- Pfizer doesn't intend to further develop domagrozumab as a treatment for Duchenne muscular dystrophy (DMD) after clinical studies conclusively found the drug didn't provide substantial benefits to patients with the rare disease.
- The decision means a Phase 2 trial and an open-label extension study will be shut down. In the former, investigators tested domagrozumab against placebo to see whether patients would have a greater mean change from baseline in the time it took them to climb four stairs. After one year of treatment, domagrozumab didn't significantly outperform placebo.
- "We are disappointed by these results and while we are not progressing with the studies, the data will contribute to a greater understanding of this disease and we will evaluate the total data set to see if there is a place for this medicine in muscular diseases," Seng Cheng, chief scientific officer in Pfizer's rare disease research unit, said in an Aug. 30 statement.
Once a niche therapeutic area, rare disease has become a key piece of many drugmakers' portfolios. Though the target patient populations there are inherently small, the profits can be quite large. Pfizer, for instance, brought in $1.12 billion through its rare disease business during the first six months of 2018.
For DMD, there is just one Food and Drug Administration-approved treatment. Sarepta Therapeutics' Exondys 51 (eteplirsen) got a thumbs up back in September 2016, and fetched $154.6 million for Sarepta during its first full year on the market. Analysts believe it is now on track to hit the company's sales expectation of $295 million to $305 million for 2018. Yet the drug's weak efficacy in the clinic and highly controversial approval have fueled calls for more DMD therapies.
Pfizer looked to fill the void with a couple pipeline programs: domagrozumab, a monoclonal antibody thought to block a protein responsible for inhibiting muscle growth, and a gene therapy that employs a recombinant adeno-associated virus.
Domagrozumab's failure puts a damper on those aims, though Pfizer is still assessing whether the drug could be meaningful in other muscular disorders. As for the gene therapy asset, Pfizer has one ongoing trial in DMD, and recently said it continues to build out its gene therapy business.
On a second quarter earnings call, CEO Ian Read said the company has put hundreds of millions of dollars into that business already, and may do tuck-in deals if appropriate.
"That's part of our view on buying intellectual property that has within the next five years launch potential," he said, "and we're committed to this area and we think we have a strong franchise. We certainly are not going to buy gene therapy that we think is way overpriced, but we will buy gene therapy that we think has value."