- Regeneron Pharmaceuticals and Teva Pharmaceutical Industries announced last week their experimental drug, fasinumab, met early efficacy and safety targets of a Phase 3 trial that's testing the candidate for pain relief and improvement in function in 646 patients with chronic knee and hip osteoarthritis pain.
- The drug has been haunted by safety problems. In 2016, the FDA halted a Phase 2b fasinumab trial due to concerns about joint damage. And in May, an independent committee monitoring the Phase 3 trial recommended stopping use of the highest dosages of the drug.
- Despite analyst concerns about fasinumab, Regeneron has expressed confidence in the drug as well as the remainder of its pipeline. It’s expected that the final results of the 52-week fasinumab trial will provide the best assessment of the drug’s true long-term safety — particularly joint damage.
Regeneron and Teva aren't alone in the pursuit to produce new medications that successfully reduce osteoarthritis pain.
Pfizer and Eli Lilly are also testing a monoclonal antibody, tanezumab, in the indication. Initial 16-week results from a Phase 3 trial were promising, but showed a 1.5% complication rate for rapidly progressing osteoarthritis.
Both tanezumab and fasinumab block nerve growth factor (NGF), a protein that plays a significant role in pain signals. The hope is that these drugs can offer an effective alternative to nonsteroidal anti-inflammatories and opioids for chronic pain — but without the respective risks of gastric side effects or addiction.
Yet anti-NGF monoclonal antibodies have also caused safety concerns, as patients taking them have sometimes developed arthropathy, a joint disease that can cause inflammation and reduced range of motion, as well as rapid progression of their arthritis. Other patients have experienced the more common side effects of tingling sensations, joint pain, reduced sense of touch and limb swelling.
The initial safety data on the Phase 3 fasinumab trial, however, indicated that such adverse events led to treatment discontinuation in only 5% of patients who took 1 mg of the treatment drug every eight weeks, 6% in those who took 1 mg every four weeks, and 6% in the placebo group. At 16 weeks, 65% of patients had undergone radiograph monitoring, and the rate of arthropathies was 2%. No patients experienced osteonecrosis, or bone tissue death.
In the trial, efficacy data indicated that patients on fasinumab experienced significant improvements in joint pain and physical function — at a rate about double that of the placebo group. Those on the fasinumab dose of 1 mg every 4 weeks experienced the greatest relief of pain and changes in physical function. Detailed data on the trial's early efficacy and safety results will be presented at an upcoming medical meeting, according to Regeneron.