Cladribine

How it works

As a purine nucleoside analogue it is preferentially incorporated into lymphocyte DNA, producing selective and sustained depletion of B and T lymphocytes with relative sparing of innate immunity.

Prescribing in practice

• Pregnancy must be excluded before each course and effective contraception used by both sexes during and for a defined period after treatment, as cladribine is teratogenic and genotoxic.
• Screen for and exclude active infection, latent tuberculosis, hepatitis and HIV before starting, and complete necessary vaccinations beforehand given the prolonged lymphopenia.
• Because of a possible increased malignancy risk, follow cancer screening recommendations and avoid use in those with active malignancy.

Monitoring

Monitor lymphocyte counts before and during each treatment course and watch for signs of infection and herpes zoster reactivation during the period of lymphopenia.

Counselling the patient

• Reliable contraception is essential during and after treatment for the advised interval.
• Report fever, persistent cough or other signs of infection promptly.
• Attend all blood tests and recommended cancer screening.

Evidence & guidelines

The CLARITY trial showed that oral cladribine reduced relapse rate and disability progression in relapsing-remitting multiple sclerosis, underpinning its NICE-approved use.