High Doses of Fasinumab May Improve Chronic Low Back Pain in Patients With Inadequately Controlled Pain

A posterior view of a male torso revealing the skeletal and nerve structures of the back.
Fasinumab, a fully human monoclonal antibody, may offer relief for people with chronic low back pain that has not responded to treatment.

Fasinumab at doses of 9 mg was associated with improvements in chronic low back pain and function in patients with inadequate pain control, but lower doses of the fully human monoclonal antibody offered less benefit, according to a study in Annals of the Rheumatic Diseases.

This phase 2/3, double-blind, placebo-controlled study included patients with chronic low back pain with inadequate pain relief or intolerance to acetaminophen, nonsteroidal anti-inflammatory drugs, and opioids. Patients were randomly assigned to fasinumab at 6 mg (n=141) or 9 mg (n=140) subcutaneously every 4 weeks or 9 mg intravenously (IV) every 8 weeks (n=141), or to placebo (n=141).

The primary end point of the study was the change from baseline to week 16 in the mean daily low back pain intensity (LBPI) numeric rating score. Additional secondary efficacy endpoints included the Roland-Morris Disability Questionnaire (RMDQ) and Patient Global Assessment (PGA).

Study investigators observed significantly greater LBPI reductions by week 16 for 9 mg fasinumab every 4 weeks and every 8 weeks compared with placebo (least squares mean [standard error], −0.7 [0.3]; both nominal P <.05). No significant reduction in LBPI was observed with the 6-mg dose compared with placebo (least squares mean, –0.3 [0.3]; P =.39).

All fasinumab doses were associated with reductions in LBPI scores vs placebo at week 8 (6 mg subcutaneous: least square mean, –0.5 [0.3], nominal P =.04; 9 mg subcutaneous every 4 weeks, –1.1 [0.3], nominal P <.01; 9 mg IV every 8 weeks, –1.0 [0.3], nominal P <.01).

The changes in RMDQ at week 16 ranged between –2.2 and –2.5 across fasinumab groups compared with placebo (all nominal P <.01). In addition, the placebo-adjusted changes in PGA at week 16 were between –0.1 and –0.3 and reached significance only for 9-mg fasinumab IV (nominal P =.01).

Approximately 65.6% of patients who received fasinumab and 67.1% of patients who received placebo experienced a treatment-emergent adverse event. Joint adverse events, including rapid progressive osteoarthritis type 1, were more frequently reported in the combined fasinumab arms than in the placebo group (3.8% vs 0.7%).

A limitation of the study was its early termination due to an FDA hold, leading to an incomplete cohort of participants receiving all planned study drug doses.

Pending findings from larger and more complete studies, the researchers suggest fasinumab could be considered “a possible new treatment option for patients with [chronic low back pain] with inadequate pain control, or who are intolerant to or have a contraindication for existing therapies.”

Disclosure: This clinical trial was supported by Regeneron Pharmaceuticals and Teva Pharmaceutical Industries. Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.


Dakin P, Kivitz AJ, Gimbel JS, et al. Efficacy and safety of fasinumab in patients with chronic low back pain: a phase II/III randomised clinical trial. Published online November 16, 2020. Ann Rheum Dis. doi: 10.1136/annrheumdis-2020-217259