Barts-MS rose-tinted-odometer: ★★★★★ (a bright blue buzz – #0096FF)
I was at a mid-summer party last night when someone suggested that I should not waste my time trying to answer peripheral or trivial questions in relation to MS and focus on the really big questions.
This got me thinking about which are the biggest MS questions in MS that I can try to tackle and answer. Apart from (1) MS prevention, i.e. does preventing primary EBV infection with a sterilizing EBV vaccine prevent MS, the next major question must relate to (2) curing MS.
The BIG-C issue is one I have been exploring on this blog for several years but is hampered by defining what an MS cure looks like and then looking for it. The problem with the latter is the issue of smouldering MS, which clouds the definition of a cure. Even if you cure someone from the biological drivers of MS, if they have relatively advanced MS they may still get worse from downstream smouldering processes that become independent of the initial MS attack(s). So the only solution is to test the hypothesis of an MS cure is very early in the disease, i.e. at the RIS (radiologically-isolated syndrome) or CIS (clinically-isolated syndrome) stage.
To cure MS what treatment strategy do you need to use? I have made the point that we can only cure MS with an IRT (immune reconstitution therapy) and at present we only have three IRTs that are used routinely in MS., i.e. cladribine, alemtuzumab and AHSCT. It is clear that cladribine is the safest IRT and has the added advantage as being the most CNS penetrant, which I think is important. Cladribine levels in the spinal fluid of treated patients are high enough to have an effect on CNS resident T and B-cells. Cladribine is also the safest and easiest IRT to use and therefore the most likely to get widely adopted. I am convinced that a proportion of pwMS treated early, within 12 to 24 months of MS diagnosis, with either alemtuzumab and AHSCT are cured. Despite the stunning results of this treatment approach the adoption of both alemtuzumab and AHSCT as a mainstream treatment for MS has been abysmal. I suspect cladribine as an early effective treatment would have a greater chance of being adopted. My conclusion then is that the IRT has to be cladribine and it has to be done evry early at the CIS or RIS stage.
But this experiment has already been done. The ORACLE study below was of oral cladribine in CIS. So what has happened to these patients? We don’t know, which is why Merck is doing the CLASSIC MS study to try and find out what has happened to these patients with CIS. Wouldn’t it be brilliant if a significant proportion of the cladribine exposed patients have not developed MS compared to those in the placebo group? Would this be sufficient to convince the wider MS community that very early cladribine treatment cures a proportion of people with CIS, i.e. prevents them from developing MS? I suspect not. This is why a new global RIS-CIS study will need to be done.
Please note some people would argue that stopping people with CIS from getting MS is MS prevention, whereas others would argue, including me, that CIS is already MS and hence preventing CIS from becoming MS is an MS cure. This is not just semantics but challenges disease definitions and is an important philosophical debate. This is why I want to study medical philosophy to tackle some of these issues.
Kaplan–Meier estimates of time to conversion to CDMS and McDonald MS in the intention-to-treat population during the double-blind period. Cumulative percentage probability of conversion to (A) CDMS according to the Poser criteria and (B) MS according to the 2005 McDonald criteria. CDMS=clinically definite multiple sclerosis. MS=multiple sclerosis. Figure from Lancet Neurol 2014.
Leist et al. Effect of oral cladribine on time to conversion to clinically definite multiple sclerosis in patients with a first demyelinating event (ORACLE MS): a phase 3 randomised trial. Lancet Neurol. 2014 Mar;13(3):257-67.
Background: Patients who develop relapsing-remitting multiple sclerosis (MS) present with a first clinical demyelinating event. In this double-blind, multicentre, randomised, phase 3 study we investigated the effect of oral cladribine on conversion to clinically definite MS in patients with a first clinical demyelinating event, when given at the same doses shown to be effective in relapsing-remitting MS.
Methods: Between Oct 21, 2008, and Oct 11, 2010, we recruited patients aged 18-55 years, inclusive, from 160 hospitals, private clinics, or treatment centres in 34 countries. Eligible patients had a first clinical demyelinating event within 75 days before screening, at least two clinically silent lesions of at least 3 mm on a T2-weighted brain MRI scan, and an Expanded Disability Status Scale score of 5.0 or lower. Patients with a first clinical demyelinating event ≤75 days before screening were randomly assigned (1:1:1) to receive cladribine tablets at cumulative doses of 5.25 mg/kg or 3.5 mg/kg or placebo. Randomisation was done with a central web-based randomisation system and was stratified by geographic region. Masking was maintained using a two-physician model. The primary endpoint of this 96-week study was time to conversion to clinically definite MS according to the Poser criteria. This study is registered with ClinicalTrials.gov, number NCT00725985.
Findings: Of 903 participants assessed for eligibility, 616 patients received cladribine 5.25 mg/kg (n=204), cladribine 3.5 mg/kg (n=206), or placebo (n=206). At trial termination on Oct 25, 2011, cladribine was associated with a risk reduction versus placebo for time to conversion to clinically definite MS (hazard ratio [HR] for 5.25 mg/kg=0.38, 95% CI 0.25-0.58, p<0.0001; HR for 3.5 mg/kg=0.33, 0.21-0.51, p<0.0001). Adverse events were reported in 165 (81%) patients in the cladribine 5.25 mg/kg group, 168 (82%) patients in the cladribine 3.5 mg/kg group, and 162 (79%) patients in the placebo group. We noted no increase in risk of adverse events with active treatment versus placebo apart from lymphopenia, which was a severe event in 10 (5%) patients in the 5.25 mg/kg group and four (2%) patients in the 3.5 mg/kg group.
Interpretation: Both doses of cladribine significantly delayed MS diagnosis compared with placebo. The safety profile of cladribine was similar to that noted in a trial in patients with relapsing-remitting MS. Further research could clarify the potential effects of oral cladribine treatment in the early stages of MS.
General Disclaimer: Please note that the opinions expressed here are those of Professor Giovannoni and do not necessarily reflect the positions of the Barts and The London School of Medicine and Dentistry nor Barts Health NHS Trust and are not meant to be interpreted as personal clinical advice.
