A Study to Compare if the Uptake of Ticagrelor in the Body Differs When Different Tablets Are Administered
An Open-label, Randomized, 4-period, 4-treatment, Cross-over, Single-center, Single-dose Study to Assess the Relative Bioavailability of Ticagrelor in Different Formulations in Healthy Adult Subjects
Study Overview
Status
Status
Conditions
Conditions
Intervention / Treatment
Intervention / Treatment
Detailed Description
Study Type
Study Type
Enrollment (Actual)
Enrollment
Phase
Phase
- Phase 1
Contacts and Locations
Study Locations
-
-
-
Berlin, Germany, 14050
- Research Site
-
-
Participation Criteria
Eligibility Criteria
Eligibility Criteria
Ages Eligible for Study
Accepts Healthy Volunteers
Genders Eligible for Study
Description
Inclusion Criteria:
- Provision of signed and dated written informed consent prior to any study specific procedures.
- Healthy male and female subjects aged 18 to 55 years with suitable veins for cannulation or repeated venipuncture.
Females must have a negative pregnancy test at Screening and on each admission to the Clinical Unit, must not be lactating and if of non child-bearing potential, confirmed at Screening by fulfilling one of the following criteria:
- Postmenopausal defined as amenorrhea for at least 12 months or more following cessation of all exogenous hormonal treatments and follicle-stimulating hormone (FSH) levels in the post-menopausal range (> 40 milli international units per milliliter (mIU/mL)). - Documentation of irreversible surgical sterilization by hysterectomy, bilateral oophorectomy or bilateral salpingectomy but not tubal ligation. - Childbearing potential and are sexually active must use 1 highly effective method of birth control in combination with a barrier method, from the time of IMP administration until 3 months after the last dose of IMP.
- Have a body mass index (BMI) between 18 and 30 kg/m2 inclusive and weigh at least 50 kg and no more than 100 kg inclusive.
- Able to understand, read and speak the German language.
Exclusion Criteria:
- History of any clinically significant disease or disorder which, in the opinion of the Investigator, may either put the potential subject at risk because of participation in the study, or influence the results or the potential subject's ability to participate in the study.
- History or presence of gastrointestinal, hepatic or renal disease, or any other condition known to interfere with absorption, distribution, metabolism, or excretion of drugs.
- Any clinically significant illness, medical/surgical procedure, or trauma within 4 weeks of the first administration of IMP.
- Any clinically significant abnormalities in hematology, clinical chemistry, coagulation or urinalysis results at Screening or Day -1 of Treatment Period 1, as judged by the Investigator.
- Any clinically significant abnormal findings in vital signs at Screening or Day -1 of Treatment Period 1, as judged by the Investigator.
- Any clinically significant abnormalities on 12-lead ECG at Screening, as judged by the Investigator.
- Any positive result on screening for serum hepatitis B surface antigen (HBsAg), hepatitis B core antibodies (anti-HBcAb), hepatitis C antibodies (anti- HCV) and human immunodeficiency virus (HIV) antibodies.
- Has received a new chemical entity (defined as a compound which has not been approved for marketing) within 3 months of the first administration of IMP in this study. The period of exclusion begins 3 months after the final dose or 1 month after the last visit whichever is the longest.
- Plasma donation within 1 month of Screening or any blood donation/loss more than 500 mL during the 3 months prior to Screening. 10. History of severe allergy/hypersensitivity or ongoing allergy/hypersensitivity, as judged by the Investigator, or history of hypersensitivity to drugs with a similar chemical structure or class to ticagrelor.
11. Current smokers or those who have smoked or used nicotine products within the previous 3 months.
12. Positive screen for drugs of abuse or cotinine (cotinine level above 500 ng/mL) at Screening or on each admission to the Clinical Unit or positive screen for alcohol on each admission to the Clinical Unit.
13. Use of drugs with enzyme-inducing properties such as St John's Wort within 3 weeks prior to the first administration of IMP.
14. Use of any prescribed or non-prescribed medication including antacids, analgesics (other than paracetamol/acetaminophen), herbal remedies, megadose vitamins (intake of 20 to 600 times the recommended daily dose) and minerals during 2 weeks prior to the first administration of IMP or longer if the medication has a long half-life.
15. Known or suspected history of alcohol or drug abuse or excessive intake of alcohol, as judged by the Investigator.
16. Involvement of any AstraZeneca or Clinical Unit employee or their close relatives.
17. Judgment by the Investigator that the potential subject should not participate in the study if they have any ongoing or recent (i.e., during the Screening period) minor medical complaints that may interfere with the interpretation of study data or are considered unlikely to comply with study procedures, restrictions and requirements.
