CLARITY Extension Study
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ClinicalTrials.gov Identifier: NCT00641537 |
Recruitment Status :
Completed
First Posted : March 24, 2008
Results First Posted : December 2, 2013
Last Update Posted : December 7, 2020
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Condition or disease | Intervention/treatment | Phase |
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Relapsing-Remitting Multiple Sclerosis | Drug: Cladribine Drug: Placebo | Phase 3 |
Study Type : | Interventional (Clinical Trial) |
Actual Enrollment : | 867 participants |
Allocation: | Randomized |
Intervention Model: | Parallel Assignment |
Masking: | Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor) |
Primary Purpose: | Treatment |
Official Title: | A Phase IIIb, Double-Blind, Placebo-Controlled, Multicenter, Parallel Group, Extension Trial to Evaluate the Safety and Tolerability of Oral Cladribine in Subjects With Relapsing-Remitting Multiple Sclerosis Who Have Completed Trial 25643 (CLARITY) |
Actual Study Start Date : | February 29, 2008 |
Actual Primary Completion Date : | December 31, 2011 |
Actual Study Completion Date : | December 31, 2011 |

Arm | Intervention/treatment |
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Placebo Comparator: Cladribine Low/Placebo (LLPP) |
Drug: Placebo
Participants who received Cladribine 3.5 mg/kg in the previous study 25643 (NCT00213135) and completed will be re-randomized in this extension study and receive placebo matched to cladribine tablet 0.875 mg/kg orally administered over a course of 4 or 5 consecutive days of 28-day period at Week 1, 5, 48, and 52 during the treatment period of 96 weeks. |
Placebo Comparator: Cladribine High Dose/Placebo (HLPP) |
Drug: Placebo
Participants who received Cladribine 5.25 mg/kg in the previous study 25643 (NCT00213135) and completed will be re-randomized in this extension study and receive placebo matched to cladribine tablet 0.875 mg/kg orally administered over a course of 4 or 5 consecutive days of 28-day period at Week 1, 5, 48, and 52 during the treatment period of 96 weeks. |
Experimental: Cladribine Low/Low Dose (LLLL) |
Drug: Cladribine
Participants who received Cladribine 3.5 mg/kg in the previous study 25643 (NCT00213135) and completed will be re-randomized in this extension study and receive cladribine tablet orally as cumulative dose of 0.875 mg/kg over a course of 4 or 5 consecutive days of 28-day period at Week 1, 5, 48, and 52 resulting in total cladribine dose of 3.5 mg/kg during the treatment period of 96 weeks. |
Experimental: Cladribine High/Low Dose (HLLL) |
Drug: Cladribine
Participants who received Cladribine 5.25 mg/kg in the previous study 25643 (NCT00213135) and completed will be re-randomized in this extension study and receive cladribine tablet orally as cumulative dose of 0.875 mg/kg over a course of 4 or 5 consecutive days of 28-day period at Week 1, 5, 48, and 52 resulting in total cladribine dose of 3.5 mg/kg during the treatment period of 96 weeks. |
Experimental: Placebo/Cladribine Low Dose (PPLL) |
Drug: Cladribine
Participants who received placebo in the previous study 25643 (NCT00213135) and completed will be re-randomized in this extension study and receive cladribine tablet orally as cumulative dose of 0.875 mg/kg over a course of 4 or 5 consecutive days of 28-day period at Week 1, 5, 48, and 52 resulting in total cladribine dose of 3.5 mg/kg during the treatment period of 96 weeks. |
No Intervention: Placebo/No Treatment | |
No Intervention: Cladribine 3.5 mg/kg/No Treatment
Participants who received cladribine 3.5 mg/kg in previous study 25643 (NCT00213135) and completed were enrolled in this extension study and received no cladribine treatment and were followed up for safety assessment for 96 weeks (during the treatment period) and followed up for 24 weeks (during supplemental follow-up period).
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No Intervention: Cladribine 5.25 mg/kg/No Treatment
Participants who received cladribine 5.25 mg/kg in previous study 25643 (NCT00213135) and completed were enrolled in this extension study and received no cladribine treatment and were followed up for safety assessment for 96 weeks (during the treatment period) and followed up for 24 weeks (during supplemental follow-up period).
