If Sahm Adrangi’s past predictions on the success and failures of different medications in development stand correct, Proteostasis’ new medication in development, PTI-428, is doomed to failure. PTI-428 is a medication that is supposed to treat the serious ill cystic fibrosis which interferes with a patient’s ability to properly breathe. While their Phase 2 studies showed about a 5% increase in lung function, Sahm Adrangi and the experts at Kerrisdale Capital Management think this is mostly due to skewed data and a small placebo group. The trial which only lasted 28 days consisted of only 4 cystic fibrosis patients in the placebo group. Some of these patients experienced a dramatic drop in lung performance that sometimes naturally happens with the disease.
Unfortunately, this anomaly made the therapy group’s results look much better than they actually were. If the patients that experienced the drop in function were discluded from the results, the gap between the two groups would close significantly and the difference would only be around 1% according to Sahm Adrangi. These results would not impress anyone which is why Sahm Adrangi believes that the Proteostasis purposely omitted certain information from the results that were released to the general public. These skewed results may be a big reason why Proteostasis was avoiding a larger trial. Kerrisdale Capital adds that some important results such as sweat chloride are completely ignored or sloppy in the published results by Proteostasis. There are even questions from Sahm Adrangi and his team at Kerrisdale Capital on whether or not the biomarkers being used in the study could actually be properly measured by Proteostasis. To some, it’s doubtful that the company truly knows how their own drug is supposed to work.
Whether on its own or in conjunction with other drugs that are standards of care for the treatment of cystic fibrosis, it is doubtful that PTI-428 will help patients or even pass its phase 3 trials.