18. Consumption of poppy seeds within 7 days of first admission to the Clinical Unit.
19. History of hemophilia, von Willebrand's disease, lupus anticoagulant, or other diseases/syndromes that can either alter or increase the propensity for bleeding. 20. A personal history of vascular abnormalities including aneurysms; a personal history of severe hemorrhage, hematemesis, melena, hemoptysis, severe epistaxis, severe thrombocytopenia, intracranial hemorrhage; or rectal bleeding within 1 year prior to Screening; or history suggestive of peptic ulcer disease; or at the discretion of the Investigator.
21. History of a clinically significant non-traumatic bleed or clinically significant bleeding risk, as judged by the Investigator.
22. Use of aspirin, ibuprofen, NSAIDs, or any other drug known to increase the propensity for bleeding for 2 weeks before randomization. 23. Platelet count less than 150 x 109/L.
24. Vulnerable subjects, e.g., kept in detention, protected adults under guardianship, trusteeship or committed to an institution by governmental or juridical order.
Study Plan
How is the study designed?
Design Details
- Primary Purpose: Other
- Allocation: Randomized
- Interventional Model: Crossover Assignment
- Masking: None (Open Label)
Number of Arms
Arms and Interventions
Participant Group / ArmParticipant Group / Arm |
Intervention / TreatmentIntervention / Treatment |
|---|---|
|
Experimental: Treatment Sequence 1 (ADBC)
Subjects were randomized to treatment sequence ADBC: On Day 1, following an overnight fast of at least 10 hours, each subject will receive single dose of the treatment assigned to that treatment period. A =Ticagrelor granule for oral suspension equal to 90 mg. B = Ticagrelor pediatric tablets equal to 90 mg. C= Ticagrelor pediatric tablets suspended in water equal to 90 mg. D = Ticagrelor commercial IR (1 x 90 mg) tablet |
A P2Y12 receptor inhibitor provided as granule for suspension.
A P2Y12 receptor inhibitor provided as pediatric tablets to be swallowed whole.
A P2Y12 receptor inhibitor provided as pediatric tablets suspended in water.
A P2Y12 platelet inhibitor indicated to reduce the rate of thrombotic cardiovascular events in patients with acute coronary syndrome (unstable angina, non-ST (S and T waves) elevation MI or ST elevation MI) and in patients with a history of MI
Other Names:
|
|
Experimental: Treatment Sequence 2 (BACD)
Subjects were randomized to treatment sequence BACD: On Day 1, following an overnight fast of at least 10 hours, each subjects will receive single dose of the treatment assigned to that treatment period. A =Ticagrelor granule for oral suspension equal to 90 mg. B = Ticagrelor pediatric tablets equal to 90 mg. C= Ticagrelor pediatric tablets suspended in water equal to 90 mg. D = Ticagrelor commercial IR (1 x 90 mg) tablet |
A P2Y12 receptor inhibitor provided as granule for suspension.
A P2Y12 receptor inhibitor provided as pediatric tablets to be swallowed whole.
A P2Y12 receptor inhibitor provided as pediatric tablets suspended in water.
A P2Y12 platelet inhibitor indicated to reduce the rate of thrombotic cardiovascular events in patients with acute coronary syndrome (unstable angina, non-ST (S and T waves) elevation MI or ST elevation MI) and in patients with a history of MI
Other Names:
|
|
Experimental: Treatment Sequence 3 (CBDA)
Subjects were randomized to treatment sequence CBDA: On Day 1, following an overnight fast of at least 10 hours, each subjects will receive single dose of the treatment assigned to that treatment period. A =Ticagrelor granule for oral suspension equal to 90 mg. B = Ticagrelor pediatric tablets equal to 90 mg. C= Ticagrelor pediatric tablets suspended in water equal to 90 mg. D = Ticagrelor commercial IR (1 x 90 mg) tablet |
A P2Y12 receptor inhibitor provided as granule for suspension.
A P2Y12 receptor inhibitor provided as pediatric tablets to be swallowed whole.
A P2Y12 receptor inhibitor provided as pediatric tablets suspended in water.
A P2Y12 platelet inhibitor indicated to reduce the rate of thrombotic cardiovascular events in patients with acute coronary syndrome (unstable angina, non-ST (S and T waves) elevation MI or ST elevation MI) and in patients with a history of MI
Other Names:
|
|
Active Comparator: Treatment Sequence 4 (DCAB)
Subjects were randomized to treatment sequence DCAB: On Day 1, following an overnight fast of at least 10 hours, each subjects will receive single dose of the treatment assigned to that treatment period. A =Ticagrelor granule for oral suspension equal to 90 mg. B = Ticagrelor pediatric tablets equal to 90 mg. C= Ticagrelor pediatric tablets suspended in water equal to 90 mg. D = Ticagrelor commercial IR (1 x 90 mg) tablet |
A P2Y12 receptor inhibitor provided as granule for suspension.
