NCT00641537 is a Phase 3 clinical trial of Cladribine in Relapsing-Remitting Multiple Sclerosis, sponsored by EMD Serono Research & Development Institute, Inc..

Who is sponsoring NCT00641537?

NCT00641537 is sponsored by EMD Serono Research & Development Institute, Inc..

What drugs are being tested in NCT00641537?

Interventions in NCT00641537: Cladribine, Placebo, Cladribine, Cladribine, Placebo.

What condition does NCT00641537 study?

NCT00641537 studies Relapsing-Remitting Multiple Sclerosis.

Is NCT00641537 still recruiting?

NCT00641537 is currently completed. Last updated 7 December 2020.

Are results published for NCT00641537?

Yes — primary outcome results have been posted to ClinicalTrials.gov. See the outcomes section above for details.

Last reviewed 2020-12-07 · How we verify

NCT00641537

Name: Drug Landscape Pharmaceutical Database
Creator: Drug Landscape
Published: 2026-01-01
License: https://creativecommons.org/licenses/by/4.0/

CLARITY Extension Study

Completed Phase 3 Results posted Last updated 7 December 2020

What this trial tests

Phase 3 trial testing Cladribine in Relapsing-Remitting Multiple Sclerosis in 867 participants. Completed in 31 December 2011.

Timeline

29 February 2008

Primary endpoint
31 December 2011

31 December 2011

Quick facts

Lead sponsor	EMD Serono Research & Development Institute, Inc.
Phase	Phase 3
Status	Completed
Study type	INTERVENTIONAL
Allocation	randomized
Design	parallel
Masking	quadruple
Primary purpose	treatment
Enrollment	867
Start date	29 February 2008
Primary completion	31 December 2011
Estimated completion	31 December 2011
Sites	116 locations across Italy, Finland, Poland, Lebanon, Croatia, Tunisia, Denmark, Netherlands

Drugs / interventions tested

Cladribine (CLADRIBINE) — full drug profile →
Placebo
Cladribine (CLADRIBINE) — full drug profile →
Cladribine (CLADRIBINE) — full drug profile →
Placebo

Conditions studied

Relapsing-Remitting Multiple Sclerosis — all drugs for Relapsing-Remitting Multiple Sclerosis →

Sponsor

EMD Serono Research & Development Institute, Inc. — full company profile →

Who can join

Adults 18 to 65, any sex, with Relapsing-Remitting Multiple Sclerosis. Patients with the condition only — healthy volunteers not accepted.

Results — posted to ClinicalTrials.gov

Per-arm endpoint measurements with 95% confidence intervals where reported. Source: trial results section.

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 Primary · 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.

Lymphocyte toxicity

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	0.0
Cladribine High Dose/Placebo (HLPP)	0.0
Cladribine Low/Low Dose (LLLL)	2.7
Cladribine High/Low Dose (HLLL)	3.2
Placebo/Cladribine Low Dose (PPLL)	0.4

Hemoglobin Toxicity

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	0.0
Cladribine High Dose/Placebo (HLPP)	0.0
Cladribine Low/Low Dose (LLLL)	0.0
Cladribine High/Low Dose (HLLL)	0.0
Placebo/Cladribine Low Dose (PPLL)	0.0

White Blood Cell Toxicity

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	0.0
Cladribine High Dose/Placebo (HLPP)	0.0
Cladribine Low/Low Dose (LLLL)	0.5
Cladribine High/Low Dose (HLLL)	0.0
Placebo/Cladribine Low Dose (PPLL)	0.0

Absolute Neutrophil Count Toxicity

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	0.0
Cladribine High Dose/Placebo (HLPP)	2.2
Cladribine Low/Low Dose (LLLL)	0.5
Cladribine High/Low Dose (HLLL)	0.0
Placebo/Cladribine Low Dose (PPLL)	0.4

Platelets Toxicity

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	0.0
Cladribine High Dose/Placebo (HLPP)	0.0
Cladribine Low/Low Dose (LLLL)	0.5
Cladribine High/Low Dose (HLLL)	0.0
Placebo/Cladribine Low Dose (PPLL)	0.0

