, 0% and 0.4% of patients with grade 4 lymphopenia in year 1 and year 2). It is expected that most patients recover to either normal lymphocyte counts or grade 1 lymphopenia within 9 months.
To decrease the risk for severe lymphopenia, lymphocyte counts must be determined before, during and after cladribine treatment (see section 4.4) and strict criteria for initiating and continuing cladribine treatment must be followed (see section 4.2).
Malignancies
In clinical studies and long-term follow-up of patients treated with a cumulative dose of 3.5 mg/kg oral cladribine, events of malignancies were observed more frequently in cladribine-treated patients (10 events in 3,414 patient-years [0.29 events per 100 patient-years]) compared to patients who received placebo (3 events in 2,022 patient-years [0.15 events per 100 patient-years]) (see section 4.4).
Reporting of suspected adverse reactions
Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via:
United Kingdom
Yellow Card Scheme
Website: www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store
Ireland
HPRA Pharmacovigilance Earlsfort Terrace
IRL - Dublin 2
Tel: +353 1 6764971
Fax: +353 1 6762517
Website: www.hpra.ie
e-mail: medsafety@hpra.ie
Malta
ADR Reporting
Website: www.medicinesauthority.gov.mt/adrportal
4.9 Overdose
There is limited experience with overdose of oral cladribine. Lymphopenia is known to be dose- dependent (see sections 4.4 and 4.8).
Particularly close monitoring of haematological parameters is recommended in patients who have been exposed to an overdose of cladribine.
There is no known specific antidote to an overdose of cladribine. Treatment consists of careful observation and initiation of appropriate supportive measures. Discontinuation of MAVENCLAD may need to be considered. Because of the rapid and extensive intracellular and tissue distribution, haemodialysis is unlikely to eliminate cladribine to a significant extent.
5. Pharmacological properties
5.1 Pharmacodynamic properties
Pharmacotherapeutic group: Selective Immunosuppressants, ATC code: L04AA40
Mechanism of action
Cladribine is a nucleoside analogue of deoxyadenosine. A chlorine substitution in the purine ring protects cladribine from degradation by adenosine deaminase, increasing the intracellular residence time of the cladribine prodrug. Subsequent phosphorylation of cladribine to its active triphosphate form, 2-chlorodeoxyadenosine triphosphate (Cd-ATP), is particularly efficiently achieved in lymphocytes, due to their constitutively high deoxycytidine kinase (DCK) and relatively low 5'-nucleotidase (5'-NTase) levels. A high DCK to 5'-NTase ratio favours the accumulation of Cd-ATP, making lymphocytes particularly susceptible to cell death. As a result of a lower DCK/5'-NTase ratio other bone marrow derived cells are less affected than lymphocytes. DCK is the rate limiting enzyme for conversion of the cladribine prodrug into its active triphosphate form, leading to selective depletion of dividing and non-dividing T and B cells.
The primary apoptosis-inducing mechanism of action of Cd-ATP has direct and indirect actions on DNA synthesis and mitochondrial functio |