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- Safety Population: Percentage of Participants With at Least 1 Common Terminology Criteria for Adverse Events Version 3.0 (CTCAE) Grade 4 Hematologic and Hepatic Toxicity [ Time Frame: Baseline up to Week 120 ]Hematologic and hepatic toxicity was assessed using Common Terminology Criteria for Adverse Events v 3.0 (CTCAE). Hematologic and hepatic function included absolute lymphocyte count (ALC), hemoglobin level, white blood cell (WBC) count, absolute neutrophil count (ANC), platelets, alanine transaminase (ALT), aspartate transaminase (AST) and bilirubin. According to CTCAE v3.0: Grade 1=mild, Grade 2=moderate, Grade 3=severe, Grade 4=life threatening or disabling and Grade 5=Death.
- Safety Population: Mean Change From Baseline in Absolute Lymphocyte Count, Platelet, Neutrophils and Leukocytes at Week 120 [ Time Frame: Baseline, Week 120 ]Mean change from baseline in absolute lymphocyte count, platelet, neutrophils and leukocytes at week 120 were reported.
- Safety Population: Mean Change From Baseline in Hemoglobin at Week 120 [ Time Frame: Baseline, Week 120 ]Mean change from baseline in hemoglobin at Week 120 was reported.
- Safety Population: Mean Change From Baseline in Aspartate Aminotransferase and Alanine Aminotransferase at Week 120 [ Time Frame: Baseline, Week 120 ]Mean change from baseline in aspartate aminotransferase and alanine aminotransferase at week 120 were reported.
- Safety Population: Mean Change From Baseline in Bilirubin at Week 120 [ Time Frame: Baseline, Week 120 ]Mean Change From Baseline in Bilirubin at week 120 was reported.
- Safety Population: Number of Participants With Treatment Emergent Adverse Events (TEAEs) and Serious TEAEs [ Time Frame: Baseline up to Week 120 ]An adverse event (AE) was defined as any untoward medical occurrence in the form of signs, symptoms, abnormal laboratory findings, or diseases that emerges or worsens relative to baseline during a clinical study with an Investigational Medicinal Product (IMP), regardless of causal relationship and even if no IMP has been administered. Serious AE (SAE): Any AE that resulted in death; was life threatening; resulted in persistent/significant disability/incapacity; resulted in/prolonged an existing in-patient hospitalization; was a congenital anomaly/birth defect; or was a medically important condition. The term TEAE is defined as AEs starting or worsening after the first intake of the study drug. Number of participants with TEAEs included participants with both non-serious TEAEs and serious TEAEs.
- SAFUP Analysis Set: Number of Participants With Treatment Emergent Adverse Events (TEAEs) and Serious TEAEs [ Time Frame: Baseline up to Week 120 ]An AE was defined as any untoward medical occurrence in the form of signs, symptoms, abnormal laboratory findings, or diseases that emerges or worsens relative to baseline during a clinical study with an Investigational Medicinal Product (IMP), regardless of causal relationship and even if no IMP has been administered. SAE: Any AE that resulted in death; was life threatening; resulted in persistent/significant disability/incapacity; resulted in/prolonged an existing in-patient hospitalization; was a congenital anomaly/birth defect; or was a medically important condition. The term TEAE is defined as AEs starting or worsening after the first intake of the study drug. Number of participants with TEAEs included participants with both non-serious TEAEs and serious TEAEs.
- Safety Population: Number of Participants Who Developed Infections (Herpes Viral Infection, Viral Infectious Disorder and Opportunistic Infection), Infection-related Adverse Events and Malignancies [ Time Frame: Baseline up to Week 120 ]Number of participants who developed Herpes viral infection, Viral infectious disorder and Opportunistic infection are reported. Number of participants with infection related adverse events are the number of participants who had at least one adverse event coded to medical dictionary for regulatory activities (MedDRA) preferred terms under infection and infestation system organ class. Malignancy is defined as having at least one adverse event coded to MedDRA preferred terms under the pre-specified grouping Malignant and unspecified tumors.