Alanine Transaminase Toxicity

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	0.0
Cladribine High Dose/Placebo (HLPP)	0.0
Cladribine Low/Low Dose (LLLL)	0.0
Cladribine High/Low Dose (HLLL)	0.0
Placebo/Cladribine Low Dose (PPLL)	0.0

AsparateTransaminase Toxicity

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	0.0
Cladribine High Dose/Placebo (HLPP)	0.0
Cladribine Low/Low Dose (LLLL)	0.0
Cladribine High/Low Dose (HLLL)	0.0
Placebo/Cladribine Low Dose (PPLL)	0.0

Bilirubin Toxicity

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	0.0
Cladribine High Dose/Placebo (HLPP)	0.0
Cladribine Low/Low Dose (LLLL)	0.0
Cladribine High/Low Dose (HLLL)	0.0
Placebo/Cladribine Low Dose (PPLL)	0.0

Safety Population: Mean Change From Baseline in Absolute Lymphocyte Count, Platelet, Neutrophils and Leukocytes at Week 120 Primary · Baseline, Week 120

Mean change from baseline in absolute lymphocyte count, platelet, neutrophils and leukocytes at week 120 were reported.

Lymphocyte Count

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	0.3	± 0.4
Cladribine High Dose/Placebo (HLPP)	0.3	± 0.4
Cladribine Low/Low Dose (LLLL)	0.0	± 0.4
Cladribine High/Low Dose (HLLL)	0.0	± 0.5
Placebo/Cladribine Low Dose (PPLL)	-0.6	± 0.6

Platelet

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	-7.7	± 26.2
Cladribine High Dose/Placebo (HLPP)	-11.9	± 35.3
Cladribine Low/Low Dose (LLLL)	-20.6	± 37.9
Cladribine High/Low Dose (HLLL)	-9.7	± 51.2
Placebo/Cladribine Low Dose (PPLL)	-34.0	± 37.2

Leukocytes

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	0.8	± 1.5
Cladribine High Dose/Placebo (HLPP)	0.5	± 1.2
Cladribine Low/Low Dose (LLLL)	-0.2	± 1.5
Cladribine High/Low Dose (HLLL)	-0.1	± 1.4
Placebo/Cladribine Low Dose (PPLL)	-0.9	± 1.7

Neutrophils

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	0.4	± 1.3
Cladribine High Dose/Placebo (HLPP)	0.1	± 1.2
Cladribine Low/Low Dose (LLLL)	-0.2	± 1.4
Cladribine High/Low Dose (HLLL)	-0.2	± 1.3
Placebo/Cladribine Low Dose (PPLL)	-0.3	± 1.7

Safety Population: Mean Change From Baseline in Hemoglobin at Week 120 Primary · Baseline, Week 120

Mean change from baseline in hemoglobin at Week 120 was reported.

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	0.2	± 0.9
Cladribine High Dose/Placebo (HLPP)	0.2	± 0.7
Cladribine Low/Low Dose (LLLL)	-0.1	± 0.9
Cladribine High/Low Dose (HLLL)	0.1	± 0.9
Placebo/Cladribine Low Dose (PPLL)	-0.1	± 0.9

Safety Population: Mean Change From Baseline in Aspartate Aminotransferase and Alanine Aminotransferase at Week 120 Primary · Baseline, Week 120

Mean change from baseline in aspartate aminotransferase and alanine aminotransferase at week 120 were reported.

Aspartate Aminotransferase

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	0.7	± 10.6
Cladribine High Dose/Placebo (HLPP)	-1.1	± 6.4
Cladribine Low/Low Dose (LLLL)	2.2	± 7.3
Cladribine High/Low Dose (HLLL)	0.7	± 11.3
Placebo/Cladribine Low Dose (PPLL)	0.5	± 5.1

Alanine Aminotransferase

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	2.2	± 26.0
Cladribine High Dose/Placebo (HLPP)	-1.0	± 11.7
Cladribine Low/Low Dose (LLLL)	4.3	± 14.3
Cladribine High/Low Dose (HLLL)	0.7	± 17.5
Placebo/Cladribine Low Dose (PPLL)	1.4	± 12.2

Safety Population: Mean Change From Baseline in Bilirubin at Week 120 Primary · Baseline, Week 120

Mean Change From Baseline in Bilirubin at week 120 was reported.

