
largest ulcer in size that is fitting the area selection criteria will be established. At
ASSE, a first picture will be taken before cleansing and debridement and a second picture
will be taken after cleansing and debridement. The investigator will check that the selection
RU area is compliant with the selection criteria. Patients will start the selection period
and will be switched from their current pharmacological and/or local treatment (if any) for
venous leg ulcer to local wound care with sterile saline solution or sterile water,
"non-active" dressings and standardized compression (same strength and type of compression).
They will be administrated the placebo selection treatment for a period of fourteen days.

Three (or four) working days before the inclusion visit, the participants will come to the
site for a RU picture in order to get the RU area central measurement for inclusion visit
(W000).

At W000, the investigator will check that the inclusion RU area is compliant with the
inclusion criteria. The investigator will also check that the participant is compliant with
the selection treatment and stockings wearing.

All participants found to be eligible for inclusion will be randomized to one of the
following six groups - S42909: 100, 200, 400, 800 or 1200 mg per day- or placebo.

The participants will enter a 6 weeks ambulatory Investigational Medicinal Product (IMP)
treatment period on top of standard of care (standardized compression and local wound care
with sterile saline solution or sterile water and "non-active" dressing) followed by a 2
weeks follow-up period of standard of care only. During this period the participants will
return to the investigator's site for intermediate visits after one week (W001), two weeks
(W002), three weeks (W003), four weeks (W004), six weeks (W006) and eight weeks (W008).
Participants will continue receiving standardized compression therapy and local wound care
(sterile saline solution or sterile water and "non-active" dressing) until the end of the
study (W008).

Inclusion Criteria:

- Caucasian (defined for this study as having 2 Caucasian parents), men or women

- Age ≥ 18 years old

- 18.5 kg/m2 ≤ BMI ≤ 45.0 kg/m2 (= Weight (kg) / height² (m²))

- Patients with chronic venous disease documented by imaging to detect a venous disorder
in one or both the sub- and extra-fascial venous systems. The examination performed
within 6 months before selection can be used.

- Patients with at least one active venous leg ulcer localised in the gaiter area (CEAP
C6) diagnosed or reoccurred for more than 6 weeks and less than 2 years at selection
and 3 cm away from other ulcers. Patients with bilateral ulcerations or multiple
ulcerations on one or both legs are eligible for selection.

- Size of Reference Ulcer (defined as the largest ulcer in size that is fitting the area
selection criteria) should be ≥ 5 cm2 and ≤ 100 cm2 at the selection visit and ≥ 4.5
cm2 and ≤ 100 cm2 at the inclusion visit (measured by transparent sheet and confirmed
with the digital 3D imaging device).

- Ankle Brachial Pressure Index (ABPI) ≥ 0.8 and ≤ 1.3 measured by Doppler ultrasound.

Exclusion Criteria:

- Unlikely or unwilling to be compliant to standardized compression recommendation,
study medication and visits, previous records of poor compliance to compression
stockings.

- Inadequately controlled type 1 and type 2 diabetes with an HbA1c > 8%.