- SAFUP Analysis Set: Number of Participants Who Developed Infections (Herpes Viral Infection, Viral Infectious Disorder and Opportunistic Infection), Infection-related Adverse Events and Malignancies [ Time Frame: Baseline up to Week 120 ]Number of participants who developed Herpes viral infection, Viral infectious disorder and Opportunistic infection were reported. Number of participants with infection related adverse events are the number of participants who had at least one adverse event coded to medical dictionary for regulatory activities (MedDRA) preferred terms under infection and infestation system organ class. Malignancy is defined as having at least one adverse event coded to MedDRA preferred terms under the pre-specified grouping Malignant and unspecified tumors.
- Safety Population: Time to First Grade 3 or 4 Hematological Toxicity and Liver Toxicity [ Time Frame: Baseline up to Week 120 ]Hematologic and hepatic toxicity was assessed using Common Terminology Criteria for Adverse Events version 3.0 (CTCAE). Hematologic and hepatic function included absolute lymphocyte count (ALC), hemoglobin level, white blood cell (WBC) count, absolute neutrophil count (ANC), platelets, alanine transaminase (ALT), aspartate transaminase (AST) and bilirubin. Time to first CTCAE Grade 3 or 4 hematological or liver toxicity was analyzed by treatment group using Kaplan-Meier plots of probability of surviving toxicity-free and point estimates of percentiles. According to CTCAE version 3.0: Grade 1=mild, Grade 2=moderate, Grade 3=severe, Grade 4=life threatening or disabling and Grade 5=Death. 10th, 20th, 25th, 50th and 75th percentiles were estimated from Kaplan-Meier survival curve.
- Safety Population: Median Time to Recovery From Grade 3 or 4 Hematological and Hepatic Toxicity [ Time Frame: Baseline up to Week 120 ]Hematologic and hepatic toxicity was assessed using Common Terminology Criteria for Adverse Events (CTCAE). Hematologic and hepatic function included absolute lymphocyte count (ALC), hemoglobin level, white blood cell (WBC) count, absolute neutrophil count (ANC), platelets, alanine transaminase (ALT), aspartate transaminase (AST) and bilirubin. According to CTCAE version 3.0: Grade 1=mild, Grade 2=moderate, Grade 3=severe, Grade 4=life threatening or disabling and Grade 5=Death. Time to recovery from grade 3 or 4 hematological or liver toxicity were reported: lymphocytes, platelets, neutrophils, white blood cells, hemoglobin, Alanine transaminase (ALT), Aspartate transaminase (AST), Platelets and Bilirubin. Recovery from a Grade 3 or 4 toxicity is defined as a return to a Grade 0 or 1.
- Safety Population: Mean Time to Recovery From Grade 3 or 4 Hematological and Liver Toxicity [ Time Frame: Baseline up to Week 120 ]Hematologic and hepatic toxicity was assessed using Common Terminology Criteria for Adverse Events (CTCAE). Hematologic and hepatic function included absolute lymphocyte count (ALC), hemoglobin level, white blood cell (WBC) count, absolute neutrophil count (ANC), platelets, alanine transaminase (ALT), aspartate transaminase (AST) and bilirubin. According to CTCAE v3.0: Grade 1=mild, Grade 2=moderate, Grade 3=severe, Grade 4=life threatening or disabling and Grade 5=Death. Time to recovery from grade 3 or 4 hematological or liver toxicity were reported: lymphocytes, platelets, neutrophils, white blood cells, hemoglobin, Alanine transaminase (ALT), Aspartate transaminase (AST) and Platelets. Recovery from a Grade 3 or 4 toxicity is defined as a return to a Grade 0 or 1.
- Safety Population: Median Time to Nadir of Absolute Lymphocyte Count [ Time Frame: Baseline up to Week 120 ]Median time to nadir of absolute lymphocyte count was reported.
- Safety Population: Mean Time to Nadir of Absolute Lymphocyte Count [ Time Frame: Baseline up to Week 120 ]Mean time to nadir of absolute lymphocyte count was reported.