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	0.1	± 3.7
Cladribine High Dose/Placebo (HLPP)	0.0	± 3.5
Cladribine Low/Low Dose (LLLL)	-0.8	± 3.7
Cladribine High/Low Dose (HLLL)	-0.8	± 3.3
Placebo/Cladribine Low Dose (PPLL)	-0.4	± 3.7

Safety Population: Number of Participants With Treatment Emergent Adverse Events (TEAEs) and Serious TEAEs Primary · 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 cond

TEAEs

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	74
Cladribine High Dose/Placebo (HLPP)	71
Cladribine Low/Low Dose (LLLL)	149
Cladribine High/Low Dose (HLLL)	149
Placebo/Cladribine Low Dose (PPLL)	194

Serious TEAEs

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	16
Cladribine High Dose/Placebo (HLPP)	8
Cladribine Low/Low Dose (LLLL)	25
Cladribine High/Low Dose (HLLL)	23
Placebo/Cladribine Low Dose (PPLL)	22

SAFUP Analysis Set: Number of Participants With Treatment Emergent Adverse Events (TEAEs) and Serious TEAEs Primary · 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 defin

TEAEs

Group	Value	95% CI
Placebo/No Treatment	16
Cladribine 3.5 mg/kg/No Treatment	13
Cladribine 5.25 mg/kg/No Treatment	18

Serious TEAEs

Group	Value	95% CI
Placebo/No Treatment	2
Cladribine 3.5 mg/kg/No Treatment	1
Cladribine 5.25 mg/kg/No Treatment	3

Safety Population: Number of Participants Who Developed Infections (Herpes Viral Infection, Viral Infectious Disorder and Opportunistic Infection), Infection-related Adverse Events and Malignancies Primary · 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.

Herpes viral infection

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	6
Cladribine High Dose/Placebo (HLPP)	4
Cladribine Low/Low Dose (LLLL)	6
Cladribine High/Low Dose (HLLL)	13
Placebo/Cladribine Low Dose (PPLL)	11

Opportunistic infection

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	8
Cladribine High Dose/Placebo (HLPP)	4
Cladribine Low/Low Dose (LLLL)	9
Cladribine High/Low Dose (HLLL)	17
Placebo/Cladribine Low Dose (PPLL)	15

Viral infectious disorder

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	20
Cladribine High Dose/Placebo (HLPP)	16
Cladribine Low/Low Dose (LLLL)	28
Cladribine High/Low Dose (HLLL)	41
Placebo/Cladribine Low Dose (PPLL)	39

Infections related adverse event

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	49
Cladribine High Dose/Placebo (HLPP)	45
Cladribine Low/Low Dose (LLLL)	92
Cladribine High/Low Dose (HLLL)	88
Placebo/Cladribine Low Dose (PPLL)	112

Malignancies

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	2
Cladribine High Dose/Placebo (HLPP)	1
Cladribine Low/Low Dose (LLLL)	7
Cladribine High/Low Dose (HLLL)	2
Placebo/Cladribine Low Dose (PPLL)	2

SAFUP Analysis Set: Number of Participants Who Developed Infections (Herpes Viral Infection, Viral Infectious Disorder and Opportunistic Infection), Infection-related Adverse Events and Malignancies Primary · 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.

Herpes viral infection

Group	Value	95% CI
Placebo/No Treatment	0
Cladribine 3.5 mg/kg/No Treatment	1
Cladribine 5.25 mg/kg/No Treatment	1

Opportunistic infection

Group	Value	95% CI
Placebo/No Treatment	0
Cladribine 3.5 mg/kg/No Treatment	1
Cladribine 5.25 mg/kg/No Treatment	2

Viral infectious disorder

Group	Value	95% CI
Placebo/No Treatment	6
Cladribine 3.5 mg/kg/No Treatment	5
Cladribine 5.25 mg/kg/No Treatment	3

Infections related adverse event

Group	Value	95% CI
Placebo/No Treatment	11
Cladribine 3.5 mg/kg/No Treatment	6
Cladribine 5.25 mg/kg/No Treatment	12

