Celtaxsys spins ‘clinically meaningful’ data on another failed PhII cystic fibrosis study

At first glance, you would think Atlanta-based Celtaxsys had plenty to be happy about in its release about their Phase II study of an experimental drug for cystic fibrosis called acebilustat. The anti-inflammatory drug had produced the first “clinically meaningful” evidence of its potential to reduce pulmonary exacerbations in patients.

That must be worth a celebration, right?

But if you look at it closely, the data — such as they are — leave a lot to be desired.

First, the study was a failure. The primary efficacy endpoint in the 200-patient study was a classic measure of FEV1 from baseline — forced expiratory volume in 1 second — as outlined in clinicaltrials.gov. If you dig into their statement, you’ll find there was no difference in lung function between the drug and the control arm.

So what about those “clinically meaningful” benefits for patients on pulmonary exacerbations? 

The company said there was a “19% reduction in PEx and a 22% reduced risk in progressing to first PEx versus placebo.” And in subgroup analysis, some patients did even better. The pulmonary exacerbation results were based on a per protocol basis as opposed to intent-to-treat. 

I asked a spokesperson for the company what p-values the company had nailed down for these secondary endpoints. She replied that data were being held back for a future conference (at least the part that wasn’t in the release), then noted that the secondary endpoints on pulmonary exacerbations were not powered sufficiently to determine statistical significance.

OK. I replied. But the company had those p-values, right? So what were they and could it be translated to significance?

Here’s what I got:

The reduction in the rate of pulmonary exacerbations and increased time to first PEx reported are numeric reductions for patients treated with acebilustat, not statistically significant.

For context, the magnitude and consistency of the effects across our key, pre-specified subgroups (i.e. mild lung disease, concomitant CFTR modulator therapy) has been characterized by the CF Foundation, who have expressed continued support of our P3 program, as clinically meaningful.

So you have a failed study with no hard evidence of a clear drug benefit for patients, now being steered into Phase III. The Reuters report helpfully noted that the company is looking to raise funds somehow, though company execs haven’t exactly determined how.

There’s been considerable attention on cystic fibrosis as Vertex continues to dominate the space and move forward with promising combo studies. A host of rivals have appeared, including Galapagos, but no one has provided any recent data to support one of these other contenders.

Celtaxsys didn’t change that picture today, either.

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VP Oncology Biology
Skyhawk Therapeutics Waltham, MA
Research Scientist - Immunology
Recursion Pharmaceuticals Salt Lake City, UT

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