Primary objective is to demonstrate the superiority of riferminogene pecaplasmid (XRP0038/NV1FGF) over placebo in the prevention of major amputation above the ankle of the treated leg or of death from any cause, whichever comes first, in critical limb ischemia (CLI) patients with skin lesions.

Secondary objectives are to evaluate:

• The efficacy of riferminogene pecaplasmid versus placebo for delaying the time to major amputation;
• The efficacy of riferminogene pecaplasmid versus placebo for delaying the time to death;
• The safety of riferminogene pecaplasmid in the study population.

The study consists in 6-week treatment then a follow-up period up to 12 months. A follow-up contact is then scheduled 6 months later.

Per protocol amendment a 18-month long-term safety survey was added.

Inclusion Criteria:

• Having peripheral artery disease at the stage of Critical Limb Ischemia (CLI) with skin lesions (either ulcer(s) or gangrene);
• With objective evidence of CLI such as ankle systolic pressure <70 mmHg and/or toe systolic pressure <50 mmHg or transcutaneous oxygen pressure (TcPO2) <30 mmHg;
• Unsuitable for standard revascularization of his/her peripheral arterial disease;
• Having a negative screening for cancer.

Exclusion Criteria:

• Previous major amputation on the leg to be treated or planned major amputation within the first month following randomization;
• Known Buerger's disease;
• Successful lower extremity revascularization procedure within 3 months prior randomization;
• Uncontrolled blood pressure defined as systolic blood pressure (SBP) ≥180 mmHg or diastolic blood pressure (DBP) ≥110 mmHg despite adequate antihypertensive treatment;
• Acute cardiovascular events within 3 months prior to randomization;
• Active proliferative retinopathy and severe macular oedema;
• Previous or current history of malignant disease within the past 5 years;
• Previous treatment with systemic angiogenic factors or with stem cells therapy;
• Pregnant or breast-feeding woman or woman of childbearing potential not protected by an effective contraceptive method of birth control. Man not following effective contraceptive method with his partner of childbearing potential during the course of the study.

The above information is not intended to contain all considerations relevant to a patient's potential participation in a clinical trial.