- Pfizer is scrapping of one of two experimental weight-loss pills it’s been developing after spotting signs of potential safety concerns in clinical testing.
- The company on Monday said the decision to stop testing of the pill, lotiglipron, was made after receiving the results from drug-drug interaction studies and observing liver enzyme elevations in early- and mid-stage tests. Patients with the liver enzyme spikes, which can be signs of organ damage, didn’t have side effects or require treatment, Pfizer said.
- Pfizer will now focus on its other, similar weight-loss prospect, danuglipron, which so far hasn’t had such concerns. Danuglipron is currently in Phase 2 testing in Type 2 diabetes and obesity, and could move into late-stage development by the end of the year.
Like many of its peers, Pfizer is investing heavily in drugs for obesity, having brought two similar medicines known as GLP-1 agonists into mid-stage testing.
Pfizer, though, is behind its rivals. Eli Lilly and Novo Nordisk have injectable drugs that are proven to help obese and overweight people lose weight. Lilly and Novo are also ahead with oral versions of their drugs, both of which are in late-stage testing. Results for each were presented at a medical meeting this weekend and show the potential for efficacy that’s comparable to what’s observed with injectable treatments.
Still, Pfizer is putting significant resources into a plan to catch up. It’s been testing danuglipron and lotiglipron in parallel Phase 2 tests in diabetes and obesity, with science chief Mikael Dolsten telling Wall Street analysts earlier this year that the company planned to eventually “cherry pick” the best one.
Initially, Pfizer expected to make that call after observing Phase 2 study results. But the safety concerns that cropped up in testing of lotiglipron have accelerated Pfizer’s decision and placed more pressure on its other prospect to succeed.
Danuglipron has shown promise. Study data in Type 2 diabetes, published in JAMA in May, showed treatment led to a similar level of weight loss as Novo’s medicines after 16 weeks. A Phase 2 study in obesity is fully enrolled, with data coming by the end of 2023, according to a federal database. Its safety profile so far has been “similar” to that of injectable GLP-1 drugs, and Pfizer hasn’t seen any evidence of liver enzyme elevations in the more than 1,400 patients who have been enrolled in its studies so far, Pfizer said.
Yet results for lotiglipron had been eagerly anticipated because the drug is a once-daily pill. Danuglipron, by comparison, is taken twice daily. Though Pfizer said that it’s now developing a once-daily “modified release” version, the discontinuation of lotiglipron is a “big setback,” not just for its obesity drug ambitions but a “broader pipeline perspective, wrote Evercore ISI analyst Umer Raffat.
”Sure, they’ll move forward with danuglipron … but it's not the best shot they had,” Raffat wrote.
The company expects to finalize its late-stage development plans by the end of the year.
“We look forward to analyzing the danuglipron Phase 2 results and selecting the dose and titration schedule that will maximize the therapeutic benefit and safety and tolerability,” said William Sessa, the company’s senior vice president and chief scientific officer of internal medicine, in a statement.
Pfizer shares fell more than 3% in early trading on Monday.