This Is MS Multiple Sclerosis Community: Knowledge & Support

Here are the Phase II Campath results.

http://www.genzyme.com/corp/investors/G ... 050207.asp

I think they are impressive for those with RR MS (I'm biased because I've seen excellent results following my first infusion last November). And the impressive reduction in relapses is when compared with Rebif.

These sorts of treatments are riskier than the CRAB drugs, but the risks identified to date can be monitored and treated. And you don't see the following results from the CRAB drugs:



Ian

Thanks for the information Ian. Heck, progression of disability is the main concern....I'd go with the low dose!

I'm probably an ingrate but I actually expected the numbers to be a little more favorable?

Bob

probably?

At first I must admit I was a little underimpressed with the results, but the thing to remember is that this is as compared to another drug, not placeebo.

Hi Cure,
I wish I were a little better with math and statistics because I've never fully understood what that means.

So with the crabs being (supposedly) about 30% that means Campath would be close to 100% ??

Bob

Don't we all wish it worked that way.

If there are two effects, first reducing a rate by 30% and the other by 80% on top of the first, the effect is multiplicative.

I.e., after the first, the rate is at 70% of where it would have been before, and after the second, at 14% (.7*.2). Thus, the overall reduction would be 86%.

Hi Gary,
Yup, I knew I wouldn't understand it so thanks for including the final tally!

Jeez, 86% doesn't sound too bad!

Bob

Thanks gkalman,

I tried to come up with an understandable interpretation using some illustrative numbers - but it got too complicated. It's complicated because: (a) the two doses of Campath used in the trial (b) the fact that the trial period covered two years (c) the comparison with Rebif (d) that the dosing of Campath was stopped during the trial.

Professor Compston from Cambridge said at a presentation last September that Campath reduced relapses by c.95%. Given that it wipes out your T and B cell for a while - the c.95% looks feasible.

I'm in Cambridge later this month for my check-up and will ask about the numbers.

As one case study - I had three relapses in 2006 (Jan / June / October (bad one)) - and was on Rebif since Feb 2006 until start of November 2006. I had my five day infusion at the end of November and, so far (six months in), not a whisper of a relapse and a really impressive recovery of deficits.

This drug won't be for everyone (it comes with higher risks) but at least for someone with very active RRMS, it's an option if the CRABs aren't having much effect. The longer impact of this drug on the disease is unknown but the researchers at Cambridge are learning a lot more about (a) the immune system response (b) repair.

Ian

We're talking about relative change here, not multicaptive effect.

We know that the more effective dose of Campath reduced relapses 87% more than Rebif. Thus, if Rebif reduced relapses by 30%, Campath would have reduced them by 56,1%. The relative difference between 56,1% and 30% is 87% ((56,1-30)/30x100=87).

Unfortunately we just can't calculate the absolute effect of Campath in the study as long as we don't know how effective Rebif was.

Be well.

-finn

_________________
"The great tragedy of science - the slaying of a beautiful hypothesis by an ugly fact.” -Thomas Henry Huxley

I dont agree with your numbers finn, and Rebif has a generally accepted (ie derived from previous large studies) effectiveness of around 30% (i think for relapses, not for disability progression, but thats another misalignment in all our calcs). However, assuming 30% is right. And there were no anomolies such as there actually were with people coming off of treatments etc etc etc The simple maths in my eyes is:

Rebif is 100%-30% = 70% Not effective.
Campath is 88% more effective (from the results), so Campath would be:
70 % * (100 - 88)/100 = 8.4% ineffective
Therefore, 100-8.4 = 91.6% effective by my math, which also sorta aggrees with what Ian has been told ie around 95%.

The trick to remember in the maths is that Campath is working on the numbers that Rebif failed on (ie the 70% and not the 30%)

Or, by example, if we have 200 people in the study (100 on each treatment), 70 people on rebif would of "failed" while only 8.4 people on Campath would of "failed". Giving the final figure of 88% via, 100 - (8.4 / 70) = 88% where we are comparing the numbers of those that failed (ie 8.4 to 70)

NB: I know there are a LOT of assumptions, simplifications and crossing of numbers in the above.

Cure, Thanks - we might be 12,000 miles apart but we think the same.

Finn - I'm assuming your stats lecturer was a certain Professor Z


All of this will become clearer when the data are published with the research paper about this trial.

Ian

COB, thanks for your comment. We seem to disagree with the numbers. I'm sorry, but I'm not going to change my opinion. I'd still say that they are talking about relative* difference between treatment groups, and if Rebif reduced relapses by 30% campath would have done it by 56%.

But I do agree with you on one thing. We don't know the absolute* numbers so these calculations are all based on speculation.

Thanks Ian, but I'm trying to think with my own brain ;-)

Be well.

-finn

*The difference between absolute and relative way to tell the difference between two groups is well explained in this Accelerated Cure's newsletter: "If 20% of the placebo group had relapses and only 10% of the active drug group did, then there was a 50% reduction in relapses for the drug compared to placebo (that’s relative) but only a 10% reduction overall (absolute)."

_________________
"The great tragedy of science - the slaying of a beautiful hypothesis by an ugly fact.” -Thomas Henry Huxley

Thanks finn,
At least for me, that makes the whole thing a lot more understandable.
Bob

Finn,

You wrote:



We could argue forever about the stats. Remember - statistics are like a hostage, you can torture them and get them to say anything.

I'm pretty confident that Campath reduces relapses by more than 56.1%. Professor Compston who heads up the Campath teams uses 95% in presentations. Out of interest I just received an e-mail from a neuro who was at the AAN conference (he is not connected to the Campath team). I had asked him about the Rituximab results. His response:



I can't believe he would be so impressed with a treatment which only reduces relapses by 56%.

I await the publication of the data.

Ian

For me, this about says it all From what I've seen, being diagnosed with MS is a little like finding yourself hanging by your fingertips on a cable suspended over a great chasm.

That scenario seems to leave a person with only two options:

Option one is to stay put and hang on for deal life in hopes of holding off the inevitable as long as possible. At most, the use of the "recommended treatments" might be akin to taking vitamins in hopes that your fingers will grip the cable a little longer.

Option two is attempting to move hand over hand to the edge of the chasm with hopes of saving yourself. Sure, that might seem risky because it will cause your arm to tire more quickly, possibly before you make it to safety.

For some reason in the topsy turvy world of MS the perception has gotten twisted so that the "safe" thing to do is to stay put and wait for the inevitable and the "risky" thing is attempting to save yourself.

Bob

Ian,

I agree with you in this one:

Yes. Actually, we have a saying here; "lie, mother of all lies, statistics". For once I'd like to see data from MS-drug trial presented only "raw", without any statistical interpretation. It would be nice to know the total amount of clinical and pathological events (relapses, lesions, changes in EDSS, etc) in all treatment groups before and after treatment, and also learn about the way the information was collected and interpreted (for example, how long it took before a relapse turned into a permanent change in disability). It might be possible to find all that information in some of the full articles to be published, but not usually in abstracts and never in drug company press releases.

I'm sure he wouldn't. That is why evaluating raw data instead of statistical interpretations would be better. But who knows, maybe he has been able to do it, and my calculations are fundamentally wrong. After all, I couldn't know how well Rebif worked in the study, and how the comparison between treatment groups was really done to get the numbers presented in the article.

Me too.

Be well.

-finn

_________________
"The great tragedy of science - the slaying of a beautiful hypothesis by an ugly fact.” -Thomas Henry Huxley