Monday 23 March 2015

Understanding the VX-661 Phase 2b Results

Pharmaceutical company Vertex, today released the results of a recent Phase 2b trial, which looked at safety of a drug known as VX-661 in combination with ivacaftor (Kalydeco). There has been a lot of anticipation about these results because it is only the second time that the company has issued trial data. Below, Dr Anoushka de Almeida-Carragher, Senior Research Manager looks a what they tell us.

This study involved 39 people with cystic fibrosis who have two copies of the F508del mutation, and confirmed that the treatment is safe and well tolerated.  The stated improvement in lung function, from baseline, within four weeks of treatment is also encouraging. It should be noted that the number of people who took part in the study is extremely small. However the results provide solid support for the next stage of trials – Phase 3 – which Vertex commenced in the early part of this year.

This program of four Phase 3 clinical trials will look at lung function after the administration of the VX-661/ivacaftor combination, but this time involves not only people with two copies of the F508del mutation – who were studied in the phase 2b trial, and make up roughly 51% of the CF population – but also includes people who have one copy of the F508del mutation and a second mutation that is either a gating mutation, residual function mutation or a mutation that results in minimal CFTR function.

This will the first time that the efficacy of this drug regime is being tested in a large population of people with cystic fibrosis (approximately 1150, aged 12 and older). Furthermore, the fact that 4 different ‘mutation combinations’ are being investigated, thus impacting on a larger number of CF patients, means this next-stage trial is vital in enhancing our knowledge-base in striving to reach our goal of beating CF for good.

The Trust will be watching the Phase 3 trials with interest and ensure that our CF community remain updated on the progress in transformational treatments.

1 comment:

  1. Surely the improvement in FEV1 to 12 weeks (rather than just 4) is rather more relevant. While you can expect Vertex to emphasise the 4 week figures (because they are more flattering) I would expect greater objectivity from this review (especially as the relative improvement to 12 weeks when compared with the placebo group was even smaller).

    However, as you say, this was a very small trial and any outliers would have had a disproportionate impact on the results (as happened in Vertex's similarly underpowered trial of ivacaftor monotherapy for pwcf heterozygous for the R117H mutation). It is good news that Vertex is proceeding with a Phase 3 trial which will yield more robust results.