Malignancies

Group	Value	95% CI
Placebo/No Treatment	2
Cladribine 3.5 mg/kg/No Treatment	0
Cladribine 5.25 mg/kg/No Treatment	1

Safety Population: Time to First Grade 3 or 4 Hematological Toxicity and Liver Toxicity Primary · 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=m

10th percentile: Lymphocytes Count

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	NA	NA – NA
Cladribine High Dose/Placebo (HLPP)	NA	NA – NA
Cladribine Low/Low Dose (LLLL)	14	8 – 34
Cladribine High/Low Dose (HLLL)	8	8 – 12
Placebo/Cladribine Low Dose (PPLL)	362	85 – 378

20th percentile: Lymphocytes Count

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	NA	NA – NA
Cladribine High Dose/Placebo (HLPP)	NA	NA – NA
Cladribine Low/Low Dose (LLLL)	58	34 – 162
Cladribine High/Low Dose (HLLL)	15	12 – 50
Placebo/Cladribine Low Dose (PPLL)	412	379 – 583

25th percentile: Lymphocytes Count

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	NA	NA – NA
Cladribine High Dose/Placebo (HLPP)	NA	NA – NA
Cladribine Low/Low Dose (LLLL)	108	57 – 379
Cladribine High/Low Dose (HLLL)	34	15 – 57
Placebo/Cladribine Low Dose (PPLL)	583	406 – NA

50th percentile: Lymphocytes Count

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	NA	NA – NA
Cladribine High Dose/Placebo (HLPP)	NA	NA – NA
Cladribine Low/Low Dose (LLLL)	NA	NA – NA
Cladribine High/Low Dose (HLLL)	449	361 – NA
Placebo/Cladribine Low Dose (PPLL)	NA	NA – NA

75th percentile: Lymphocytes Count

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	NA	NA – NA
Cladribine High Dose/Placebo (HLPP)	NA	NA – NA
Cladribine Low/Low Dose (LLLL)	NA	NA – NA
Cladribine High/Low Dose (HLLL)	NA	NA – NA
Placebo/Cladribine Low Dose (PPLL)	NA	NA – NA

10th percentile: Hemoglobin

Group	Value	95% CI
Cladribine High Dose/Placebo (HLPP)	NA	NA – NA
Cladribine Low/Low Dose (LLLL)	NA	NA – NA
Cladribine High/Low Dose (HLLL)	NA	NA – NA
Placebo/Cladribine Low Dose (PPLL)	NA	NA – NA

20th percentile: Hemoglobin

Group	Value	95% CI
Cladribine High Dose/Placebo (HLPP)	NA	NA – NA
Cladribine Low/Low Dose (LLLL)	NA	NA – NA
Cladribine High/Low Dose (HLLL)	NA	NA – NA
Placebo/Cladribine Low Dose (PPLL)	NA	NA – NA

25th percentile: Hemoglobin

Group	Value	95% CI
Cladribine High Dose/Placebo (HLPP)	NA	NA – NA
Cladribine Low/Low Dose (LLLL)	NA	NA – NA
Cladribine High/Low Dose (HLLL)	NA	NA – NA
Placebo/Cladribine Low Dose (PPLL)	NA	NA – NA

Safety Population: Median Time to Recovery From Grade 3 or 4 Hematological and Hepatic Toxicity Primary · 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, neutrophil

Lymphocyte

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	22.0	14 – 85
Cladribine High Dose/Placebo (HLPP)	31.5	26 – 51
Cladribine Low/Low Dose (LLLL)	212.0	8 – 1184
Cladribine High/Low Dose (HLLL)	168.0	7 – 799
Placebo/Cladribine Low Dose (PPLL)	111.3	5 – 701

Hemoglobin

Group	Value	95% CI
Cladribine High Dose/Placebo (HLPP)	99.0	99 – 99
Cladribine Low/Low Dose (LLLL)	64.0	64 – 64
Cladribine High/Low Dose (HLLL)	57.0	57 – 57
Placebo/Cladribine Low Dose (PPLL)	173.5	22 – 325