A P2Y12 receptor inhibitor provided as pediatric tablets to be swallowed whole.
A P2Y12 receptor inhibitor provided as pediatric tablets suspended in water.
A P2Y12 platelet inhibitor indicated to reduce the rate of thrombotic cardiovascular events in patients with acute coronary syndrome (unstable angina, non-ST (S and T waves) elevation MI or ST elevation MI) and in patients with a history of MI
Other Names:
|
What is the study measuring?
Primary Outcome Measures
Primary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
|
Maximum observed plasma concentration (Cmax)
Time Frame: At 0 hours (pre-dose) and post-dose at 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose in each treatment period
|
|
At 0 hours (pre-dose) and post-dose at 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose in each treatment period
|
|
Area under plasma concentration-time curve from zero to infinity (AUC)
Time Frame: At 0 hours (pre-dose) and post-dose at 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose.
|
|
At 0 hours (pre-dose) and post-dose at 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose.
|
Secondary Outcome Measures
Secondary Outcome Measures
Outcome Measure |
Measure Description |
Time Frame |
|---|---|---|
|
Area under the plasma concentration-time curve from time zero to the time of the last measurable concentration (AUC(0-t))
Time Frame: At 0 hours (pre-dose) and post-dose at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose in each treatment period
|
To compare the pharmacokinetic (PK) profiles of ticagrelor and its active metabolite (AR-C124910XX) in healthy subjects when administered as granule for oral suspension, pediatric ticagrelor tablet, pediatric ticagrelor tablet suspended in water and commercial ticagrelor tablet.
|
At 0 hours (pre-dose) and post-dose at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose in each treatment period
|
|
Time to reach maximum observed plasma concentration, taken directly from the individual concentration-time curve (tmax).
Time Frame: At 0 hours (pre-dose) and post-dose at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose in each treatment period
|
To compare the PK profiles of ticagrelor and its active metabolite (AR-C124910XX) in healthy subjects when administered as granule for oral suspension, pediatric ticagrelor tablet, pediatric ticagrelor tablet suspended in water and commercial ticagrelor tablet.
|
At 0 hours (pre-dose) and post-dose at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose in each treatment period
|
|
Half-life associated with terminal slope (λz) of a semi-logarithmic concentration-time curve (t½λz).
Time Frame: At 0 hours (pre-dose) and post-dose at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose in each treatment period
|
To compare the PK profiles of ticagrelor and its active metabolite (AR-C124910XX) in healthy subjects when administered as granule for oral suspension, pediatric ticagrelor tablet, pediatric ticagrelor tablet suspended in water and commercial ticagrelor tablet.
|
At 0 hours (pre-dose) and post-dose at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose in each treatment period
|
|
Terminal rate constant, estimated by log-linear regression of the terminal part of the concentration-time curve (λz).
Time Frame: At 0 hours (pre-dose) and post-dose at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose in each treatment period
|
To compare the PK profiles of ticagrelor and its active metabolite (AR-C124910XX) in healthy subjects when administered as granule for oral suspension, pediatric ticagrelor tablet, pediatric ticagrelor tablet suspended in water and commercial ticagrelor tablet.
|
At 0 hours (pre-dose) and post-dose at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose in each treatment period
|
|
Apparent clearance, estimated as dose divided by AUC (ticagrelor only) (CL/F).
Time Frame: At 0 hours (pre-dose) and post-dose at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose in each treatment period
|
To compare the PK profiles of ticagrelor and its active metabolite (AR-C124910XX) in healthy subjects when administered as granule for oral suspension, pediatric ticagrelor tablet, pediatric ticagrelor tablet suspended in water and commercial ticagrelor tablet.
|
At 0 hours (pre-dose) and post-dose at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose in each treatment period
|
|
Apparent volume of distribution at the terminal phase, estimated by dividing the apparent clearance (CL/F) by λz (ticagrelor only) (Vz/F).
Time Frame: At 0 hours (pre-dose) and post-dose at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose in each treatment period
|
To compare the PK profiles of ticagrelor and its active metabolite (AR-C124910XX) in healthy subjects when administered as granule for oral suspension, pediatric ticagrelor tablet, pediatric ticagrelor tablet suspended in water and commercial ticagrelor tablet.
|
At 0 hours (pre-dose) and post-dose at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose in each treatment period
|
|
Ratio of metabolite Cmax to parent Cmax, adjusted for differences in molecular weights (MRCmax).
