Collagenase Total Occlusion-1 Trial

Enrolment is expected to occur over 24 months with total study duration of approximately 30 months. Five (5) subjects will be enrolled into each dose cohort. The dose cohorts will be studied in a sequential fashion, starting with the lowest doses and escalating to the highest doses. It is anticipated that each subject's involvement with the study will be 3.5 months. In addition, eight (8) subjects will be included in the highest dose cohort to collect pharmacokinetic plasma samples.

Subject enrollment and dosing within each dose cohort will be staged such that the next subsequent subject will not be dosed until the previous subject has been successfully discharged from the hospital after the angioplasty attempt. At a minimum there will be 3 days in between each subject dosing to ensure product safety.

There will be no advancement to the higher dose cohort until all 5 subjects have been discharged from the hospital and a safety review is conducted by the Data Safety Monitoring Board (DSMB) on the cardiac safety measures and the treatment deemed safe to proceed to the next dosing level.

A total of 28 male and / or female subjects suffering from CAD with a CTO will be enrolled into the study at three sites (Sunnybrook Health Sciences Centre and St. Michael's Hospital, Toronto, Ontario, and and Laval Hospital Research Centre, Quebec City, Quebec,Canada). All subjects will have had one or more previous failed angioplasty attempt(s) of the occluded artery. Subjects who have signed an Informed Consent Form (ICF) and meeting all inclusion criteria and having none of the exclusion criteria at Visit 1 (Screening) will be included in the study. All potentially enrollable subjects at Sunnybrook will be reviewed by either of two cardiologist not involved in the study to discuss the available options for the subject and to approve enrollment decisions. Eligible subjects that agree to participate will be treated in a two part procedure. On Day0 using standard angioplasty techniques to access the specified occluded coronary artery, Collagenase (MZ-004) will be directly injected into the occluded artery through a microcatheter that has been positioned immediately adjacent to or into the proximal cap of the occlusion. The catheters and arterial sheath will then be removed and the subject will be monitored overnight on the ward. The following day (Day1), the subject will be brought back to the catheterization laboratory and undergo an angioplasty using standard angioplasty techniques. Routine post-procedural management will then be followed. The subject will be discharged on Day2 in the absence of any cardiac complications (such as elevated cardiac enzymes or large pericardial effusion as judged by the Investigator and determined by echocardiography). Prior to the angioplasty procedure on Day1 and again on Day2 prior to discharge, the subject will undergo an echocardiogram to determine the presence and severity of a pericardial effusion. A moderate or large pericardial effusion or any sign of tamponade on Day1 will be a contraindication to performing the procedure, and the subject will be terminated from the study. A telephone follow-up will be performed 30 days post Day1 in all subjects who have signed an ICF and been enrolled in the study. At 3 months, subjects will undergo an outpatient coronary Computer Tomography (CT) angiogram to ensure there are no delayed effects on the treated vessel (e.g. aneurysm formation), the myocardium or the pericardium.

The primary objective is to evaluate the safety and tolerability of acute intracoronary doses of collagenase (MZ-004) in symptomatic subjects with coronary CTO.

The secondary objective is to obtain preliminary efficacy information of guidewire crossing with increasing doses of intracoronary collagenase in subjects with previously failed at least one previous attempt in coronary CTO.