- Safety Population: Mean Time to Recovery From Nadir of Absolute Lymphocyte Count to Normal Value [ Time Frame: Baseline up to Week 120 ]Mean time to recovery from nadir of absolute lymphocyte count to normal was reported. Recovery from Nadir is defined as a return to baseline value. Normal absolute lymphocyte count is 1.02 x 10^3 cells/microliter.
- Safety Population: Mean Change in Corrected QT (QTc) Interval From Baseline [ Time Frame: Baseline, Week 5, 48, 52 and 96 ]The QT interval is a measure of the time between the start of the Q wave and the end of the T wave. Corrected QT (QTc) is the QT interval corrected for heart rate and RR, which is the interval between two R waves. Mean change in corrected QT (QTc) interval from baseline was reported.

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Ages Eligible for Study: | 18 Years to 65 Years (Adult, Older Adult) |
Sexes Eligible for Study: | All |
Accepts Healthy Volunteers: | No |
Inclusion Criteria:
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Randomized in Trial 25643 and satisfied one of the following:
- Completed randomized treatment course and scheduled visits for the full 96 weeks; or
- Did not complete the randomized treatment course in Trial 25643 but elected to receive rescue treatment with Rebif®, another beta-interferon, or glatiramer acetate and completed scheduled clinic visits for the full 96 weeks; or
- Did not complete the randomized treatment course in Trial 25643, declined rescue with Rebif®, another beta-interferon, or glatiramer acetate and still completed scheduled clinic visits for the full 96 weeks; or
- Did not complete the randomized treatment course in Trial 25643, were not eligible for rescue option with Rebif®, and still completed scheduled clinic visits for the full 96 weeks
- Male or female, between 18 and 65 years of age (inclusive, at time of informed consent for Trial 25643)
- No medical history or evidence of latent tuberculosis infection (LTBI) or tuberculosis (TB), as evidenced by TB skin test or chest X-ray
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All of the following laboratory hematologic parameters evaluated as normal (as define below, inclusively) within 28 days of first dosing of blinded study medication at study Day 1:
- Hemoglobin = 11.6 to 16.2 gram per deciliter (g/dL)
- Leukocytes (total white blood cell) = 4.1 to 12.3*10^3 per microliter
- Absolute lymphocyte count (ALC) = 1.02 to 3.36*10^3 per microliter
- Absolute neutrophil count (ANC) = 2.03 to 8.36*10^3 per microliter
- Platelet count = 140 to 450*10^3 per microliter
- Other protocol-defined inclusion/exclusion criteria may apply
Exclusion Criteria:
- Participants who were not enrolled in Trial 25643
- Participant has moderate to severe renal impairment
- Use of mitoxantrone, total lymphoid irradiation, myelosuppressive therapy, campath-1h, cyclophosphamide, azathioprine, methotrexate or natalizumab at any time during and since Trial 25643
- Use of cytokine or anti-cytokine therapy, intravenous immunoglobulin (IVIG) or plasmapheresis at any time during and since Trial 25643
- Treatment with oral or systemic corticosteroids or adrenocorticotropic hormone within 28 days before Study Day 1

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT00641537

Study Director: | Medical Responsible | Merck Healthcare KGaA, Darmstadt, Germany, an affiliate of Merck KGaA, Darmstadt, Germany |
Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
Responsible Party: | EMD Serono Research & Development Institute, Inc. |
ClinicalTrials.gov Identifier: | NCT00641537 |
Other Study ID Numbers: |
27820 2007-000381-20 ( EudraCT Number ) |
First Posted: | March 24, 2008 Key Record Dates |
Results First Posted: | December 2, 2013 |
Last Update Posted: | December 7, 2020 |
Last Verified: | October 2020 |
Multiple Sclerosis Multiple Sclerosis, Relapsing-Remitting Sclerosis Pathologic Processes Demyelinating Autoimmune Diseases, CNS Autoimmune Diseases of the Nervous System Nervous System Diseases Demyelinating Diseases |
Autoimmune Diseases Immune System Diseases Cladribine Antineoplastic Agents Immunosuppressive Agents Immunologic Factors Physiological Effects of Drugs |