White Blood Cell Count

Group	Value	95% CI
Cladribine High Dose/Placebo (HLPP)	29.0	29 – 29
Cladribine Low/Low Dose (LLLL)	30.0	19 – 295
Cladribine High/Low Dose (HLLL)	42.5	19 – 715
Placebo/Cladribine Low Dose (PPLL)	79.0	28 – 125

Absolute Neutrophil Count

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	43.0	13 – 91
Cladribine High Dose/Placebo (HLPP)	57.0	29 – 85
Cladribine Low/Low Dose (LLLL)	23.8	8 – 85
Cladribine High/Low Dose (HLLL)	34.0	19 – 127
Placebo/Cladribine Low Dose (PPLL)	37.5	15 – 162

Platelets

Group	Value	95% CI
Cladribine High/Low Dose (HLLL)	197.0	197 – 197

Alanine Transaminase (ALT)

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	72.5	51 – 94
Cladribine High/Low Dose (HLLL)	73.0	19 – 127
Placebo/Cladribine Low Dose (PPLL)	15.0	1 – 55

Aspartate Transaminase (AST)

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	72.5	51 – 94
Cladribine Low/Low Dose (LLLL)	84.0	84 – 84
Cladribine High/Low Dose (HLLL)	18.0	18 – 18
Placebo/Cladribine Low Dose (PPLL)	55.0	55 – 55

Safety Population: Mean Time to Recovery From Grade 3 or 4 Hematological and Liver Toxicity Primary · 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, whit

Lymphocyte

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	41.0	± 33.5
Cladribine High Dose/Placebo (HLPP)	34.9	± 11.7
Cladribine Low/Low Dose (LLLL)	256.7	± 239.7
Cladribine High/Low Dose (HLLL)	241.8	± 216.1
Placebo/Cladribine Low Dose (PPLL)	160.2	± 160.4

Hemoglobin

Group	Value	95% CI
Cladribine High Dose/Placebo (HLPP)	99.0
Cladribine Low/Low Dose (LLLL)	64.0
Cladribine High/Low Dose (HLLL)	57.0
Placebo/Cladribine Low Dose (PPLL)	173.5	± 214.3

White Blood Cell Count

Group	Value	95% CI
Cladribine High Dose/Placebo (HLPP)	29.0
Cladribine Low/Low Dose (LLLL)	79.3	± 91.9
Cladribine High/Low Dose (HLLL)	132.0	± 213.9
Placebo/Cladribine Low Dose (PPLL)	71.5	± 39.7

Absolute Neutrophil Count

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	49.0	± 39.3
Cladribine High Dose/Placebo (HLPP)	57.0	± 39.6
Cladribine Low/Low Dose (LLLL)	35.3	± 29.9
Cladribine High/Low Dose (HLLL)	46.8	± 35.1
Placebo/Cladribine Low Dose (PPLL)	61.0	± 55.3

Platelets

Group	Value	95% CI
Cladribine High/Low Dose (HLLL)	197.0

Alanine Transaminase

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	72.5	± 30.4
Cladribine High/Low Dose (HLLL)	73.0	± 76.4
Placebo/Cladribine Low Dose (PPLL)	23.7	± 28.0

Aspartate Transaminase

Group	Value	95% CI
Cladribine Low/Placebo (LLPP)	72.5	± 30.4
Cladribine Low/Low Dose (LLLL)	84.0
Cladribine High/Low Dose (HLLL)	18.0
Placebo/Cladribine Low Dose (PPLL)	55.0

Adverse events — posted to ClinicalTrials.gov

Time frame: Baseline up to Week 120. Reporting threshold: 5%. Adverse-event reports describe events observed during the trial — not all are caused by the drug.