Time Frame: At 0 hours (pre-dose) and post-dose at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose in each treatment period
|
To compare the PK profiles of ticagrelor and its active metabolite (AR-C124910XX) in healthy subjects when administered as granule for oral suspension, pediatric ticagrelor tablet, pediatric ticagrelor tablet suspended in water and commercial ticagrelor tablet.
|
At 0 hours (pre-dose) and post-dose at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose in each treatment period
|
|
Ratio of metabolite AUC(0-t) to parent AUC(0-t), adjusted for differences in molecular weights (MRAUC(0-t)).
Time Frame: At 0 hours (pre-dose) and post-dose at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose in each treatment period
|
To compare the PK profiles of ticagrelor and its active metabolite (AR-C124910XX) in healthy subjects when administered as granule for oral suspension, pediatric ticagrelor tablet, pediatric ticagrelor tablet suspended in water and commercial ticagrelor tablet.
|
At 0 hours (pre-dose) and post-dose at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose in each treatment period
|
|
Ratio of metabolite AUC to parent AUC, adjusted for differences in molecular weights (MRAUC)
Time Frame: At 0 hours (pre-dose) and post-dose at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose in each treatment period
|
To compare the PK profiles of ticagrelor and its active metabolite (AR-C124910XX) in healthy subjects when administered as granule for oral suspension, pediatric ticagrelor tablet, pediatric ticagrelor tablet suspended in water and commercial ticagrelor tablet.
|
At 0 hours (pre-dose) and post-dose at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 16, 24, 36 and 48 hours post-dose in each treatment period
|
|
Number of patients with Adverse Events (AEs)
Time Frame: From screening (day -28) until follow-up/early termination (ET) (Day 5 to Day 10 (after treatment Period 4/ET))
|
To assess the adverse events as a criteria of safety and tolerability variables.
|
From screening (day -28) until follow-up/early termination (ET) (Day 5 to Day 10 (after treatment Period 4/ET))
|
|
Vital sign (systolic and diastolic blood pressure [BP])
Time Frame: At screening (Day -28), admission (Day -1), treatment periods 1, 2, 3, 4 (Day 1 - 3) and follow-up/ET (Day 5 to Day 10 (after treatment Period 4/ET))
|
To assess the vital signs as a criteria of safety and tolerability variables.
|
At screening (Day -28), admission (Day -1), treatment periods 1, 2, 3, 4 (Day 1 - 3) and follow-up/ET (Day 5 to Day 10 (after treatment Period 4/ET))
|
|
Vital sign (pulse rate)
Time Frame: At screening (Day -28), admission (Day -1), treatment periods 1, 2, 3, 4 (Day 1 - 3) and follow-up/ET (Day 5 to Day 10 (after treatment Period 4/ET))
|
To assess the vital signs as a criteria of safety and tolerability variables.
|
At screening (Day -28), admission (Day -1), treatment periods 1, 2, 3, 4 (Day 1 - 3) and follow-up/ET (Day 5 to Day 10 (after treatment Period 4/ET))
|
|
Twelve-lead electrocardiograms (ECGs)
Time Frame: At screening (Day -28) and follow-up/ET (Day 5 to Day 10 (after treatment Period 4/ET))
|
To assess the cardiovascular system functioning as a criteria of safety and tolerability variables.
|
At screening (Day -28) and follow-up/ET (Day 5 to Day 10 (after treatment Period 4/ET))
|
|
Physical examination
Time Frame: At screening (Day -28) and follow-up/ET (Day 5 to Day 10 (after treatment Period 4/ET))
|
To assess the physical examination as a criteria of safety and tolerability variables.
|
At screening (Day -28) and follow-up/ET (Day 5 to Day 10 (after treatment Period 4/ET))
|
|
Laboratory assessments (hematology and clinical chemistry)
Time Frame: At screening (Day -28), admission (day -1) and follow-up/ET (Day 5 to Day 10 (after treatment Period 4/ET))
|
To assess the hematology and clinical chemistry as a criteria of safety and tolerability variables.
|
At screening (Day -28), admission (day -1) and follow-up/ET (Day 5 to Day 10 (after treatment Period 4/ET))
|
|
Laboratory assessments (Urinalysis (dipstick))
Time Frame: At screening (Day -28), admission (day -1) and follow-up/ET (Day 5 to Day 10 (after treatment Period 4/ET))
|
To assess the urinalysis as a criteria of safety and tolerability variables.
