- A high dose of Pfizer and Eli Lilly's experimental drug tanezumab improved lower back pain better than placebo in a Phase 3 study, but the treatment failed to show a significantly superior result at a lower dose.
- According to results released by the companies Tuesday, tanezumab beat out placebo in treating moderate-to-severe chronic low back pain after 16 weeks. The 10 mg dose arm succeeded in delivering a statistically significant result, while the 5 mg did not. (Although results were numerically better.)
- Treatment with the nerve growth factor (NGF) inhibitor was well tolerated, the companies stated. Rapidly progressive osteoarthritis was seen in 1.4% of tanezumab patients compared to 0.1% on other treatment groups, and there were no reports of osteonecrosis in the study.
Safety has been a key question mark for this class of non-opioid pain treatments. While these topline results don't raise new red flags, the data doesn't entirely dispel the lingering concerns surrounding tanezumab either.
Between 2010 and 2012, clinical holds placed by the Food and Drug Administration due to these safety concerns slowed development of the drug class. Lilly and Pfizer partnered on tanezumab in 2013, and in 2015 the FDA lifted a hold allowing studies to continue. Now, Phase 3 results have begun rolling in for the therapy.
Pfizer and Lilly did not break out safety results by dose level in this latest trial, instead pooling adverse event rates from the 5 mg and 10 mg arms.
The pooled data show a 1.4% incidence rate of rapidly progressive osteoarthritis, with most of those patients experiencing accelerated joint space narrowing rather than the more serious damage and deterioration of the joint.
One key question is how many cases came from patients treated with 10 mg tanezumab, which is the dose Pfizer and Lilly would likely seek to market.
As opioid addiction has become a full-fledged crisis, a changing regulatory environment prioritizing non-opioid pain treatments could help tanezumab on its path to approval.
As recently as a week ago, FDA head Scott Gottlieb said the agency is working on new guidance to "modernize the development pathway for non-opioid analgesics," encouraging companies to take a more focused development approach rather than aiming drugs at broad indications in acute or chronic pain.
"This can make the development process more efficient and lead to the approval of drugs more carefully tailored to specific patient needs," the agency's leader said.
How, and if, tanezumab can navigate the regulatory pathway to win approval will carry implications for the rest of the NGF inhibitor class, Cowen & Co. analyst Ken Cacciatore wrote in a Feb. 15 note. Regeneron and Teva are partnered on fasinumab, which could follow tanezumab, the analyst stated.
Tanezumab's back pain readout follows two other Phase 3 results in the past few months. Those two studies were focused on osteoarthritis pain and largely met efficacy endpoints. They showed incidence rates of rapid progressive osteoarthritis in 2.1% and 1.3% of the treatment arms.
The companies still have two more Phase 3 trials to readout this year, respectively focused on osteoarthritis pain and chronic low back pain.