Cladribine Low/Placebo (LLPP)

Serious: 16/98 (16%)

Deaths: 2/98

Cladribine High Dose/Placebo (HLPP)

Serious: 8/92 (9%)

Deaths: 0/92

Cladribine Low/Low Dose (LLLL)

Serious: 25/186 (13%)

Deaths: 1/186

Cladribine High/Low Dose (HLLL)

Serious: 23/186 (12%)

Deaths: 0/186

Placebo/Cladribine Low Dose (PPLL)

Serious: 22/244 (9%)

Deaths: 0/244

Placebo/No Treatment

Serious: 2/22 (9%)

Deaths: 0/22

Cladribine 3.5 mg/kg/No Treatment

Serious: 1/17 (6%)

Deaths: 0/17

Cladribine 5.25 mg/kg/No Treatment

Serious: 3/22 (14%)

Deaths: 0/22

Serious adverse events (115 terms)

Reaction	System	Cladribine Low/Placebo (LL…	Cladribine High Dose/Place…	Cladribine Low/Low Dose (L…	Cladribine High/Low Dose (…	Placebo/Cladribine Low Dos…	Placebo/No Treatment	Cladribine 3.5 mg/kg/No Tr…	Cladribine 5.25 mg/kg/No T…
Pneumonia	Infections and infestations	—	—	—	—	—	—	—	—
Uterine leiomyoma	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—	—	—	—	—
Lipoma	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—	—	—	—	—
Herpes zoster	Infections and infestations	—	—	—	—	—	—	—	—
Urinary tract infection	Infections and infestations	—	—	—	—	—	—	—	—
Cholelithiasis	Hepatobiliary disorders	—	—	—	—	—	—	—	—
Iridocyclitis	Eye disorders	—	—	—	—	—	—	—	—
Malignant melanoma	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—	—	—	—	—
Adrenal adenoma	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—	—	—	—	—
Basal cell carcinoma	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—	—	—	—	—
Bile duct cancer	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—	—	—	—	—
Breast cancer	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—	—	—	—	—
Breast fibroma	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—	—	—	—	—
Colorectal cancer metastatic	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—	—	—	—	—
Fibrous histiocytoma	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—	—	—	—	—
Haemangioma of liver	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—	—	—	—	—
Juvenile melanoma benign	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—	—	—	—	—
Lung neoplasm	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—	—	—	—	—
Melanocytic naevus	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—	—	—	—	—
Metastases to lung	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—	—	—	—	—
Metastases to lymph nodes	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—	—	—	—	—
Neurilemmoma benign	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—	—	—	—	—
Prostatic adenoma	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—	—	—	—	—
Rectal cancer	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—	—	—	—	—
Renal cell carcinoma	Neoplasms benign, malignant and unspecified (incl cysts and polyps)	—	—	—	—	—	—	—	—

Other adverse events (151 terms — click to expand)