|
At screening (Day -28), admission (day -1) and follow-up/ET (Day 5 to Day 10 (after treatment Period 4/ET))
|
Collaborators and Investigators
Sponsor
Sponsor
Collaborators
Collaborators
Investigators
Investigators
- Principal Investigator: Rainard Fuhr, Dr. med., Parexel Early Phase Clinical Unit Berlin
Publications and helpful links
Study record dates
Study Major Dates
Study Start (Actual)
Study Start
Primary Completion (Actual)
Primary Completion
Study Completion (Actual)
Study Completion
Study Registration Dates
First Submitted
First Submitted
First Submitted That Met QC Criteria
First Submitted That Met QC Criteria
First Posted (Actual)
First Posted
Study Record Updates
Last Update Posted (Actual)
Last Update Posted
Last Update Submitted That Met QC Criteria
Last Update Submitted That Met QC Criteria
Last Verified
Last Verified
More Information
Terms related to this study
Keywords
Additional Relevant MeSH Terms
- Hematologic Diseases
- Genetic Diseases, Inborn
- Anemia
- Anemia, Hemolytic, Congenital
- Anemia, Hemolytic
- Hemoglobinopathies
- Anemia, Sickle Cell
- Physiological Effects of Drugs
- Neurotransmitter Agents
- Molecular Mechanisms of Pharmacological Action
- Platelet Aggregation Inhibitors
- Purinergic P2Y Receptor Antagonists
- Purinergic P2 Receptor Antagonists
- Purinergic Antagonists
- Purinergic Agents
- Ticagrelor
Other Study ID Numbers
Other Study ID Numbers
- D5136C00011
Drug and device information, study documents
Studies a U.S. FDA-regulated drug product
Studies a U.S. FDA-regulated device product
This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.
Clinical Trials on Sickle Cell Disease
-
NCT07540767Not yet recruitingSickle Cell Disease | Sickle Cell Disease (SCD) | Sickle Cell Anemia in Children | Sickle Cell | Sickle Cell Anemia (HbSS)
-
NCT04579926CompletedSickle Cell Disease | Sickle Cell Anemia in Children | Sickle Cell Thalassemia | Sickle Cell SC Disease
-
NCT03763656CompletedSickle Cell Disease | Sickle Cell Hemoglobin C | Sickle Cell-beta-thalassemia | Sickle-Cell; Hemoglobin Disease, Thalassemia
-
NCT06396403CompletedSickle Cell Disease | Sickle Cell SC Disease | Sickle Cell-SS Disease | Sickle Cell Retinopathy
-
NCT01925001WithdrawnSickle Cell Disease | Anemia, Sickle Cell | Sickle Cell Anemia | Hemoglobin SC Disease | Sickle Cell Disorders | Sickle Cell Hemoglobin C Disease
-
NCT01356485CompletedSickle Cell Disease | Anemia, Sickle Cell | Sickle Cell Anemia | Hemoglobin SC Disease | Sickle Cell Disorders | Sickle Cell Hemoglobin C Disease
-
NCT05506358CompletedSickle Cell Disease | Beta-Thalassemia | Sickle Cell Trait | Sickle Cell-Beta Thalassemia | Sickle Cell-SS Disease
-
NCT01350232TerminatedSickle Cell Anemia | Sickle Cell-hemoglobin C Disease | Sickle Cell-β0-thalassemia
-
NCT04201210RecruitingSickle Cell Disease | Sickle Cell Anemia | Sickle Cell Disorders | HbS Disease | Hemoglobin S Disease | Sickling Disorder Due to Hemoglobin S
-
NCT03971136RecruitingSickle-Cell Disease Nos With Crisis
Clinical Trials on Ticagrelor granule
-
NCT01486186UnknownPulmonary Disease, Chronic Obstructive
-
NCT03443531Unknown
-
NCT03228134RecruitingBronchial Asthma
-
NCT05369884RecruitingNon-erosive Reflux Disease | Diarrhea-Predominant Irritable Bowel Syndrome
-
NCT05312463RecruitingGastroesophageal Reflux | Functional Dysphonia
-
NCT04492787CompletedIrritable Bowel Syndrome with Diarrhea
-
NCT06134063RecruitingAcute Exacerbation of Chronic Obstructive Pulmonary Disease
-
NCT04408261UnknownCoronary Artery Disease | Diabetic Peripheral Neuropathy | Stroke, Ischemic | Angina Pectoris, Stable
-
NCT05187481RecruitingColorectal Neoplasms