Cladribine

What it does
Cytotoxic to lymphocytes, particularly B cells, and suppresses bone marrow (purine analogue). Also used to treat leukaemias.

Indications (NICE)
'highly active' RRMS, i.e....
 * 'rapidly evolving' = 2 relapses in the previous year
 * and MRI evidence of disease activity
 * i.e. any enhancing lesion, or a 'significant' increase in lesion load
 * or already on DMT and 1 relapse (< 12 months ago) and active MRI

How is it given?
orally as tablets two courses 12m apart (4-5d/wk for 2wks/m for 2m)

Contra-indications, screening and monitoring

 * moderate or severe renal impairment
 * exclude HIV, latent TB, HBV/HCV before each course
 * baseline MRI for PML monitoring
 * watch for lymphopaenia in particular

Why would you choose it?

 * other options for patients in same position
 * natalizumab, ocrelizumab, alemtuzumab as first-line
 * as second-line, others including fingolimod
 * highly active MS only?
 * its effect was the same under subgroup analysis in the trial
 * in highly active MS, clearly better than DMF or injectables, similar to fingolimod, but not as good as natalizumab (differences less clear in non-highly active MS) [Signori et al. 2020]
 * convenient, safe and well tolerated
 * negligible numbers of pts in trials dropped out owing to non-tolerability
 * no significant risk of PML or cancer
 * effective
 * roughly 50% reduction in relapse rate
 * some evidence of reduction in relapse-related disability
 * can switch to it from another DMT
 * no rebound activity after stopping
 * planning pregnancy
 * a common choice in this context
 * cytotoxic drugs are generally teratogenic, so no preg during treatment
 * for men as well as women!
 * but can start trying to conceive 6m after second course

Blueteq
Blueteq is only required for initiating the first dose and covers the second dose.

Links

 * BNF entry
 * Summary of Product Characteristics (SmPC)
 * NICE guidance 2019