Reaction	System	Cladribine Low/Placebo (LL…	Cladribine High Dose/Place…	Cladribine Low/Low Dose (L…	Cladribine High/Low Dose (…	Placebo/Cladribine Low Dos…	Placebo/No Treatment	Cladribine 3.5 mg/kg/No Tr…	Cladribine 5.25 mg/kg/No T…
Lymphopenia	Blood and lymphatic system disorders	—	—	—	—	—	—	—	—
Nasopharyngitis	Infections and infestations	—	—	—	—	—	—	—	—
Headache	Nervous system disorders	—	—	—	—	—	—	—	—
Back pain	Musculoskeletal and connective tissue disorders	—	—	—	—	—	—	—	—
Influenza	Infections and infestations	—	—	—	—	—	—	—	—
Leukopenia	Blood and lymphatic system disorders	—	—	—	—	—	—	—	—
Upper respiratory tract infection	Infections and infestations	—	—	—	—	—	—	—	—
Urinary tract infection	Infections and infestations	—	—	—	—	—	—	—	—
Bronchitis	Infections and infestations	—	—	—	—	—	—	—	—
Diarrhoea	Gastrointestinal disorders	—	—	—	—	—	—	—	—
Influenza like illness	General disorders	—	—	—	—	—	—	—	—
Arthralgia	Musculoskeletal and connective tissue disorders	—	—	—	—	—	—	—	—
Fatigue	General disorders	—	—	—	—	—	—	—	—
Nausea	Gastrointestinal disorders	—	—	—	—	—	—	—	—
Pain in extremity	Musculoskeletal and connective tissue disorders	—	—	—	—	—	—	—	—
Neutropenia	Blood and lymphatic system disorders	—	—	—	—	—	—	—	—
Depression	Psychiatric disorders	—	—	—	—	—	—	—	—
Anxiety	Psychiatric disorders	—	—	—	—	—	—	—	—
Hypertension	Vascular disorders	—	—	—	—	—	—	—	—
Vertigo	Ear and labyrinth disorders	—	—	—	—	—	—	—	—
Toothache	Gastrointestinal disorders	—	—	—	—	—	—	—	—
Vomiting	Gastrointestinal disorders	—	—	—	—	—	—	—	—
Thrombocytopenia	Blood and lymphatic system disorders	—	—	—	—	—	—	—	—
Ear pain	Ear and labyrinth disorders	—	—	—	—	—	—	—	—
Asthenia	General disorders	—	—	—	—	—	—	—	—
Hyperthermia	General disorders	—	—	—	—	—	—	—	—
Respiratory tract infection viral	Infections and infestations	—	—	—	—	—	—	—	—
Pneumonia	Infections and infestations	—	—	—	—	—	—	—	—
White blood cell count decreased	Investigations	—	—	—	—	—	—	—	—
Alanine aminotransferase increased	Investigations	—	—	—	—	—	—	—	—
Blood creatine phosphokinase increased	Investigations	—	—	—	—	—	—	—	—
Red blood cell burr cells present	Investigations	—	—	—	—	—	—	—	—
Musculoskeletal pain	Musculoskeletal and connective tissue disorders	—	—	—	—	—	—	—	—
Dizziness	Nervous system disorders	—	—	—	—	—	—	—	—
Pharyngolaryngeal pain	Respiratory, thoracic and mediastinal disorders	—	—	—	—	—	—	—	—
Anaemia of pregnancy	Blood and lymphatic system disorders	—	—	—	—	—	—	—	—
Iron deficiency anaemia	Blood and lymphatic system disorders	—	—	—	—	—	—	—	—
Eye irritation	Eye disorders	—	—	—	—	—	—	—	—
Eye pruritus	Eye disorders	—	—	—	—	—	—	—	—
Tooth disorder	Gastrointestinal disorders	—	—	—	—	—	—	—	—

Most-reported serious reactions: Pneumonia, Uterine leiomyoma, Lipoma, Herpes zoster, Urinary tract infection, Cholelithiasis, Iridocyclitis, Malignant melanoma.

Data from ClinicalTrials.gov NCT00641537 adverse events section.

Sponsor's own description

The purpose of this extension trial was to further evaluate the safety and tolerability of oral cladribine in subjects who have previously completed treatment within Trial 25643 (CLARITY). This trial also explored clinical benefit of prolonged 192-week versus 96-week treatment.

Publications & conference data

8 peer-reviewed publications reference this trial (live from Europe PMC):

Effects of cladribine tablets on lymphocyte subsets in patients with multiple sclerosis: an extended analysis of surface markers.
Stuve O, Soelberg Soerensen P, Leist T, Giovannoni G, et al · · 2019 · cited 78× · PMID 31244898 · DOI 10.1177/1756286419854986
The Clinical Pharmacology of Cladribine Tablets for the Treatment of Relapsing Multiple Sclerosis.
Hermann R, Karlsson MO, Novakovic AM, Terranova N, et al · · 2019 · cited 52× · PMID 29987837 · DOI 10.1007/s40262-018-0695-9
The Development of Cladribine Tablets for the Treatment of Multiple Sclerosis: A Comprehensive Review.
Rammohan K, Coyle PK, Sylvester E, Galazka A, et al · · 2020 · cited 44× · PMID 33247831 · DOI 10.1007/s40265-020-01422-9
Long-term effects of cladribine tablets on MRI activity outcomes in patients with relapsing-remitting multiple sclerosis: the CLARITY Extension study.
Comi G, Cook S, Rammohan K, Soelberg Sorensen P, et al · · 2018 · cited 41× · PMID 29399054 · DOI 10.1177/1756285617753365
Long-Term Disease Stability Assessed by the Expanded Disability Status Scale in Patients Treated with Cladribine Tablets 3.5 mg/kg for Relapsing Multiple Sclerosis: An Exploratory Post Hoc Analysis of the CLARITY and CLARITY Extension Studies.
Giovannoni G, Comi G, Rammohan K, Rieckmann P, et al · · 2021 · cited 28× · PMID 34370275 · DOI 10.1007/s12325-021-01865-w
Pregnancy Outcomes During the Clinical Development Program of Cladribine in Multiple Sclerosis: An Integrated Analysis of Safety.
Giovannoni G, Galazka A, Schick R, Leist T, et al · · 2020 · cited 27× · PMID 32447743 · DOI 10.1007/s40264-020-00948-x
Prognostic models for predicting clinical disease progression, worsening and activity in people with multiple sclerosis.
Reeve K, On BI, Havla J, Burns J, et al · · 2023 · cited 25× · PMID 37681561 · DOI 10.1002/14651858.cd013606.pub2
Effectiveness and safety profile of cladribine in an Italian real-life cohort of relapsing-remitting multiple sclerosis patients: a monocentric longitudinal observational study.
Zanetta C, Rocca MA, Meani A, Martinelli V, et al · · 2023 · cited 25× · PMID 37027018 · DOI 10.1007/s00415-023-11700-7

