proves, trials, arms

Can someone explain in rather simple language what the terms of clinical trials mean.  People report their standings and results but I do not understand.  What is a prove, an arm and a stage when it comes to clinical trials?

[Andiamo1]

The prove trials are a name given by Vertex pharmaceuticals to their clinical trial.  The current trial has 4 arms or treatment protocols.  These arms are names a,b,c and d.

A  48 weeks of ifn/riba with a placebo taken for the first 24 weeks.
B 48 weeks of ifn/riba with the first 24 weeks including Telaprevir - the new Vertex drug.
C 24 weeks of ifn and Telaprevir wothout Riba
D 24 weeks of ifn/riba with Telaprevir for the first 12 weeks changing to a placebo for the next 12 weeks.

I think when people refer to stage, they are talking about a liver biopsy stage of 0 - 4.  This is a measure of fibrosis with 4 being cirrhosis.

[FlGuy]

Go to this site      http://www.clinicaltrials.gov/

Click on the 'learn more' link when you get there.

[Willy50]

I wonder if you mean "Phase" instead of "stage".  Most FDA trials are broken into Phases.

Phase 1 might be where the basic drug is tested  perhaps on animals or people to answer questions about relative safety and effectiveness in short or limited dosing.  Phase 2 ramps up a bit and answers those same questions but in larger groups of people and in longer dosing.  They may in this phase try dosing in what they perceive to be actual treatments dosage and durations.

Phase 3 in the trials is generally the last step.  The dosing, durations, and target cure rates are all worked out for what they percieve to be the finished product and treatment.  At the end of Phase 3 FDA tests the company files a NDA (new drug application) and the FDA reviews all the data from the trials and either appproves, rejects, or asks for more testing.  It doesn't happen often but there is a Phase 4 and that is where a drug is approved....and due to some issue more additional tests are required.  The Vertex ""Prove" trials (1,2 and 3) were part of a Phase 2 FDA trials for Telaprevir (VX-950).

Willy