title: Collagenase Total Occlusion-1 (CTO-1) trial: a phase I, dose-escalation, safety study.
abstract: BACKGROUND
  Percutaneous interventions for chronic total occlusions have low success rates, primarily because of failure of guide wire crossing. Collagen-rich matrix constitutes the main barrier to chronic total occlusion crossing. In preclinical studies, local delivery of a bacterial collagenase formulation improved guide wire crossing. The Collagenase Total Occlusion-1 (CTO-1) Trial is a phase I, dose-escalation trial to assess the safety and efficacy of collagenase therapy to facilitate guide wire crossing in coronary artery chronic occlusions.
  
  
  RESULTS
  Twenty subjects with ≥1 previous failure of chronic total occlusion guide wire crossing were enrolled at 2 sites. Subjects were treated in 4 distinct cohorts of 5 patients, with escalation of collagenase dose in each cohort from 300 to 1200 μg. Collagenase was locally delivered into the occlusions with either an over-the-wire balloon system (n=8) or a fine-cross microcatheter (n=12) for a period of 30 minutes. Subjects were brought back to the catheterization laboratory for guide wire crossing and angioplasty the next day. Guide wire crossing was successfully achieved in 15 subjects (75%). A soft-tip guide wire (Whisper, Pilot-50, Fielder XT) was either the sole or predominant guide wire used in 75% of successful crossings. Non-ST-segment-elevation myocardial infarctions occurred in 3 patients as a result of side-branch ischemia during stenting. Computed tomographic angiography at 3 months showed no late complications and patent stents in successfully treated chronic total occlusion. Anginal improvement occurred with a reduction in Canadian Cardiovascular Society class from baseline to 3 months (2.5±0.6 versus 0.9±0.9; P<0.001).
  
  
  CONCLUSIONS
  Local delivery of collagenase into coronary chronic total occlusion is feasible and safe with encouraging guide wire crossing results in previously failed cases. Larger clinical trials are required to determine efficacy.
  
  
  BACKGROUND
  URL: http://www.clinicaltrials.gov. Unique identifier: NCT01271335.
authors.affiliation: Sunnybrook Health Sciences Center, 2075 Bayview Ave, D4-06, Toronto, Ontario, Canada. Bradley.strauss@sunnybrook.ca
authors.forename: Bradley H
authors.initials: BH
authors.lastname: Strauss
authors.forename: Azriel B
authors.initials: AB
authors.lastname: Osherov
authors.forename: Sam
authors.initials: S
authors.lastname: Radhakrishnan
authors.forename: G B John
authors.initials: GB
authors.lastname: Mancini
authors.forename: Allison
authors.initials: A
authors.lastname: Manners
authors.forename: John D
authors.initials: JD
authors.lastname: Sparkes
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Chisholm
mesh_terms: D000328:Adult; D000368:Aged; D015906:Angioplasty, Balloon, Coronary / Q000379:methods*; D001426:Bacterial Proteins / Q000008:administration & dosage / Q000009:adverse effects; D002908:Chronic Disease; D017364:Collagenases / Q000008:administration & dosage* / Q000009:adverse effects*; D003131:Combined Modality Therapy; D017023:Coronary Angiography; D054059:Coronary Occlusion / Q000000981:diagnostic imaging / Q000188:drug therapy* / Q000628:therapy*; D004305:Dose-Response Relationship, Drug; D005240:Feasibility Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D016896:Treatment Outcome
chemical_list: D001426:Bacterial Proteins; D017364:Collagenases