Verify or expand the search:

Other trials of Cladribine

Trials testing the same drug.

NCT06965114 — Testing the Combination of Anti-cancer Drugs, Tovorafenib Plus Rituximab, in Patients With Hairy Cell Leukemia · Phase 1, PHASE2 · recruiting
NCT07311746 — Phase Ib/II Trial of Cladribine/Ruxolitinib/Venetoclax in Patients With Relapsed/Refractory T-cell Prolymphocytic Leukem · Phase 1, PHASE2 · not yet recruiting
NCT06474663 — A Phase I Study Investigating the Combination of Cladribine, Low Dose Cytarabine and Sorafenib Alternating With Decitabi · Phase 1 · withdrawn
NCT06504459 — Venetoclax in Combination With Cladribine and Cytarabine Alternating With Azacitidine Plus Venetoclax for the Treatment · Phase 2 · recruiting
NCT06561360 — A Study of Vemurafenib and Obinutuzumab Compared to Cladribine and Rituximab in People With Hairy Cell Leukemia (HCL) · Phase 2 · recruiting

Other recruiting trials for Relapsing-Remitting Multiple Sclerosis

Currently open trials in the same condition.

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NCT04530318 — Dendritic Cells Therapy Combined With Immunomodulatory Treatment in Multiple Sclerosis · Phase 2 · active not recruiting

Other EMD Serono Research & Development Institute, Inc. trials

Trials by the same sponsor.

NCT07355218 — A Study of Enpatoran in Participants With Cutaneous Manifestations of Lupus With or Without Systemic Disease (ELOWEN-2) · Phase 3 · recruiting
NCT07332481 — A Study of Enpatoran in Participants With Cutaneous Manifestations of Lupus With or Without Systemic Disease · Phase 3 · recruiting
NCT07360314 — Anti-Ly6E Exatecan ADC M7437 in Advanced Solid Tumors · Phase 1 · recruiting
NCT07166601 — M0324 as Monotherapy and in Combination With Pembrolizumab or Chemotherapy in Participants With Selected Advanced Solid · Phase 1 · recruiting
NCT07097259 — A Study to Assess the Bioequivalence of Follitropin Alfa Solution in Pen and Follitropin Alfa Powder in Vial in Healthy · Phase 1 · completed

Verify against primary sources

ClinicalTrials.gov — authoritative US registry record
WHO ICTRP — international registry index
EU Clinical Trials Register
Sponsor press releases (Google)

Data sources for this page

Trial protocol + status: ClinicalTrials.gov NCT00641537 (US National Library of Medicine, public domain)
Publications: Europe PMC API search by NCT ID, retrieved 10 June 2026
Drug + disease cross-links: matched in real time against Drug Landscape's normalised drug + company + condition tables
Sponsor: as reported to ClinicalTrials.gov by EMD Serono Research & Development Institute, Inc.
Last refreshed: 7 December 2020

Drug Landscape aggregates and links these public records for informational use only. Always verify against the primary source before clinical or regulatory decisions. Canonical URL: https://druglandscape.com/trial/NCT00641537.

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